A comparison of three fiber tract delineation methods and their impact on white matter analysis.

PubMed

Sydnor, Valerie J; Rivas-Grajales, Ana María; Lyall, Amanda E; Zhang, Fan; Bouix, Sylvain; Karmacharya, Sarina; Shenton, Martha E; Westin, Carl-Fredrik; Makris, Nikos; Wassermann, Demian; O'Donnell, Lauren J; Kubicki, Marek

2018-05-19

Diffusion magnetic resonance imaging (dMRI) is an important method for studying white matter connectivity in the brain in vivo in both healthy and clinical populations. Improvements in dMRI tractography algorithms, which reconstruct macroscopic three-dimensional white matter fiber pathways, have allowed for methodological advances in the study of white matter; however, insufficient attention has been paid to comparing post-tractography methods that extract white matter fiber tracts of interest from whole-brain tractography. Here we conduct a comparison of three representative and conceptually distinct approaches to fiber tract delineation: 1) a manual multiple region of interest-based approach, 2) an atlas-based approach, and 3) a groupwise fiber clustering approach, by employing methods that exemplify these approaches to delineate the arcuate fasciculus, the middle longitudinal fasciculus, and the uncinate fasciculus in 10 healthy male subjects. We enable qualitative comparisons across methods, conduct quantitative evaluations of tract volume, tract length, mean fractional anisotropy, and true positive and true negative rates, and report measures of intra-method and inter-method agreement. We discuss methodological similarities and differences between the three approaches and the major advantages and drawbacks of each, and review research and clinical contexts for which each method may be most apposite. Emphasis is given to the means by which different white matter fiber tract delineation approaches may systematically produce variable results, despite utilizing the same input tractography and reliance on similar anatomical knowledge. Copyright © 2018. Published by Elsevier Inc.

Effects of sensitivity to life stress on uncinate fasciculus segments in early adolescence

PubMed Central

King, Lucy S.; Leong, Josiah K.; Colich, Natalie L.; Humphreys, Kathryn L.; Ordaz, Sarah J.; Gotlib, Ian H.

2017-01-01

Abstract Previous research suggests that exposure to early life stress (ELS) affects the structural integrity of the uncinate fasciculus (UF), a frontolimbic white matter tract that undergoes protracted development throughout adolescence. Adolescence is an important transitional period characterized by the emergence of internalizing psychopathology such as anxiety, particularly in individuals with high levels of stress sensitivity. We examined the relations among sensitivity to ELS, structural integrity of the UF, and anxiety symptoms in 104 early adolescents. We conducted structured interviews to assess exposure to ELS and obtained subjective and objective ratings of stress severity, from which we derived an index of ELS sensitivity. We also acquired diffusion MRI and conducted deterministic tractography to visualize UF trajectories and to compute measures of structural integrity from three distinct segments of the UF: frontal, insular, temporal. We found that higher sensitivity to ELS predicted both reduced fractional anisotropy in right frontal UF and higher levels of anxiety symptoms. These findings suggest that fibers in frontal UF, which are still developing throughout adolescence, are most vulnerable to the effects of heightened sensitivity to ELS, and that reduced structural integrity of frontal UF may underlie the relation between early stress and subsequent internalizing psychopathology. PMID:28460088

Anterior Temporal Lobe Morphometry Predicts Categorization Ability.

PubMed

Garcin, Béatrice; Urbanski, Marika; Thiebaut de Schotten, Michel; Levy, Richard; Volle, Emmanuelle

2018-01-01

Categorization is the mental operation by which the brain classifies objects and events. It is classically assessed using semantic and non-semantic matching or sorting tasks. These tasks show a high variability in performance across healthy controls and the cerebral bases supporting this variability remain unknown. In this study we performed a voxel-based morphometry study to explore the relationships between semantic and shape categorization tasks and brain morphometric differences in 50 controls. We found significant correlation between categorization performance and the volume of the gray matter in the right anterior middle and inferior temporal gyri. Semantic categorization tasks were associated with more rostral temporal regions than shape categorization tasks. A significant relationship was also shown between white matter volume in the right temporal lobe and performance in the semantic tasks. Tractography revealed that this white matter region involved several projection and association fibers, including the arcuate fasciculus, inferior fronto-occipital fasciculus, uncinate fasciculus, and inferior longitudinal fasciculus. These results suggest that categorization abilities are supported by the anterior portion of the right temporal lobe and its interaction with other areas.

White matter correlates of cognitive domains in normal aging with diffusion tensor imaging.

PubMed

Sasson, Efrat; Doniger, Glen M; Pasternak, Ofer; Tarrasch, Ricardo; Assaf, Yaniv

2013-01-01

The ability to perform complex as well as simple cognitive tasks engages a network of brain regions that is mediated by the white matter fiber bundles connecting them. Different cognitive tasks employ distinctive white matter fiber bundles. The temporal lobe and its projections subserve a variety of key functions known to deteriorate during aging. In a cohort of 52 healthy subjects (ages 25-82 years), we performed voxel-wise regression analysis correlating performance in higher-order cognitive domains (executive function, information processing speed, and memory) with white matter integrity, as measured by diffusion tensor imaging (DTI) fiber tracking in the temporal lobe projections [uncinate fasciculus (UF), fornix, cingulum, inferior longitudinal fasciculus (ILF), and superior longitudinal fasciculus (SLF)]. The fiber tracts were spatially registered and statistical parametric maps were produced to spatially localize the significant correlations. Results showed that performance in the executive function domain is correlated with DTI parameters in the left SLF and right UF; performance in the information processing speed domain is correlated with fractional anisotropy (FA) in the left cingulum, left fornix, right and left ILF and SLF; and the memory domain shows significant correlations with DTI parameters in the right fornix, right cingulum, left ILF, left SLF and right UF. These findings suggest that DTI tractography enables anatomical definition of region of interest (ROI) for correlation of behavioral parameters with diffusion indices, and functionality can be correlated with white matter integrity.

Cortico-Cortical, Cortico-Striatal, and Cortico-Thalamic White Matter Fiber Tracts Generated in the Macaque Brain via Dynamic Programming

PubMed Central

Lal, Rakesh M.; An, Michael; Poynton, Clare B.; Li, Muwei; Jiang, Hangyi; Oishi, Kenichi; Selemon, Lynn D.; Mori, Susumu; Miller, Michael I.

2013-01-01

Abstract Probabilistic methods have the potential to generate multiple and complex white matter fiber tracts in diffusion tensor imaging (DTI). Here, a method based on dynamic programming (DP) is introduced to reconstruct fibers pathways whose complex anatomical structures cannot be resolved beyond the resolution of standard DTI data. DP is based on optimizing a sequentially additive cost function derived from a Gaussian diffusion model whose covariance is defined by the diffusion tensor. DP is used to determine the optimal path between initial and terminal nodes by efficiently searching over all paths, connecting the nodes, and choosing the path in which the total probability is maximized. An ex vivo high-resolution scan of a macaque hemi-brain is used to demonstrate the advantages and limitations of DP. DP can generate fiber bundles between distant cortical areas (superior longitudinal fasciculi, arcuate fasciculus, uncinate fasciculus, and fronto-occipital fasciculus), neighboring cortical areas (dorsal and ventral banks of the principal sulcus), as well as cortical projections to the hippocampal formation (cingulum bundle), neostriatum (motor cortical projections to the putamen), thalamus (subcortical bundle), and hippocampal formation projections to the mammillary bodies via the fornix. Validation is established either by comparison with in vivo intracellular transport of horseradish peroxidase in another macaque monkey or by comparison with atlases. DP is able to generate known pathways, including crossing and kissing tracts. Thus, DP has the potential to enhance neuroimaging studies of cortical connectivity. PMID:23879573

Preliminary evidence of white matter abnormality in the uncinate fasciculus in generalized social anxiety disorder.

PubMed

Phan, K Luan; Orlichenko, Anton; Boyd, Erin; Angstadt, Mike; Coccaro, Emil F; Liberzon, Israel; Arfanakis, Konstantinos

2009-10-01

Individuals with generalized social anxiety disorder (GSAD) exhibit exaggerated amygdala reactivity to aversive social stimuli. These findings could be explained by microstructural abnormalities in white matter (WM) tracts that connect the amygdala and prefrontal cortex, which is known to modulate the amygdala's response to threat. The goal of this study was to investigate brain frontal WM abnormalities using diffusion tensor imaging (DTI) in patients with social anxiety disorder. A Turboprop DTI sequence was used to acquire diffusion tensor images in 30 patients with GSAD and 30 matched healthy control subjects. Fractional anisotropy, an index of axonal organization, within WM was quantified in individual subjects, and an automated voxel-based, whole-brain method was used to analyze group differences. Compared with healthy control subjects, patients had significantly lower fractional anisotropy localized to the right uncinate fasciculus WM near the orbitofrontal cortex. There were no areas of higher fractional anisotropy in patients than controls. These findings point to an abnormality in the uncinate fasciculus, the major WM tract connecting the frontal cortex to the amygdala and other limbic temporal regions, in GSAD, which could underlie the aberrant amygdala-prefrontal interactions resulting in dysfunctional social threat processing in this illness.

White matter tracts associated with set-shifting in healthy aging.

PubMed

Perry, Michele E; McDonald, Carrie R; Hagler, Donald J; Gharapetian, Lusineh; Kuperman, Joshua M; Koyama, Alain K; Dale, Anders M; McEvoy, Linda K

2009-11-01

Attentional set-shifting ability, commonly assessed with the Trail Making Test (TMT), decreases with increasing age in adults. Since set-shifting performance relies on activity in widespread brain regions, deterioration of the white matter tracts that connect these regions may underlie the age-related decrease in performance. We used an automated fiber tracking method to investigate the relationship between white matter integrity in several cortical association tracts and TMT performance in a sample of 24 healthy adults, 21-80 years. Diffusion tensor images were used to compute average fractional anisotropy (FA) for five cortical association tracts, the corpus callosum (CC), and the corticospinal tract (CST), which served as a control. Results showed that advancing age was associated with declines in set-shifting performance and with decreased FA in the CC and in association tracts that connect frontal cortex to more posterior brain regions, including the inferior fronto-occipital fasciculus (IFOF), uncinate fasciculus (UF), and superior longitudinal fasciculus (SLF). Declines in average FA in these tracts, and in average FA of the right inferior longitudinal fasciculus (ILF), were associated with increased time to completion on the set-shifting subtask of the TMT but not with the simple sequencing subtask. FA values in these tracts were strong mediators of the effect of age on set-shifting performance. Automated tractography methods can enhance our understanding of the fiber systems involved in performance of specific cognitive tasks and of the functional consequences of age-related changes in those systems.

Enhanced Brain Connectivity in Long-term Meditation Practitioners

PubMed Central

Luders, Eileen; Clark, Kristi; Narr, Katherine L.; Toga, Arthur W.

2011-01-01

Very little is currently known about the cerebral characteristics that underlie the complex processes of meditation as only a limited number of studies have addressed this topic. Research exploring structural connectivity in meditation practitioners is particularly rare. We thus acquired diffusion tensor imaging (DTI) data of high angular and spatial resolution and used atlas-based tract mapping methods to investigate white matter fiber characteristics in a well-matched sample of long-term meditators and controls (n=54). A broad field mapping approach estimated the fractional anisotropy (FA) for twenty different fiber tracts (i.e., nine tracts in each hemisphere and two inter-hemispheric tracts) that were subsequently used as dependent measures. Results showed pronounced structural connectivity in meditators compared to controls throughout the entire brain within major projection pathways, commissural pathways, and association pathways. The largest group differences were observed within the corticospinal tract, the temporal component of the superior longitudinal fasciculus, and the uncinate fasciculus. While cross-sectional studies represent a good starting point for elucidating possible links between meditation and white matter fiber characteristics, longitudinal studies will be necessary to determine the relative contribution of nature and nurture to enhanced structural connectivity in long-term meditators. PMID:21664467

Structural white matter asymmetries in relation to functional asymmetries during speech perception and production.

PubMed

Ocklenburg, Sebastian; Hugdahl, Kenneth; Westerhausen, René

2013-12-01

Functional hemispheric asymmetries of speech production and perception are a key feature of the human language system, but their neurophysiological basis is still poorly understood. Using a combined fMRI and tract-based spatial statistics approach, we investigated the relation of microstructural asymmetries in language-relevant white matter pathways and functional activation asymmetries during silent verb generation and passive listening to spoken words. Tract-based spatial statistics revealed several leftward asymmetric clusters in the arcuate fasciculus and uncinate fasciculus that were differentially related to activation asymmetries in the two functional tasks. Frontal and temporal activation asymmetries during silent verb generation were positively related to the strength of specific microstructural white matter asymmetries in the arcuate fasciculus. In contrast, microstructural uncinate fasciculus asymmetries were related to temporal activation asymmetries during passive listening. These findings suggest that white matter asymmetries may indeed be one of the factors underlying functional hemispheric asymmetries. Moreover, they also show that specific localized white matter asymmetries might be of greater relevance for functional activation asymmetries than microstructural features of whole pathways. © 2013.

Preliminary Evidence of White Matter Abnormality in the Uncinate Fasciculus in Generalized Social Anxiety Disorder

PubMed Central

Phan, K. Luan; Orlichenko, Anton; Boyd, Erin; Angstadt, Mike; Coccaro, Emil F.; Liberzon, Israel; Arfanakis, Konstantinos

2009-01-01

Background Individuals with generalized social anxiety disorder (GSAD) exhibit exaggerated amygdala reactivity to aversive social stimuli. These findings could be explained by microstructural abnormalities in white matter (WM) tracts that connect the amygdala and prefrontal cortex, which is known to modulate the amygdala’s response to threat. The goal of this study was to investigate brain frontal WM abnormalities by using diffusion tensor imaging (DTI) in patients with social anxiety disorder. Method A Turboprop DTI sequence was used to acquire diffusion tensor images in thirty patients with GSAD and thirty matched healthy controls. Fractional anisotropy, an index of axonal organization, within WM was quantified in individual subjects and an automated voxel-based, whole-brain method was used to analyze group differences. Results Compared to healthy controls, patients had significantly lower fractional anisotropy localized to the right uncinate fasciculus WM near the orbitofrontal cortex. There were no areas of higher fractional anisotropy in patients than controls. Conclusions These findings point to an abnormality in the uncinate fasciculus, the major WM tract connecting the frontal cortex to the amygdala and other limbic temporal regions, in GSAD which could underlie the aberrant amygdala-prefrontal interactions resulting in dysfunctional social threat processing in this illness. PMID:19362707

DTI Tractography and White Matter Fiber Tract Characteristics in Euthymic Bipolar I Patients and Healthy Control Subjects

PubMed Central

Irimia, Andrei; Leow, Alex D.; Bartzokis, George; Moody, Teena D.; Jennings, Robin G.; Alger, Jeffry R.; Van Horn, John Darrell; Altshuler, Lori L.

2012-01-01

With the introduction of diffusion tensor imaging (DTI), structural differences in white matter (WM) architecture between psychiatric populations and healthy controls can be systematically observed and measured. In particular, DTI-tractography can be used to assess WM characteristics over the entire extent of WM tracts and aggregated fiber bundles. Using 64-direction DTI scanning in 27 participants with bipolar disorder (BD) and 26 age-and-gender-matched healthy control subjects, we compared relative length, density, and fractional anisotrophy (FA) of WM tracts involved in emotion regulation or theorized to be important neural components in BD neuropathology. We interactively isolated 22 known white matter tracts using region-of-interest placement (TrackVis software program) and then computed relative tract length, density, and integrity. BD subjects demonstrated significantly shorter WM tracts in the genu, body and splenium of the corpus callosum compared to healthy controls. Additionally, bipolar subjects exhibited reduced fiber density in the genu and body of the corpus callosum, and in the inferior longitudinal fasciculus bilaterally. In the left uncinate fasciculus, however, BD subjects exhibited significantly greater fiber density than healthy controls. There were no significant differences between groups in WM tract FA for those tracts that began and ended in the brain. The significance of differences in tract length and fiber density in BD is discussed. PMID:23070746

Cortical Terminations of the Inferior Fronto-Occipital and Uncinate Fasciculi: Anatomical Stem-Based Virtual Dissection

PubMed Central

Hau, Janice; Sarubbo, Silvio; Perchey, Guy; Crivello, Fabrice; Zago, Laure; Mellet, Emmanuel; Jobard, Gaël; Joliot, Marc; Mazoyer, Bernard M.; Tzourio-Mazoyer, Nathalie; Petit, Laurent

2016-01-01

We combined the neuroanatomists’ approach of defining a fascicle as all fibers passing through its compact stem with diffusion-weighted tractography to investigate the cortical terminations of two association tracts, the inferior fronto-occipital fasciculus (IFOF) and the uncinate fasciculus (UF), which have recently been implicated in the ventral language circuitry. The aim was to provide a detailed and quantitative description of their terminations in 60 healthy subjects and to do so to apply an anatomical stem-based virtual dissection, mimicking classical post-mortem dissection, to extract with minimal a priori the IFOF and UF from tractography datasets. In both tracts, we consistently observed more extensive termination territories than their conventional definitions, within the middle and superior frontal, superior parietal and angular gyri for the IFOF and the middle frontal gyrus and superior, middle and inferior temporal gyri beyond the temporal pole for the UF. We revealed new insights regarding the internal organization of these tracts by investigating for the first time the frequency, distribution and hemispheric asymmetry of their terminations. Interestingly, we observed a dissociation between the lateral right-lateralized and medial left-lateralized fronto-occipital branches of the IFOF. In the UF, we observed a rightward lateralization of the orbito-frontal and temporal branches. We revealed a more detailed map of the terminations of these fiber pathways that will enable greater specificity for correlating with diseased populations and other behavioral measures. The limitations of the diffusion tensor model in this study are also discussed. We conclude that anatomical stem-based virtual dissection with diffusion tractography is a fruitful method for studying the structural anatomy of the human white matter pathways. PMID:27252628

Elevated left and reduced right orbitomedial prefrontal fractional anisotropy in adults with bipolar disorder revealed by tract-based spatial statistics.

PubMed

Versace, Amelia; Almeida, Jorge R C; Hassel, Stefanie; Walsh, Nicholas D; Novelli, Massimiliano; Klein, Crystal R; Kupfer, David J; Phillips, Mary L

2008-09-01

Diffusion tensor imaging (DTI) studies in adults with bipolar disorder (BD) indicate altered white matter (WM) in the orbitomedial prefrontal cortex (OMPFC), potentially underlying abnormal prefrontal corticolimbic connectivity and mood dysregulation in BD. To use tract-based spatial statistics (TBSS) to examine WM skeleton (ie, the most compact whole-brain WM) in subjects with BD vs healthy control subjects. Cross-sectional, case-control, whole-brain DTI using TBSS. University research institute. Fifty-six individuals, 31 having a DSM-IV diagnosis of BD type I (mean age, 35.9 years [age range, 24-52 years]) and 25 controls (mean age, 29.5 years [age range, 19-52 years]). Fractional anisotropy (FA) longitudinal and radial diffusivities in subjects with BD vs controls (covarying for age) and their relationships with clinical and demographic variables. Subjects with BD vs controls had significantly greater FA (t > 3.0, P 3.0, P

Trait conscientiousness and the personality meta-trait stability are associated with regional white matter microstructure.

PubMed

Lewis, Gary J; Cox, Simon R; Booth, Tom; Muñoz Maniega, Susana; Royle, Natalie A; Valdés Hernández, Maria; Wardlaw, Joanna M; Bastin, Mark E; Deary, Ian J

2016-08-01

Establishing the neural bases of individual differences in personality has been an enduring topic of interest. However, while a growing literature has sought to characterize grey matter correlates of personality traits, little attention to date has been focused on regional white matter correlates of personality, especially for the personality traits agreeableness, conscientiousness and openness. To rectify this gap in knowledge we used a large sample (n > 550) of older adults who provided data on both personality (International Personality Item Pool) and white matter tract-specific fractional anisotropy (FA) from diffusion tensor MRI. Results indicated that conscientiousness was associated with greater FA in the left uncinate fasciculus (β = 0.17, P < 0.001). We also examined links between FA and the personality meta-trait 'stability', which is defined as the common variance underlying agreeableness, conscientiousness, and neuroticism/emotional stability. We observed an association between left uncinate fasciculus FA and stability (β = 0.27, P < 0.001), which fully accounted for the link between left uncinate fasciculus FA and conscientiousness. In sum, these results provide novel evidence for links between regional white matter microstructure and key traits of human personality, specifically conscientiousness and the meta-trait, stability. Future research is recommended to replicate and address the causal directions of these associations. © The Author (2016). Published by Oxford University Press.

The neural circuitry of visual artistic production and appreciation: A proposition.

PubMed

Chakravarty, Ambar

2012-04-01

The nondominant inferior parietal lobule is probably a major "store house" of artistic creativity. The ventromedial prefrontal lobe (VMPFL) is supposed to be involved in creative cognition and the dorsolateral prefrontal lobe (DLPFL) in creative output. The conceptual ventral and dorsal visual system pathways likely represent the inferior and superior longitudinal fasciculi. During artistic production, conceptualization is conceived in the VMPFL and the executive part is operated through the DLFPL. The latter transfers the concept to the visual brain through the superior longitudinal fasciculus (SLF), relaying on its path to the parietal cortex. The conceptualization at VMPFL is influenced by activity from the anterior temporal lobe through the uncinate fasciculus and limbic system pathways. The final visual image formed in the visual brain is subsequently transferred back to the DLPFL through the SLF and then handed over to the motor cortex for execution. During art appreciation, the image at the visual brain is transferred to the frontal lobe through the SLF and there it is matched with emotional and memory inputs from the anterior temporal lobe transmitted through the uncinate fasiculus. Beauty is perceived at the VMPFL and transferred through the uncinate fasciculus to the hippocampo-amygdaloid complex in the anterior temporal lobe. The limbic system (Papez circuit) is activated and emotion of appreciation is evoked. It is postulated that in practice the entire circuitry is activated simultaneously.

The neural circuitry of visual artistic production and appreciation: A proposition

PubMed Central

Chakravarty, Ambar

2012-01-01

The nondominant inferior parietal lobule is probably a major “store house” of artistic creativity. The ventromedial prefrontal lobe (VMPFL) is supposed to be involved in creative cognition and the dorsolateral prefrontal lobe (DLPFL) in creative output. The conceptual ventral and dorsal visual system pathways likely represent the inferior and superior longitudinal fasciculi. During artistic production, conceptualization is conceived in the VMPFL and the executive part is operated through the DLFPL. The latter transfers the concept to the visual brain through the superior longitudinal fasciculus (SLF), relaying on its path to the parietal cortex. The conceptualization at VMPFL is influenced by activity from the anterior temporal lobe through the uncinate fasciculus and limbic system pathways. The final visual image formed in the visual brain is subsequently transferred back to the DLPFL through the SLF and then handed over to the motor cortex for execution. During art appreciation, the image at the visual brain is transferred to the frontal lobe through the SLF and there it is matched with emotional and memory inputs from the anterior temporal lobe transmitted through the uncinate fasiculus. Beauty is perceived at the VMPFL and transferred through the uncinate fasciculus to the hippocampo–amygdaloid complex in the anterior temporal lobe. The limbic system (Papez circuit) is activated and emotion of appreciation is evoked. It is postulated that in practice the entire circuitry is activated simultaneously. PMID:22566716

The anatomy of extended limbic pathways in Asperger syndrome: a preliminary diffusion tensor imaging tractography study.

PubMed

Pugliese, Luca; Catani, Marco; Ameis, Stephanie; Dell'Acqua, Flavio; Thiebaut de Schotten, Michel; Murphy, Clodagh; Robertson, Dene; Deeley, Quinton; Daly, Eileen; Murphy, Declan G M

2009-08-15

It has been suggested that people with autistic spectrum disorder (ASD) have altered development (and connectivity) of limbic circuits. However, direct evidence of anatomical differences specific to white matter pathways underlying social behaviour and emotions in ASD is lacking. We used Diffusion Tensor Imaging Tractography to compare, in vivo, the microstructural integrity and age-related differences in the extended limbic pathways between subjects with Asperger syndrome and healthy controls. Twenty-four males with Asperger syndrome (mean age 23+/-12 years, age range: 9-54 years) and 42 age-matched male controls (mean age 25+/-10 years, age range: 9-54 years) were studied. We quantified tract-specific diffusivity measurements as indirect indexes of microstructural integrity (e.g. fractional anisotropy, FA; mean diffusivity, MD) and tract volume (e.g. number of streamlines) of the main limbic tracts. The dissected limbic pathways included the inferior longitudinal fasciculus, inferior frontal occipital fasciculus, uncinate, cingulum and fornix. There were no significant between-group differences in FA and MD. However, compared to healthy controls, individuals with Asperger syndrome had a significantly higher number of streamlines in the right (p=.003) and left (p=.03) cingulum, and in the right (p=.03) and left (p=.04) inferior longitudinal fasciculus. In contrast, people with Asperger syndrome had a significantly lower number of streamlines in the right uncinate (p=.02). Within each group there were significant age-related differences in MD and number of streamlines, but not FA. However, the only significant age-related between-group difference was in mean diffusivity of the left uncinate fasciculus (Z(obs)=2.05) (p=.02). Our preliminary findings suggest that people with Asperger syndrome have significant differences in the anatomy, and maturation, of some (but not all) limbic tracts.

Whole brain white matter connectivity analysis using machine learning: An application to autism.

PubMed

Zhang, Fan; Savadjiev, Peter; Cai, Weidong; Song, Yang; Rathi, Yogesh; Tunç, Birkan; Parker, Drew; Kapur, Tina; Schultz, Robert T; Makris, Nikos; Verma, Ragini; O'Donnell, Lauren J

2018-05-15

In this paper, we propose an automated white matter connectivity analysis method for machine learning classification and characterization of white matter abnormality via identification of discriminative fiber tracts. The proposed method uses diffusion MRI tractography and a data-driven approach to find fiber clusters corresponding to subdivisions of the white matter anatomy. Features extracted from each fiber cluster describe its diffusion properties and are used for machine learning. The method is demonstrated by application to a pediatric neuroimaging dataset from 149 individuals, including 70 children with autism spectrum disorder (ASD) and 79 typically developing controls (TDC). A classification accuracy of 78.33% is achieved in this cross-validation study. We investigate the discriminative diffusion features based on a two-tensor fiber tracking model. We observe that the mean fractional anisotropy from the second tensor (associated with crossing fibers) is most affected in ASD. We also find that local along-tract (central cores and endpoint regions) differences between ASD and TDC are helpful in differentiating the two groups. These altered diffusion properties in ASD are associated with multiple robustly discriminative fiber clusters, which belong to several major white matter tracts including the corpus callosum, arcuate fasciculus, uncinate fasciculus and aslant tract; and the white matter structures related to the cerebellum, brain stem, and ventral diencephalon. These discriminative fiber clusters, a small part of the whole brain tractography, represent the white matter connections that could be most affected in ASD. Our results indicate the potential of a machine learning pipeline based on white matter fiber clustering. Copyright © 2017 Elsevier Inc. All rights reserved.

Correlation between white matter damage and gray matter lesions in multiple sclerosis patients.

PubMed

Han, Xue-Mei; Tian, Hong-Ji; Han, Zheng; Zhang, Ce; Liu, Ying; Gu, Jie-Bing; Bakshi, Rohit; Cao, Xia

2017-05-01

We observed the characteristics of white matter fibers and gray matter in multiple sclerosis patients, to identify changes in diffusion tensor imaging fractional anisotropy values following white matter fiber injury. We analyzed the correlation between fractional anisotropy values and changes in whole-brain gray matter volume. The participants included 20 patients with relapsing-remitting multiple sclerosis and 20 healthy volunteers as controls. All subjects underwent head magnetic resonance imaging and diffusion tensor imaging. Our results revealed that fractional anisotropy values decreased and gray matter volumes were reduced in the genu and splenium of corpus callosum, left anterior thalamic radiation, hippocampus, uncinate fasciculus, right corticospinal tract, bilateral cingulate gyri, and inferior longitudinal fasciculus in multiple sclerosis patients. Gray matter volumes were significantly different between the two groups in the right frontal lobe (superior frontal, middle frontal, precentral, and orbital gyri), right parietal lobe (postcentral and inferior parietal gyri), right temporal lobe (caudate nucleus), right occipital lobe (middle occipital gyrus), right insula, right parahippocampal gyrus, and left cingulate gyrus. The voxel sizes of atrophic gray matter positively correlated with fractional anisotropy values in white matter association fibers in the patient group. These findings suggest that white matter fiber bundles are extensively injured in multiple sclerosis patients. The main areas of gray matter atrophy in multiple sclerosis are the frontal lobe, parietal lobe, caudate nucleus, parahippocampal gyrus, and cingulate gyrus. Gray matter atrophy is strongly associated with white matter injury in multiple sclerosis patients, particularly with injury to association fibers.

Callous-unemotional traits drive reduced white-matter integrity in youths with conduct problems.

PubMed

Breeden, A L; Cardinale, E M; Lozier, L M; VanMeter, J W; Marsh, A A

2015-10-01

Callous-unemotional (CU) traits represent a significant risk factor for severe and persistent conduct problems in children and adolescents. Extensive neuroimaging research links CU traits to structural and functional abnormalities in the amygdala and ventromedial prefrontal cortex. In addition, adults with psychopathy (a disorder for which CU traits are a developmental precursor) exhibit reduced integrity in uncinate fasciculus, a white-matter (WM) tract that connects prefrontal and temporal regions. However, research in adolescents has not yet yielded similarly consistent findings. We simultaneously modeled CU traits and externalizing behaviors as continuous traits, while controlling for age and IQ, in order to identify the unique relationship of each variable with WM microstructural integrity, assessed using diffusion tensor imaging. We used tract-based spatial statistics to evaluate fractional anisotropy, an index of WM integrity, in uncinate fasciculus and stria terminalis in 47 youths aged 10-17 years, of whom 26 exhibited conduct problems and varying levels of CU traits. Whereas both CU traits and externalizing behaviors were negatively correlated with WM integrity in bilateral uncinate fasciculus and stria terminalis/fornix, simultaneously modeling both variables revealed that these effects were driven by CU traits; the severity of externalizing behavior was not related to WM integrity after controlling for CU traits. These results indicate that WM abnormalities similar to those observed in adult populations with psychopathy may emerge in late childhood or early adolescence, and may be critical to understanding the social and affective deficits observed in this population.

Clinical, cognitive, and behavioural correlates of white matter damage in progressive supranuclear palsy.

PubMed

Agosta, Federica; Galantucci, Sebastiano; Svetel, Marina; Lukić, Milica Ječmenica; Copetti, Massimiliano; Davidovic, Kristina; Tomić, Aleksandra; Spinelli, Edoardo G; Kostić, Vladimir S; Filippi, Massimo

2014-05-01

White matter (WM) tract alterations were assessed in patients with progressive supranuclear palsy (PSP) relative to healthy controls and patients with idiopathic Parkinson's disease (PD) to explore the relationship of WM tract damage with clinical disease severity, performance on cognitive tests, and apathy. 37 PSP patients, 41 PD patients, and 34 healthy controls underwent an MRI scan and clinical testing to evaluate physical disability, cognitive impairment, and apathy. In PSP, the contribution of WM tract damage to global disease severity and cognitive and behavioural disturbances was assessed using Random Forest analysis. Relative to controls, PSP patients showed diffusion tensor (DT) MRI abnormalities of the corpus callosum, superior cerebellar peduncle (SCP), cingulum and uncinate fasciculus bilaterally, and right inferior longitudinal fasciculus. Corpus callosum and SCP DT MRI measures distinguished PSP from PD patients with high accuracy (area under the curve ranging from 0.89 to 0.72). In PSP, DT MRI metrics of the corpus callosum and superior cerebellar peduncles were the best predictors of global disease severity scale scores. DT MRI metrics of the corpus callosum, right superior longitudinal and inferior longitudinal fasciculus, and left uncinate were the best predictors of executive dysfunction. In PSP, apathy severity was related to the damage to the corpus callosum, right superior longitudinal, and uncinate fasciculi. In conclusion, WM tract damage contributes to the motor, cognitive, and behavioural deficits in PSP. DT MRI offers markers for PSP diagnosis, assessment, and monitoring.

Diffusion-tensor imaging of major white matter tracts and their role in language processing in aphasia.

PubMed

Ivanova, Maria V; Isaev, Dmitry Yu; Dragoy, Olga V; Akinina, Yulia S; Petrushevskiy, Alexey G; Fedina, Oksana N; Shklovsky, Victor M; Dronkers, Nina F

2016-12-01

A growing literature is pointing towards the importance of white matter tracts in understanding the neural mechanisms of language processing, and determining the nature of language deficits and recovery patterns in aphasia. Measurements extracted from diffusion-weighted (DW) images provide comprehensive in vivo measures of local microstructural properties of fiber pathways. In the current study, we compared microstructural properties of major white matter tracts implicated in language processing in each hemisphere (these included arcuate fasciculus (AF), superior longitudinal fasciculus (SLF), inferior longitudinal fasciculus (ILF), inferior frontal-occipital fasciculus (IFOF), uncinate fasciculus (UF), and corpus callosum (CC), and corticospinal tract (CST) for control purposes) between individuals with aphasia and healthy controls and investigated the relationship between these neural indices and language deficits. Thirty-seven individuals with aphasia due to left hemisphere stroke and eleven age-matched controls were scanned using DW imaging sequences. Fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), axial diffusivity (AD) values for each major white matter tract were extracted from DW images using tract masks chosen from standardized atlases. Individuals with aphasia were also assessed with a standardized language test in Russian targeting comprehension and production at the word and sentence level. Individuals with aphasia had significantly lower FA values for left hemisphere tracts and significantly higher values of MD, RD and AD for both left and right hemisphere tracts compared to controls, all indicating profound impairment in tract integrity. Language comprehension was predominantly related to integrity of the left IFOF and left ILF, while language production was mainly related to integrity of the left AF. In addition, individual segments of these three tracts were differentially associated with language production and comprehension in aphasia. Our findings highlight the importance of fiber pathways in supporting different language functions and point to the importance of temporal tracts in language processing, in particular, comprehension. Copyright © 2016 Elsevier Ltd. All rights reserved.

Development of the uncinate fasciculus: Implications for theory and developmental disorders.

PubMed

Olson, Ingrid R; Von Der Heide, Rebecca J; Alm, Kylie H; Vyas, Govinda

2015-08-01

The uncinate fasciculus (UF) is a long-range white matter tract that connects limbic regions in the temporal lobe to the frontal lobe. The UF is one of the latest developing tracts, and continues maturing into the third decade of life. As such, individual differences in the maturational profile of the UF may serve to explain differences in behavior. Indeed, atypical macrostructure and microstructure of the UF have been reported in numerous studies of individuals with developmental and psychiatric disorders such as social deprivation and maltreatment, autism spectrum disorders, conduct disorder, risk taking, and substance abuse. The present review evaluates what we currently know about the UF's developmental trajectory and reviews the literature relating UF abnormalities to specific disorders. Additionally, we take a dimensional approach and critically examine symptoms and behavioral impairments that have been demonstrated to cluster with UF aberrations, in an effort to relate these impairments to our speculations regarding the functionality of the UF. We suggest that developmental disorders with core problems relating to memory retrieval, reward and valuation computation, and impulsive decision making may be linked to aberrations in uncinate microstructure. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Psychopathic traits modulate microstructural integrity of right uncinate fasciculus in a community population.

PubMed

Sobhani, Mona; Baker, Laura; Martins, Bradford; Tuvblad, Catherine; Aziz-Zadeh, Lisa

2015-01-01

Individuals with psychopathy possess emotional and behavioral abnormalities. Two neural regions, involved in behavioral control and emotion regulation, are often implicated: amygdala and ventromedial prefrontal cortex (VMPFC). Recently, in studies using adult criminal populations, reductions in microstructural integrity of the white matter connections (i.e., uncinate fasciculus (UF)) between these two neural regions have been discovered in criminals with psychopathy, supporting the notion of neural dysfunction in the amygdala-VMPFC circuit. Here, a young adult, community sample is used to assess whether psychopathic traits modulate microstructural integrity of UF, and whether this relationship is dependent upon levels of trait anxiety, which is sometimes used to distinguish subtypes of psychopathy. Results reveal a negative association between psychopathic traits and microstructural integrity of UF, supporting previous findings. However, no moderation of the relationship by trait anxiety was discovered. Findings provide further support for the notion of altered amygdala-VMPFC connectivity in association with higher psychopathic traits.

Relationship between white matter integrity and serum cortisol levels in drug-naive patients with major depressive disorder: diffusion tensor imaging study using tract-based spatial statistics.

PubMed

Liu, Xiaodan; Watanabe, Keita; Kakeda, Shingo; Yoshimura, Reiji; Abe, Osamu; Ide, Satoru; Hayashi, Kenji; Katsuki, Asuka; Umene-Nakano, Wakako; Watanabe, Rieko; Ueda, Issei; Nakamura, Jun; Korogi, Yukunori

2016-06-01

Higher daytime cortisol levels because of a hyperactive hypothalamic-pituitary-adrenal axis have been reported in patients with major depressive disorder (MDD). The elevated glucocorticoids inhibit the proliferation of the oligodendrocytes that are responsible for myelinating the axons of white matter fibre tracts. To evaluate the relationship between white matter integrity and serum cortisol levels during a first depressive episode in drug-naive patients with MDD (MDD group) using a tract-based spatial statistics (TBSS) method. The MDD group (n = 29) and a healthy control group (n = 47) underwent diffusion tensor imaging (DTI) scans and an analysis was conducted using TBSS. Morning blood samples were obtained from both groups for cortisol measurement. Compared with the controls, the MDD group had significantly reduced fractional anisotropy values (P<0.05, family-wise error (FWE)-corrected) in the inferior fronto-occipital fasciculus, uncinate fasciculus and anterior thalamic radiation. The fractional anisotropy values of the inferior fronto-occipital fasciculus, uncinate fasciculus and anterior thalamic radiation had significantly negative correlations with the serum cortisol levels in the MDD group (P<0.05, FWE-corrected). Our findings indicate that the elevated cortisol levels in the MDD group may injure the white matter integrity in the frontal-subcortical and frontal-limbic circuits. © The Royal College of Psychiatrists 2016.

Structural and Diffusion Property Alterations in Unaffected Siblings of Patients with Obsessive-Compulsive Disorder

PubMed Central

Shi, Changzheng; Miao, Guodong; Yang, Qiong; Gao, Wei; Wolff, Jason J.; Chan, Raymond C. K.; Shen, Dinggang

2014-01-01

Disrupted white matter integrity and abnormal cortical thickness are widely reported in the pathophysiology of obsessive-compulsive disorder (OCD). However, the relationship between alterations in white matter connectivity and cortical thickness in OCD is unclear. In addition, the heritability of this relationship is poorly understood. To investigate the relationship of white matter microstructure with cortical thickness, we measure fractional anisotropy (FA) of white matter in 30 OCD patients, 19 unaffected siblings and 30 matched healthy controls. Then, we take those regions of significantly altered FA in OCD patients compared with healthy controls to perform fiber tracking. Next, we calculate the fiber quantity in the same tracts. Lastly, we compare cortical thickness in the target regions of those tracts. Patients with OCD exhibited decreased FA in cingulum, arcuate fibers near the superior parietal lobule, inferior longitudinal fasciculus near the right superior temporal gyrus and uncinate fasciculus. Siblings showed reduced FA in arcuate fibers near the superior parietal lobule and anterior limb of internal capsule. Significant reductions in both fiber quantities and cortical thickness in OCD patients and their unaffected siblings were also observed in the projected brain areas when using the arcuate fibers near the left superior parietal lobule as the starting points. Reduced FA in the left superior parietal lobule was observed not only in patients with OCD but also in their unaffected siblings. Originated from the superior parietal lobule, the number of fibers was also found to be decreased and the corresponding cortical regions were thinner relative to controls. The linkage between disrupted white matter integrity and the abnormal cortical thickness may be a vulnerability marker for OCD. PMID:24489665

Three-Dimensional Anatomy of the White Matter Fibers of the Temporal Lobe: Surgical Implications.

PubMed

Pescatori, Lorenzo; Tropeano, Maria Pia; Manfreda, Andrea; Delfini, Roberto; Santoro, Antonio

2017-04-01

The aim of this work is to describe in detail the complex 3-dimensional organization of the white matter of the temporal lobe and discuss the surgical implications of the approaches to lesions located into the mesial temporal region and within the temporal horn and the atrium of the lateral ventricles. Sixteen human cerebral hemispheres fixed in a 10% formalin solution for at least 40 days were studied. After removal of the arachnoid membrane, the hemispheres were frozen at -15°C for at least 14 days, and the Klingler technique, which consists of the microscopic dissection and progressive identification of white matter fibers, was performed. The dissection allowed us to appreciate the topographical organization of the white matter of the temporal lobe identifying the most important association, projection, and commissural fasciculi. The dissection from the lateral side allowed the progressive visualization of the superior longitudinal fasciculus and its components, the extreme and external capsule, the uncinate fasciculus, the inferior fronto-occipital fasciculus, the anterior commissure, the internal capsule, and the optic radiations. The dissection was completed from the inferior and medial side for identification of the cingulum and the fornix. The complex 3-dimensional organization of the white matter substance of the temporal lobe is characterized by 2 main systems of boundaries: the sagittal stratum and the temporal stem. Their knowledge is essential for the appropriate treatment of pathologies localized in this region as demonstrated by the 2 clinical cases presented in this work. Copyright © 2017 Elsevier Inc. All rights reserved.

White matter properties associated with pre-reading skills in 6-year-old children born preterm and at term.

PubMed

Dodson, Cory K; Travis, Katherine E; Borchers, Lauren R; Marchman, Virginia A; Ben-Shachar, Michal; Feldman, Heidi M

2018-05-03

To assess associations between white matter properties and pre-reading skills (phonological awareness and receptive and expressive language) in children born preterm and at term at the onset of reading acquisition. Six-year-old children born preterm (n=36; gestational age 22-32wks) and at term (n=43) underwent diffusion magnetic resonance imaging and behavioural assessments. Tracts were selected a priori based on findings from a study of 6-year-old children born at term: the left-hemisphere arcuate fasciculus and superior longitudinal fasciculus, and right-hemisphere uncinate fasciculus. Using linear regression, we assessed associations between fractional anisotropy of tracts and phonological awareness and receptive and expressive language scores. We investigated whether associations were moderated by prematurity. Fractional anisotropy of the left-hemisphere arcuate fasciculus contributed unique variance to phonological awareness across birth groups. The association between fractional anisotropy of the right-hemisphere uncinate fasciculus and receptive and expressive language was significantly moderated by prematurity. A left-hemisphere tract was associated with phonological awareness in both birth groups. A right-hemisphere tract was associated with language only in the term group, suggesting that expressive and receptive language is mediated by different white matter pathways in 6-year-old children born preterm. These findings provide novel insights into similarities and differences of the neurobiology of pre-reading skills between children born preterm and at term at reading onset. White matter properties and pre-reading abilities were associated in children born preterm at the onset of reading. The neurobiology of phonological awareness was similar in children born preterm versus children born at term at 6 years. The neurobiology of language was different in children born preterm versus children born at term at 6 years. © 2018 Mac Keith Press.

Widespread reductions of white matter integrity in patients with long-term remission of Cushing's disease.

PubMed

van der Werff, Steven J A; Andela, Cornelie D; Nienke Pannekoek, J; Meijer, Onno C; van Buchem, Mark A; Rombouts, Serge A R B; van der Mast, Roos C; Biermasz, Nienke R; Pereira, Alberto M; van der Wee, Nic J A

2014-01-01

Hypercortisolism leads to various physical, psychological and cognitive symptoms, which may partly persist after the treatment of Cushing's disease. The aim of the present study was to investigate abnormalities in white matter integrity in patients with long-term remission of Cushing's disease, and their relation with psychological symptoms, cognitive impairment and clinical characteristics. In patients with long-term remission of Cushing's disease (n = 22) and matched healthy controls (n = 22) we examined fractional anisotropy (FA) values of white matter in a region-of-interest (ROI; bilateral cingulate cingulum, bilateral hippocampal cingulum, bilateral uncinate fasciculus and corpus callosum) and the whole brain, using 3 T diffusion tensor imaging (DTI) and a tract-based spatial statistics (TBSS) approach. Psychological and cognitive functioning were assessed with validated questionnaires and clinical severity was assessed using the Cushing's syndrome Severity Index. The ROI analysis showed FA reductions in all of the hypothesized regions, with the exception of the bilateral hippocampal cingulum, in patients when compared to controls. The exploratory whole brain analysis showed multiple regions with lower FA values throughout the brain. Patients reported more apathy (p = .003) and more depressive symptoms (p < .001), whereas depression symptom severity in the patient group was negatively associated with FA in the left uncinate fasciculus (p < 0.05). Post-hoc analyses showed increased radial and mean diffusivity in the patient group. Patients with a history of endogenous hypercortisolism in present remission show widespread changes of white matter integrity in the brain, with abnormalities in the integrity of the uncinate fasciculus being related to the severity of depressive symptoms, suggesting persistent structural effects of hypercortisolism.

Widespread reductions of white matter integrity in patients with long-term remission of Cushing's disease

PubMed Central

van der Werff, Steven J.A.; Andela, Cornelie D.; Nienke Pannekoek, J.; Meijer, Onno C.; van Buchem, Mark A.; Rombouts, Serge A.R.B.; van der Mast, Roos C.; Biermasz, Nienke R.; Pereira, Alberto M.; van der Wee, Nic J.A.

2014-01-01

Background Hypercortisolism leads to various physical, psychological and cognitive symptoms, which may partly persist after the treatment of Cushing's disease. The aim of the present study was to investigate abnormalities in white matter integrity in patients with long-term remission of Cushing's disease, and their relation with psychological symptoms, cognitive impairment and clinical characteristics. Methods In patients with long-term remission of Cushing's disease (n = 22) and matched healthy controls (n = 22) we examined fractional anisotropy (FA) values of white matter in a region-of-interest (ROI; bilateral cingulate cingulum, bilateral hippocampal cingulum, bilateral uncinate fasciculus and corpus callosum) and the whole brain, using 3 T diffusion tensor imaging (DTI) and a tract-based spatial statistics (TBSS) approach. Psychological and cognitive functioning were assessed with validated questionnaires and clinical severity was assessed using the Cushing's syndrome Severity Index. Results The ROI analysis showed FA reductions in all of the hypothesized regions, with the exception of the bilateral hippocampal cingulum, in patients when compared to controls. The exploratory whole brain analysis showed multiple regions with lower FA values throughout the brain. Patients reported more apathy (p = .003) and more depressive symptoms (p < .001), whereas depression symptom severity in the patient group was negatively associated with FA in the left uncinate fasciculus (p < 0.05). Post-hoc analyses showed increased radial and mean diffusivity in the patient group. Conclusion Patients with a history of endogenous hypercortisolism in present remission show widespread changes of white matter integrity in the brain, with abnormalities in the integrity of the uncinate fasciculus being related to the severity of depressive symptoms, suggesting persistent structural effects of hypercortisolism. PMID:24936417

Effectiveness of diffusion tensor imaging in differentiating early-stage subcortical ischemic vascular disease, Alzheimer's disease and normal ageing.

PubMed

Tu, Min-Chien; Lo, Chung-Ping; Huang, Ching-Feng; Hsu, Yen-Hsuan; Huang, Wen-Hui; Deng, Jie Fu; Lee, Yung-Chuan

2017-01-01

To describe and compare diffusion tensor imaging (DTI) parameters between patients with subcortical ischemic vascular disease (SIVD) and Alzheimer's disease (AD) diagnosed using structuralized neuropsychiatric assessments, and investigate potential neuronal substrates related to cognitive performance. Thirty-five patients with SIVD, 40 patients with AD, and 33 cognitively normal control (NC) subjects matched by age and education level were consecutively recruited and underwent cognitive function assessments and DTI examinations. Comparisons among these three subgroups with regards to cognitive performance and DTI parameters including fractional anisotropy (FA) and mean diffusivity (MD) values were performed. Partial correlation analysis after controlling for age and education was used to evaluate associations between cognitive performance and DTI parameters. With regards to cognitive performance, the patients with SIVD had lower total scores in frontal assessment battery (FAB) compared to those with AD (p < 0.05) in the context of comparable Mini-Mental Status Examination and Cognitive Abilities Screening Instrument scores. With regards to DTI parameters, there were more regions of significant differences in FA among these three subgroups compared with MD. Compared with NC group, the patients with SIVD had significant global reductions in FA (p < 0.001 ~ 0.05), while significant reductions in FA among the patients with AD were regionally confined within the left superior longitudinal fasciculus, genu and splenium of the corpus callosum, and bilateral forceps major, and the anterior thalamic radiation, uncinate fasciculus, and cingulum of the left side (p < 0.01 ~ 0.05). Analysis of FA values within the left forceps major, left anterior thalamic radiation, and genu of the corpus callosum revealed a 71.8% overall correct classification (p < 0.001) with sensitivity of 69.4%, specificity of 73.8%, positive predictive value of 69.4%, and negative predictive value of 73.8% in discriminating patients with SIVD from those with AD. In combined analysis of the patients with SIVD and AD (n = 75), the total FAB score was positively correlated with FA within the bilateral forceps minor, genu of the corpus callosum, left forceps major, left uncinate fasciculus, and right inferior longitudinal fasciculus (p = 0.001 ~ 0.038), and inversely correlated with MD within the right superior longitudinal fasciculus, genu and body of the corpus callosum, bilateral forceps minor, right uncinate fasciculus, and right inferior longitudinal fasciculus (p = 0.003 ~ 0.040). Our findings suggest the effectiveness of DTI measurements in distinguishing patients with early-stage AD from those with SIVD, with discernible changes in spatial distribution and magnitude of significance of the DTI parameters. Strategic FA assessments provided the most robust discriminative power to differentiate SIVD from AD, and FAB may serve as an additional cognitive marker. We also identified the neuronal substrates responsible for FAB performance.

Microstructural integrity of a pathway connecting the prefrontal cortex and amygdala moderates the association between cognitive reappraisal and negative emotions.

PubMed

d'Arbeloff, Tracy C; Kim, M Justin; Knodt, Annchen R; Radtke, Spenser R; Brigidi, Bartholomew D; Hariri, Ahmad R

2018-05-21

Cognitive reappraisal is a commonly used form of emotion regulation that utilizes frontal-executive control to reframe an approaching emotional event to moderate its potential psychological impact. Use of cognitive reappraisal has been associated with diminished experience of anxiety and depressive symptoms, as well as greater overall well-being. Using data from a study of 647 healthy young adults, we provide initial evidence that an association between typical use of cognitive reappraisal in daily life and the experience of anxiety and depressive symptoms is moderated by the microstructural integrity of the uncinate fasciculus, which provides a major anatomical link between the amygdala and prefrontal cortex. Our findings are consistent with the nature of top-down regulation of bottom-up negative emotions and suggest the uncinate fasciculus may be a useful target in the search for biomarkers predicting not only disorder risk but also response to psychotherapy utilizing cognitive reappraisal. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Interpersonal traits of psychopathy linked to reduced integrity of the uncinate fasciculus.

PubMed

Wolf, Richard C; Pujara, Maia S; Motzkin, Julian C; Newman, Joseph P; Kiehl, Kent A; Decety, Jean; Kosson, David S; Koenigs, Michael

2015-10-01

Psychopathy is a personality disorder characterized by callous lack of empathy, impulsive antisocial behavior, and criminal recidivism. Here, we performed the largest diffusion tensor imaging (DTI) study of incarcerated criminal offenders to date (N = 147) to determine whether psychopathy severity is linked to the microstructural integrity of major white matter tracts in the brain. Consistent with the results of previous studies in smaller samples, we found that psychopathy was associated with reduced fractional anisotropy in the right uncinate fasciculus (UF; the major white matter tract connecting ventral frontal and anterior temporal cortices). We found no such association in the left UF or in adjacent frontal or temporal white matter tracts. Moreover, the right UF finding was specifically related to the interpersonal features of psychopathy (glib superficial charm, grandiose sense of self-worth, pathological lying, manipulativeness), rather than the affective, antisocial, or lifestyle features. These results indicate a neural marker for this key dimension of psychopathic symptomatology. © 2015 Wiley Periodicals, Inc.

Tract specific analysis in patients with sickle cell disease

NASA Astrophysics Data System (ADS)

Chai, Yaqiong; Coloigner, Julie; Qu, Xiaoping; Choi, Soyoung; Bush, Adam; Borzage, Matt; Vu, Chau; Lepore, Natasha; Wood, John

2015-12-01

Sickle cell disease (SCD) is a hereditary blood disorder in which the oxygen-carrying hemoglobin molecule in red blood cells is abnormal. It affects numerous people in the world and leads to a shorter life span, pain, anemia, serious infections and neurocognitive decline. Tract-Specific Analysis (TSA) is a statistical method to evaluate white matter alterations due to neurocognitive diseases, using diffusion tensor magnetic resonance images. Here, for the first time, TSA is used to compare 11 major brain white matter (WM) tracts between SCD patients and age-matched healthy subjects. Alterations are found in the corpus callosum (CC), the cortico-spinal tract (CST), inferior fronto-occipital fasciculus (IFO), inferior longitudinal fasciculus (ILF), superior longitudinal fasciculus (SLF), and uncinated fasciculus (UNC). Based on previous studies on the neurocognitive functions of these tracts, the significant areas found in this paper might be related to several cognitive impairments and depression, both of which are observed in SCD patients.

White matter fiber compromise contributes differentially to attention and emotion processing impairment in alcoholism, HIV-infection, and their comorbidity.

PubMed

Schulte, T; Müller-Oehring, E M; Sullivan, E V; Pfefferbaum, A

2012-10-01

Alcoholism (ALC) and HIV-1 infection (HIV) each affects emotional and attentional processes and integrity of brain white matter fibers likely contributing to functional compromise. The highly prevalent ALC+HIV comorbidity may exacerbate compromise. We used diffusion tensor imaging (DTI) and an emotional Stroop Match-to-Sample task in 19 ALC, 16 HIV, 15 ALC+HIV, and 15 control participants to investigate whether disruption of fiber system integrity accounts for compromised attentional and emotional processing. The task required matching a cue color to that of an emotional word with faces appearing between the color cue and the Stroop word in half of the trials. Nonmatched cue-word color pairs assessed selective attention, and face-word pairs assessed emotion. Relative to controls, DTI-based fiber tracking revealed lower inferior longitudinal fasciculus (ilf) integrity in HIV and ALC+HIV and lower uncinate fasciculus (uf) integrity in all three patient groups. Controls exhibited Stroop effects to positive face-word emotion, and greater interference was related to greater callosal, cingulum and ilf integrity. By contrast, HIV showed greater interference from negative Stroop words during color-nonmatch trials, correlating with greater uf compromise. For face trials, ALC and ALC+HIV showed greater Stroop-word interference, correlating with lower cingulate and callosal integrity. Thus, in HIV, conflict resolution was diminished when challenging conditions usurped resources needed to manage interference from negative emotion and to disengage attention from wrongly cued colors (nonmatch). In ALC and ALC+HIV, poorer callosal integrity was related to enhanced emotional interference suggesting curtailed interhemispheric exchange needed between preferentially right-hemispheric emotion and left-hemispheric Stroop-word functions. Copyright © 2012 Elsevier Ltd. All rights reserved.

White matter alterations in temporal lobe epilepsy

NASA Astrophysics Data System (ADS)

Diniz, P. B.; Salmon, C. E.; Velasco, T. R.; Sakamoto, A. C.; Leite, J. P.; Santos, A. C.

2011-03-01

In This study, we used Fractional anisotropy (FA), mean diffusivity (D), parallel diffusivity (D//) and perpendicular diffusivity (D), to localize the regions where occur axonal lesion and demyelization. TBSS was applied to analyze the FA data. After, the regions with alteration were studied with D, D// and D maps. Patients exhibited widespread degradation of FA. With D, D// and D maps analysis we found alterations in corpus callosum, corticospinal tract, fornix, internal capsule, corona radiate, Sagittal stratum, cingulum, fronto-occipital fasciculus and uncinate fasciculus. Our results are consistent with the hypothesis that exist demyelization and axonal damage in patients with TLE.

The white matter structural network underlying human tool use and tool understanding.

PubMed

Bi, Yanchao; Han, Zaizhu; Zhong, Suyu; Ma, Yujun; Gong, Gaolang; Huang, Ruiwang; Song, Luping; Fang, Yuxing; He, Yong; Caramazza, Alfonso

2015-04-29

The ability to recognize, create, and use complex tools is a milestone in human evolution. Widely distributed brain regions in parietal, frontal, and temporal cortices have been implicated in using and understanding tools, but the roles of their anatomical connections in supporting tool use and tool conceptual behaviors are unclear. Using deterministic fiber tracking in healthy participants, we first examined how 14 cortical regions that are consistently activated by tool processing are connected by white matter (WM) tracts. The relationship between the integrity of each of the 33 obtained tracts and tool processing deficits across 86 brain-damaged patients was investigated. WM tract integrity was measured with both lesion percentage (structural imaging) and mean fractional anisotropy (FA) values (diffusion imaging). Behavioral abilities were assessed by a tool use task, a range of conceptual tasks, and control tasks. We found that three left hemisphere tracts connecting frontoparietal and intrafrontal areas overlapping with left superior longitudinal fasciculus are crucial for tool use such that larger lesion and lower mean FA values on these tracts were associated with more severe tool use deficits. These tracts and five additional left hemisphere tracts connecting frontal and temporal/parietal regions, mainly overlapping with left superior longitudinal fasciculus, inferior frontooccipital fasciculus, uncinate fasciculus, and anterior thalamic radiation, are crucial for tool concept processing. Largely consistent results were also obtained using voxel-based symptom mapping analyses. Our results revealed the WM structural networks that support the use and conceptual understanding of tools, providing evidence for the anatomical skeleton of the tool knowledge network. Copyright © 2015 the authors 0270-6474/15/356822-14$15.00/0.

White matter microstructure integrity in relation to reading proficiency☆.

PubMed

Nikki Arrington, C; Kulesz, Paulina A; Juranek, Jenifer; Cirino, Paul T; Fletcher, Jack M

2017-11-01

Components of reading proficiency such asaccuracy, fluency, and comprehension require the successful coordination of numerous, yet distinct, cortical regions. Underlying white matter tracts allow for communication among these regions. This study utilized unique residualized tract - based spatial statistics methodology to identify the relations of white matter microstructure integrity to three components of reading proficiency in 49 school - aged children with typically developing phonological decoding skills and 27 readers with poor decoders. Results indicated that measures of white matter integrity were differentially associated with components of reading proficiency. In both typical and poor decoders, reading comprehension correlated with measures of integrity of the right uncinate fasciculus; reading comprehension was also related to the left inferior longitudinal fasciculus in poor decoders. Also in poor decoders, word reading fluency was related to the right uncinate and left inferior fronto - occipital fasciculi. Word reading was unrelated to white matter integrity in either group. These findings expand our knowledge of the association between white matter integrity and different elements of reading proficiency. Copyright © 2017 Elsevier Inc. All rights reserved.

The effect of sex and handedness on white matter anisotropy: a diffusion tensor magnetic resonance imaging study.

PubMed

Powell, J L; Parkes, L; Kemp, G J; Sluming, V; Barrick, T R; García-Fiñana, M

2012-04-05

Diffusion tensor magnetic resonance imaging provides a way of assessing the asymmetry of white matter (WM) connectivity, the degree of anisotropic diffusion within a given voxel being a marker of coherently bundled myelinated fibers. Voxel-based statistical analysis was performed on fractional anisotropy (FA) images of 42 right- and 40 left-handers, to assess differences in underlying WM anisotropy and FA asymmetry across the whole brain. Right-handers show greater anisotropy than left-handers in the uncinate fasciculus (UF) within the limbic lobe, and WM underlying prefrontal cortex, medial and inferior frontal gyri. Significantly greater leftward FA asymmetry in cerebellum posterior lobe is seen in left- than right-handers, and males show significantly greater rightward (right-greater-than-left) FA asymmetry in regions of middle occipital lobe, medial temporal gyrus, and a region of the superior longitudinal fasciculus underlying the supramarginal gyrus. Leftward (left-greater-than-right) anisotropy is found in regions of the arcuate fasciculus (AF), UF, and WM underlying pars triangularis in both handedness groups, with right-handers alone showing additional leftward FA asymmetry along the length of the superior temporal gyrus. Overall results indicate that although both handedness groups show anisotropy in similar WM regions, greater anisotropy is observed in right-handers compared with left-handers. The largest differences in FA asymmetry are found between males and females, suggesting a greater effect of sex than handedness on FA asymmetry. Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

Neuroticism is linked to microstructural left-right asymmetry of fronto-limbic fibre tracts in adolescents with opposite effects in boys and girls.

PubMed

Madsen, Kathrine Skak; Jernigan, Terry L; Vestergaard, Martin; Mortensen, Erik Lykke; Baaré, William F C

2018-06-01

Neuroticism is a fundamental personality trait that reflects a tendency to experience heightened negative affect and susceptibility to stress. Negative emotionality has been associated with fronto-limbic brain structures and connecting fibre tracts. The major fibre tracts connecting the frontal and limbic brain regions are the cingulum bundle and uncinate fasciculus. We previously found that healthy adults with higher neuroticism scores had decreased left relative to right fractional anisotropy (FA) of the cingulum. Both cingulum and uncinate fasciculus FA increases throughout childhood and into early adulthood. Since adolescence is associated with an increased incidence of anxiety and mood disorders, for which neuroticism is a known risk factor, the question arises whether the association between neuroticism and fronto-limbic white matter microstructure asymmetry is already present in children and adolescents or whether such relationship emerges during this age period. To address this question, we assessed 72 typically-developing 10-to-15 year-olds with diffusion-weighted imaging on a 3 T magnetic resonance scanner. Neuroticism was assessed with the Junior Eysenck Personality Questionnaire. FA and parallel and perpendicular diffusivity measures were extracted for cingulum, uncinate fasciculus as well as the white matter underlying the ventromedial prefrontal cortex. Higher neuroticism scores were associated with decreased left relative to right cingulum FA in boys, while in girls, higher neuroticism scores were associated with increased left relative to right cingulum and ventromedial prefrontal white matter FA, indicating that there are sex differences in the neural correlates of neuroticism. Our findings suggest that the link between neuroticism and frontal-limbic white matter microstructure asymmetry likely predates early adolescence. Future studies need to elucidate the significance of the observed sex differences in the neural correlates of neuroticism. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Fronto-temporal white matter connectivity predicts reversal learning errors

PubMed Central

Alm, Kylie H.; Rolheiser, Tyler; Mohamed, Feroze B.; Olson, Ingrid R.

2015-01-01

Each day, we make hundreds of decisions. In some instances, these decisions are guided by our innate needs; in other instances they are guided by memory. Probabilistic reversal learning tasks exemplify the close relationship between decision making and memory, as subjects are exposed to repeated pairings of a stimulus choice with a reward or punishment outcome. After stimulus–outcome associations have been learned, the associated reward contingencies are reversed, and participants are not immediately aware of this reversal. Individual differences in the tendency to choose the previously rewarded stimulus reveal differences in the tendency to make poorly considered, inflexible choices. Lesion studies have strongly linked reversal learning performance to the functioning of the orbitofrontal cortex, the hippocampus, and in some instances, the amygdala. Here, we asked whether individual differences in the microstructure of the uncinate fasciculus, a white matter tract that connects anterior and medial temporal lobe regions to the orbitofrontal cortex, predict reversal learning performance. Diffusion tensor imaging and behavioral paradigms were used to examine this relationship in 33 healthy young adults. The results of tractography revealed a significant negative relationship between reversal learning performance and uncinate axial diffusivity, but no such relationship was demonstrated in a control tract, the inferior longitudinal fasciculus. Our findings suggest that the uncinate might serve to integrate associations stored in the anterior and medial temporal lobes with expectations about expected value based on feedback history, computed in the orbitofrontal cortex. PMID:26150776

Long-Term Cognitive and Behavioral Therapies, Combined with Augmentative Communication, Are Related to Uncinate Fasciculus Integrity in Autism

ERIC Educational Resources Information Center

Pardini, Matteo; Elia, Maurizio; Garaci, Francesco G.; Guida, Silvia; Coniglione, Filadelfo; Krueger, Frank; Benassi, Francesca; Gialloreti, Leonardo Emberti

2012-01-01

Recent evidence points to white-matter abnormalities as a key factor in autism physiopathology. Using Diffusion Tensor Imaging, we studied white-matter structural properties in a convenience sample of twenty-two subjects with low-functioning autism exposed to long-term augmentative and alternative communication, combined with sessions of cognitive…

Segregation of anterior temporal regions critical for retrieving names of unique and nonunique entities reflects underlying long-range connectivity

PubMed Central

Mehta, Sonya; Inoue, Kayo; Rudrauf, David; Damasio, Hanna; Tranel, Daniel; Grabowski, Thomas

2015-01-01

Lesion-deficit studies support the hypothesis that the left anterior temporal lobe (ATL) plays a critical role in retrieving names of concrete entities. They further suggest that different regions of the left ATL process different conceptual categories. Here we test the specificity of these relationships and whether the anatomical segregation is related to the underlying organization of white matter connections. We reanalyzed data from a previous lesion study of naming and recognition across five categories of concrete entities. In voxelwise logistic regressions of lesion-deficit associations, we formally incorporated measures of disconnection of long-range association fiber tracts (FTs) and covaried for recognition and non-category specific naming deficits. We also performed fiber tractwise analyses to assess whether damage to specific FTs was preferentially associated with category-selective naming deficits. Damage to the basolateral ATL was associated with naming deficits for both unique (famous faces) and non-unique entities, whereas the damage to the temporal pole was associated with naming deficits for unique entities only. This segregation pattern remained after accounting for comorbid recognition deficits or naming deficits in other categories. The tractwise analyses showed that damage to the uncinate fasciculus was associated with naming impairments for unique entities, while damage to the inferior longitudinal fasciculus was associated with naming impairments for non-unique entities. Covarying for FT transection in voxelwise analyses rendered the cortical association for unique entities more focal. These results are consistent with the partial segregation of brain system support for name retrieval of unique and non-unique entities at both the level of cortical components and underlying white matter fiber bundles. Our study reconciles theoretic accounts of the functional organization of the left ATL by revealing both category-related processing and semantic hub sectors. PMID:26707082

Highways of the emotional intellect: white matter microstructural correlates of an ability-based measure of emotional intelligence.

PubMed

Pisner, Derek A; Smith, Ryan; Alkozei, Anna; Klimova, Aleksandra; Killgore, William D S

2017-06-01

Individuals differ in their ability to understand emotional information and apply that understanding to make decisions and solve problems effectively - a construct known as Emotional Intelligence (EI). While considerable evidence supports the importance of EI in social and occupational functioning, the neural underpinnings of this capacity are relatively unexplored. We used Tract-Based Spatial Statistics (TBSS) to determine the white matter correlates of EI as measured by the ability-based Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT). Participants included 32 healthy adults (16 men; 16 women), aged 18-45 years. White matter integrity in key tracts was positively correlated with the Strategic Area branches of the MSCEIT (Understanding Emotions and Managing Emotions), but not the Experiential branches (Perceiving and Facilitating Emotions). Specifically, the Understanding Emotions branch was associated with greater fractional anisotropy (FA) within somatosensory and sensory-motor fiber bundles, particularly those of the left superior longitudinal fasciculus and corticospinal tract. Managing Emotions was associated with greater FA within frontal-affective association tracts including the anterior forceps and right uncinate fasciculus, along with frontal-parietal cingulum and interhemispheric corpus callosum tracts. These findings suggest that specific components of EI are directly related to the structural microarchitecture of major axonal pathways.

Verbal Memory Performance and Reduced Cortical Thickness of Brain Regions Along the Uncinate Fasciculus in Young Adult Cannabis Users

PubMed Central

Levar, Nina; Francis, Alan N.; Smith, Matthew J.; Ho, Wilson C.; Gilman, Jodi M.

2018-01-01

Abstract Introduction: Memory impairment is one of the most commonly reported effects of cannabis use, especially among those who initiate use earlier, perhaps due to the effects of delta-9- tetrahydrocannabinol on cannabinoid (CB1) receptors in the brain. Studies have increasingly investigated whether cannabis use is associated with impairments in verbal memory, and with alterations in brain structures underlying verbal memory. The uncinate fasciculus (UF), a long-range white matter tract, connects regions with densely localized CB1 receptors that are important in verbal memory. This study investigated the impact of cannabis use on UF structures and its association with memory performance in young adult cannabis users (CU) and non-using controls (CON). Materials and Methods: Nineteen CU and 22 CON completed a verbal memory task and a neuroimaging protocol, in which diffusion tensor imaging and structural scans were collected. We compared memory performance, diffusion and tractography measures of the UF, and cortical thickness of regions connected by the UF, between CU and CON. In regions showing a significant group effect, we also examined associations between verbal memory performance, cortical thickness, and age of onset of cannabis use. Results: Compared to non-users, CU had worse memory performance, decreased fiber bundle length in the UF, and decreased cortical thickness of brain regions along the UF such as the entorhinal cortex and fusiform gyrus. Verbal memory performance was significantly associated with age of onset of cannabis use, indicating that those who initiated cannabis use at an earlier age performed worse. Cortical thickness of the entorhinal cortex was significantly correlated with age of first use and memory performance. Conclusion: This study provides evidence that cannabis use, especially when initiated at a young age, may be associated with worse verbal memory and altered neural development along the UF. Reductions in cortical thickness in regions implicated in memory processes may underlie weaknesses in verbal memory performance. PMID:29607411

Comprehensive Investigation of White Matter Tracts in Professional Chess Players and Relation to Expertise: Region of Interest and DMRI Connectometry.

PubMed

Mayeli, Mahsa; Rahmani, Farzaneh; Aarabi, Mohammad Hadi

2018-01-01

Purpose: Expertise is the product of training. Few studies have used functional connectivity or conventional diffusometric methods to identify neural underpinnings of chess expertise. Diffusometric variables of white matter might reflect these adaptive changes, along with changes in structural connectivity, which is a sensitive measure of microstructural changes. Method: Diffusometric variables of 29 professional chess players and 29 age-sex matched controls were extracted for white matter regions based on John Hopkin's Mori white matter atlas and partially correlated against professional training time and level of chess proficiency. Diffusion MRI connectometry was implemented to identify changes in structural connectivity in professional players compared to novices. Result: Compared to novices, higher planar anisotropy (CP) was observed in inferior longitudinal fasciculus (ILF), superior longitudinal fasciculus (SLF) and cingulate gyrus, in professional chess players, which correlated with higher RPM score in this group. Higher fractional anisotropy (FA) was observed in ILF, uncinate fasciculus (UF) and hippocampus and correlated with better scores in Raven's progressive matrices (RPM) score and longer duration of chess training in professional players. Consistently, radial diffusivity in bilateral IFOF, bilateral ILF and bilateral SLF was inversely correlated with level of training in professional players. DMRI connectometry analysis identified increased connectivity in bilateral UF, bilateral IFOF, bilateral cingulum, and corpus callosum in chess player's compared to controls. Conclusion: Structural connectivity of major associational subcortical white matter fibers are increased in professional chess players. FA and CP of ILF, SLF and UF directly correlates with duration of professional training and RPM score, in professional chess players.

Comprehensive Investigation of White Matter Tracts in Professional Chess Players and Relation to Expertise: Region of Interest and DMRI Connectometry

PubMed Central

Mayeli, Mahsa; Rahmani, Farzaneh; Aarabi, Mohammad Hadi

2018-01-01

Purpose: Expertise is the product of training. Few studies have used functional connectivity or conventional diffusometric methods to identify neural underpinnings of chess expertise. Diffusometric variables of white matter might reflect these adaptive changes, along with changes in structural connectivity, which is a sensitive measure of microstructural changes. Method: Diffusometric variables of 29 professional chess players and 29 age-sex matched controls were extracted for white matter regions based on John Hopkin's Mori white matter atlas and partially correlated against professional training time and level of chess proficiency. Diffusion MRI connectometry was implemented to identify changes in structural connectivity in professional players compared to novices. Result: Compared to novices, higher planar anisotropy (CP) was observed in inferior longitudinal fasciculus (ILF), superior longitudinal fasciculus (SLF) and cingulate gyrus, in professional chess players, which correlated with higher RPM score in this group. Higher fractional anisotropy (FA) was observed in ILF, uncinate fasciculus (UF) and hippocampus and correlated with better scores in Raven's progressive matrices (RPM) score and longer duration of chess training in professional players. Consistently, radial diffusivity in bilateral IFOF, bilateral ILF and bilateral SLF was inversely correlated with level of training in professional players. DMRI connectometry analysis identified increased connectivity in bilateral UF, bilateral IFOF, bilateral cingulum, and corpus callosum in chess player's compared to controls. Conclusion: Structural connectivity of major associational subcortical white matter fibers are increased in professional chess players. FA and CP of ILF, SLF and UF directly correlates with duration of professional training and RPM score, in professional chess players. PMID:29773973

Variation in White Matter Connectivity Predicts the Ability to Remember Faces and Discriminate Their Emotions

PubMed Central

Unger, Ashley; Alm, Kylie H.; Collins, Jessica A.; O’Leary, Jacqueline M.; Olson, Ingrid R.

2017-01-01

Objective The extended face network contains clusters of neurons that perform distinct functions on facial stimuli. Regions in the posterior ventral visual stream appear to perform basic perceptual functions on faces, while more anterior regions, such as the ventral anterior temporal lobe and amygdala, function to link mnemonic and affective information to faces. Anterior and posterior regions are interconnected by a long-range white matter tracts however it is not known if variation in connectivity of these pathways explains cognitive performance. Methods Here, we used diffusion imaging and deterministic tractography in a cohort of 28 neurologically normal adults ages 18–28 to examine microstructural properties of visual fiber pathways and their relationship to certain mnemonic and affective functions involved in face processing. We investigated how inter-individual variability in two tracts, the inferior longitudinal fasciculus (ILF) and the inferior fronto-occipital fasciculus (IFOF), related to performance on tests of facial emotion recognition and face memory. Results Results revealed that microstructure of both tracts predicted variability in behavioral performance indexed by both tasks, suggesting that the ILF and IFOF play a role in facilitating our ability to discriminate emotional expressions in faces, as well as to remember unique faces. Variation in a control tract, the uncinate fasciculus, did not predict performance on these tasks. Conclusions These results corroborate and extend the findings of previous neuropsychology studies investigating the effects of damage to the ILF and IFOF, and demonstrate that differences in face processing abilities are related to white matter microstructure, even in healthy individuals. PMID:26888615

Monkey to human comparative anatomy of the frontal lobe association tracts.

PubMed

Thiebaut de Schotten, Michel; Dell'Acqua, Flavio; Valabregue, Romain; Catani, Marco

2012-01-01

The greater expansion of the frontal lobes along the phylogeny scale has been interpreted as the signature of evolutionary changes underlying higher cognitive abilities in humans functions in humans. However, it is unknown how an increase in number of gyri, sulci and cortical areas in the frontal lobe have coincided with a parallel increase in connectivity. Here, using advanced tractography based on spherical deconvolution, we produced an atlas of human frontal association connections that we compared with axonal tracing studies of the monkey brain. We report several similarities between human and monkey in the cingulum, uncinate, superior longitudinal fasciculus, frontal aslant tract and orbito-polar tract. These similarities suggest to preserved functions across anthropoids. In addition, we found major differences in the arcuate fasciculus and the inferior fronto-occipital fasciculus. These differences indicate possible evolutionary changes in the connectional anatomy of the frontal lobes underlying unique human abilities. Copyright © 2011 Elsevier Srl. All rights reserved.

Diminution of context association memory structure in subjects with subjective cognitive decline.

PubMed

Fan, Ling-Yun; Lai, Ya-Mei; Chen, Ta-Fu; Hsu, Yung-Chin; Chen, Pin-Yu; Huang, Kuo-Zhou; Cheng, Ting-Wen; Tseng, Wen-Yi Isaac; Hua, Mau-Sun; Chen, Ya-Fang; Chiu, Ming-Jang

2018-06-01

Alzheimer's disease (AD) progresses insidiously from the preclinical stage to dementia. While people with subjective cognitive decline (SCD) have normal cognitive performance, some may be in the preclinical stage of AD. Neurofibrillary tangles appear first in the transentorhinal cortex, followed by the entorhinal cortex in the clinically silent stage of AD. We expected the earliest changes in subjects with SCD to occur in medial temporal subfields other than the hippocampal proper. These selective structural changes would affect specific memory subcomponents. We used the Family Picture subtest of the Wechsler Memory Scale-III, which was modified to separately compute character, activity, and location subscores for episodic memory subcomponents. We recruited 43 subjects with SCD, 44 subjects with amnesic mild cognitive impairment, and 34 normal controls. MRI was used to assess cortical thickness, subcortical gray matter volume, and fractional anisotropy. The results demonstrated that SCD subjects showed significant cortical atrophy in their bilateral parahippocampus and perirhinal and the left entorhinal cortices but not in their hippocampal regions. SCD subjects also exhibited significantly decreased mean fractional anisotropy in their bilateral uncinate fasciculi. The diminution of cortical thickness over the mesial temporal subfields corresponded to brain areas with early tangle deposition, and early degradation of the uncinate fasciculus was in accordance with the retrogenesis hypothesis. The parahippocampus and perirhinal cortex contribute mainly to context association memory while the entorhinal cortex, along with the uncinate fasciculus, contributes to content-related contextual memory. We proposed that context association and related memory structures are vulnerable in the SCD stage. © 2018 Wiley Periodicals, Inc.

Disconnection mechanism and regional cortical atrophy contribute to impaired processing of facial expressions and theory of mind in multiple sclerosis: a structural MRI study.

PubMed

Mike, Andrea; Strammer, Erzsebet; Aradi, Mihaly; Orsi, Gergely; Perlaki, Gabor; Hajnal, Andras; Sandor, Janos; Banati, Miklos; Illes, Eniko; Zaitsev, Alexander; Herold, Robert; Guttmann, Charles R G; Illes, Zsolt

2013-01-01

Successful socialization requires the ability of understanding of others' mental states. This ability called as mentalization (Theory of Mind) may become deficient and contribute to everyday life difficulties in multiple sclerosis. We aimed to explore the impact of brain pathology on mentalization performance in multiple sclerosis. Mentalization performance of 49 patients with multiple sclerosis was compared to 24 age- and gender matched healthy controls. T1- and T2-weighted three-dimensional brain MRI images were acquired at 3Tesla from patients with multiple sclerosis and 18 gender- and age matched healthy controls. We assessed overall brain cortical thickness in patients with multiple sclerosis and the scanned healthy controls, and measured the total and regional T1 and T2 white matter lesion volumes in patients with multiple sclerosis. Performances in tests of recognition of mental states and emotions from facial expressions and eye gazes correlated with both total T1-lesion load and regional T1-lesion load of association fiber tracts interconnecting cortical regions related to visual and emotion processing (genu and splenium of corpus callosum, right inferior longitudinal fasciculus, right inferior fronto-occipital fasciculus, uncinate fasciculus). Both of these tests showed correlations with specific cortical areas involved in emotion recognition from facial expressions (right and left fusiform face area, frontal eye filed), processing of emotions (right entorhinal cortex) and socially relevant information (left temporal pole). Thus, both disconnection mechanism due to white matter lesions and cortical thinning of specific brain areas may result in cognitive deficit in multiple sclerosis affecting emotion and mental state processing from facial expressions and contributing to everyday and social life difficulties of these patients.

White matter tracts in first-episode psychosis: A DTI tractography study of the uncinate fasciculus

PubMed Central

Price, Gary; Cercignani, Mara; Parker, Geoffrey J.M.; Altmann, Daniel R.; Barnes, Thomas R.E.; Barker, Gareth J.; Joyce, Eileen M.; Ron, Maria A.

2008-01-01

A model of disconnectivity involving abnormalities in the cortex and connecting white matter pathways may explain the symptoms and cognitive abnormalities of schizophrenia. Recently, diffusion imaging tractography has made it possible to study white matter pathways in detail, and we present here a study of patients with first-episode psychosis using this technique. We studied the uncinate fasciculus (UF), the largest white matter tract that connects the frontal and temporal lobes, two brain regions significantly implicated in schizophrenia. Nineteen patients with first-episode schizophrenia and 23 controls were studied using a probabilistic tractography algorithm (PICo). Fractional anisotropy (FA) and probability of connection were obtained for every voxel in the tract, and the group means and distributions of these variables were compared. The spread of the FA distribution in the upper tail, as measured by the squared coefficient of variance (SCV), was reduced in the left UF in the patient group, indicating that the number of voxels with high FA values was reduced in the core of the tract and suggesting the presence of changes in fibre alignment and tract coherence in the patient group. The SCV of FA was lower in females across both groups and there was no correlation between the SCV of FA and clinical ratings. PMID:17988894

Heritability of the limbic networks

PubMed Central

Kawadler, Jamie M.; Dell'Acqua, Flavio; Rijsdijk, Frühling V.; Kane, Fergus; Picchioni, Marco; McGuire, Philip; Toulopoulou, Timothea; Georgiades, Anna; Kalidindi, Sridevi; Kravariti, Eugenia; Murray, Robin M.; Murphy, Declan G.; Craig, Michael C.; Catani, Marco

2016-01-01

Individual differences in cognitive ability and social behaviour are influenced by the variability in the structure and function of the limbic system. A strong heritability of the limbic cortex has been previously reported, but little is known about how genetic factors influence specific limbic networks. We used diffusion tensor imaging tractography to investigate heritability of different limbic tracts in 52 monozygotic and 34 dizygotic healthy adult twins. We explored the connections that contribute to the activity of three distinct functional limbic networks, namely the dorsal cingulum (‘medial default-mode network’), the ventral cingulum and the fornix (‘hippocampal-diencephalic-retrosplenial network’) and the uncinate fasciculus (‘temporo-amygdala-orbitofrontal network’). Genetic and environmental variances were mapped for multiple tract-specific measures that reflect different aspects of the underlying anatomy. We report the highest heritability for the uncinate fasciculus, a tract that underpins emotion processing, semantic cognition, and social behaviour. High to moderate genetic and shared environmental effects were found for pathways important for social behaviour and memory, for example, fornix, dorsal and ventral cingulum. These findings indicate that within the limbic system inheritance of specific traits may rely on the anatomy of distinct networks and is higher for fronto-temporal pathways dedicated to complex social behaviour and emotional processing. PMID:26714573

Pediatric traumatic brain injury: language outcomes and their relationship to the arcuate fasciculus.

PubMed

Liégeois, Frédérique J; Mahony, Kate; Connelly, Alan; Pigdon, Lauren; Tournier, Jacques-Donald; Morgan, Angela T

2013-12-01

Pediatric traumatic brain injury (TBI) may result in long-lasting language impairments alongside dysarthria, a motor-speech disorder. Whether this co-morbidity is due to the functional links between speech and language networks, or to widespread damage affecting both motor and language tracts, remains unknown. Here we investigated language function and diffusion metrics (using diffusion-weighted tractography) within the arcuate fasciculus, the uncinate fasciculus, and the corpus callosum in 32 young people after TBI (approximately half with dysarthria) and age-matched healthy controls (n=17). Only participants with dysarthria showed impairments in language, affecting sentence formulation and semantic association. In the whole TBI group, sentence formulation was best predicted by combined corpus callosum and left arcuate volumes, suggesting this "dual blow" seriously reduces the potential for functional reorganisation. Word comprehension was predicted by fractional anisotropy in the right arcuate. The co-morbidity between dysarthria and language deficits therefore seems to be the consequence of multiple tract damage. Copyright © 2013 Elsevier Inc. All rights reserved.

Disconnection as a mechanism for social cognition impairment in multiple sclerosis.

PubMed

Batista, Sonia; Alves, Carolina; d'Almeida, Otília C; Afonso, Ana; Félix-Morais, Ricardo; Pereira, João; Macário, Carmo; Sousa, Lívia; Castelo-Branco, Miguel; Santana, Isabel; Cunha, Luís

2017-07-04

To assess the contribution of microstructural normal-appearing white matter (NAWM) damage to social cognition impairment, specifically in the theory of mind (ToM), in multiple sclerosis (MS). We enrolled consecutively 60 patients with MS and 60 healthy controls (HC) matched on age, sex, and education level. All participants underwent ToM testing (Eyes Test, Videos Test) and 3T brain MRI including conventional and diffusion tensor imaging sequences. Tract-based spatial statistics (TBSS) were applied for whole-brain voxel-wise analysis of fractional anisotropy (FA) and mean diffusivity (MD) on NAWM. Patients with MS performed worse on both tasks of ToM compared to HC (Eyes Test 58.7 ± 13.8 vs 81.9 ± 10.4, p < 0.001, Hedges g -1.886; Videos Test 75.3 ± 9.3 vs 88.1 ± 7.1, p < 0.001, Hedges g -1.537). Performance on ToM tests was correlated with higher values of FA and lower values of MD across widespread white matter tracts. The largest effects (≥90% of voxels with statistical significance) for the Eyes Test were body and genu of corpus callosum, fornix, tapetum, uncinate fasciculus, and left inferior cerebellar peduncle, and for the Videos Test genu and splenium of corpus callosum, fornix, uncinate fasciculus, left tapetum, and right superior fronto-occipital fasciculus. These results indicate that a diffuse pattern of NAWM damage in MS contributes to social cognition impairment in the ToM domain, probably due to a mechanism of disconnection within the social brain network. Gray matter pathology is also expected to have an important role; thus further research is required to clarify the neural basis of social cognition impairment in MS. © 2017 American Academy of Neurology.

Regional neuronal network failure and cognition in late-onset sporadic Alzheimer disease.

PubMed

Carter, S F; Embleton, K V; Anton-Rodriguez, J M; Burns, A; Ralph, M A L; Herholz, K

2014-06-01

The severe cognitive deficits in Alzheimer disease are associated with structural lesions in gray and white matter in addition to changes in synaptic function. The current investigation studied the breakdown of the structure and function in regional networks involving the Papez circuit and extended neocortical association areas. Cortical volumetric and diffusion tensor imaging (3T MR imaging), positron-emission tomography with (18)F fluorodeoxyglucose on a high-resolution research tomograph, and comprehensive neuropsychological assessments were performed in patients with late-onset sporadic Alzheimer disease, those with mild cognitive impairment, and elderly healthy controls. Atrophy of the medial temporal lobes was the strongest and most consistent abnormality in patients with mild cognitive impairment and Alzheimer disease. Atrophy in the temporal, frontal, and parietal regions was most strongly related to episodic memory deficits, while deficits in semantic cognition were also strongly related to reductions of glucose metabolism in the posterior cingulate cortex and temporoparietal regions. Changes in fractional anisotropy within white matter tracts, particularly in the left cingulum bundle, uncinate fasciculus, superior longitudinal fasciculus, and inferior fronto-occipital fasciculus, were significantly associated with the cognitive deficits in multiple regression analyses. Posterior cingulate and orbitofrontal metabolic deficits appeared to be related to microstructural changes in projecting white matter tracts. Many lesioned network components within the Papez circuit and extended neocortical association areas were significantly associated with cognitive dysfunction in both mild cognitive impairment and late-onset sporadic Alzheimer disease. Hippocampal atrophy was the most prominent lesion, with associated impairment of the uncinate and cingulum white matter microstructures and hippocampal and posterior cingulate metabolic impairment. © 2014 by American Journal of Neuroradiology.

Segregation of anterior temporal regions critical for retrieving names of unique and non-unique entities reflects underlying long-range connectivity.

PubMed

Mehta, Sonya; Inoue, Kayo; Rudrauf, David; Damasio, Hanna; Tranel, Daniel; Grabowski, Thomas

2016-02-01

Lesion-deficit studies support the hypothesis that the left anterior temporal lobe (ATL) plays a critical role in retrieving names of concrete entities. They further suggest that different regions of the left ATL process different conceptual categories. Here we test the specificity of these relationships and whether the anatomical segregation is related to the underlying organization of white matter connections. We reanalyzed data from a previous lesion study of naming and recognition across five categories of concrete entities. In voxelwise logistic regressions of lesion-deficit associations, we formally incorporated measures of disconnection of long-range association fiber tracts (FTs) and covaried for recognition and non-category-specific naming deficits. We also performed fiber tractwise analyses to assess whether damage to specific FTs was preferentially associated with category-selective naming deficits. Damage to the basolateral ATL was associated with naming deficits for both unique (famous faces) and non-unique entities, whereas the damage to the temporal pole was associated with naming deficits for unique entities only. This segregation pattern remained after accounting for comorbid recognition deficits or naming deficits in other categories. The tractwise analyses showed that damage to the uncinate fasciculus (UNC) was associated with naming impairments for unique entities, while damage to the inferior longitudinal fasciculus (ILF) was associated with naming impairments for non-unique entities. Covarying for FT transection in voxelwise analyses rendered the cortical association for unique entities more focal. These results are consistent with the partial segregation of brain system support for name retrieval of unique and non-unique entities at both the level of cortical components and underlying white matter fiber bundles. Our study reconciles theoretic accounts of the functional organization of the left ATL by revealing both category-related processing and semantic hub sectors. Copyright © 2015 Elsevier Ltd. All rights reserved.

Damage to the anterior arcuate fasciculus predicts non-fluent speech production in aphasia.

PubMed

Fridriksson, Julius; Guo, Dazhou; Fillmore, Paul; Holland, Audrey; Rorden, Chris

2013-11-01

Non-fluent aphasia implies a relatively straightforward neurological condition characterized by limited speech output. However, it is an umbrella term for different underlying impairments affecting speech production. Several studies have sought the critical lesion location that gives rise to non-fluent aphasia. The results have been mixed but typically implicate anterior cortical regions such as Broca's area, the left anterior insula, and deep white matter regions. To provide a clearer picture of cortical damage in non-fluent aphasia, the current study examined brain damage that negatively influences speech fluency in patients with aphasia. It controlled for some basic speech and language comprehension factors in order to better isolate the contribution of different mechanisms to fluency, or its lack. Cortical damage was related to overall speech fluency, as estimated by clinical judgements using the Western Aphasia Battery speech fluency scale, diadochokinetic rate, rudimentary auditory language comprehension, and executive functioning (scores on a matrix reasoning test) in 64 patients with chronic left hemisphere stroke. A region of interest analysis that included brain regions typically implicated in speech and language processing revealed that non-fluency in aphasia is primarily predicted by damage to the anterior segment of the left arcuate fasciculus. An improved prediction model also included the left uncinate fasciculus, a white matter tract connecting the middle and anterior temporal lobe with frontal lobe regions, including the pars triangularis. Models that controlled for diadochokinetic rate, picture-word recognition, or executive functioning also revealed a strong relationship between anterior segment involvement and speech fluency. Whole brain analyses corroborated the findings from the region of interest analyses. An additional exploratory analysis revealed that involvement of the uncinate fasciculus adjudicated between Broca's and global aphasia, the two most common kinds of non-fluent aphasia. In summary, the current results suggest that the anterior segment of the left arcuate fasciculus, a white matter tract that lies deep to posterior portions of Broca's area and the sensory-motor cortex, is a robust predictor of impaired speech fluency in aphasic patients, even when motor speech, lexical processing, and executive functioning are included as co-factors. Simply put, damage to those regions results in non-fluent aphasic speech; when they are undamaged, fluent aphasias result.

Damage to the anterior arcuate fasciculus predicts non-fluent speech production in aphasia

PubMed Central

Guo, Dazhou; Fillmore, Paul; Holland, Audrey; Rorden, Chris

2013-01-01

Non-fluent aphasia implies a relatively straightforward neurological condition characterized by limited speech output. However, it is an umbrella term for different underlying impairments affecting speech production. Several studies have sought the critical lesion location that gives rise to non-fluent aphasia. The results have been mixed but typically implicate anterior cortical regions such as Broca’s area, the left anterior insula, and deep white matter regions. To provide a clearer picture of cortical damage in non-fluent aphasia, the current study examined brain damage that negatively influences speech fluency in patients with aphasia. It controlled for some basic speech and language comprehension factors in order to better isolate the contribution of different mechanisms to fluency, or its lack. Cortical damage was related to overall speech fluency, as estimated by clinical judgements using the Western Aphasia Battery speech fluency scale, diadochokinetic rate, rudimentary auditory language comprehension, and executive functioning (scores on a matrix reasoning test) in 64 patients with chronic left hemisphere stroke. A region of interest analysis that included brain regions typically implicated in speech and language processing revealed that non-fluency in aphasia is primarily predicted by damage to the anterior segment of the left arcuate fasciculus. An improved prediction model also included the left uncinate fasciculus, a white matter tract connecting the middle and anterior temporal lobe with frontal lobe regions, including the pars triangularis. Models that controlled for diadochokinetic rate, picture-word recognition, or executive functioning also revealed a strong relationship between anterior segment involvement and speech fluency. Whole brain analyses corroborated the findings from the region of interest analyses. An additional exploratory analysis revealed that involvement of the uncinate fasciculus adjudicated between Broca’s and global aphasia, the two most common kinds of non-fluent aphasia. In summary, the current results suggest that the anterior segment of the left arcuate fasciculus, a white matter tract that lies deep to posterior portions of Broca’s area and the sensory-motor cortex, is a robust predictor of impaired speech fluency in aphasic patients, even when motor speech, lexical processing, and executive functioning are included as co-factors. Simply put, damage to those regions results in non-fluent aphasic speech; when they are undamaged, fluent aphasias result. PMID:24131592

Structural differences in interictal migraine attack after epilepsy: A diffusion tensor imaging analysis.

PubMed

Huang, Qi; Lv, Xin; He, Yushuang; Wei, Xing; Ma, Meigang; Liao, Yuhan; Qin, Chao; Wu, Yuan

2017-12-01

Patients with epilepsy (PWE) are more likely to suffer from migraine attack, and aberrant white matter (WM) organization may be the mechanism underlying this phenomenon. This study aimed to use diffusion tensor imaging (DTI) technique to quantify WM structural differences in PWE with interictal migraine. Diffusion tensor imaging data were acquired in 13 PWE with migraine and 12 PWE without migraine. Diffusion metrics were analyzed using tract-atlas-based spatial statistics analysis. Atlas-based and tract-based spatial statistical analyses were conducted for robustness analysis. Correlation was explored between altered DTI metrics and clinical parameters. The main results are as follows: (i) Axonal damage plays a key role in PWE with interictal migraine. (ii) Significant diffusing alterations included higher fractional anisotropy (FA) in the fornix, higher mean diffusivity (MD) in the middle cerebellar peduncle (CP), left superior CP, and right uncinate fasciculus, and higher axial diffusivity (AD) in the middle CP and right medial lemniscus. (iii) Diffusion tensor imaging metrics has the tendency of correlation with seizure/migraine type and duration. Results indicate that characteristic structural impairments exist in PWE with interictal migraine. Epilepsy may contribute to migraine by altering WMs in the brain stem. White matter tracts in the fornix and right uncinate fasciculus also mediate migraine after epilepsy. This finding may improve our understanding of the pathological mechanisms underlying migraine attack after epilepsy. Copyright © 2017 Elsevier Inc. All rights reserved.

Development and aging of the healthy human brain uncinate fasciculus across the lifespan using diffusion tensor tractography.

PubMed

Hasan, Khader M; Iftikhar, Amal; Kamali, Arash; Kramer, Larry A; Ashtari, Manzar; Cirino, Paul T; Papanicolaou, Andrew C; Fletcher, Jack M; Ewing-Cobbs, Linda

2009-06-18

The human brain uncinate fasciculus (UF) is an important cortico-cortical white matter pathway that directly connects the frontal and temporal lobes, although there is a lack of conclusive support for its exact functional role. Using diffusion tensor tractography, we extracted the UF, calculated its volume and normalized it with respect to each subject's intracranial volume (ICV) and analyzed its corresponding DTI metrics bilaterally on a cohort of 108 right-handed children and adults aged 7-68 years. Results showed inverted U-shaped curves for fractional anisotropy (FA) with advancing age and U-shaped curves for radial and axial diffusivities reflecting white matter progressive and regressive myelination and coherence dynamics that continue into young adulthood. The mean FA values of the UF were significantly larger on the left side in children (p=0.05), adults (p=0.0012) and the entire sample (p=0.0002). The FA leftward asymmetry (Left>Right) is shown to be due to increased leftward asymmetry in the axial diffusivity (p<0.0001) and a lack of asymmetry (p>0.23) for the radial diffusivity. This is the first study to provide baseline normative macro and microstructural age trajectories of the human UF across the lifespan. Results of this study may lend themselves to better understanding of UF role in future behavioral and clinical studies.

Variations in the neurobiology of reading in children and adolescents born full term and preterm

PubMed Central

Travis, Katherine E.; Ben-Shachar, Michal; Myall, Nathaniel J.; Feldman, Heidi M.

2016-01-01

Diffusion properties of white matter tracts have been associated with individual differences in reading. Individuals born preterm are at risk of injury to white matter. In this study we compared the associations between diffusion properties of white matter and reading skills in children and adolescents born full term and preterm. 45 participants, aged 9–17 years, included 26 preterms (born < 36 weeks' gestation) and 19 full-terms. Tract fractional anisotropy (FA) profiles were generated for five bilateral white matter tracts previously associated with reading: anterior superior longitudinal fasciculus (aSLF), arcuate fasciculus (Arc), corticospinal tract (CST), uncinate fasciculus (UF) and inferior longitudinal fasciculus (ILF). Mean scores on reading for the two groups were in the normal range and were not statistically different. In both groups, FA was associated with measures of single word reading and comprehension in the aSLF, AF, CST, and UF. However, correlations were negative in the full term group and positive in the preterm group. These results demonstrate variations in the neurobiology of reading in children born full term and preterm despite comparable reading skills. Findings suggest that efficient information exchange required for strong reading abilities may be accomplished via a different balance of neurobiological mechanisms in different groups of readers. PMID:27158588

Anatomic Connections of the Subgenual Cingulate Region.

PubMed

Vergani, Francesco; Martino, Juan; Morris, Christopher; Attems, Johannes; Ashkan, Keyoumars; DellʼAcqua, Flavio

2016-09-01

The subgenual cingulate gyrus (SCG) has been proposed as a target for deep brain stimulation (DBS) in neuropsychiatric disorders, mainly major depression. Despite promising clinical results, the mechanism of action of DBS in this region is poorly understood. Knowledge of the connections of the SCG can elucidate the network involved by DBS in this area and can help refine the targeting for DBS electrode placement. To investigate the anatomic connections of the SCG region. An anatomic study of the connections of the SCG was performed on postmortem specimens and in vivo with MR diffusion imaging tractography. Postmortem dissections were performed according to the Klingler technique. Specimens were fixed in 10% formalin and frozen at -15°C for 2 weeks. After thawing, dissection was performed with blunt dissectors. Whole brain tractography was performed using spherical deconvolution tractography. Four main connections were found: (1) fibers of the cingulum, originating at the level of the SCG and terminating at the medial aspect of the temporal lobe (parahippocampal gyrus); (2) fibers running toward the base of the frontal lobe, connecting the SCG with frontopolar areas; (3) fibers running more laterally, converging onto the ventral striatum (nucleus accumbens); (4) fibers of the uncinate fasciculus, connecting the orbitofrontal with the anterior temporal region. The SCG shows a wide range of white matter connections with limbic, prefrontal, and mesiotemporal areas. These findings can help to explain the role of the SCG in DBS for psychiatric disorders. DBS, deep brain stimulationSCG, subgenual cingulate gyrus.

Psychological and neural correlates of embitterment in old age.

PubMed

Kühn, Simone; Düzel, Sandra; Drewelies, Johanna; Gerstorf, Denis; Lindenberger, Ulman; Gallinat, Jürgen

2018-01-01

Posttraumatic embitterment disorder (PTED) comprises a stress-related response to a negative life event that violates the belief system of the individual. Characteristic symptoms involve repeated intrusive thoughts, emotional arousal when reminded of the event, and decreases in well-being. Within the scope of the present study, embitterment was treated as a continuous rather than categorical concept, and we investigated its psychological and brain structural correlates in a sample of healthy older adults. We found a negative association between the PTED self-rating score and self-reported well-being, life satisfaction, and future time perspective and a positive association with loneliness, perceived stress, chronic strain, and external control beliefs. We found no significant association between embitterment and brain regions that have been associated with stress exposure and posttraumatic stress disorder (PTSD)-hippocampus and the medial prefrontal cortex. This may emphasize the fundamental difference between PTED and PTSD. In a whole-brain analysis, we found a positive correlation between embitterment and gray matter volume in the precuneus and white matter volume in the bilateral uncinate fasciculus. The precuneus and uncinate fasciculus are brain regions that have been related to episodic memory retrieval, matching well to the symptoms of intrusive thoughts and an overwhelming preoccupation with the event that caused the PTED. Further longitudinal research is needed to unravel whether these structural correlates represent preconditions or rather the consequence of embitterment. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Prenatal exposure to maternal and paternal depressive symptoms and white matter microstructure in children.

PubMed

El Marroun, Hanan; Zou, Runyu; Muetzel, Ryan L; Jaddoe, Vincent W; Verhulst, Frank C; White, Tonya; Tiemeier, Henning

2018-04-01

Prenatal maternal depression has been associated with multiple problems in offspring involving affect, cognition, and neuroendocrine functioning. This suggests that prenatal depression influences neurodevelopment. However, the underlying neurodevelopmental mechanism remains unclear. We prospectively assessed whether maternal depressive symptoms during pregnancy and at the child's age 3 years are related to white matter microstructure in 690 children. The association of paternal depressive symptoms with childhood white matter microstructure was assessed to evaluate genetic or familial confounding. Parental depressive symptoms were measured using the Brief Symptom Inventory. In children aged 6-9 years, we used diffusion tensor imaging to assess white matter microstructure characteristics including fractional anisotropy (FA) and mean diffusivity (MD). Exposure to maternal depressive symptoms during pregnancy was associated with higher MD in the uncinate fasciculus and to lower FA and higher MD in the cingulum bundle. No associations of maternal depressive symptoms at the child's age of 3 years with white matter characteristics were observed. Paternal depressive symptoms also showed a trend toward significance for a lower FA in the cingulum bundle. Prenatal maternal depressive symptoms were associated with higher MD in the uncinate fasciculus and the cingulum bundle. These structures are part of the limbic system, which is involved in motivation, emotion, learning, and memory. As paternal depressive symptoms were also related to lower FA in the cingulum, the observed effect may partly reflect a genetic predisposition and shared environmental family factors and to a lesser extent a specific intrauterine effect. © 2018 Wiley Periodicals, Inc.

Multiple determinants of lifespan memory differences.

PubMed

Henson, Richard N; Campbell, Karen L; Davis, Simon W; Taylor, Jason R; Emery, Tina; Erzinclioglu, Sharon; Kievit, Rogier A

2016-09-07

Memory problems are among the most common complaints as people grow older. Using structural equation modeling of commensurate scores of anterograde memory from a large (N = 315), population-derived sample (www.cam-can.org), we provide evidence for three memory factors that are supported by distinct brain regions and show differential sensitivity to age. Associative memory and item memory are dramatically affected by age, even after adjusting for education level and fluid intelligence, whereas visual priming is not. Associative memory and item memory are differentially affected by emotional valence, and the age-related decline in associative memory is faster for negative than for positive or neutral stimuli. Gray-matter volume in the hippocampus, parahippocampus and fusiform cortex, and a white-matter index for the fornix, uncinate fasciculus and inferior longitudinal fasciculus, show differential contributions to the three memory factors. Together, these data demonstrate the extent to which differential ageing of the brain leads to differential patterns of memory loss.

Individual differences in white matter microstructure predict semantic control.

PubMed

Nugiel, Tehila; Alm, Kylie H; Olson, Ingrid R

2016-12-01

In everyday conversation, we make many rapid choices between competing concepts and words in order to convey our intent. This process is termed semantic control, and it is thought to rely on information transmission between a distributed semantic store in the temporal lobes and a more discrete region, optimized for retrieval and selection, in the left inferior frontal gyrus. Here, we used diffusion tensor imaging in a group of neurologically normal young adults to investigate the relationship between semantic control and white matter tracts that have been implicated in semantic memory retrieval. Participants completed a verb generation task that taps semantic control (Snyder & Munakata, 2008; Snyder et al., 2010) and underwent a diffusion imaging scan. Deterministic tractography was performed to compute indices representing the microstructural properties of the inferior fronto-occipital fasciculus (IFOF), the uncinate fasciculus (UF), and the inferior longitudinal fasciculus (ILF). Microstructural measures of the UF failed to predict semantic control performance. However, there was a significant relationship between microstructure of the left IFOF and ILF and individual differences in semantic control. Our findings support the view put forth by Duffau (2013) that the IFOF is a key structural pathway in semantic retrieval.

Distribution and Network of Basal Temporal Language Areas: A Study of the Combination of Electric Cortical Stimulation and Diffusion Tensor Imaging.

PubMed

Enatsu, Rei; Kanno, Aya; Ookawa, Satoshi; Ochi, Satoko; Ishiai, Sumio; Nagamine, Takashi; Mikuni, Nobuhiro

2017-10-01

The basal temporal language area (BTLA) is considered to have several functions in language processing; however, its brain network is still unknown. This study investigated the distribution and networks of the BTLA using a combination of electric cortical stimulation and diffusion tensor imaging (DTI). 10 patients with intractable focal epilepsy who underwent presurgical evaluation with subdural electrodes were enrolled in this study (language dominant side: 6 patients, language nondominant side: 4 patients). Electric stimulation at 50 Hz was applied to the electrodes during Japanese sentence reading, morphograms (kanji) reading, and syllabograms (kana) reading tasks to identify the BTLA. DTI was used to identify the subcortical fibers originating from the BTLA found by electric stimulation. The BTLA was found in 6 patients who underwent implantation of the subdural electrodes in the dominant hemisphere. The BTLA was located anywhere between 20 mm and 56 mm posterior to the temporal tips. In 3 patients, electric stimulation of some or all areas within the BTLA induced disturbance in reading of kanji words only. DTI detected the inferior longitudinal fasciculus (ILF) in all patients and the uncinate fasciculus (UF) in 1 patient, originating from the BTLA. ILF was detected from both kanji-specific areas and kanji-nonspecific areas. This study indicates that the network of the BTLA is a part of a ventral stream and is mainly composed of the ILF, which acts as a critical structure for lexical retrieval. ILF is also associated with the specific processing of kanji words. Copyright © 2017 Elsevier Inc. All rights reserved.

Temporal association tracts and the breakdown of episodic memory in mild cognitive impairment

PubMed Central

Metzler-Baddeley, Claudia; Hunt, Sarah; Jones, Derek K.; Leemans, Alexander; Aggleton, John P.

2012-01-01

Objective: To examine the pattern of association between microstructure of temporal lobe connections and the breakdown of episodic memory that is a core feature of mild cognitive impairment (MCI). Methods: Twenty-five individuals with MCI and 20 matched controls underwent diffusion MRI and cognitive assessment. Three temporal pathways were reconstructed by tractography: fornix, parahippocampal cingulum (PHC), and uncinate fasciculus. Tissue volume fraction—a tract-specific measure of atrophy—and microstructural measures were derived for each tract. To test specificity of associations, a comparison tract (corticospinal tract) and control cognitive domains were also examined. Results: In MCI, tissue volume fraction was reduced in the fornix. Axial and radial diffusivity were increased in uncinate and PHC implying more subtle microstructural change. In controls, tissue volume fraction in the fornix was the predominant correlate of free recall. In contrast, in MCI, the strongest relationship was with left PHC. Microstructure of uncinate and PHC also correlated with recognition memory, and recognition confidence, in MCI. Conclusions: Episodic memory in MCI is related to the structure of multiple temporal association pathways. These associations are not confined to the fornix, as they are in healthy young and older adults. In MCI, because of a compromised fornix, alternative pathways may contribute disproportionally to episodic memory performance. PMID:23175726

Microstructural white matter alterations and hippocampal volumes are associated with cognitive deficits in craniopharyngioma.

PubMed

Fjalldal, S; Follin, C; Svärd, D; Rylander, L; Gabery, S; Petersén, Å; van Westen, D; Sundgren, P C; Björkman-Burtscher, I M; Lätt, J; Ekman, B; Johanson, A; Erfurth, E M

2018-06-01

Patients with craniopharyngioma (CP) and hypothalamic lesions (HL) have cognitive deficits. Which neural pathways are affected is unknown. To determine whether there is a relationship between microstructural white matter (WM) alterations detected with diffusion tensor imaging (DTI) and cognition in adults with childhood-onset CP. A cross-sectional study with a median follow-up time of 22 (6-49) years after operation. The South Medical Region of Sweden (2.5 million inhabitants). Included were 41 patients (24 women, ≥17 years) surgically treated for childhood-onset CP between 1958-2010 and 32 controls with similar age and gender distributions. HL was found in 23 patients. Subjects performed cognitive tests and magnetic resonance imaging, and images were analyzed using DTI of uncinate fasciculus, fornix, cingulum, hippocampus and hypothalamus as well as hippocampal volumetry. Right uncinate fasciculus was significantly altered ( P  ≤ 0.01). Microstructural WM alterations in left ventral cingulum were significantly associated with worse performance in visual episodic memory, explaining approximately 50% of the variation. Alterations in dorsal cingulum were associated with worse performance in immediate, delayed recall and recognition, explaining 26-38% of the variation, and with visuospatial ability and executive function, explaining 19-29%. Patients who had smaller hippocampal volume had worse general knowledge ( P  = 0.028), and microstructural WM alterations in hippocampus were associated with a decline in general knowledge and episodic visual memory. A structure to function relationship is suggested between microstructural WM alterations in cingulum and in hippocampus with cognitive deficits in CP. © 2018 The authors.

Shape analysis of the cingulum, uncinate and arcuate fasciculi in patients with bipolar disorder

PubMed Central

Sun, Zhong Yi; Houenou, Josselin; Duclap, Delphine; Sarrazin, Samuel; Linke, Julia; Daban, Claire; Hamdani, Nora; d’Albis, Marc-Antoine; Le Corvoisier, Philippe; Guevara, Pamela; Delavest, Marine; Bellivier, Frank; Almeida, Jorge; Versace, Amelia; Poupon, Cyril; Leboyer, Marion; Phillips, Mary; Wessa, Michèle; Mangin, Jean-François

2017-01-01

Background Abnormal maturation of brain connectivity is supposed to underlie the dysfunctional emotion regulation in patients with bipolar disorder (BD). To test this hypothesis, white matter integrity is usually investigated using measures of water diffusivity provided by MRI. Here we consider a more intuitive aspect of the morphometry of the white matter tracts: the shape of the fibre bundles, which is associated with neurodevelopment. We analyzed the shape of 3 tracts involved in BD: the cingulum (CG), uncinate fasciculus (UF) and arcuate fasciculus (AF). Methods We analyzed diffusion MRI data in patients with BD and healthy controls. The fibre bundles were reconstructed using Q-ball–based tractography and automated segmentation. Using Isomap, a manifold learning method, the differences in the shape of the reconstructed bundles were visualized and quantified. Results We included 112 patients and 82 controls in our analysis. We found the left AF of patients to be further extended toward the temporal pole, forming a tighter hook than in controls. We found no significant difference in terms of shape for the left UF, the left CG or the 3 right fasciculi. However, in patients compared with controls, the ventrolateral branch of the left UF in the orbitofrontal region had a tendency to be larger, and the left CG of patients had a tendency to be smaller in the frontal lobe and larger in the parietal lobe. Limitations This was a cross-sectional study. Conclusion Our results suggest neurodevelopmental abnormalities in the left AF in patients with BD. The statistical tendencies observed for the left UF and left CG deserve further study. PMID:28234596

Shape analysis of the cingulum, uncinate and arcuate fasciculi in patients with bipolar disorder.

PubMed

Sun, Zhong Yi; Houenou, Josselin; Duclap, Delphine; Sarrazin, Samuel; Linke, Julia; Daban, Claire; Hamdani, Nora; d'Albis, Marc-Antoine; Le Corvoisier, Philippe; Guevara, Pamela; Delavest, Marine; Bellivier, Frank; Bellivier, Frank; Almeida, Jorge; Versace, Amelia; Poupon, Cyril; Leboyer, Marion; Phillips, Mary; Wessa, Michèle; Mangin, Jean-François

2017-01-01

Abnormal maturation of brain connectivity is supposed to underlie the dysfunctional emotion regulation in patients with bipolar disorder (BD). To test this hypothesis, white matter integrity is usually investigated using measures of water diffusivity provided by MRI. Here we consider a more intuitive aspect of the morphometry of the white matter tracts: the shape of the fibre bundles, which is associated with neurodevelopment. We analyzed the shape of 3 tracts involved in BD: the cingulum (CG), uncinate fasciculus (UF) and arcuate fasciculus (AF). We analyzed diffusion MRI data in patients with BD and healthy controls. The fibre bundles were reconstructed using Q-ball-based tractography and automated segmentation. Using Isomap, a manifold learning method, the differences in the shape of the reconstructed bundles were visualized and quantified. We included 112 patients and 82 controls in our analysis. We found the left AF of patients to be further extended toward the temporal pole, forming a tighter hook than in controls. We found no significant difference in terms of shape for the left UF, the left CG or the 3 right fasciculi. However, in patients compared with controls, the ventrolateral branch of the left UF in the orbitofrontal region had a tendency to be larger, and the left CG of patients had a tendency to be smaller in the frontal lobe and larger in the parietal lobe. This was a cross-sectional study. Our results suggest neurodevelopmental abnormalities in the left AF in patients with BD. The statistical tendencies observed for the left UF and left CG deserve further study.

Separate Brain Circuits Support Integrative and Semantic Priming in the Human Language System.

PubMed

Feng, Gangyi; Chen, Qi; Zhu, Zude; Wang, Suiping

2016-07-01

Semantic priming is a crucial phenomenon to study the organization of semantic memory. A novel type of priming effect, integrative priming, has been identified behaviorally, whereby a prime word facilitates recognition of a target word when the 2 concepts can be combined to form a unitary representation. We used both functional and anatomical imaging approaches to investigate the neural substrates supporting such integrative priming, and compare them with those in semantic priming. Similar behavioral priming effects for both semantic (Bread-Cake) and integrative conditions (Cherry-Cake) were observed when compared with an unrelated condition. However, a clearly dissociated brain response was observed between these 2 types of priming. The semantic-priming effect was localized to the posterior superior temporal and middle temporal gyrus. In contrast, the integrative-priming effect localized to the left anterior inferior frontal gyrus and left anterior temporal cortices. Furthermore, fiber tractography showed that the integrative-priming regions were connected via uncinate fasciculus fiber bundle forming an integrative circuit, whereas the semantic-priming regions connected to the posterior frontal cortex via separated pathways. The results point to dissociable neural pathways underlying the 2 distinct types of priming, illuminating the neural circuitry organization of semantic representation and integration. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Multiple determinants of lifespan memory differences

PubMed Central

Henson, Richard N.; Campbell, Karen L.; Davis, Simon W.; Taylor, Jason R.; Emery, Tina; Erzinclioglu, Sharon; Tyler, Lorraine K.; Brayne, Carol; Bullmore, Edward T.; Calder, Andrew C.; Cusack, Rhodri; Dalgleish, Tim; Duncan, John; Matthews, Fiona E.; Marslen-Wilson, William D.; Rowe, James B.; Shafto, Meredith A.; Cheung, Teresa; Geerligs, Linda; McCarrey, Anna; Mustafa, Abdur; Price, Darren; Samu, David; Treder, Matthias; Tsvetanov, Kamen A.; van Belle, Janna; Williams, Nitin; Bates, Lauren; Gadie, Andrew; Gerbase, Sofia; Georgieva, Stanimira; Hanley, Claire; Parkin, Beth; Troy, David; Auer, Tibor; Correia, Marta; Gao, Lu; Green, Emma; Henriques, Rafael; Allen, Jodie; Amery, Gillian; Amunts, Liana; Barcroft, Anne; Castle, Amanda; Dias, Cheryl; Dowrick, Jonathan; Fair, Melissa; Fisher, Hayley; Goulding, Anna; Grewa, Adarsh; Hale, Geoff; Hilton, Andrew; Johnson, Frances; Johnston, Patricia; Kavanagh-Williamson, Thea; Kwasniewska, Magdalena; McMinn, Alison; Norman, Kim; Penrose, Jessica; Roby, Fiona; Rowland, Diane; Sargeant, John; Squire, Maggie; Stevens, Beth; Stoddart, Aldabra; Stone, Cheryl; Thompson, Tracy; Yazlik, Ozlem; Barnes, Dan; Dixon, Marie; Hillman, Jaya; Mitchell, Joanne; Villis, Laura; Kievit, Rogier A.

2016-01-01

Memory problems are among the most common complaints as people grow older. Using structural equation modeling of commensurate scores of anterograde memory from a large (N = 315), population-derived sample (www.cam-can.org), we provide evidence for three memory factors that are supported by distinct brain regions and show differential sensitivity to age. Associative memory and item memory are dramatically affected by age, even after adjusting for education level and fluid intelligence, whereas visual priming is not. Associative memory and item memory are differentially affected by emotional valence, and the age-related decline in associative memory is faster for negative than for positive or neutral stimuli. Gray-matter volume in the hippocampus, parahippocampus and fusiform cortex, and a white-matter index for the fornix, uncinate fasciculus and inferior longitudinal fasciculus, show differential contributions to the three memory factors. Together, these data demonstrate the extent to which differential ageing of the brain leads to differential patterns of memory loss. PMID:27600595

Development of white matter microstructure in relation to verbal and visuospatial working memory—A longitudinal study

PubMed Central

Fjell, Anders M.; Tamnes, Christian K.; Grydeland, Håkon; Due-Tønnessen, Paulina; Bjørnerud, Atle; Sampaio-Baptista, Cassandra; Andersson, Jesper; Johansen-Berg, Heidi; Walhovd, Kristine B.

2018-01-01

Working memory capacity is pivotal for a broad specter of cognitive tasks and develops throughout childhood. This must in part rely on development of neural connections and white matter microstructure maturation, but there is scarce knowledge of specific relations between this and different aspects of working memory. Diffusion tensor imaging (DTI) enables us to study development of brain white matter microstructure. In a longitudinal DTI study of 148 healthy children between 4 and 11 years scanned twice with an on average 1.6 years interval, we characterized change in fractional anisotropy (FA), mean (MD), radial (RD) and axial diffusivity (AD) in 10 major white matter tracts hypothesized to be of importance for working memory. The results showed relationships between change in several tracts and change in visuospatial working memory. Specifically, improvement in visuospatial working memory capacity was significantly associated with decreased MD, RD and AD in inferior longitudinal fasciculus (ILF), inferior fronto-occipital fasciculus (IFOF) and uncinate fasciculus (UF) in the right hemisphere, as well as forceps major (FMaj). No significant relationships were found between change in DTI metrics and change in verbal working memory capacity. These findings yield new knowledge about brain development and corresponding working memory improvements in childhood. PMID:29689058

Comparison of diffusion tensor imaging tractography of language tracts and intraoperative subcortical stimulations.

PubMed

Leclercq, Delphine; Duffau, Hugues; Delmaire, Christine; Capelle, Laurent; Gatignol, Peggy; Ducros, Mathieu; Chiras, Jacques; Lehéricy, Stéphane

2010-03-01

Diffusion tensor (DT) imaging tractography is increasingly used to map fiber tracts in patients with surgical brain lesions to reduce the risk of postoperative functional deficit. There are few validation studies of DT imaging tractography in these patients. The aim of this study was to compare DT imaging tractography of language fiber tracts by using intraoperative subcortical electrical stimulations. The authors included 10 patients with low-grade gliomas or dysplasia located in language areas. The MR imaging examination included 3D T1-weighted images for anatomical coregistration, FLAIR, and DT images. Diffusion tensors and fiber tracts were calculated using in-house software. Four tracts were reconstructed in each patient including the arcuate fasciculus, the inferior occipitofrontal fasciculus, and 2 premotor fasciculi (the subcallosal medialis fiber tract and cortical fibers originating from the medial and lateral premotor areas). The authors compared fiber tracts reconstructed using DT imaging with those evidenced using intraoperative subcortical language mapping. Seventeen (81%) of 21 positive stimulations were concordant with DT imaging fiber bundles (located within 6 mm of a fiber tract). Four positive stimulations were not located in the vicinity of a DT imaging fiber tract. Stimulations of the arcuate fasciculus mostly induced articulatory and phonemic/syntactic disorders and less frequently semantic paraphasias. Stimulations of the inferior occipitofrontal fasciculus induced semantic paraphasias. Stimulations of the premotor-related fasciculi induced dysarthria and articulatory planning deficit. There was a good correspondence between positive stimulation sites and fiber tracts, suggesting that DT imaging fiber tracking is a reliable technique but not yet optimal to map language tracts in patients with brain lesions. Negative tractography does not rule out the persistence of a fiber tract, especially when invaded by the tumor. Stimulations of the different tracts induced variable language disorders that were specific to each fiber tract.

Beyond the word and image: II- Structural and functional connectivity of a common semantic system.

PubMed

Jouen, A L; Ellmore, T M; Madden-Lombardi, C J; Pallier, C; Dominey, P F; Ventre-Dominey, J

2018-02-01

Understanding events requires interplaying cognitive processes arising in neural networks whose organisation and connectivity remain subjects of controversy in humans. In the present study, by combining diffusion tensor imaging and functional interaction analysis, we aim to provide new insights on the organisation of the structural and functional pathways connecting the multiple nodes of the identified semantic system -shared by vision and language (Jouen et al., 2015). We investigated a group of 19 healthy human subjects during experimental tasks of reading sentences or seeing pictures. The structural connectivity was realised by deterministic tractography using an algorithm to extract white matter fibers terminating in the selected regions of interest (ROIs) and the functional connectivity by independent component analysis to measure correlated activities among these ROIs. The major connections link ventral neural stuctures including the parietal and temporal cortices through inferior and middle longitudinal fasciculi, the retrosplenial and parahippocampal cortices through the cingulate bundle, and the temporal and prefrontal structures through the uncinate fasciculus. The imageability score provided when the subject was reading a sentence was significantly correlated with the factor of anisotropy of the left parieto-temporal connections of the middle longitudinal fasciculus. A large part of this ventrally localised structural connectivity corresponds to functional interactions between the main parietal, temporal and frontal nodes. More precisely, the strong coactivation both in the anterior temporal pole and in the region of the temporo-parietal cortex suggests dual and cooperating roles for these areas within the semantic system. These findings are discussed in terms of two semantics-related sub-systems responsible for conceptual representation. Copyright © 2017 Elsevier Inc. All rights reserved.

Korsakoff Syndrome in Non-alcoholic Psychiatric Patients. Variable Cognitive Presentation and Impaired Frontotemporal Connectivity.

PubMed

Nikolakaros, Georgios; Kurki, Timo; Paju, Janina; Papageorgiou, Sokratis G; Vataja, Risto; Ilonen, Tuula

2018-01-01

Background: Non-alcoholic Wernicke's encephalopathy and Korsakoff syndrome are greatly underdiagnosed. There are very few reported cases of neuropsychologically documented non-alcoholic Korsakoff syndrome, and diffusion tensor imaging (DTI) data are scarce. Methods: We report clinical characteristics and neuropsychological as well as radiological findings from three psychiatric patients (one woman and two men) with a history of probable undiagnosed non-alcoholic Wernicke's encephalopathy and subsequent chronic memory problems. Results: All patients had abnormal neuropsychological test results, predominantly in memory. Thus, the neuropsychological findings were compatible with Korsakoff syndrome. However, the neuropsychological findings were not uniform. The impairment of delayed verbal memory of the first patient was evident only when the results of the memory tests were compared to her general cognitive level. In addition, the logical memory test and the verbal working memory test were abnormal, but the word list memory test was normal. The second patient had impaired attention and psychomotor speed in addition to impaired memory. In the third patient, the word list memory test was abnormal, but the logical memory test was normal. All patients had intrusions in the neuropsychological examination. Executive functions were preserved, except for planning and foresight, which were impaired in two patients. Conventional MRI examination was normal. DTI showed reduced fractional anisotropy values in the uncinate fasciculus in two patients, and in the corpus callosum and in the subgenual cingulum in one patient. Conclusions: Non-alcoholic Korsakoff syndrome can have diverse neuropsychological findings. This may partly explain its marked underdiagnosis. Therefore, a strong index of suspicion is needed. The presence of intrusions in the neuropsychological examination supports the diagnosis. Damage in frontotemporal white matter tracts, particularly in the uncinate fasciculus, may be a feature of non-alcoholic Korsakoff syndrome in psychiatric patients.

Impaired anatomical connectivity and related executive functions: differentiating vulnerability and disease marker in bipolar disorder.

PubMed

Linke, Julia; King, Andrea V; Poupon, Cyril; Hennerici, Michael G; Gass, Achim; Wessa, Michèle

2013-12-15

Bipolar 1 disorder (BD1) has been associated with impaired set shifting, increased risk taking, and impaired integrity of frontolimbic white matter. However, it remains unknown to what extent these findings are related to each other and whether these abnormalities represent risk factors or consequences of the illness. We addressed the first question by comparing 19 patients with BD1 and 19 healthy control subjects (sample 1) with diffusion tensor imaging, the Intra-Extra Dimensional Set Shift Task, and the Cambridge Gambling Task. The second question we approached by applying the same protocol to 22 healthy first-degree relatives of patients with BD1 and 22 persons without a family history of mental disorders (sample 2). In comparison with their control groups, BD1 patients and healthy first-degree relatives of patients with BD1 showed significantly reduced fractional anisotropy (FA) in the right anterior limb of the internal capsule and right uncinate fasciculus. White matter integrity in corpus callosum was reduced in BD1 patients only. In addition, reduced FA in anterior limb of the internal capsule correlated significantly with an increased number of errors during set shifting and increased risk taking and reduced FA in uncinate fasciculus correlated significantly with increased risk taking. Similar white matter alterations in BD1 patients and healthy relatives of BD1 patients are associated with comparable behavioral abnormalities. Further, results indicate that altered frontolimbic and frontothalamic connectivity and corresponding behavioral abnormalities might be a trait and vulnerability marker of BD1, whereas interhemispheric connectivity appears to be a disease marker. Copyright © 2013 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Korsakoff Syndrome in Non-alcoholic Psychiatric Patients. Variable Cognitive Presentation and Impaired Frontotemporal Connectivity

PubMed Central

Nikolakaros, Georgios; Kurki, Timo; Paju, Janina; Papageorgiou, Sokratis G.; Vataja, Risto; Ilonen, Tuula

2018-01-01

Background: Non-alcoholic Wernicke's encephalopathy and Korsakoff syndrome are greatly underdiagnosed. There are very few reported cases of neuropsychologically documented non-alcoholic Korsakoff syndrome, and diffusion tensor imaging (DTI) data are scarce. Methods: We report clinical characteristics and neuropsychological as well as radiological findings from three psychiatric patients (one woman and two men) with a history of probable undiagnosed non-alcoholic Wernicke's encephalopathy and subsequent chronic memory problems. Results: All patients had abnormal neuropsychological test results, predominantly in memory. Thus, the neuropsychological findings were compatible with Korsakoff syndrome. However, the neuropsychological findings were not uniform. The impairment of delayed verbal memory of the first patient was evident only when the results of the memory tests were compared to her general cognitive level. In addition, the logical memory test and the verbal working memory test were abnormal, but the word list memory test was normal. The second patient had impaired attention and psychomotor speed in addition to impaired memory. In the third patient, the word list memory test was abnormal, but the logical memory test was normal. All patients had intrusions in the neuropsychological examination. Executive functions were preserved, except for planning and foresight, which were impaired in two patients. Conventional MRI examination was normal. DTI showed reduced fractional anisotropy values in the uncinate fasciculus in two patients, and in the corpus callosum and in the subgenual cingulum in one patient. Conclusions: Non-alcoholic Korsakoff syndrome can have diverse neuropsychological findings. This may partly explain its marked underdiagnosis. Therefore, a strong index of suspicion is needed. The presence of intrusions in the neuropsychological examination supports the diagnosis. Damage in frontotemporal white matter tracts, particularly in the uncinate fasciculus, may be a feature of non-alcoholic Korsakoff syndrome in psychiatric patients.

Diffusion tensor tractography of the arcuate fasciculus in patients with brain tumors: Comparison between deterministic and probabilistic models

PubMed Central

Li, Zhixi; Peck, Kyung K.; Brennan, Nicole P.; Jenabi, Mehrnaz; Hsu, Meier; Zhang, Zhigang; Holodny, Andrei I.; Young, Robert J.

2014-01-01

Purpose The purpose of this study was to compare the deterministic and probabilistic tracking methods of diffusion tensor white matter fiber tractography in patients with brain tumors. Materials and Methods We identified 29 patients with left brain tumors <2 cm from the arcuate fasciculus who underwent pre-operative language fMRI and DTI. The arcuate fasciculus was reconstructed using a deterministic Fiber Assignment by Continuous Tracking (FACT) algorithm and a probabilistic method based on an extended Monte Carlo Random Walk algorithm. Tracking was controlled using two ROIs corresponding to Broca’s and Wernicke’s areas. Tracts in tumoraffected hemispheres were examined for extension between Broca’s and Wernicke’s areas, anterior-posterior length and volume, and compared with the normal contralateral tracts. Results Probabilistic tracts displayed more complete anterior extension to Broca’s area than did FACT tracts on the tumor-affected and normal sides (p < 0.0001). The median length ratio for tumor: normal sides was greater for probabilistic tracts than FACT tracts (p < 0.0001). The median tract volume ratio for tumor: normal sides was also greater for probabilistic tracts than FACT tracts (p = 0.01). Conclusion Probabilistic tractography reconstructs the arcuate fasciculus more completely and performs better through areas of tumor and/or edema. The FACT algorithm tends to underestimate the anterior-most fibers of the arcuate fasciculus, which are crossed by primary motor fibers. PMID:25328583

Brain structural connectivity and context-dependent extinction memory.

PubMed

Hermann, Andrea; Stark, Rudolf; Blecker, Carlo R; Milad, Mohammed R; Merz, Christian J

2017-08-01

Extinction of conditioned fear represents an important mechanism in the treatment of anxiety disorders. Return of fear after successful extinction or exposure therapy in patients with anxiety disorders might be linked to poor temporal or contextual generalization of extinction due to individual differences in brain structural connectivity. The goal of this magnetic resonance imaging study was therefore to investigate the association of context-dependent extinction recall with brain structural connectivity. Diffusion-tensor imaging was used to determine the fractional anisotropy as a measure of white matter structural integrity of fiber tracts connecting central brain regions of the fear and extinction circuit (uncinate fasciculus, cingulum). Forty-five healthy men participated in a two-day fear conditioning experiment with fear acquisition in context A and extinction learning in context B on the first day. Extinction recall in the extinction context as well as renewal in the acquisition context and a novel context C took place one day later. Renewal of conditioned fear (skin conductance responses) in the acquisition context was associated with higher structural integrity of the hippocampal part of the cingulum. Enhanced structural integrity of the cingulum might be related to stronger hippocampal modulation of the dorsal anterior cingulate cortex, a region important for modulating conditioned fear output by excitatory projections to the amygdala. This finding underpins the crucial role of individual differences in the structural integrity of relevant fiber tracts for context-dependent extinction recall and return of fear after exposure therapy in anxiety disorders. © 2017 Wiley Periodicals, Inc.

White matter changes in preclinical Alzheimer's disease: a magnetic resonance imaging-diffusion tensor imaging study on cognitively normal older people with positive amyloid β protein 42 levels.

PubMed

Molinuevo, José Luis; Ripolles, Pablo; Simó, Marta; Lladó, Albert; Olives, Jaume; Balasa, Mircea; Antonell, Anna; Rodriguez-Fornells, Antoni; Rami, Lorena

2014-12-01

The aim of this study was to use diffusion tensor imaging measures to determine the existence of white matter microstructural differences in the preclinical phases of Alzheimer's disease, assessing cognitively normal older individuals with positive amyloid β protein (Aβ42) levels (CN_Aβ42+) on the basis of normal cognition and cerebrospinal fluid Aβ42 levels below 500 pg/mL. Nineteen CN_Aβ42+ and 19 subjects with Aβ42 levels above 500 pg/mL (CN_Aβ42-) were included. We encountered increases in axial diffusivity (AxD) in CN_Aβ42+ relative to CN_Aβ42- in the corpus callosum, corona radiata, internal capsule, and superior longitudinal fasciculus bilaterally, and also in the left fornix, left uncinate fasciculus, and left inferior fronto-occipital fasciculus. However, no differences were found in other diffusion tensor imaging indexes. Cognitive reserve scores were positively associated with AxD exclusively in the CN_Aβ42+ group. The finding of AxD alteration together with preserved fractional anisotropy, mean diffusivity, and radial diffusivity indexes in the CN_Aβ42+ group may indicate that, subtle axonal changes may be happening in the preclinical phases of Alzheimer's disease, whereas white matter integrity is still widely preserved. Copyright © 2014 Elsevier Inc. All rights reserved.

Longitudinal changes in microstructural white matter metrics in Alzheimer's disease.

PubMed

Mayo, Chantel D; Mazerolle, Erin L; Ritchie, Lesley; Fisk, John D; Gawryluk, Jodie R

2017-01-01

Alzheimer's disease (AD) is a progressive neurodegenerative disorder. Current avenues of AD research focus on pre-symptomatic biomarkers that will assist with early diagnosis of AD. The majority of magnetic resonance imaging (MRI) based biomarker research to date has focused on neuronal loss in grey matter and there is a paucity of research on white matter. Longitudinal DTI data from the Alzheimer's Disease Neuroimaging Initiative 2 database were used to examine 1) the within-group microstructural white matter changes in individuals with AD and healthy controls at baseline and year one; and 2) the between-group microstructural differences in individuals with AD and healthy controls at both time points. 1) Within-group: longitudinal Tract-Based Spatial Statistics revealed that individuals with AD and healthy controls both had widespread reduced fractional anisotropy (FA) and increased mean diffusivity (MD) with changes in the hippocampal cingulum exclusive to the AD group. 2) Between-group: relative to healthy controls, individuals with AD had lower FA and higher MD in the hippocampal cingulum, as well as the corpus callosum, internal and external capsule; corona radiata; posterior thalamic radiation; superior and inferior longitudinal fasciculus; fronto-occipital fasciculus; cingulate gyri; fornix; uncinate fasciculus; and tapetum. The current results indicate that sensitivity to white matter microstructure is a promising avenue for AD biomarker research. Additional longitudinal studies on both white and grey matter are warranted to further evaluate potential clinical utility.

Neural organization of ventral white matter tracts parallels the initial steps of reading development: A DTI tractography study.

PubMed

Vanderauwera, Jolijn; De Vos, Astrid; Forkel, Stephanie J; Catani, Marco; Wouters, Jan; Vandermosten, Maaike; Ghesquière, Pol

2018-05-18

Insight in the developmental trajectory of the neuroanatomical reading correlates is important to understand related cognitive processes and disorders. In adults, a dual pathway model has been suggested encompassing a dorsal phonological and a ventral orthographic white matter system. This dichotomy seems not present in pre-readers, and the specific role of ventral white matter in reading remains unclear. Therefore, the present longitudinal study investigated the relation between ventral white matter and cognitive processes underlying reading in children with a broad range of reading skills (n = 61). Ventral pathways of the reading network were manually traced using diffusion tractography: the inferior fronto-occipital fasciculus (IFOF), inferior longitudinal fasciculus (ILF) and uncinate fasciculus (UF). Pathways were examined pre-reading (5-6 years) and after two years of reading acquisition (7-8 years). Dimension reduction for the cognitive measures resulted in one component for pre-reading cognitive measures and a separate phonological and orthographic component for the early reading measures. Regression analyses revealed a relation between the pre-reading cognitive component and bilateral IFOF and left ILF. Interestingly, exclusively the left IFOF was related to the orthographic component, whereas none of the pathways was related to the phonological component. Hence, the left IFOF seems to serve as the lexical reading route, already in the earliest reading stages. Copyright © 2018 Elsevier Inc. All rights reserved.

White-matter microstructure and hearing acuity in older adults: a population-based cross-sectional DTI study.

PubMed

Rigters, Stephanie C; Cremers, Lotte G M; Ikram, M Arfan; van der Schroeff, Marc P; de Groot, Marius; Roshchupkin, Gennady V; Niessen, Wiro J N; Baatenburg de Jong, Robert J; Goedegebure, André; Vernooij, Meike W

2018-01-01

To study the relation between the microstructure of white matter in the brain and hearing function in older adults we carried out a population-based, cross-sectional study. In 2562 participants of the Rotterdam Study, we conducted diffusion tensor imaging to determine the microstructure of the white-matter tracts. We performed pure-tone audiogram and digit-in-noise tests to quantify hearing acuity. Poorer white-matter microstructure, especially in the association tracts, was related to poorer hearing acuity. After differentiating the separate white-matter tracts in the left and right hemisphere, poorer white-matter microstructure in the right superior longitudinal fasciculus and the right uncinate fasciculus remained significantly associated with worse hearing. These associations did not significantly differ between middle-aged (51-69 years old) and older (70-100 years old) participants. Progressing age was thus not found to be an effect modifier. In a voxel-based analysis no voxels in the white matter were significantly associated with hearing impairment. Copyright © 2017 Elsevier Inc. All rights reserved.

Decreased and Increased Anisotropy along Major Cerebral White Matter Tracts in Preterm Children and Adolescents

PubMed Central

Ben-Shachar, Michal; Feldman, Heidi M.

2015-01-01

Premature birth is highly prevalent and associated with neurodevelopmental delays and disorders. Adverse outcomes, particularly in children born before 32 weeks of gestation, have been attributed in large part to white matter injuries, often found in periventricular regions using conventional imaging. To date, tractography studies of white matter pathways in children and adolescents born preterm have evaluated only a limited number of tracts simultaneously. The current study compares diffusion properties along 18 major cerebral white matter pathways in children and adolescents born preterm (n = 27) and full term (n = 19), using diffusion magnetic resonance imaging and tractography. We found that compared to the full term group, the preterm group had significantly decreased FA in segments of the bilateral uncinate fasciculus and anterior segments of the right inferior fronto-occipital fasciculus. Additionally, the preterm group had significantly increased FA in segments of the right and left anterior thalamic radiations, posterior segments of the right inferior fronto-occipital fasciculus, and the right and left inferior longitudinal fasciculus. Increased FA in the preterm group was generally associated with decreased radial diffusivity. These findings indicate that prematurity-related white matter differences in later childhood and adolescence do not affect all tracts in the periventricular zone and can involve both decreased and increased FA. Differences in the patterns of radial diffusivity and axial diffusivity suggest that the tissue properties underlying group FA differences may vary within and across white matter tracts. Distinctive diffusion properties may relate to variations in the timing of injury in the neonatal period, extent of white matter dysmaturity and/or compensatory processes in childhood. PMID:26560745

Anatomy of the Temporal Lobe

PubMed Central

Kiernan, J. A.

2012-01-01

Only primates have temporal lobes, which are largest in man, accommodating 17% of the cerebral cortex and including areas with auditory, olfactory, vestibular, visual and linguistic functions. The hippocampal formation, on the medial side of the lobe, includes the parahippocampal gyrus, subiculum, hippocampus, dentate gyrus, and associated white matter, notably the fimbria, whose fibres continue into the fornix. The hippocampus is an inrolled gyrus that bulges into the temporal horn of the lateral ventricle. Association fibres connect all parts of the cerebral cortex with the parahippocampal gyrus and subiculum, which in turn project to the dentate gyrus. The largest efferent projection of the subiculum and hippocampus is through the fornix to the hypothalamus. The choroid fissure, alongside the fimbria, separates the temporal lobe from the optic tract, hypothalamus and midbrain. The amygdala comprises several nuclei on the medial aspect of the temporal lobe, mostly anterior the hippocampus and indenting the tip of the temporal horn. The amygdala receives input from the olfactory bulb and from association cortex for other modalities of sensation. Its major projections are to the septal area and prefrontal cortex, mediating emotional responses to sensory stimuli. The temporal lobe contains much subcortical white matter, with such named bundles as the anterior commissure, arcuate fasciculus, inferior longitudinal fasciculus and uncinate fasciculus, and Meyer's loop of the geniculocalcarine tract. This article also reviews arterial supply, venous drainage, and anatomical relations of the temporal lobe to adjacent intracranial and tympanic structures. PMID:22934160

Asymmetries of the arcuate fasciculus in monozygotic twins: genetic and nongenetic influences.

PubMed

Häberling, Isabelle S; Badzakova-Trajkov, Gjurgjica; Corballis, Michael C

2013-01-01

We assessed cerebral asymmetry for language in 35 monozygotic twin pairs. Using DTI, we reconstructed the arcuate fasciculus in each twin. Among the male twins, right-handed pairs showed greater left-sided asymmetry of connectivity in the arcuate fasciculus than did those with discordant handedness, and within the discordant group the right-handers had greater left-sided volume asymmetry of the arcuate fasciculus than did their left-handed co-twins. There were no such effects in the female twins. Cerebral asymmetry for language showed more consistent results, with the more left-cerebrally dominant twins also showing more leftward asymmetry of high anisotropic fibers in the arcuate fasciculus, a result applying equally to female as to male twins. Reversals of arcuate fasciculus asymmetry were restricted to pairs discordant for language dominance, with the left-cerebrally dominant twins showing leftward and the right-cerebrally dominant twins rightward asymmetry of anisotropic diffusion in the arcuate fasciculus. Because monozygotic twin pairs share the same genotype, our results indicate a strong nongenetic component in arcuate fasciculus asymmetry, particularly in those discordant for cerebral asymmetry.

Higher education is an age-independent predictor of white matter integrity and cognitive control in late adolescence.

PubMed

Noble, Kimberly G; Korgaonkar, Mayuresh S; Grieve, Stuart M; Brickman, Adam M

2013-09-01

Socioeconomic status is an important predictor of cognitive development and academic achievement. Late adolescence provides a unique opportunity to study how the attainment of socioeconomic status (in the form of years of education) relates to cognitive and neural development, during a time when age-related cognitive and neural development is ongoing. During late adolescence it is possible to disambiguate age- and education-related effects on the development of these processes. Here we assessed the degree to which higher educational attainment was related to performance on a cognitive control task, controlling for age. We then used diffusion tensor imaging (DTI) to assess the degree to which white matter microstructure might mediate this relationship. When covarying age, significant associations were found between educational attainment and fractional anisotropy (FA) in the superior longitudinal fasciculus (SLF) and cingulum bundle (CB). Further, when covarying age, FA in these regions was associated with cognitive control. Finally, mediation analyses revealed that the age-independent association between educational attainment and cognitive control was completely accounted for by FA in these regions. The uncinate fasciculus, a late-myelinated control region not implicated in cognitive control, did not mediate this effect. © 2013 John Wiley & Sons Ltd.

The Ins and Outs of Meaning: Behavioral and Neuroanatomical Dissociation of Semantically-Driven Word Retrieval and Multimodal Semantic Recognition in Aphasia

PubMed Central

Mirman, Daniel; Zhang, Yongsheng; Wang, Ze; Coslett, H. Branch; Schwartz, Myrna F.

2015-01-01

Theories about the architecture of language processing differ with regard to whether verbal and nonverbal comprehension share a functional and neural substrate and how meaning extraction in comprehension relates to the ability to use meaning to drive verbal production. We (re-)evaluate data from 17 cognitive-linguistic performance measures of 99 participants with chronic aphasia using factor analysis to establish functional components and support vector regression-based lesion-symptom mapping to determine the neural correlates of deficits on these functional components. The results are highly consistent with our previous findings: production of semantic errors is behaviorally and neuroanatomically distinct from verbal and nonverbal comprehension. Semantic errors were most strongly associated with left ATL damage whereas deficits on tests of verbal and non-verbal semantic recognition were most strongly associated with damage to deep white matter underlying the frontal lobe at the confluence of multiple tracts, including the inferior fronto-occipital fasciculus, the uncinate fasciculus, and the anterior thalamic radiations. These results suggest that traditional views based on grey matter hub(s) for semantic processing are incomplete and that the role of white matter in semantic cognition has been underappreciated. PMID:25681739

Network specific change in white matter integrity in mesial temporal lobe epilepsy.

PubMed

Imamura, Hisaji; Matsumoto, Riki; Takaya, Shigetoshi; Nakagawa, Tomokazu; Shimotake, Akihiro; Kikuchi, Takayuki; Sawamoto, Nobukatsu; Kunieda, Takeharu; Mikuni, Nobuhiro; Miyamoto, Susumu; Fukuyama, Hidenao; Takahashi, Ryosuke; Ikeda, Akio

2016-02-01

To identify the specific change of white matter integrity that occurs in the brain network related to epileptic activity in patients with mesial temporal lobe epilepsy (MTLE). We recruited 18 patients with MTLE and 18 healthy subjects. In MTLE patients, the remote functional-deficit zone was delineated using fluorodeoxyglucose positron emission tomography as an extratemporal region showing glucose hypometabolism. Using diffusion magnetic resonance imaging tractography, we defined a seizure propagation tract (PT) as a white matter pathway that connects the focus with a remote functional deficit zone. We also used the corticospinal tract (CST) and inferior longitudinal fasciculus (ILF) as control tracts in the hemisphere ipsilateral to the focus. Fractional anisotropy (FA), mean diffusivity (MD), and volume of the tracts were compared among PT, CST, and ILF. Tractographic analysis identified the uncinate fasciculus, arcuate fasciculus, and fornix as PTs. A decrease in FA was found in MTLE patients compared with healthy subjects in all tracts, but PTs showed a more significant decrease in FA than did the two control tracts. Although the change in MD was also found in MTLE patients compared with healthy controls, a tract-specific change was not observed. Although white-matter damage was observed in all candidate tracts examined, the integrity of white matter was most significantly decreased in PTs in MTLE. The change in white matter integrity occurs specifically in the pathways that connect the focus and remote functional deficit zones in patients with MTLE, i.e., the pathways that are assume to be associated with seizure propagation. Copyright © 2015 Elsevier B.V. All rights reserved.

Altered white matter microstructure is associated with social cognition and psychotic symptoms in 22q11.2 microdeletion syndrome

PubMed Central

Jalbrzikowski, Maria; Villalon-Reina, Julio E.; Karlsgodt, Katherine H.; Senturk, Damla; Chow, Carolyn; Thompson, Paul M.; Bearden, Carrie E.

2014-01-01

22q11.2 Microdeletion Syndrome (22q11DS) is a highly penetrant genetic mutation associated with a significantly increased risk for psychosis. Aberrant neurodevelopment may lead to inappropriate neural circuit formation and cerebral dysconnectivity in 22q11DS, which may contribute to symptom development. Here we examined: (1) differences between 22q11DS participants and typically developing controls in diffusion tensor imaging (DTI) measures within white matter tracts; (2) whether there is an altered age-related trajectory of white matter pathways in 22q11DS; and (3) relationships between DTI measures, social cognition task performance, and positive symptoms of psychosis in 22q11DS and typically developing controls. Sixty-four direction diffusion weighted imaging data were acquired on 65 participants (36 22q11DS, 29 controls). We examined differences between 22q11DS vs. controls in measures of fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD), using both a voxel-based and region of interest approach. Social cognition domains assessed were: Theory of Mind and emotion recognition. Positive symptoms were assessed using the Structured Interview for Prodromal Syndromes. Compared to typically developing controls, 22q11DS participants showed significantly lower AD and RD in multiple white matter tracts, with effects of greatest magnitude for AD in the superior longitudinal fasciculus. Additionally, 22q11DS participants failed to show typical age-associated changes in FA and RD in the left inferior longitudinal fasciculus. Higher AD in the left inferior fronto-occipital fasciculus (IFO) and left uncinate fasciculus was associated with better social cognition in 22q11DS and controls. In contrast, greater severity of positive symptoms was associated with lower AD in bilateral regions of the IFO in 22q11DS. White matter microstructure in tracts relevant to social cognition is disrupted in 22q11DS, and may contribute to psychosis risk. PMID:25426042

Diffusion tensor imaging depicting damage to the arcuate fasciculus in patients with conduction aphasia: a study of the Wernicke-Geschwind model.

PubMed

Zhang, Yumei; Wang, Chunxue; Zhao, Xingquan; Chen, Hongyan; Han, Zaizhu; Wang, Yongjun

2010-09-01

In contrast with disorders of comprehension and spontaneous expression, conduction aphasia is characterized by poor repetition, which is a hallmark of the syndrome. There are many theories on the repetition impairment of conduction aphasia. The disconnection theory suggests that a damaged in the arcuate fasciculus, which connects Broca's and Wernicke's area, is the cause of conduction aphasia. In this study, we examined the disconnection theory. We enrolled ten individuals with conduction aphasia and ten volunteers, and analysed their arcuate fasciculus using diffusion tensor imaging (DTI) and obtained fractional anisotropy (FA) values. Then, the results of the left hemisphere were compared with those of the right hemisphere, and the results of the conduction aphasia cases were compared with those of the volunteers. There were significant differences in the FA values between the left and right hemispheres of volunteers and conduction cases. In volunteers, there was an increase in fiber in the left hemisphere compared with the right hemisphere, whereas there was an increase in fiber in the right hemisphere compared with the left hemisphere in conduction aphasia patients. The results of diffusion tensor tractography suggested that the configuration of the arcuate fasciculus was different between conduction aphasia patients and volunteers, suggesting that there was damage to the arcuate fasciculus of conduction aphasia cases. The damage seen in the arcuate fasciculus of conduction aphasia cases in this study supports the Wernicke-Geschwind disconnection theory. A disconnection between Broca's area and Wernicke's area is likely to be one mechanism of conduction aphasia repetition impairment.

Bidirectional iterative parcellation of diffusion weighted imaging data: Separating cortical regions connected by the arcuate fasciculus and extreme capsule

PubMed Central

Patterson, Dianne K.; Van Petten, Cyma; Beeson, Pélagie M.; Rapcsak, Steven Z.; Plante, Elena

2014-01-01

This paper introduces a Bidirectional Iterative Parcellation (BIP) procedure designed to identify the location and size of connected cortical regions (parcellations) at both ends of a white matter tract in diffusion weighted images. The procedure applies the FSL option “probabilistic tracking with classification targets” in a bidirectional and iterative manner. To assess the utility of BIP, we applied the procedure to the problem of parcellating a limited set of well-established gray matter seed regions associated with the dorsal (arcuate fasciculus/superior longitudinal fasciculus) and ventral (extreme capsule fiber system) white matter tracts in the language networks of 97 participants. These left hemisphere seed regions and the two white matter tracts, along with their right hemisphere homologues, provided an excellent test case for BIP because the resulting parcellations overlap and their connectivity via the arcuate fasciculi and extreme capsule fiber systems are well studied. The procedure yielded both confirmatory and novel findings. Specifically, BIP confirmed that each tract connects within the seed regions in unique, but expected ways. Novel findings included increasingly left-lateralized parcellations associated with the arcuate fasciculus/superior longitudinal fasciculus as a function of age and education. These results demonstrate that BIP is an easily implemented technique that successfully confirmed cortical connectivity patterns predicted in the literature, and has the potential to provide new insights regarding the architecture of the brain. PMID:25173414

Neuropsychological Correlates of Diffusion Tensor Imaging in Schizophrenia

PubMed Central

Nestor, Paul G.; Kubicki, Marek; Gurrera, Ronald J.; Niznikiewicz, Margaret; Frumin, Melissa; McCarley, Robert W.; Shenton, Martha E.

2009-01-01

Patients with schizophrenia (n = 41) and healthy comparison participants (n = 46) completed neuropsychological measures of intelligence, memory, and executive function. A subset of each group also completed magnetic resonance diffusion tensor imaging (DTI) studies (fractional anisotropy and cross-sectional area) of the uncinate fasciculus (UF) and cingulate bundle (CB). Patients with schizophrenia showed reduced levels of functioning across all neuropsychological measures. In addition, selective neuropsychological–DTI relationships emerged. Among patients but not controls, lower levels of declarative–episodic verbal memory correlated with reduced left UF, whereas executive function errors related to performance monitoring correlated with reduced left CB. The data suggested abnormal DTI patterns linking declarative–episodic verbal memory deficits to the left UF and executive function deficits to the left CB among patients with schizophrenia. PMID:15506830

Associations between autistic traits and fractional anisotropy values in white matter tracts in a nonclinical sample of young adults.

PubMed

Bradstreet, Lauren E; Hecht, Erin E; King, Tricia Z; Turner, Jessica L; Robins, Diana L

2017-01-01

Whereas a number of studies have examined relationships among brain activity, social cognitive skills, and autistic traits, fewer studies have evaluated whether structural connections among brain regions relate to these traits and skills. Uncinate fasciculus (UF) and inferior longitudinal fasciculus (ILF) are white matter tracts that may underpin the behavioral expression of these skills because they connect regions within or provide sensory information to brain areas implicated in social cognition, and structural differences in these tracts have been associated with autistic traits. We examined relationships among self-reported autistic traits, mentalizing, and water diffusivity in UF and ILF in a nonclinical sample of 24 young adults (mean age = 21.92 years, SD = 4.72 years; 15 women). We measured autistic traits using the Autism-Spectrum Quotient, and we measured mentalizing using the Dynamic Interactive Shapes Clips task. We used Tract-Based Spatial Statistics and randomize to examine relationships among fractional anisotropy (FA) values in bilateral ILF and UF, age, cognitive abilities, autistic traits, and mentalizing. Autistic traits were positively related to FA values in left ILF. No other relationships between FA values and other variables were significant. Results suggest that left ILF may be involved in the expression of autistic traits in individuals without clinical diagnoses.

Structural connectivity of right frontal hyperactive areas scales with stuttering severity

PubMed Central

Neef, Nicole E; Bütfering, Christoph; Schmidt-Samoa, Carsten; Friederici, Angela D; Paulus, Walter; Sommer, Martin

2018-01-01

Abstract A neuronal sign of persistent developmental stuttering is the magnified coactivation of right frontal brain regions during speech production. Whether and how stuttering severity relates to the connection strength of these hyperactive right frontal areas to other brain areas is an open question. Scrutinizing such brain–behaviour and structure–function relationships aims at disentangling suspected underlying neuronal mechanisms of stuttering. Here, we acquired diffusion-weighted and functional images from 31 adults who stutter and 34 matched control participants. Using a newly developed structural connectivity measure, we calculated voxel-wise correlations between connection strength and stuttering severity within tract volumes that originated from functionally hyperactive right frontal regions. Correlation analyses revealed that with increasing speech motor deficits the connection strength increased in the right frontal aslant tract, the right anterior thalamic radiation, and in U-shaped projections underneath the right precentral sulcus. In contrast, with decreasing speech motor deficits connection strength increased in the right uncinate fasciculus. Additional group comparisons of whole-brain white matter skeletons replicated the previously reported reduction of fractional anisotropy in the left and right superior longitudinal fasciculus as well as at the junction of right frontal aslant tract and right superior longitudinal fasciculus in adults who stutter compared to control participants. Overall, our investigation suggests that right fronto-temporal networks play a compensatory role as a fluency enhancing mechanism. In contrast, the increased connection strength within subcortical-cortical pathways may be implied in an overly active global response suppression mechanism in stuttering. Altogether, this combined functional MRI–diffusion tensor imaging study disentangles different networks involved in the neuronal underpinnings of the speech motor deficit in persistent developmental stuttering. PMID:29228195

Structural connectivity of right frontal hyperactive areas scales with stuttering severity.

PubMed

Neef, Nicole E; Anwander, Alfred; Bütfering, Christoph; Schmidt-Samoa, Carsten; Friederici, Angela D; Paulus, Walter; Sommer, Martin

2018-01-01

A neuronal sign of persistent developmental stuttering is the magnified coactivation of right frontal brain regions during speech production. Whether and how stuttering severity relates to the connection strength of these hyperactive right frontal areas to other brain areas is an open question. Scrutinizing such brain-behaviour and structure-function relationships aims at disentangling suspected underlying neuronal mechanisms of stuttering. Here, we acquired diffusion-weighted and functional images from 31 adults who stutter and 34 matched control participants. Using a newly developed structural connectivity measure, we calculated voxel-wise correlations between connection strength and stuttering severity within tract volumes that originated from functionally hyperactive right frontal regions. Correlation analyses revealed that with increasing speech motor deficits the connection strength increased in the right frontal aslant tract, the right anterior thalamic radiation, and in U-shaped projections underneath the right precentral sulcus. In contrast, with decreasing speech motor deficits connection strength increased in the right uncinate fasciculus. Additional group comparisons of whole-brain white matter skeletons replicated the previously reported reduction of fractional anisotropy in the left and right superior longitudinal fasciculus as well as at the junction of right frontal aslant tract and right superior longitudinal fasciculus in adults who stutter compared to control participants. Overall, our investigation suggests that right fronto-temporal networks play a compensatory role as a fluency enhancing mechanism. In contrast, the increased connection strength within subcortical-cortical pathways may be implied in an overly active global response suppression mechanism in stuttering. Altogether, this combined functional MRI-diffusion tensor imaging study disentangles different networks involved in the neuronal underpinnings of the speech motor deficit in persistent developmental stuttering. © The Author (2017). Published by Oxford University Press on behalf of the Guarantors of Brain.

Preoperative automated fibre quantification predicts postoperative seizure outcome in temporal lobe epilepsy.

PubMed

Keller, Simon S; Glenn, G Russell; Weber, Bernd; Kreilkamp, Barbara A K; Jensen, Jens H; Helpern, Joseph A; Wagner, Jan; Barker, Gareth J; Richardson, Mark P; Bonilha, Leonardo

2017-01-01

Approximately one in every two patients with pharmacoresistant temporal lobe epilepsy will not be rendered completely seizure-free after temporal lobe surgery. The reasons for this are unknown and are likely to be multifactorial. Quantitative volumetric magnetic resonance imaging techniques have provided limited insight into the causes of persistent postoperative seizures in patients with temporal lobe epilepsy. The relationship between postoperative outcome and preoperative pathology of white matter tracts, which constitute crucial components of epileptogenic networks, is unknown. We investigated regional tissue characteristics of preoperative temporal lobe white matter tracts known to be important in the generation and propagation of temporal lobe seizures in temporal lobe epilepsy, using diffusion tensor imaging and automated fibre quantification. We studied 43 patients with mesial temporal lobe epilepsy associated with hippocampal sclerosis and 44 healthy controls. Patients underwent preoperative imaging, amygdalohippocampectomy and postoperative assessment using the International League Against Epilepsy seizure outcome scale. From preoperative imaging, the fimbria-fornix, parahippocampal white matter bundle and uncinate fasciculus were reconstructed, and scalar diffusion metrics were calculated along the length of each tract. Altogether, 51.2% of patients were rendered completely seizure-free and 48.8% continued to experience postoperative seizure symptoms. Relative to controls, both patient groups exhibited strong and significant diffusion abnormalities along the length of the uncinate bilaterally, the ipsilateral parahippocampal white matter bundle, and the ipsilateral fimbria-fornix in regions located within the medial temporal lobe. However, only patients with persistent postoperative seizures showed evidence of significant pathology of tract sections located in the ipsilateral dorsal fornix and in the contralateral parahippocampal white matter bundle. Using receiver operating characteristic curves, diffusion characteristics of these regions could classify individual patients according to outcome with 84% sensitivity and 89% specificity. Pathological changes in the dorsal fornix were beyond the margins of resection, and contralateral parahippocampal changes may suggest a bitemporal disorder in some patients. Furthermore, diffusion characteristics of the ipsilateral uncinate could classify patients from controls with a sensitivity of 98%; importantly, by co-registering the preoperative fibre maps to postoperative surgical lacuna maps, we observed that the extent of uncinate resection was significantly greater in patients who were rendered seizure-free, suggesting that a smaller resection of the uncinate may represent insufficient disconnection of an anterior temporal epileptogenic network. These results may have the potential to be developed into imaging prognostic markers of postoperative outcome and provide new insights for why some patients with temporal lobe epilepsy continue to experience postoperative seizures. © The Author (2016). Published by Oxford University Press on behalf of the Guarantors of Brain.

Preoperative automated fibre quantification predicts postoperative seizure outcome in temporal lobe epilepsy

PubMed Central

Keller, Simon S; Glenn, G Russell; Weber, Bernd; Kreilkamp, Barbara A K; Jensen, Jens H; Helpern, Joseph A; Wagner, Jan; Barker, Gareth J; Richardson, Mark P; Bonilha, Leonardo

2017-01-01

Abstract Approximately one in every two patients with pharmacoresistant temporal lobe epilepsy will not be rendered completely seizure-free after temporal lobe surgery. The reasons for this are unknown and are likely to be multifactorial. Quantitative volumetric magnetic resonance imaging techniques have provided limited insight into the causes of persistent postoperative seizures in patients with temporal lobe epilepsy. The relationship between postoperative outcome and preoperative pathology of white matter tracts, which constitute crucial components of epileptogenic networks, is unknown. We investigated regional tissue characteristics of preoperative temporal lobe white matter tracts known to be important in the generation and propagation of temporal lobe seizures in temporal lobe epilepsy, using diffusion tensor imaging and automated fibre quantification. We studied 43 patients with mesial temporal lobe epilepsy associated with hippocampal sclerosis and 44 healthy controls. Patients underwent preoperative imaging, amygdalohippocampectomy and postoperative assessment using the International League Against Epilepsy seizure outcome scale. From preoperative imaging, the fimbria-fornix, parahippocampal white matter bundle and uncinate fasciculus were reconstructed, and scalar diffusion metrics were calculated along the length of each tract. Altogether, 51.2% of patients were rendered completely seizure-free and 48.8% continued to experience postoperative seizure symptoms. Relative to controls, both patient groups exhibited strong and significant diffusion abnormalities along the length of the uncinate bilaterally, the ipsilateral parahippocampal white matter bundle, and the ipsilateral fimbria-fornix in regions located within the medial temporal lobe. However, only patients with persistent postoperative seizures showed evidence of significant pathology of tract sections located in the ipsilateral dorsal fornix and in the contralateral parahippocampal white matter bundle. Using receiver operating characteristic curves, diffusion characteristics of these regions could classify individual patients according to outcome with 84% sensitivity and 89% specificity. Pathological changes in the dorsal fornix were beyond the margins of resection, and contralateral parahippocampal changes may suggest a bitemporal disorder in some patients. Furthermore, diffusion characteristics of the ipsilateral uncinate could classify patients from controls with a sensitivity of 98%; importantly, by co-registering the preoperative fibre maps to postoperative surgical lacuna maps, we observed that the extent of uncinate resection was significantly greater in patients who were rendered seizure-free, suggesting that a smaller resection of the uncinate may represent insufficient disconnection of an anterior temporal epileptogenic network. These results may have the potential to be developed into imaging prognostic markers of postoperative outcome and provide new insights for why some patients with temporal lobe epilepsy continue to experience postoperative seizures. PMID:28031219

Neuroticism, depressive symptoms and white-matter integrity in the Lothian Birth Cohort 1936.

PubMed

McIntosh, A M; Bastin, M E; Luciano, M; Maniega, S Muñoz; Del C Valdés Hernández, M; Royle, N A; Hall, J; Murray, C; Lawrie, S M; Starr, J M; Wardlaw, J M; Deary, I J

2013-06-01

Clinical depression is associated with reductions in white-matter integrity in several long tracts of the brain. The extent to which these findings are localized or related to depressive symptoms or personality traits linked to disease risk remains unclear. Method Members of the Lothian Birth Cohort 1936 (LBC936) were assessed in two waves at mean ages of 70 and 73 years. At wave 1, they underwent assessments of depressive symptoms and the personality traits of neuroticism and extraversion. Brain diffusion magnetic resonance imaging (MRI) data were obtained at the second wave and mood assessments were repeated. We tested whether depressive symptoms were related to reduced white-matter tract fractional anisotropy (FA), a measure of integrity, and then examined whether high neuroticism or low extraversion mediated this relationship. Six hundred and sixty-eight participants provided useable data. Bilateral uncinate fasciculus FA was significantly negatively associated with depressive symptoms at both waves (standardized β=0.12-0.16). Higher neuroticism and lower extraversion were also significantly associated with lower uncinate FA bilaterally (standardized β=0.09-0.15) and significantly mediated the relationship between FA and depressive symptoms. Trait liability to depression and depressive symptoms are associated with reduced structural connectivity in tracts connecting the prefrontal cortex with the amygdala and anterior temporal cortex. These effects suggest that frontotemporal disconnection is linked to the etiology of depression, in part through personality trait differences.

Structural correlates of subjective and objective memory performance in multiple sclerosis.

PubMed

Pardini, Matteo; Bergamino, Maurizio; Bommarito, Giulia; Bonzano, Laura; Luigi Mancardi, Gian; Roccatagliata, Luca

2014-04-01

Subjective and objective memory deficits represent a frequent and ill-understood aspect of multiple sclerosis (MS), and a significant cause of disability and quality of life reduction. The aim of the study is to verify the role of hippocampal and temporal associative fibers' damage in MS-related memory complaints. To reach this aim, 25 patients with low disability relapsing-remitting MS and 19 healthy controls were included in the study. All subjects underwent 3D T1 structural imaging and Diffusion Tensor Imaging. Additionally, MS patients underwent neuropsychological evaluation of objective (Selective Reminding Test and Spatial Recall Test) and of subjective (Perceived Deficit Questionnaire, Retrospective and Prospective Memory Subscales) memory deficits. Normalized hippocampal volume (NHV) and mean Fractional Anisotropy (FA) for the uncinate fasciculus (UF) and for the ventral division of the cingulum bundle (VCB) were calculated for all subjects. We showed that, compared to controls, MS subjects presented with reduced right NHV and with reduced mean FA bilaterally in the UF and the VCB. In the MS group, verbal memory scores correlated with left NHV, spatial memory scores correlated with right NHV, while perceived retrospective and prospective memory deficits correlated with left VCB and left UF mean FA respectively. Our data confirm an early involvement of memory-related brain structures in MS patients. Our data suggest that verbal and nonverbal memory as well as perceived retrospective and prospective memory deficits are related to alterations of discrete anatomical structures in the low-disability phase of MS. Copyright © 2013 Wiley Periodicals, Inc.

Plasticity of white matter connectivity in phonetics experts.

PubMed

Vandermosten, Maaike; Price, Cathy J; Golestani, Narly

2016-09-01

Phonetics experts are highly trained to analyze and transcribe speech, both with respect to faster changing, phonetic features, and to more slowly changing, prosodic features. Previously we reported that, compared to non-phoneticians, phoneticians had greater local brain volume in bilateral auditory cortices and the left pars opercularis of Broca's area, with training-related differences in the grey-matter volume of the left pars opercularis in the phoneticians group (Golestani et al. 2011). In the present study, we used diffusion MRI to examine white matter microstructure, indexed by fractional anisotropy, in (1) the long segment of arcuate fasciculus (AF_long), which is a well-known language tract that connects Broca's area, including left pars opercularis, to the temporal cortex, and in (2) the fibers arising from the auditory cortices. Most of these auditory fibers belong to three validated language tracts, namely to the AF_long, the posterior segment of the arcuate fasciculus and the middle longitudinal fasciculus. We found training-related differences in phoneticians in left AF_long, as well as group differences relative to non-experts in the auditory fibers (including the auditory fibers belonging to the left AF_long). Taken together, the results of both studies suggest that grey matter structural plasticity arising from phonetic transcription training in Broca's area is accompanied by changes to the white matter fibers connecting this very region to the temporal cortex. Our findings suggest expertise-related changes in white matter fibers connecting fronto-temporal functional hubs that are important for phonetic processing. Further studies can pursue this hypothesis by examining the dynamics of these expertise related grey and white matter changes as they arise during phonetic training.

White matter integrity in major depressive disorder: Implications of childhood trauma, 5-HTTLPR and BDNF polymorphisms.

PubMed

Tatham, Erica L; Ramasubbu, Rajamannar; Gaxiola-Valdez, Ismael; Cortese, Filomeno; Clark, Darren; Goodyear, Bradley; Foster, Jane; Hall, Geoffrey B

2016-07-30

This study examined the impact of childhood neglect, serotonin transporter (5-HTTLPR) and brain derived neurotrophic factor (BDNF) polymorphisms on white matter (WM) integrity in major depressive disorder (MDD) using diffusion tensor imaging (DTI). Fifty-five medication-free MDD patients and 18 controls underwent diffusion tensor imaging scanning, genotyping and completed the Childhood Trauma Questionnaire. Tract based spatial statistics (TBSS) findings revealed reduced fractional anisotropy (FA) in the MDD group in the anterior internal capsule. 5-HTTLPR-S'L' heterozygotes in the MDD group exhibited reduced FA in the internal capsule relative to S'S' and reduced FA in corona radiata compared to L'L'. Probabilistic tractography revealed higher FA in the uncinate fasciculus (UF) for BDNF val/val genotype relative to met-carriers, particularly in individuals with high depression severity. High depression severity and experiences of childhood physical or emotional neglect predicted higher FA in the UF and superior longitudinal fasciculus. Reductions in FA were identified for subgroups of MDD patients who were 5-HTTLPR heterozygotes and BDNF-met carriers. An association between emotional/physical neglect and FA was observed in subjects with high depressive symptoms. Our findings suggest that WM connectivity within frontal and limbic regions are affected by depression and influenced by experiences of neglect and genetic risk factors. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Changes in language white matter tract microarchitecture associated with cognitive deficits in patients with presumed low-grade glioma.

PubMed

Incekara, Fatih; Satoer, Djaina; Visch-Brink, Evy; Vincent, Arnaud; Smits, Marion

2018-06-08

OBJECTIVE The authors conducted a study to determine whether cognitive functioning of patients with presumed low-grade glioma is associated with white matter (WM) tract changes. METHODS The authors included 77 patients with presumed low-grade glioma who underwent awake surgery between 2005 and 2013. Diffusion tensor imaging with deterministic tractography was performed preoperatively to identify the arcuate, inferior frontooccipital, and uncinate fasciculi and to obtain the mean fractional anisotropy (FA) and mean diffusivity per tract. All patients were evaluated preoperatively using an extensive neuropsychological protocol that included assessments of the language, memory, and attention/executive function domains. Linear regression models were used to analyze each cognitive domain and each diffusion tensor imaging metric of the 3 WM tracts. RESULTS Significant correlations (corrected for multiple testing) were found between FA of the arcuate fasciculus and results of the repetition test for the language domain (β = 0.59, p < 0.0001) and between FA of the inferior frontooccipital fasciculus and results of the imprinting test for the memory domain (β = -0.55, p = 0.002) and the attention test for the attention and executive function domain (β = -0.62, p = 0.006). CONCLUSIONS In patients with glioma, language deficits in repetition of speech, imprinting, and attention deficits are associated with changes in the microarchitecture of the arcuate and inferior frontooccipital fasciculi.

Sharp Curvature of Frontal Lobe White Matter Pathways in Children with Autism Spectrum Disorder: Tract-Based Morphometry Analysis

PubMed Central

Jeong, Jeong-Won; Kumar, Ajay; Sundaram, Senthil K.; Chugani, Harry T.; Chugani, Diane C.

2013-01-01

Background and Purpose As we had previously observed geometrical changes of frontal lobe association pathways in children with autism spectrum disorder (ASD), in the present study we analyzed the curvature of these white matter pathways using an objective tract based morphometry (TBM) analysis. Materials and Methods Diffusion tensor imaging (DTI) was performed in 32 children with ASD and 14 children with typical development. Curvature, fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD) of bilateral arcuate fasciculus (AF), uncinate fasciculus (UF), and genu of corpus callosum (gCC) were investigated using the TBM group analysis assessed by False Discovery Rate p-value (PFDR) for multiple comparisons. Results Significantly higher curvatures were found in children with ASD especially at the parieto-temporal junction for AF (left: PFDR < 0.001; right: PFDR < 0.01), at the fronto-temporal junction for UF (left: PFDR < 0.005; right: PFDR < 0.03), and at the midline of the gCC (PFDR < 0.0001). RD was significantly higher in children with ASD at the same bending regions of AF (left: PFDR < 0.03, right: PFDR < 0.02), UF (left: PFDR < 0.04), and gCC (PFDR < 0.01). Conclusion Higher curvature and curvature dependent RD changes in children with ASD may be the result of higher density of thinner axons in these frontal lobe tracts. PMID:21757519

White matter properties differ in 6-year old Readers and Pre-Readers

PubMed Central

Kovachy, Vanessa N; Ben-Shachar, Michal; Feldman, Heidi M

2016-01-01

Reading, an essential life skill in modern society, is typically learned during childhood. Adults who can read show white matter differences compared to adults who never learned to read. Studies have not established whether children who can read show similar white matter differences compared to children who cannot read. We compared 6-year old children who could decode written English words and pseudowords (n=31; Readers) and 6-year old children who could not decode pseudowords and had a standard score < 100 on a task for reading single words (n=11; Pre-Readers). We employed diffusion MRI and tractography to extract fractional anisotropy (FA) along the trajectory of 6 bilateral intra-hemispheric tracts and 2 posterior subdivisions of the corpus callosum. Readers demonstrated significantly increased FA within the left anterior segment of the superior longitudinal fasciculus (aSLF-L) and the right uncinate fasciculus (UF-R) compared to Pre-Readers. FA in the aSLF-L was significantly correlated with phonological awareness; FA in the UF-R was significantly correlated with language. Correlations in the UF-R but not the aSLF-L remained significant after controlling for reading ability, revealing that UF-R group differences were related to both children's language and reading abilities. Taken together, these findings demonstrate new evidence showing that individual differences in white matter structure relate to whether children have begun to read. PMID:27631434

Non-alcoholic Korsakoff syndrome in psychiatric patients with a history of undiagnosed Wernicke's encephalopathy.

PubMed

Nikolakaros, Georgios; Ilonen, Tuula; Kurki, Timo; Paju, Janina; Papageorgiou, Sokratis G; Vataja, Risto

2016-11-15

Wernicke's encephalopathy is often undiagnosed, particularly in non-alcoholics. There are very few reports of non-alcoholic patients diagnosed with Korsakoff syndrome in the absence of a prior diagnosis of Wernicke's encephalopathy and no studies of diffusion tensor imaging in non-alcoholic Korsakoff syndrome. We report on three non-alcoholic psychiatric patients (all women) with long-term non-progressive memory impairment that developed after malnutrition accompanied by at least one of the three Wernicke's encephalopathy manifestations: ocular abnormalities, ataxia or unsteadiness, and an altered mental state or mild memory impairment. In neuropsychological examination, all patients had memory impairment, including intrusions. One patient had mild cerebellar vermis atrophy in MRI taken after the second episode of Wernicke's encephalopathy. The same patient had mild hypometabolism in the lateral cortex of the temporal lobes. Another patient had mild symmetrical atrophy and hypometabolism of the superior frontal lobes. Two patients were examined with diffusion tensor imaging. Reduced fractional anisotropy values were found in the corona radiata in two patients, and the uncinate fasciculus and the inferior longitudinal fasciculus in one patient. Our results suggest that non-alcoholic Korsakoff syndrome is underdiagnosed. Psychiatric patients with long-term memory impairment may have Korsakoff syndrome and, therefore, they should be evaluated for a history of previously undiagnosed Wernicke's encephalopathy. Copyright © 2016 Elsevier B.V. All rights reserved.

Altered integrity of the right arcuate fasciculus as a trait marker of schizophrenia: a sibling study using tractography-based analysis of the whole brain.

PubMed

Wu, Chen-Hao; Hwang, Tzung-Jeng; Chen, Yu-Jen; Hsu, Yun-Chin; Lo, Yu-Chun; Liu, Chih-Min; Hwu, Hai-Gwo; Liu, Chen-Chung; Hsieh, Ming H; Chien, Yi Ling; Chen, Chung-Ming; Tseng, Wen-Yih Isaac

2015-03-01

Trait markers of schizophrenia aid the dissection of the heterogeneous phenotypes into distinct subtypes and facilitate the genetic underpinning of the disease. The microstructural integrity of the white matter tracts could serve as a trait marker of schizophrenia, and tractography-based analysis (TBA) is the current method of choice. Manual tractography is time-consuming and limits the analysis to preselected fiber tracts. Here, we sought to identify a trait marker of schizophrenia from among 74 fiber tracts across the whole brain using a novel automatic TBA method. Thirty-one patients with schizophrenia, 31 unaffected siblings and 31 healthy controls were recruited to undergo diffusion spectrum magnetic resonance imaging at 3T. Generalized fractional anisotropy (GFA), an index reflecting tract integrity, was computed for each tract and compared among the three groups. Ten tracts were found to exhibit significant differences between the groups with a linear, stepwise order from controls to siblings to patients; they included the right arcuate fasciculus, bilateral fornices, bilateral auditory tracts, left optic radiation, the genu of the corpus callosum, and the corpus callosum to the bilateral dorsolateral prefrontal cortices, bilateral temporal poles, and bilateral hippocampi. Posthoc between-group analyses revealed that the GFA of the right arcuate fasciculus was significantly decreased in both the patients and unaffected siblings compared to the controls. Furthermore, the GFA of the right arcuate fasciculus exhibited a trend toward positive symptom scores. In conclusion, the right arcuate fasciculus may be a candidate trait marker and deserves further study to verify any genetic association. © 2014 Wiley Periodicals, Inc.

Subconcussive Head Impact Exposure and White Matter Tract Changes over a Single Season of Youth Football

PubMed Central

Bahrami, Naeim; Sharma, Dev; Rosenthal, Scott; Davenport, Elizabeth M.; Urban, Jillian E.; Wagner, Benjamin; Jung, Youngkyoo; Vaughan, Christopher G.; Gioia, Gerard A.; Stitzel, Joel D.; Maldjian, Joseph A.

2016-01-01

Purpose To examine the effects of subconcussive impacts resulting from a single season of youth (age range, 8–13 years) football on changes in specific white matter (WM) tracts as detected with diffusion-tensor imaging in the absence of clinically diagnosed concussions. Materials and Methods Head impact data were recorded by using the Head Impact Telemetry system and quantified as the combined-probability risk-weighted cumulative exposure (RWECP). Twenty-five male participants were evaluated for seasonal fractional anisotropy (FA) changes in specific WM tracts: the inferior fronto-occipital fasciculus (IFOF), inferior longitudinal fasciculus, and superior longitudinal fasciculus (SLF). Fiber tracts were segmented into a central core and two fiber terminals. The relationship between seasonal FA change in the whole fiber, central core, and the fiber terminals with RWECP was also investigated. Linear regression analysis was conducted to determine the association between RWECP and change in fiber tract FA during the season. Results There were statistically significant linear relationships between RWEcp and decreased FA in the whole (R2 = 0.433; P = .003), core (R2 = 0.3649; P = .007), and terminals (R2 = 0.5666; P < .001) of left IFOF. A trend toward statistical significance (P = .08) in right SLF was observed. A statistically significant correlation between decrease in FA of the right SLF terminal and RWECP was also observed (R2 = 0.2893; P = .028). Conclusion This study found a statistically significant relationship between head impact exposure and change of FAfractional anisotropy value of whole, core, and terminals of left IFOF and right SLF’s terminals where WM and gray matter intersect, in the absence of a clinically diagnosed concussion. © RSNA, 2016 PMID:27775478

Subconcussive Head Impact Exposure and White Matter Tract Changes over a Single Season of Youth Football.

PubMed

Bahrami, Naeim; Sharma, Dev; Rosenthal, Scott; Davenport, Elizabeth M; Urban, Jillian E; Wagner, Benjamin; Jung, Youngkyoo; Vaughan, Christopher G; Gioia, Gerard A; Stitzel, Joel D; Whitlow, Christopher T; Maldjian, Joseph A

2016-12-01

Purpose To examine the effects of subconcussive impacts resulting from a single season of youth (age range, 8-13 years) football on changes in specific white matter (WM) tracts as detected with diffusion-tensor imaging in the absence of clinically diagnosed concussions. Materials and Methods Head impact data were recorded by using the Head Impact Telemetry system and quantified as the combined-probability risk-weighted cumulative exposure (RWE CP ). Twenty-five male participants were evaluated for seasonal fractional anisotropy (FA) changes in specific WM tracts: the inferior fronto-occipital fasciculus (IFOF), inferior longitudinal fasciculus, and superior longitudinal fasciculus (SLF). Fiber tracts were segmented into a central core and two fiber terminals. The relationship between seasonal FA change in the whole fiber, central core, and the fiber terminals with RWE CP was also investigated. Linear regression analysis was conducted to determine the association between RWE CP and change in fiber tract FA during the season. Results There were statistically significant linear relationships between RWE cp and decreased FA in the whole (R 2 = 0.433; P = .003), core (R 2 = 0.3649; P = .007), and terminals (R 2 = 0.5666; P < .001) of left IFOF. A trend toward statistical significance (P = .08) in right SLF was observed. A statistically significant correlation between decrease in FA of the right SLF terminal and RWE CP was also observed (R 2 = 0.2893; P = .028). Conclusion This study found a statistically significant relationship between head impact exposure and change of FA fractional anisotropy value of whole, core, and terminals of left IFOF and right SLF's terminals where WM and gray matter intersect, in the absence of a clinically diagnosed concussion. © RSNA, 2016.

Decreased integrity of the fronto-temporal fibers of the left inferior occipito-frontal fasciculus associated with auditory verbal hallucinations in schizophrenia.

PubMed

Oestreich, Lena K L; McCarthy-Jones, Simon; Whitford, Thomas J

2016-06-01

Auditory verbal hallucinations (AVH) have been proposed to result from altered connectivity between frontal speech production regions and temporal speech perception regions. Whilst the dorsal language pathway, serviced by the arcuate fasciculus, has been extensively studied in relation to AVH, the ventral language pathway, serviced by the inferior occipito-frontal fasciculus (IOFF) has been rarely studied in relation to AVH. This study examined whether structural changes in anatomically defined subregions of the IOFF were associated with AVH in patients with schizophrenia. Diffusion tensor imaging scans and clinical data were obtained from the Australian Schizophrenia Research Bank for 113 schizophrenia patients, of whom 39 had lifetime experience of AVH (18 had current AVH, 21 had remitted AVH), 74 had no lifetime experience of AVH, and 40 healthy controls. Schizophrenia patients with a lifetime experience of AVH exhibited reduced fractional anisotropy (FA) in the fronto-temporal fibers of the left IOFF compared to both healthy controls and schizophrenia patients without AVH. In contrast, structural abnormalities in the temporal and occipital regions of the IOFF were observed bilaterally in both patient groups, relative to the healthy controls. These results suggest that while changes in the structural integrity of the bilateral IOFF are associated with schizophrenia per se, integrity reductions in the fronto-temporal fibers of the left IOFF may be specifically associated with AVH.

Occipital White Matter Tracts in Human and Macaque

PubMed Central

Takemura, Hiromasa; Pestilli, Franco; Weiner, Kevin S.; Landi, Sofia M.; Sliwa, Julia; Ye, Frank Q.; Barnett, Michael A.; Leopold, David A.; Freiwald, Winrich A.; Logothetis, Nikos K.; Wandell, Brian A.

2017-01-01

Abstract We compare several major white-matter tracts in human and macaque occipital lobe using diffusion magnetic resonance imaging. The comparison suggests similarities but also significant differences in the tracts. There are several apparently homologous tracts in the 2 species, including the vertical occipital fasciculus (VOF), optic radiation, forceps major, and inferior longitudinal fasciculus (ILF). There is one large human tract, the inferior fronto-occipital fasciculus, with no corresponding fasciculus in macaque. We could identify the macaque VOF (mVOF), which has been little studied. Its position is consistent with classical invasive anatomical studies by Wernicke. VOF homology is supported by similarity of the endpoints in V3A and ventral V4 across species. The mVOF fibers intertwine with the dorsal segment of the ILF, but the human VOF appears to be lateral to the ILF. These similarities and differences between the occipital lobe tracts will be useful in establishing which circuitry in the macaque can serve as an accurate model for human visual cortex. PMID:28369290

Restriction spectrum imaging reveals decreased neurite density in patients with temporal lobe epilepsy

PubMed Central

Loi, Richard Q.; Leyden, Kelly M.; Balachandra, Akshara; Uttarwar, Vedang; Hagler, Donald J.; Paul, Brianna M.; Dale, Anders M.; White, Nathan S.; McDonald, Carrie R.

2016-01-01

Objective Diffusion tensor imaging (DTI) has become a popular tool for delineating the location and extent of white matter injury in temporal lobe epilepsy (TLE). However, DTI yields nonspecific measures that are confounded by changes occurring within both the intracellular and extracellular environments. This study investigated whether an advanced diffusion method, restriction spectrum imaging (RSI) could provide a more robust measure of white matter injury in TLE relative to DTI due to RSI’s ability to separate intra-axonal diffusion (i.e., neurite density; ND) from diffusion associated with extra-axonal factors (e.g., inflammation; crossing fibers). Methods RSI and DTI scans were obtained on 21 patients with TLE and 11 age-matched controls. RSI-derived maps of ND, isotropic hindered (IH) and free (IF) water, and crossing fibers (CF) were compared to DTI-derived fractional anisotropy (FA) maps. Voxelwise and tract-based analyses were performed comparing patients with TLE to controls on each diffusion metric. Results Reductions in FA were seen primarily in frontotemporal white matter in TLE and were most pronounced proximal to the seizure focus. Reductions in ND corresponded to those seen in the FA maps; however, ND reductions were greater in magnitude, more lateralized to the epileptogenic hemisphere, and showed a broader pattern. Increases in IF/IH and effects from CFs also contributed to reduced FA in the ipsilateral parahippocampal cingulum and fornix, with decreases in IH extending into extratemporal regions. Reduced ND of the uncinate fasciculus was associated with longer disease duration, whereas FA was not associated with any clinical variables. Significance RSI may provide a more specific measure of white matter pathology in TLE, distinguishing regions primarily affected by axonal/myelin loss from those where CFs and increases in extracellular water also play a role. By providing a more specific measure of axonal/myelin loss, RSI-derived ND may better reflect overall white matter burden in epilepsy. PMID:27735051

Restriction spectrum imaging reveals decreased neurite density in patients with temporal lobe epilepsy.

PubMed

Loi, Richard Q; Leyden, Kelly M; Balachandra, Akshara; Uttarwar, Vedang; Hagler, Donald J; Paul, Brianna M; Dale, Anders M; White, Nathan S; McDonald, Carrie R

2016-11-01

Diffusion tensor imaging (DTI) has become a popular tool for delineating the location and extent of white matter injury in temporal lobe epilepsy (TLE). However, DTI yields nonspecific measures that are confounded by changes occurring within both the intracellular and extracellular environments. This study investigated whether an advanced diffusion method, restriction spectrum imaging (RSI) could provide a more robust measure of white matter injury in TLE relative to DTI due to RSI's ability to separate intraaxonal diffusion (i.e., neurite density; ND) from diffusion associated with extraaxonal factors (e.g., inflammation; crossing fibers). RSI and DTI scans were obtained on 21 patients with TLE and 11 age-matched controls. RSI-derived maps of ND, isotropic-hindered (IH) and isotropic-free (IF) water, and crossing fibers (CFs) were compared to DTI-derived fractional anisotropy (FA) maps. Voxelwise and tract-based analyses were performed comparing patients with TLE to controls on each diffusion metric. Reductions in FA were seen primarily in frontotemporal white matter in TLE, and they were most pronounced proximal to the seizure focus. Reductions in ND corresponded to those seen in the FA maps; however, ND reductions were greater in magnitude, more lateralized to the epileptogenic hemisphere, and showed a broader pattern. Increases in IF/IH and effects from CFs also contributed to reduced FA in the ipsilateral parahippocampal cingulum and fornix, with decreases in IH extending into extratemporal regions. Reduced ND of the uncinate fasciculus was associated with longer disease duration, whereas FA was not associated with any clinical variables. RSI may provide a more specific measure of white matter pathology in TLE, distinguishing regions primarily affected by axonal/myelin loss from those where CFs and increases in extracellular water also play a role. By providing a more specific measure of axonal/myelin loss, RSI-derived ND may better reflect overall white matter burden in epilepsy. Wiley Periodicals, Inc. © 2016 International League Against Epilepsy.

Emotion detection deficits and changes in personality traits linked to loss of white matter integrity in primary progressive aphasia.

PubMed

Multani, Namita; Galantucci, Sebastiano; Wilson, Stephen M; Shany-Ur, Tal; Poorzand, Pardis; Growdon, Matthew E; Jang, Jung Yun; Kramer, Joel H; Miller, Bruce L; Rankin, Katherine P; Gorno-Tempini, Maria Luisa; Tartaglia, Maria Carmela

2017-01-01

Non-cognitive features including personality changes are increasingly recognized in the three PPA variants (semantic-svPPA, non fluent-nfvPPA, and logopenic-lvPPA). However, differences in emotion processing among the PPA variants and its association with white matter tracts are unknown. We compared emotion detection across the three PPA variants and healthy controls (HC), and related them to white matter tract integrity and cortical degeneration. Personality traits in the PPA group were also examined in relation to white matter tracts. Thirty-three patients with svPPA, nfvPPA, lvPPA, and 32 HC underwent neuropsychological assessment, emotion evaluation task (EET), and MRI scan. Patients' study partners were interviewed on the Clinical Dementia Rating Scale (CDR) and completed an interpersonal traits assessment, the Interpersonal Adjective Scale (IAS). Diffusion tensor imaging of uncinate fasciculus (UF), superior longitudinal fasciculus (SLF) and inferior longitudinal fasciculus (ILF), and voxel-based morphometry to derive gray matter volumes for orbitofrontal cortex (OFC), anterior temporal lobe (ATL) regions were performed. In addition, gray matter volumes of white matter tract-associated regions were also calculated: inferior frontal gyrus (IFG), posterior temporal lobe (PTL), inferior parietal lobe (IPL) and occipital lobe (OL). ANCOVA was used to compare EET performance. Partial correlation and multivariate linear regression were conducted to examine association between EET and neuroanatomical regions affected in PPA. All three variants of PPA performed significantly worse than HC on EET, and the svPPA group was least accurate at recognizing emotions. Performance on EET was related to the right UF, SLF, and ILF integrity. Regression analysis revealed EET performance primarily relates to the right UF integrity. The IAS subdomain, cold-hearted, was also associated with right UF integrity. Disease-specific emotion recognition and personality changes occur in the three PPA variants and are likely associated with disease-specific neuroanatomical changes. Loss of white matter integrity contributes as significantly as focal atrophy in behavioral changes in PPA.

Intraoperative Subcortical Fiber Mapping with Subcortico-Cortical Evoked Potentials.

PubMed

Enatsu, Rei; Kanno, Aya; Ohtaki, Shunya; Akiyama, Yukinori; Ochi, Satoko; Mikuni, Nobuhiro

2016-02-01

During brain surgery, there are difficulties associated with identifying subcortical fibers with no clear landmarks. We evaluated the usefulness of cortical evoked potentials with subcortical stimuli (subcortico-cortical evoked potential [SCEP]) in identifying subcortical fibers intraoperatively. We used SCEP to identify the pyramidal tract in 4 patients, arcuate fasciculus in 1 patient, and both in 2 patients during surgical procedures. After resection, a 1 × 4-electrode plate was placed on the floor of the removal cavity and 1-Hz alternating electrical stimuli were delivered to this electrode. A 4 × 5 recording electrode plate was placed on the central cortical areas to map the pyramidal tract and temporoparietal cortical areas for the arcuate fasciculus. SCEPs were obtained by averaging electrocorticograms time locked to the stimulus onset. The subcortical stimulation within 15 mm of the target fiber induced cortical evoked potentials in the corresponding areas, whereas the stimulation apart from 20 mm did not. Five patients showed transient worsening of neurologic symptoms after surgery. However, all patients recovered. SCEP was useful for identifying subcortical fibers and confirmed the preservation of these fibers. This technique is expected to contribute to the effectiveness and safety of resective surgery in patients with lesions close to eloquent areas. Copyright © 2016 Elsevier Inc. All rights reserved.

Depressive symptoms and white matter dysfunction in retired NFL players with concussion history.

PubMed

Strain, Jeremy; Didehbani, Nyaz; Cullum, C Munro; Mansinghani, Sethesh; Conover, Heather; Kraut, Michael A; Hart, John; Womack, Kyle B

2013-07-02

To determine whether correlates of white matter integrity can provide general as well as specific insight into the chronic effects of head injury coupled with depression symptom expression in professional football players. We studied 26 retired National Football League (NFL) athletes who underwent diffusion tensor imaging (DTI) scanning. Depressive symptom severity was measured using the Beck Depression Inventory II (BDI-II) including affective, cognitive, and somatic subfactor scores (Buckley 3-factor model). Fractional anisotropy (FA) maps were processed using tract-based spatial statistics from FSL. Correlations between FA and BDI-II scores were assessed using both voxel-wise and region of interest (ROI) techniques, with ROIs that corresponded to white matter tracts. Tracts demonstrating significant correlations were further evaluated using a receiver operating characteristic curve that utilized the mean FA to distinguish depressed from nondepressed subjects. Voxel-wise analysis identified widely distributed voxels that negatively correlated with total BDI-II and cognitive and somatic subfactors, with voxels correlating with the affective component (p < 0.05 corrected) localized to frontal regions. Four tract ROIs negatively correlated (p < 0.01) with total BDI-II: forceps minor, right frontal aslant tract, right uncinate fasciculus, and left superior longitudinal fasciculus. FA of the forceps minor differentiated depressed from nondepressed athletes with 100% sensitivity and 95% specificity. Depressive symptoms in retired NFL athletes correlate negatively with FA using either an unbiased voxel-wise or an ROI-based, tract-wise approach. DTI is a promising biomarker for depression in this population.

A Whole-Brain Investigation of White Matter Microstructure in Adolescents with Conduct Disorder.

PubMed

Sarkar, Sagari; Dell'Acqua, Flavio; Froudist Walsh, Seán; Blackwood, Nigel; Scott, Stephen; Craig, Michael C; Deeley, Quinton; Murphy, Declan G M

2016-01-01

The biological basis of severe antisocial behaviour in adolescents is poorly understood. We recently reported that adolescents with conduct disorder (CD) have significantly increased fractional anisotropy (FA) of the uncinate fasciculus (a white matter (WM) tract that connects the amygdala to the frontal lobe) compared to their non-CD peers. However, the extent of WM abnormality in other brain regions is currently unclear. We used tract-based spatial statistics to investigate whole brain WM microstructural organisation in 27 adolescent males with CD, and 21 non-CD controls. We also examined relationships between FA and behavioural measures. Groups did not differ significantly in age, ethnicity, or substance use history. The CD group, compared to controls, had clusters of significantly greater FA in 7 brain regions corresponding to: 1) the bilateral inferior and superior cerebellar peduncles, corticopontocerebellar tract, posterior limb of internal capsule, and corticospinal tract; 2) right superior longitudinal fasciculus; and 3) left cerebellar WM. Severity of antisocial behavior and callous-unemotional symptoms were significantly correlated with FA in several of these regions across the total sample, but not in the CD or control groups alone. Adolescents with CD have significantly greater FA than controls in WM regions corresponding predominantly to the fronto-cerebellar circuit. There is preliminary evidence that variation in WM microstructure may be dimensionally related to behaviour problems in youngsters. These findings are consistent with the hypothesis that antisocial behaviour in some young people is associated with abnormalities in WM 'connectivity'.

White Matter Correlates of Auditory Comprehension Outcomes in Chronic Post-Stroke Aphasia

PubMed Central

Xing, Shihui; Lacey, Elizabeth H.; Skipper-Kallal, Laura M.; Zeng, Jinsheng; Turkeltaub, Peter E.

2017-01-01

Neuroimaging studies have shown that speech comprehension involves a number of widely distributed regions within the frontal and temporal lobes. We aimed to examine the differential contributions of white matter connectivity to auditory word and sentence comprehension in chronic post-stroke aphasia. Structural and diffusion MRI data were acquired on 40 patients with chronic post-stroke aphasia. A battery of auditory word and sentence comprehension tests were administered to all the patients. Tract-based spatial statistics were used to identify areas in which white matter integrity related to specific comprehension deficits. Relevant tracts were reconstructed using probabilistic tractography in healthy older participants, and the mean values of fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) of the entire tracts were examined in relation to comprehension scores. Anterior temporal white matter integrity loss and involvement of the uncinate fasciculus related to word-level comprehension deficits (RFA = 0.408, P = 0.012; RMD = −0.429, P = 0.008; RAD = −0.424, P = 0.009; RRD = −0.439, P = 0.007). Posterior temporal white matter integrity loss and involvement of the inferior longitudinal fasciculus related to sentence-level comprehension deficits (RFA = 0.382, P = 0.02; RMD = −0.461, P = 0.004; RAD = −0.457, P = 0.004; RRD = −0.453, P = 0.005). Loss of white matter integrity in the inferior fronto-occipital fasciculus related to both word- and sentence-level comprehension (word-level scores: RFA = 0.41, P = 0.012; RMD = −0.447, P = 0.006; RAD = −0.489, P = 0.002; RRD = −0.432, P = 0.008; sentence-level scores: RFA = 0.409, P = 0.012; RMD = −0.413, P = 0.011; RAD = −0.408, P = 0.012; RRD = −0.413, P = 0.011). Lesion overlap, but not white matter integrity, in the arcuate fasciculus related to sentence-level comprehension deficits. These findings suggest that word-level comprehension outcomes in chronic post-stroke aphasia rely primarily on anterior temporal lobe pathways, whereas sentence-level comprehension relies on more widespread pathways including the posterior temporal lobe. PMID:28275366

Neuroanatomical prerequisites for language functions in the maturing brain.

PubMed

Brauer, Jens; Anwander, Alfred; Friederici, Angela D

2011-02-01

The 2 major language-relevant cortical regions in the human brain, Broca's area and Wernicke's area, are connected via the fibers of the arcuate fasciculus/superior longitudinal fasciculus (AF/SLF). Here, we compared this pathway in adults and children and its relation to language processing during development. Comparison of fiber properties demonstrated lower anisotropy in children's AF/SLF, arguing for an immature status of this particular pathway with conceivably a lower degree of myelination. Combined diffusion tensor imaging (DTI) data and functional magnetic resonance imaging (fMRI) data indicated that in adults the termination of the AF/SLF fiber projection is compatible with functional activation in Broca's area, that is pars opercularis. In children, activation in Broca's area extended from the pars opercularis into the pars triangularis revealing an alternative connection to the temporal lobe (Wernicke's area) via the ventrally projecting extreme capsule fiber system. fMRI and DTI data converge to indicate that adults make use of a more confined language network than children based on ongoing maturation of the structural network. Our data suggest relations between language development and brain maturation and, moreover, indicate the brain's plasticity to adjust its function to available structural prerequisites.

Social cognition and the anterior temporal lobes: a review and theoretical framework

PubMed Central

McCoy, David; Klobusicky, Elizabeth; Ross, Lars A.

2013-01-01

Memory for people and their relationships, along with memory for social language and social behaviors, constitutes a specific type of semantic memory termed social knowledge. This review focuses on how and where social knowledge is represented in the brain. We propose that portions of the anterior temporal lobe (ATL) play a critical role in representing and retrieving social knowledge. This includes memory about people, their names and biographies and more abstract forms of social memory such as memory for traits and social concepts. This hypothesis is based on the convergence of several lines of research including anatomical findings, lesion evidence from both humans and non-human primates and neuroimaging evidence. Moreover, the ATL is closely interconnected with cortical nuclei of the amygdala and orbitofrontal cortex via the uncinate fasciculus. We propose that this pattern of connectivity underlies the function of the ATL in encoding and storing emotionally tagged knowledge that is used to guide orbitofrontal-based decision processes. PMID:23051902

Reduced prefrontal connectivity in psychopathy.

PubMed

Motzkin, Julian C; Newman, Joseph P; Kiehl, Kent A; Koenigs, Michael

2011-11-30

Linking psychopathy to a specific brain abnormality could have significant clinical, legal, and scientific implications. Theories on the neurobiological basis of the disorder typically propose dysfunction in a circuit involving ventromedial prefrontal cortex (vmPFC). However, to date there is limited brain imaging data to directly test whether psychopathy may indeed be associated with any structural or functional abnormality within this brain area. In this study, we employ two complementary imaging techniques to assess the structural and functional connectivity of vmPFC in psychopathic and non-psychopathic criminals. Using diffusion tensor imaging, we show that psychopathy is associated with reduced structural integrity in the right uncinate fasciculus, the primary white matter connection between vmPFC and anterior temporal lobe. Using functional magnetic resonance imaging, we show that psychopathy is associated with reduced functional connectivity between vmPFC and amygdala as well as between vmPFC and medial parietal cortex. Together, these data converge to implicate diminished vmPFC connectivity as a characteristic neurobiological feature of psychopathy.

Reduced Prefrontal Connectivity in Psychopathy

PubMed Central

Motzkin, Julian C.; Newman, Joseph P.; Kiehl, Kent A.; Koenigs, Michael

2012-01-01

Linking psychopathy to a specific brain abnormality could have significant clinical, legal, and scientific implications. Theories on the neurobiological basis of the disorder typically propose dysfunction in a circuit involving ventromedial prefrontal cortex (vmPFC). However, to date there is limited brain imaging data to directly test whether psychopathy may indeed be associated with any structural or functional abnormality within this brain area. In this study, we employ two complementary imaging techniques to assess the structural and functional connectivity of vmPFC in psychopathic and non-psychopathic criminals. Using diffusion tensor imaging, we show that psychopathy is associated with reduced structural integrity in the right uncinate fasciculus, the primary white matter connection between vmPFC and anterior temporal lobe. Using functional magnetic resonance imaging, we show that psychopathy is associated with reduced functional connectivity between vmPFC and amygdala as well as between vmPFC and medial parietal cortex. Together, these data converge to implicate diminished vmPFC connectivity as a characteristic neurobiological feature of psychopathy. PMID:22131397

Pattern of structural brain changes in social anxiety disorder after cognitive behavioral group therapy: a longitudinal multimodal MRI study.

PubMed

Steiger, V R; Brühl, A B; Weidt, S; Delsignore, A; Rufer, M; Jäncke, L; Herwig, U; Hänggi, J

2017-08-01

Social anxiety disorder (SAD) is characterized by fears of social and performance situations. Cognitive behavioral group therapy (CBGT) has in general positive effects on symptoms, distress and avoidance in SAD. Prior studies found increased cortical volumes and decreased fractional anisotropy (FA) in SAD compared with healthy controls (HCs). Thirty-three participants diagnosed with SAD attended in a 10-week CBGT and were scanned before and after therapy. We applied three neuroimaging methods-surface-based morphometry, diffusion tensor imaging and network-based statistics-each with specific longitudinal processing protocols, to investigate CBGT-induced structural brain alterations of the gray and white matter (WM). Surface-based morphometry revealed a significant cortical volume reduction (pre- to post-treatment) in the left inferior parietal cortex, as well as a positive partial correlation between treatment success (indexed by reductions in Liebowitz Social Anxiety Scale) and reductions in cortical volume in bilateral dorsomedial prefrontal cortex. Diffusion tensor imaging analysis revealed a significant increase in FA in bilateral uncinate fasciculus and right inferior longitudinal fasciculus. Network-based statistics revealed a significant increase of structural connectivity in a frontolimbic network. No partial correlations with treatment success have been found in WM analyses. For, we believe, the first time, we present a distinctive pattern of longitudinal structural brain changes after CBGT measured with three established magnetic resonance imaging analyzing techniques. Our findings are in line with previous cross-sectional, unimodal SAD studies and extent them by highlighting anatomical brain alterations that point toward the level of HCs in parallel with a reduction in SAD symptomatology.

Comparison of Single-Shot Echo-Planar and Line Scan Protocols for Diffusion Tensor Imaging1

PubMed Central

Kubicki, Marek; Maier, Stephan E.; Westin, Carl-Frederik; Mamata, Hatsuho; Ersner-Hershfield, Hal; Estepar, Raul; Kikinis, Ron; Jolesz, Ferenc A.

2009-01-01

Rationale and Objectives Both single-shot diffusion-weighted echo-planar imaging (EPI) and line scan diffusion imaging (LSDI) can be used to obtain magnetic resonance diffusion tensor data and to calculate directionally invariant diffusion anisotropy indices, ie, indirect measures of the organization and coherence of white matter fibers in the brain. To date, there has been no comparison of EPI and LSDI. Because EPI is the most commonly used technique for acquiring diffusion tensor data, it is important to understand the limitations and advantages of LSDI relative to EPI. Materials and Methods Five healthy volunteers underwent EPI and LSDI diffusion on a 1.5 Tesla magnet (General Electric Medical Systems, Milwaukee, WI). Four-mm thick coronal sections, covering the entire brain, were obtained. In addition, one subject was tested with both sequences over four sessions. For each image voxel, eigenvectors and eigenvalues of the diffusion tensor were calculated, and fractional anisotropy (FA) was derived. Several regions of interest were delineated, and for each, mean FA and estimated mean standard deviation were calculated and compared. Results Results showed no significant differences between EPI and LSDI for mean FA for the five subjects. When inter-session reproducibility for one subject was evaluated, there was a significant difference between EPI and LSDI in FA for the corpus callosum and the right uncinate fasciculus. Moreover, errors associated with each FA measure were larger for EPI than for LSDI. Conclusion Results indicate that both EPI- and LSDI-derived FA measures are sufficiently robust. However, when higher accuracy is needed, LSDI provides smaller error and smaller inter-subject and inter-session variability than EPI. PMID:14974598

Longitudinal changes in white matter integrity among adolescent substance users.

PubMed

Bava, Sunita; Jacobus, Joanna; Thayer, Rachel E; Tapert, Susan F

2013-01-01

The influence of repeated substance use during adolescent neurodevelopment remains unclear as there have been few prospective investigations. The aims of this study were to identify longitudinal changes in fiber tract integrity associated with alcohol- and marijuana-use severity over the course of 1.5 years. Adolescents with extensive marijuana- and alcohol-use histories by mid-adolescence (n = 41) and youth with consistently minimal if any substance use (n = 51) were followed over 18 months. Teens received diffusion tensor imaging and detailed substance-use assessments with toxicology screening at baseline and 18-month follow-ups (i.e., 182 scans in all), as well as interim substance-use interviews each 6 months. At an 18-month follow-up, substance users showed poorer white matter integrity in 7 tracts: (i) right superior longitudinal fasciculus, (ii) left superior longitudinal fasciculus, (iii) right posterior thalamic radiations, (iv) right prefrontal thalamic fibers, (v) right superior temporal gyrus white matter, (vi) right inferior longitudinal fasciculus, and (vii) left posterior corona radiata (ps < 0.01). More alcohol use during the interscan interval predicted higher mean diffusivity (i.e., worsened integrity) in right (p < 0.05) and left (p = 0.06) superior longitudinal fasciculi, above and beyond baseline values in these bundles. Marijuana use during the interscan interval did not predict change over time. More externalizing behaviors at Time 1 predicted lower fractional anisotropy and higher radial diffusivity (i.e., poorer integrity) of the right prefrontal thalamic fibers (p < 0.025). Findings add to previous cross-sectional studies reporting white matter disadvantages in youth with substance-use histories. In particular, alcohol use during adolescent neurodevelopment may be linked to reductions in white matter quality in association fiber tracts with frontal connections. In contrast, youth who engage in a variety of risk-taking behaviors may have unique neurodevelopmental trajectories characterized by truncated development in fronto-thalamic tracts, which could have functional and clinical consequences in young adulthood. Copyright © 2012 by the Research Society on Alcoholism.

Aging-Resilient Associations between the Arcuate Fasciculus and Vocabulary Knowledge: Microstructure or Morphology?

PubMed Central

Vaden, Kenneth I.; Cute, Stephanie L.; Yeatman, Jason D.; Dougherty, Robert F.

2016-01-01

Vocabulary knowledge is one of the few cognitive functions that is relatively preserved in older adults, but the reasons for this relative preservation have not been well delineated. We tested the hypothesis that individual differences in vocabulary knowledge are influenced by arcuate fasciculus macrostructure (i.e., shape and volume) properties that remain stable during the aging process, rather than white matter microstructure that demonstrates age-related declines. Vocabulary was not associated with age compared to pronounced age-related declines in cognitive processing speed across 106 healthy adults (19.92–88.29 years) who participated in this neuroimaging experiment. Fractional anisotropy in the left arcuate fasciculus was significantly related to individual variability in vocabulary. This effect was present despite marked age-related differences in a T1-weighted/T2-weighted ratio (T1w/T2w) estimate of myelin that were observed throughout the left arcuate fasciculus and associated with age-related differences in cognitive processing speed. However, atypical patterns of arcuate fasciculus morphology or macrostructure were associated with decreased vocabulary knowledge. These results suggest that deterioration of tissue in the arcuate fasciculus occurs with normal aging, while having limited impact on tract organization that underlies individual differences in the acquisition and retrieval of lexical and semantic information. SIGNIFICANCE STATEMENT Vocabulary knowledge is resilient to widespread age-related declines in brain structure that limit other cognitive functions. We tested the hypothesis that arcuate fasciculus morphology, which supports the development of reading skills that bolster vocabulary, could explain this relative preservation. We disentangled (1) the effects of age-related declines in arcuate microstructure (mean diffusivity; myelin content estimate) that predicted cognitive processing speed but not vocabulary, from (2) relatively stable arcuate macrostructure (shape/volume) that explained significant variance in an age-independent association between fractional anisotropy and vocabulary. This latter result may reflect differences in fiber trajectory and organization that are resilient to aging. We propose that developmental sculpting of the arcuate fasciculus determines acquisition, storage, and access of lexical information across the adult lifespan. PMID:27383595

Analyses of Disruption of Cerebral White Matter Integrity in Schizophrenia with MR Diffusion Tensor Fiber Tracking Method

NASA Astrophysics Data System (ADS)

Yamamoto, Utako; Kobayashi, Tetsuo; Kito, Shinsuke; Koga, Yoshihiko

We have analyzed cerebral white matter using magnetic resonance diffusion tensor imaging (MR-DTI) to measure the diffusion anisotropy of water molecules. The goal of this study is the quantitative evaluation of schizophrenia. Diffusion tensor images are acquired for patients with schizophrenia and healthy comparison subjects, group-matched for age, sex, and handedness. Fiber tracking is performed on the superior longitudinal fasciculus for the comparison between the patient and comparison groups. We have analysed and compared the cross-sectional area on the starting coronal plane and the mean and standard deviation of the fractional anisotropy and the apparent diffusion coefficient along fibers in the right and left hemispheres. In the right hemisphere, the cross-sectional areas in patient group are significantly smaller than those in the comparison group. Furthermore, in the comparison group, the cross-sectional areas in the right hemisphere are significantly larger than those in the left hemisphere, whereas there is no significant difference in the patient group. These results suggest that we may evaluate the disruption in white matter integrity in schizophrenic patients quantitatively by comparing the cross-sectional area of the superior longitudinal fasciculus in the right and left hemispheres.

Anatomical variations of uncinate process observed in chronic sinusitis.

PubMed

Tuli, Isha Preet; Sengupta, Subhabrata; Munjal, Sudeep; Kesari, Santosh Prasad; Chakraborty, Suvamoy

2013-04-01

Chronic Sinusitis, an extremely persistent illness, is surgically best treated by Functional Endoscopic Sinus Surgery. The ostiomeatal complex is the main area targeted and within it uncinate process is the first anatomical structure encountered. The significance of anatomical variations concerning age and sex of uncinate process in chronic sinusitis were evaluated. A prospective study on 50 patients of chronic sinusitis (100 uncinate processes) was done. The results were tabulated and analyzed using Statistical Package for Social Science (SPSS) 16.0. Type I superior attachment of uncinate process (67 %) was the most common variety in all ages and both sexes and a statistically significant relationship between Type I superior attachment of uncinate process and sex was found (p < 0.05). The typical uncinate process was most common (70 %) followed by medial deviation of the uncinate (24 %). This difference in occurrence was significant with respect to both age and sex (p < 0.05). Anatomical variations of uncinate process are not responsible for causing chronic sinusitis. Mere presence of these variations of uncinate is not an indication for FESS.

Decreased white matter integrity in fronto-occipital fasciculus bundles: relation to visual information processing in alcohol-dependent subjects.

PubMed

Bagga, Deepika; Sharma, Aakansha; Kumari, Archana; Kaur, Prabhjot; Bhattacharya, Debajyoti; Garg, Mohan Lal; Khushu, Subash; Singh, Namita

2014-02-01

Chronic alcohol abuse is characterized by impaired cognitive abilities with a more severe deficit in visual than in verbal functions. Neuropathologically, it is associated with widespread brain structural compromise marked by gray matter shrinkage, ventricular enlargement, and white matter degradation. The present study sought to increase current understanding of the impairment of visual processing abilities in alcohol-dependent subjects, and its correlation with white matter microstructural alterations, using diffusion tensor imaging (DTI). To that end, a DTI study was carried out on 35 alcohol-dependent subjects and 30 healthy male control subjects. Neuropsychological tests were assessed for visual processing skills and deficits were reported as raw dysfunction scores (rDyS). Reduced FA (fractional anisotropy) and increased MD (mean diffusivity) were observed bilaterally in inferior and superior fronto-occipital fasciculus (FOF) fiber bundles. A significant inverse correlation in rDyS and FA values was observed in these fiber tracts whereas a positive correlation of these scores was found with the MD values. Our results suggest that FOF fiber bundles linking the frontal lobe to occipital lobe might be related to visual processing skills. This is the first report of an alteration of the white matter microstructure of FOF fiber bundles that might have functional consequences for visual processing in alcohol-dependent subjects who exhibit no neurological complications. Copyright © 2014 Elsevier Inc. All rights reserved.

White Matter Microstructure in Superior Longitudinal Fasciculus Associated with Spatial Working Memory Performance in Children

ERIC Educational Resources Information Center

Vestergaard, Martin; Madsen, Kathrine Skak; Baare, William F. C.; Skimminge, Arnold; Ejersbo, Lisser Rye; Ramsoy, Thomas Z.; Gerlach, Christian; Akeson, Per; Paulson, Olaf B.; Jernigan, Terry L.

2011-01-01

During childhood and adolescence, ongoing white matter maturation in the fronto-parietal cortices and connecting fiber tracts is measurable with diffusion-weighted imaging. Important questions remain, however, about the links between these changes and developing cognitive functions. Spatial working memory (SWM) performance improves significantly…

Frontal networks in adults with autism spectrum disorder.

PubMed

Catani, Marco; Dell'Acqua, Flavio; Budisavljevic, Sanja; Howells, Henrietta; Thiebaut de Schotten, Michel; Froudist-Walsh, Seán; D'Anna, Lucio; Thompson, Abigail; Sandrone, Stefano; Bullmore, Edward T; Suckling, John; Baron-Cohen, Simon; Lombardo, Michael V; Wheelwright, Sally J; Chakrabarti, Bhismadev; Lai, Meng-Chuan; Ruigrok, Amber N V; Leemans, Alexander; Ecker, Christine; Consortium, Mrc Aims; Craig, Michael C; Murphy, Declan G M

2016-02-01

It has been postulated that autism spectrum disorder is underpinned by an 'atypical connectivity' involving higher-order association brain regions. To test this hypothesis in a large cohort of adults with autism spectrum disorder we compared the white matter networks of 61 adult males with autism spectrum disorder and 61 neurotypical controls, using two complementary approaches to diffusion tensor magnetic resonance imaging. First, we applied tract-based spatial statistics, a 'whole brain' non-hypothesis driven method, to identify differences in white matter networks in adults with autism spectrum disorder. Following this we used a tract-specific analysis, based on tractography, to carry out a more detailed analysis of individual tracts identified by tract-based spatial statistics. Finally, within the autism spectrum disorder group, we studied the relationship between diffusion measures and autistic symptom severity. Tract-based spatial statistics revealed that autism spectrum disorder was associated with significantly reduced fractional anisotropy in regions that included frontal lobe pathways. Tractography analysis of these specific pathways showed increased mean and perpendicular diffusivity, and reduced number of streamlines in the anterior and long segments of the arcuate fasciculus, cingulum and uncinate--predominantly in the left hemisphere. Abnormalities were also evident in the anterior portions of the corpus callosum connecting left and right frontal lobes. The degree of microstructural alteration of the arcuate and uncinate fasciculi was associated with severity of symptoms in language and social reciprocity in childhood. Our results indicated that autism spectrum disorder is a developmental condition associated with abnormal connectivity of the frontal lobes. Furthermore our findings showed that male adults with autism spectrum disorder have regional differences in brain anatomy, which correlate with specific aspects of autistic symptoms. Overall these results suggest that autism spectrum disorder is a condition linked to aberrant developmental trajectories of the frontal networks that persist in adult life. © The Author (2016). Published by Oxford University Press on behalf of the Guarantors of Brain.

Alterations of neocortico-limbic association fibers and correlation with diet in prediabetes diagnosed by impaired fasting glucose.

PubMed

Hou, Yi-Cheng; Yang, Shwu-Huey; Wu, Yu-Te; Lai, Chien-Han

2016-06-01

To assess the existence of alterations in the micro-integrity of the fasciculus in prediabetic subjects. The issue of micro-integrity in white matter tracts has not been adequately addressed in prediabetes. Sixty-four prediabetic subjects and 54 controls were enrolled. All participants completed 24-hour diet records and 3-day diet records and received diffusion tensor imaging at 3T. The data for white matter micro-integrity were analyzed and compared between prediabetic subjects and controls with age and gender as covariates. In addition, voxel-wise regression between white matter micro-integrity, diet, and preprandial glucose levels were used to explore the relationship between white matter micro-integrity and diet or serum glucose levels. We found that prediabetic subjects had significant reductions in the micro-integrity of bilateral anterior thalamic radiation, left inferior longitudinal fasciculus, and left superior longitudinal fasciculus (corrected P < 0.05). In addition, total carbohydrate intake amount and preprandial serum glucose levels were negatively correlated with the micro-integrity in the left inferior longitudinal fasciculus and left anterior thalamic radiation (r: -0.47, corrected P < 0.05). Restrictive alterations in the white matter micro-integrity of the anterior thalamic radiation and inferior and superior longitudinal fasciculi might represent the initial "hot spots" for white matter tract alterations, which might play a role in the development of prediabetes. J. Magn. Reson. Imaging 2016;43:1500-1506. © 2016 Wiley Periodicals, Inc.

Childhood maltreatment moderates the effect of combat exposure on cingulum structural integrity

PubMed Central

BANIHASHEMI, LAYLA; WALLACE, MEREDITH L.; SHEU, LEI K.; LEE, MICHAEL C.; GIANAROS, PETER J.; MACKENZIE, ROBERT P.; INSANA, SALVATORE P.; GERMAIN, ANNE; HERRINGA, RYAN J.

2017-01-01

Limbic white matter pathways link emotion, cognition, and behavior and are potentially malleable to the influences of traumatic events throughout development. However, the impact of interactions between childhood and later life trauma on limbic white matter pathways has yet to be examined. Here, we examined whether childhood maltreatment moderated the effect of combat exposure on diffusion tensor imaging measures within a sample of military veterans (N = 28). We examined five limbic tracts of interest: two components of the cingulum (cingulum, cingulate gyrus, and cingulum hippocampus [CGH]), the uncinate fasciculus, the fornix/stria terminalis, and the anterior limb of the internal capsule. Using effect sizes, clinically meaningful moderator effects were found only within the CGH. Greater combat exposure was associated with decreased CGH fractional anisotropy (overall structural integrity) and increased CGH radial diffusivity (perpendicular water diffusivity) among individuals with more severe childhood maltreatment. Our findings provide preliminary evidence of the moderating effect of childhood maltreatment on the relationship between combat exposure and CGH structural integrity. These differences in CGH structural integrity could have maladaptive implications for emotion and memory, as well as provide a potential mechanism by which childhood maltreatment induces vulnerability to later life trauma exposure. PMID:29162178

Individual structural differences in left inferior parietal area are associated with schoolchildrens' arithmetic scores

PubMed Central

Li, Yongxin; Hu, Yuzheng; Wang, Yunqi; Weng, Jian; Chen, Feiyan

2013-01-01

Arithmetic skill is of critical importance for academic achievement, professional success and everyday life, and childhood is the key period to acquire this skill. Neuroimaging studies have identified that left parietal regions are a key neural substrate for representing arithmetic skill. Although the relationship between functional brain activity in left parietal regions and arithmetic skill has been studied in detail, it remains unclear about the relationship between arithmetic achievement and structural properties in left inferior parietal area in schoolchildren. The current study employed a combination of voxel-based morphometry (VBM) for high-resolution T1-weighted images and fiber tracking on diffusion tensor imaging (DTI) to examine the relationship between structural properties in the inferior parietal area and arithmetic achievement in 10-year-old schoolchildren. VBM of the T1-weighted images revealed that individual differences in arithmetic scores were significantly and positively correlated with the gray matter (GM) volume in the left intraparietal sulcus (IPS). Fiber tracking analysis revealed that the forceps major, left superior longitudinal fasciculus (SLF), bilateral inferior longitudinal fasciculus (ILF) and inferior fronto-occipital fasciculus (IFOF) were the primary pathways connecting the left IPS with other brain areas. Furthermore, the regression analysis of the probabilistic pathways revealed a significant and positive correlation between the fractional anisotropy (FA) values in the left SLF, ILF and bilateral IFOF and arithmetic scores. The brain structure-behavior correlation analyses indicated that the GM volumes in the left IPS and the FA values in the tract pathways connecting left IPS were both related to children's arithmetic achievement. The present findings provide evidence that individual structural differences in the left IPS are associated with arithmetic scores in schoolchildren. PMID:24367320

Testing the connections within face processing circuitry in Capgras delusion with diffusion imaging tractography

PubMed Central

Bobes, Maria A.; Góngora, Daylin; Valdes, Annette; Santos, Yusniel; Acosta, Yanely; Fernandez Garcia, Yuriem; Lage, Agustin; Valdés-Sosa, Mitchell

2016-01-01

Although Capgras delusion (CD) patients are capable of recognizing familiar faces, they present a delusional belief that some relatives have been replaced by impostors. CD has been explained as a selective disruption of a pathway processing affective values of familiar faces. To test the integrity of connections within face processing circuitry, diffusion tensor imaging was performed in a CD patient and 10 age-matched controls. Voxel-based morphometry indicated gray matter damage in right frontal areas. Tractography was used to examine two important tracts of the face processing circuitry: the inferior fronto-occipital fasciculus (IFOF) and the inferior longitudinal (ILF). The superior longitudinal fasciculus (SLF) and commissural tracts were also assessed. CD patient did not differ from controls in the commissural fibers, or the SLF. Right and left ILF, and right IFOF were also equivalent to those of controls. However, the left IFOF was significantly reduced respect to controls, also showing a significant dissociation with the ILF, which represents a selective impairment in the fiber-tract connecting occipital and frontal areas. This suggests a possible involvement of the IFOF in affective processing of faces in typical observers and in covert recognition in some cases with prosopagnosia. PMID:26909325

Decreased Number of Self-Paced Saccades in Post-Concussion Syndrome Associated with Higher Symptom Burden and Reduced White Matter Integrity.

PubMed

Taghdiri, Foad; Chung, Jonathan; Irwin, Samantha; Multani, Namita; Tarazi, Apameh; Ebraheem, Ahmed; Khodadadi, Mozghan; Goswami, Ruma; Wennberg, Richard; Mikulis, David; Green, Robin; Davis, Karen; Tator, Charles; Eizenman, Moshe; Tartaglia, Maria Carmela

2018-03-01

The aim of this study was to examine the potential utility of a self-paced saccadic eye movement as a marker of post-concussion syndrome (PCS) and monitoring the recovery from PCS. Fifty-nine persistently symptomatic participants with at least two concussions performed the self-paced saccade (SPS) task. We evaluated the relationships between the number of SPSs and 1) number of self-reported concussion symptoms, and 2) integrity of major white matter (WM) tracts (as measured by fractional anisotropy [FA] and mean diffusivity) that are directly or indirectly involved in saccadic eye movements and often affected by concussion. These tracts included the uncinate fasciculus (UF), cingulum (Cg) and its three subcomponents (subgenual, retrosplenial, and parahippocampal), superior longitudinal fasciculus, and corpus callosum. Mediation analyses were carried out to examine whether specific WM tracts (left UF and left subgenual Cg) mediated the relationship between the number of SPSs and 1) interval from last concussion or 2) total number of self-reported symptoms. The number of SPSs was negatively correlated with the total number of self-reported symptoms (r = -0.419, p = 0.026). The number of SPSs were positively correlated with FA of left UF and left Cg (r = 0.421, p = 0.013 and r = 0.452, p = 0.008; respectively). FA of the subgenual subcomponent of the left Cg partially mediated the relationship between the total number of symptoms and the number of SPSs, while FA of the left UF mediated the relationship between interval from last concussion and the number of SPSs. In conclusion, SPS testing as a fast and objective assessment may reflect symptom burden in patients with PCS. In addition, since the number of SPSs is associated with the integrity of some WM tracts, it may be useful as a diagnostic biomarker in patients with PCS.

White matter microstructural abnormalities in the frontal lobe of adults with antisocial personality disorder.

PubMed

Sundram, Frederick; Deeley, Quinton; Sarkar, Sagari; Daly, Eileen; Latham, Richard; Craig, Michael; Raczek, Malgorzata; Fahy, Tom; Picchioni, Marco; Barker, Gareth J; Murphy, Declan G M

2012-02-01

Antisocial personality disorder (ASPD) and psychopathy involve significant interpersonal and behavioural impairments. However, little is known about their underlying neurobiology and in particular, abnormalities in white matter (WM) microstructure. A preliminary diffusion tensor magnetic resonance imaging (DT-MRI) study of adult psychopaths employing tractography revealed abnormalities in the right uncinate fasciculus (UF) (Craig et al., 2009), indicating fronto-limbic disconnectivity. However, it is not clear whether WM abnormalities are restricted to this tract or are or more widespread, including other tracts which are involved in connectivity with the frontal lobe. We performed whole brain voxel-based analyses on WM fractional anisotropy (FA) and mean diffusivity (MD) maps acquired with DT-MRI to compare 15 adults with ASPD and healthy age, handedness and IQ-matched controls. Also, within ASPD subjects we related differences in FA and MD to measures of psychopathy. Significant WM FA reduction and MD increases were found respectively in ASPD subjects relative to controls. FA was bilaterally reduced in the genu of corpus callosum while in the right frontal lobe FA reduction was found in the UF, inferior fronto-occipital fasciculus (IFOF), anterior corona radiata and anterior limb and genu of the internal capsule. These differences negatively correlated with measures of psychopathy. Also in the right frontal lobe, increased MD was found in the IFOF and UF, and the corpus callosum and anterior corona radiata. There was a significant positive correlation between MD and psychopathy scores. The present study confirms a previous report of reduced FA in the UF. Additionally, we report for the first time, FA deficits in tracts involved in interhemispheric as well as frontal lobe connectivity in conjunction with MD increases in the frontal lobe. Hence, we provide evidence of significant WM microstructural abnormalities in frontal brain regions in ASPD and psychopathy. Copyright © 2011 Elsevier Srl. All rights reserved.

Right arcuate fasciculus abnormality in chronic fatigue syndrome.

PubMed

Zeineh, Michael M; Kang, James; Atlas, Scott W; Raman, Mira M; Reiss, Allan L; Norris, Jane L; Valencia, Ian; Montoya, Jose G

2015-02-01

To identify whether patients with chronic fatigue syndrome (CFS) have differences in gross brain structure, microscopic structure, or brain perfusion that may explain their symptoms. Fifteen patients with CFS were identified by means of retrospective review with an institutional review board-approved waiver of consent and waiver of authorization. Fourteen age- and sex-matched control subjects provided informed consent in accordance with the institutional review board and HIPAA. All subjects underwent 3.0-T volumetric T1-weighted magnetic resonance (MR) imaging, with two diffusion-tensor imaging (DTI) acquisitions and arterial spin labeling (ASL). Open source software was used to segment supratentorial gray and white matter and cerebrospinal fluid to compare gray and white matter volumes and cortical thickness. DTI data were processed with automated fiber quantification, which was used to compare piecewise fractional anisotropy (FA) along 20 tracks. For the volumetric analysis, a regression was performed to account for differences in age, handedness, and total intracranial volume, and for the DTI, FA was compared piecewise along tracks by using an unpaired t test. The open source software segmentation was used to compare cerebral blood flow as measured with ASL. In the CFS population, FA was increased in the right arcuate fasciculus (P = .0015), and in right-handers, FA was also increased in the right inferior longitudinal fasciculus (ILF) (P = .0008). In patients with CFS, right anterior arcuate FA increased with disease severity (r = 0.649, P = .026). Bilateral white matter volumes were reduced in CFS (mean ± standard deviation, 467 581 mm(3) ± 47 610 for patients vs 504 864 mm(3) ± 68 126 for control subjects, P = .0026), and cortical thickness increased in both right arcuate end points, the middle temporal (T = 4.25) and precentral (T = 6.47) gyri, and one right ILF end point, the occipital lobe (T = 5.36). ASL showed no significant differences. Bilateral white matter atrophy is present in CFS. No differences in perfusion were noted. Right hemispheric increased FA may reflect degeneration of crossing fibers or strengthening of short-range fibers. Right anterior arcuate FA may serve as a biomarker for CFS. (©) RSNA, 2014.

Tractography for Optic Radiation Preservation in Transcortical Approaches to Intracerebral Lesions.

PubMed

Agarwal, Vijay; Malcolm, James G; Pradilla, Gustavo; Barrow, Daniel L

2017-09-28

We present a case of intraventricular meningioma resected via a transcortical approach using tractography for optic radiation and arcuate fasciculus preservation. We include a review of the literature. A 54-year-old woman with a history of breast cancer presented with gait imbalance. Workup revealed a mass in the atrium of the left lateral ventricle consistent with a meningioma. Whole brain automated diffusion tensor imaging (DTI) was used to plan a transcortical resection while sparing the optic radiations and arcuate fasciculus. A left posterior parietal craniotomy was performed using the Synaptive BrightMatter™ frameless navigation (Synaptive Medical, Toronto, Canada) to minimally disrupt the white matter pathways. A gross total resection was achieved. Postoperatively, the patient had temporary right upper extremity weakness, which improved, and her visual fields and speech remained intact. Pathology confirmed a World Health Organization (WHO) Grade I meningothelial meningioma. While a thorough understanding of cortical anatomy is essential for safe resection of eloquent or deep-seated lesions, significant variability in fiber bundles, such as optic radiations and the arcuate fasciculus, necessitates a more individualized understanding of a patient's potential surgical risk. The addition of enhanced DTI to the neurosurgeon's armamentarium may allow for more complete resections of difficult intracerebral lesions while minimizing complications, such as visual deficit.

Correlation between language function and the left arcuate fasciculus detected by diffusion tensor imaging tractography after brain tumor surgery.

PubMed

Hayashi, Yutaka; Kinoshita, Masashi; Nakada, Mitsutoshi; Hamada, Jun-ichiro

2012-11-01

Disturbance of the arcuate fasciculus in the dominant hemisphere is thought to be associated with language-processing disorders, including conduction aphasia. Although the arcuate fasciculus can be visualized in vivo with diffusion tensor imaging (DTI) tractography, its involvement in functional processes associated with language has not been shown dynamically using DTI tractography. In the present study, to clarify the participation of the arcuate fasciculus in language functions, postoperative changes in the arcuate fasciculus detected by DTI tractography were evaluated chronologically in relation to postoperative changes in language function after brain tumor surgery. Preoperative and postoperative arcuate fasciculus area and language function were examined in 7 right-handed patients with a brain tumor in the left hemisphere located in proximity to part of the arcuate fasciculus. The arcuate fasciculus was depicted, and its area was calculated using DTI tractography. Language functions were measured using the Western Aphasia Battery (WAB). After tumor resection, visualization of the arcuate fasciculus was increased in 5 of the 7 patients, and the total WAB score improved in 6 of the 7 patients. The relative ratio of postoperative visualized area of the arcuate fasciculus to preoperative visualized area of the arcuate fasciculus was increased in association with an improvement in postoperative language function (p = 0.0039). The role of the left arcuate fasciculus in language functions can be evaluated chronologically in vivo by DTI tractography after brain tumor surgery. Because increased postoperative visualization of the fasciculus was significantly associated with postoperative improvement in language functions, the arcuate fasciculus may play an important role in language function, as previously thought. In addition, postoperative changes in the arcuate fasciculus detected by DTI tractography could represent a predicting factor for postoperative language-dependent functional outcomes in patients with brain tumor.

Presence of lacunar infarctions is associated with the spatial navigation impairment in patients with mild cognitive impairment: a DTI study

PubMed Central

Liu, Qing-Ping; He, Wen-Wen; Ding, Hong; Nedelska, Zuzana; Hort, Jakub; Zhang, Bing; Xu, Yun

2016-01-01

Lacunar cerebral infarction (LI) is one of risk factors of vascular dementia and correlates with progression of cognitive impairment including the executive functions. However, little is known on spatial navigation impairment and its underlying microstructural alteration of white matter in patients with LI and with or without mild cognitive impairment (MCI). Our aim was to investigate whether the spatial navigation impairment correlated with the white matter integrity in LI patients with MCI (LI-MCI). Thirty patients with LI were included in the study and were divided into LI-MCI (n=17) and non MCI (LI-Non MCI) groups (n=13) according neuropsychological tests.The microstructural integrity of white matter was assessed by calculating a fractional anisotropy (FA) and mean diffusivity (MD) from diffusion tensor imaging (DTI) scans. The spatial navigation accuracy, separately evaluated as egocentric and allocentric, was assessed by a computerized human analogue of the Morris Water Maze tests Amunet. LI-MCI performed worse than the CN and LI-NonMCI groups on egocentric and delayed spatial navigation subtests. LI-MCI patients have spatial navigation deficits. The microstructural abnormalities in diffuse brain regions, including hippocampus, uncinate fasciculus and other brain regions may contribute to the spatial navigation impairment in LI-MCI patients at follow-up. PMID:27861154

Effects of ANK3 variation on gray and white matter in bipolar disorder.

PubMed

Lippard, E T C; Jensen, K P; Wang, F; Johnston, J A Y; Spencer, L; Pittman, B; Gelernter, J; Blumberg, H P

2017-09-01

The single-nucleotide polymorphism rs9804190 in the Ankyrin G (ANK3) gene has been reported in genome-wide association studies to be associated with bipolar disorder (BD). However, the neural system effects of rs9804190 in BD are not known. We investigated associations between rs9804190 and gray and white matter (GM and WM, respectively) structure within a frontotemporal neural system implicated in BD. A total of 187 adolescent and adult European Americans were studied: a group homozygous for the C allele (52 individuals with BD and 56 controls) and a T-carrier group, carrying the high-risk T allele (38 BD and 41 controls). Subjects participated in high-resolution structural magnetic resonance imaging and diffusion tensor imaging (DTI) scanning. Frontotemporal region of interest (ROI) and whole-brain exploratory analyses were conducted. DTI ROI-based analysis revealed a significant diagnosis by genotype interaction within the uncinate fasciculus (P⩽0.05), with BD subjects carrying the T (risk) allele showing decreased fractional anisotropy compared with other subgroups, independent of age. Genotype effects were not observed in frontotemporal GM volume. These findings support effects of rs9804190 on frontotemporal WM in adolescents and adults with BD and suggest a mechanism contributing to WM pathology in BD.

White matter disease correlates with lexical retrieval deficits in primary progressive aphasia.

PubMed

Powers, John P; McMillan, Corey T; Brun, Caroline C; Yushkevich, Paul A; Zhang, Hui; Gee, James C; Grossman, Murray

2013-01-01

To relate fractional anisotropy (FA) changes associated with the semantic and logopenic variants of primary progressive aphasia (PPA) to measures of lexical retrieval. We collected neuropsychological testing, volumetric magnetic resonance imaging, and diffusion-weighted imaging on semantic variant PPA (svPPA) (n = 11) and logopenic variant PPA (lvPPA) (n = 13) patients diagnosed using published criteria. We also acquired neuroimaging data on a group of demographically comparable healthy seniors (n = 34). FA was calculated and analyzed using a white matter (WM) tract-specific analysis approach. This approach utilizes anatomically guided data reduction to increase sensitivity and localizes results within canonically defined tracts. We used non-parametric, cluster-based statistical analysis to relate language performance to FA and determine regions of reduced FA in patients. We found widespread FA reductions in WM for both variants of PPA. FA was related to both confrontation naming and category naming fluency performance in left uncinate fasciculus and corpus callosum in svPPA and left superior and inferior longitudinal fasciculi in lvPPA. SvPPA and lvPPA are associated with distinct disruptions of a large-scale network implicated in lexical retrieval, and the WM disease in each phenotype may contribute to language impairments including lexical retrieval.

LAPAROSCOPIC UNCINATECTOMY: A MORE CONSERVATIVE APPROACH TO THE UNCINATE PROCESS OF THE PANCREAS.

PubMed

Surjan, Rodrigo Cañada; Basseres, Tiago; Makdissi, Fabio Ferrari; Machado, Marcel Autran Cesar; Ardengh, José Celso

2017-01-01

The isolate resection of the uncinate process of the pancreas is a rarely described procedure but is an adequate surgery to treat benign and low grade malignancies of the uncinate process of the pancreas. To detail laparoscopic uncinatectomy technique and present the initial results. Patient is placed in supine position with the surgeon between legs. Three 5-mm, one 10-mm and one 12-mm trocars were used to perform the isolated resection of the uncinate process of the pancreas. Parenchymal transection is performed with harmonic scalpel. A hemostatic absorbable tissue is deployed over the area previously occupied by the uncinate process. A Waterman drain is placed. This procedure was applied to an asymptomatic 62-year-old male with biopsy proven low grade neuroendocrine tumor of the pancreatic uncinate process. A laparoscopic pancreaticoduodenectomy was proposed. During the initial surgical evaluation, intraoperative sonography was performed and disclosed that the lesion was a few millimeters away from the Wirsung. The option was to perform a laparoscopic uncinatectomy. Postoperative period until full recovery was swift and uneventful. Laparoscopic uncinatectomy is a safe and efficient procedure when performed by surgical teams with large experience in minimally invasive biliopancreatic procedures.

Approaching the Atrium Through the Intraparietal Sulcus: Mapping the Sulcal Morphology and Correlating the Surgical Corridor to Underlying Fiber Tracts.

PubMed

Koutsarnakis, Christos; Liakos, Faidon; Kalyvas, Aristotelis V; Liouta, Evangelia; Emelifeonwu, John; Kalamatianos, Theodosis; Sakas, Damianos E; Johnson, Elizabeth; Stranjalis, George

2017-08-01

Although the operative corridor used during the intraparietal transsulcal approach to the atrium has been previously investigated, most anatomical studies focus on its relationship to the optic radiations. To study the intraparietal sulcus (IPS) morphology and to explore the subcortical anatomy with regard to the surgical trajectory used during the intraparietal transsulcal tranventricular approach. Twenty-five adult, formalin fixed, cerebral hemispheres were investigated. Fifteen underwent the Klingler procedure and were dissected in a lateromedial direction using the fiber microdissection technique. The trajectory of the dissection resembled that of real operative settings. The remaining 10 hemispheres were cut along the longitudinal axis of the sulcus in order to correlate its surface anatomy to corresponding parts of the ventricular system. IPS demonstrated an interrupted course in 36% of the specimens while its branching pattern was variable. The sulcus anterior half was found to overly the atrium in all occasions. Four discrete, consecutive white matter layers were identified en route to the atrium, ie, the arcuate fibers, the arcuate segment of the superior longitudinal fasciculus, the corona radiata and tapetum, with the arcuate segment being near to the dissection trajectory. Given the angle of brain transgression during the intraparietal approach, we found the optimal dissection area to be the very middle of the sulcus. The IPS-postcentral sulcus meeting point, in contrast to previous thought, proved to risk potential injury to the arcuate segment of the superior longitudinal fasciculus, thus affecting surgical outcome. Copyright © 2017 by the Congress of Neurological Surgeons

Reconstruction of the arcuate fasciculus for surgical planning in the setting of peritumoral edema using two-tensor unscented Kalman filter tractography.

PubMed

Chen, Zhenrui; Tie, Yanmei; Olubiyi, Olutayo; Rigolo, Laura; Mehrtash, Alireza; Norton, Isaiah; Pasternak, Ofer; Rathi, Yogesh; Golby, Alexandra J; O'Donnell, Lauren J

2015-01-01

Diffusion imaging tractography is increasingly used to trace critical fiber tracts in brain tumor patients to reduce the risk of post-operative neurological deficit. However, the effects of peritumoral edema pose a challenge to conventional tractography using the standard diffusion tensor model. The aim of this study was to present a novel technique using a two-tensor unscented Kalman filter (UKF) algorithm to track the arcuate fasciculus (AF) in brain tumor patients with peritumoral edema. Ten right-handed patients with left-sided brain tumors in the vicinity of language-related cortex and evidence of significant peritumoral edema were retrospectively selected for the study. All patients underwent 3-Tesla magnetic resonance imaging (MRI) including a diffusion-weighted dataset with 31 directions. Fiber tractography was performed using both single-tensor streamline and two-tensor UKF tractography. A two-regions-of-interest approach was applied to perform the delineation of the AF. Results from the two different tractography algorithms were compared visually and quantitatively. Using single-tensor streamline tractography, the AF appeared disrupted in four patients and contained few fibers in the remaining six patients. Two-tensor UKF tractography delineated an AF that traversed edematous brain areas in all patients. The volume of the AF was significantly larger on two-tensor UKF than on single-tensor streamline tractography (p < 0.01). Two-tensor UKF tractography provides the ability to trace a larger volume AF than single-tensor streamline tractography in the setting of peritumoral edema in brain tumor patients.

Arcuate fasciculus laterality by diffusion tensor imaging correlates with language laterality by functional MRI in preadolescent children.

PubMed

Sreedharan, Ruma Madhu; Menon, Amitha C; James, Jija S; Kesavadas, Chandrasekharan; Thomas, Sanjeev V

2015-03-01

Language lateralization is unique to humans. Functional MRI (fMRI) and diffusion tensor imaging (DTI) enable the study of language areas and white matter fibers involved in language, respectively. The objective of this study was to correlate arcuate fasciculus (AF) laterality by diffusion tensor imaging with that by fMRI in preadolescent children which has not yet been reported. Ten children between 8 and 12 years were subjected to fMRI and DTI imaging using Siemens 1.5 T MRI. Two language fMRI paradigms--visual verb generation and word pair task--were used. Analysis was done using SPM8 software. In DTI, the fiber volume of the arcuate fasciculus (AFV) and fractional anisotropy (FA) was measured. The fMRI Laterality Index (fMRI-LI) and DTI Laterality Index (DTI-LI) were calculated and their correlation assessed using the Pearson Correlation Index. Of ten children, mean age 10.6 years, eight showed left lateralization while bilateral language lateralization was seen in two. AFV by DTI was more on the left side in seven of the eight children who had left lateralization by fMRI. DTI could not trace the AF in one child. Of the two with bilateral language lateralization on fMRI, one showed larger AFV on the right side while the other did not show any asymmetry. There was a significant correlation (p < 0.02) between fMRI-LI and DTI-LI. Group mean of AFV by DTI was higher on the left side (2659.89 ± 654.75 mm(3)) as compared to the right (1824.11 ± 582.81 mm(3)) (p < 0.01). Like fMRI, DTI also reveals language laterality in children with a high degree of correlation between the two imaging modalities.

The vascular stapler in uncinate process division during pancreaticoduodenectomy: technical considerations and results.

PubMed

D'souza, Melroy A; Singh, Kailash; Hawaldar, Rohini V; Shukla, Parul J; Shrikhande, Shailesh V

2010-08-01

Few studies describing the use of stapling devices for uncinate process division during pancreaticoduodenectomy (PD) have data regarding outcomes. Our aim is to discuss our technique and the peri-operative outcomes with the use of the linear vascular stapler for division of the uncinate process during PD. 19 consecutive patients who underwent stapler division of the uncinate process ('stapler' group) were compared to 20 consecutive patients operated without stapler ('no-stapler' group). The overall surgical morbidity in the no-stapler group was 25% (5/20) and 31.6% (6/19) in the stapler group (p = 0.731). The mean blood loss in the no-stapler group was 1,077.5 +/- 594 ml compared to 778 +/- 302 ml in the stapler group (p = 0.113). The mean operative duration was 498 +/- 105 min in the no-stapler group and 490 +/- 60 min in the stapler group (p = 0.773). The average number of lymph nodes retrieved was 6.1 +/- 3 in the no-stapler group versus 5.9 +/- 4 in the stapler group (p = 0.627). Neither group had positive resection margins. Stapler division of the uncinate process for selected periampullary tumours compares well with the conventional method, has comparable peri-operative outcomes without compromising oncological radicality and has the potential to simplify uncinate resection.

[Anatomical and computed tomographic analysis of the interaction between uncinate process and agger nasi cells].

PubMed

Zhang, Luo; Han, De-min; Ge, Wen-tong; Zhou, Bing; Xian, Jun-fang; Liu, Zhong-yan; Wang, Kui-ji; He, Fei

2005-12-01

To investigate the anatomical interaction between uncinate process and agger nasi cell to better understand the anatomy of the frontal sinus drainage pathway by endoscopy, spiral computed tomography (CT) and sectioning. Twenty-one skeletal skulls (forty-two sides) and one cadaver head (two sides) were studied by spiral CT together with endoscopy and collodion embedded thin sectioning at coronal plane. The sections with the thickness of 100 microm were stained with hemotoxylin and eosin. Under endoscopy, a leaflet of bone to the middle turbinate, which is given off by uncinate process, forms the anterior insertion of the middle turbinate onto the lateral nasal wall. The middle portion of the uncinate process attached to the frontal process of the maxilla in all of the skeletal nasal cavities, as well as the lacrimal bone in 78.6% of the skeletal nasal cavities. On CT scans, the agger nasi cell is present in 90.5% of the skeletal nasal cavities. While the lateral wall of the agger nasi cell is formed by lacrimal bone, the medial wall of the agger nasi cell is formed by uncinate process. And the anterior wall is formed by the frontal process of the maxilla. The superior portion of the uncinate process forms the medial, posterior and top wall of the agger nasi cells. The superior portion of the uncinate extends into the frontal recess and may insert into lamina papyracea (33.3%), skull base (9.5%), middle turbinate, combination of these (57.2%). The agger nasi cell is the key that unlocks the frontal recess.

Structural changes in white matter are uniquely related to children’s reading development

PubMed Central

Myers, Chelsea A.; Vandermosten, Maaike; Farris, Emily A.; Hancock, Roeland; Gimenez, Paul; Black, Jessica M.; Casto, Brandi; Drahos, Miroslav; Tumber, Mandeep; Hendren, Robert L.; Hulme, Charles; Hoeft, Fumiko

2014-01-01

This study examined whether variations in brain development between kindergarten and Grade 3 predicted individual differences in reading ability at the latter time point. Structural MRI measurements indicated that increases in volume of two left temporo-parietal white matter clusters are unique predictors of reading outcome at Grade 3. Using diffusion MRI, the larger of these two clusters was identified as a location where fibers of the long segment of arcuate fasciculus and superior corona radiata intersect, and the smaller cluster as the posterior arcuate fasciculus. Bias-free regression analyses using regions-of-interest from prior literature revealed white matter volume changes in temporo-parietal white matter, together with preliteracy measures, predicted 56% of the variance in reading outcomes. Our findings demonstrate the important contribution of developmental differences in areas of left dorsal white matter, often implicated in phonological processing, as a sensitive early biomarker for later reading abilities, and by extension, reading difficulties. PMID:25212581

Alzheimer's disease susceptibility genes APOE and TOMM40, and brain white matter integrity in the Lothian Birth Cohort 1936☆

PubMed Central

Lyall, Donald M.; Harris, Sarah E.; Bastin, Mark E.; Muñoz Maniega, Susana; Murray, Catherine; Lutz, Michael W.; Saunders, Ann M.; Roses, Allen D.; Valdés Hernández, Maria del C.; Royle, Natalie A.; Starr, John M.; Porteous, David. J.; Wardlaw, Joanna M.; Deary, Ian J.

2014-01-01

Apolipoprotein E (APOE) ε genotype has previously been significantly associated with cognitive, brain imaging, and Alzheimer's disease-related phenotypes (e.g., age of onset). In the TOMM40 gene, the rs10524523 (“523”) variable length poly-T repeat polymorphism has more recently been associated with similar ph/enotypes, although the allelic directions of these associations have varied between initial reports. Using diffusion magnetic resonance imaging tractography, the present study aimed to investigate whether there are independent effects of apolipoprotein E (APOE) and TOMM40 genotypes on human brain white matter integrity in a community-dwelling sample of older adults, the Lothian Birth Cohort 1936 (mean age = 72.70 years, standard deviation = 0.74, N approximately = 640–650; for most analyses). Some nominally significant effects were observed (i.e., covariate-adjusted differences between genotype groups at p < 0.05). For APOE, deleterious effects of ε4 “risk” allele presence (vs. absence) were found in the right ventral cingulum and left inferior longitudinal fasciculus. To test for biologically independent effects of the TOMM40 523 repeat, participants were stratified into APOE genotype subgroups, so that any significant effects could not be attributed to APOE variation. In participants with the APOE ε3/ε4 genotype, effects of TOMM40 523 status were found in the left uncinate fasciculus, left rostral cingulum, left ventral cingulum, and a general factor of white matter integrity. In all 4 of these tractography measures, carriers of the TOMM40 523 “short” allele showed lower white matter integrity when compared with carriers of the “long” and “very-long” alleles. Most of these effects survived correction for childhood intelligence test scores and vascular disease history, though only the effect of TOMM40 523 on the left ventral cingulum integrity survived correction for false discovery rate. The effects of APOE in this older population are more specific and restricted compared with those reported in previous studies, and the effects of TOMM40 on white matter integrity appear to be novel, although replication is required in large independent samples. PMID:24508314

Alzheimer's disease susceptibility genes APOE and TOMM40, and brain white matter integrity in the Lothian Birth Cohort 1936.

PubMed

Lyall, Donald M; Harris, Sarah E; Bastin, Mark E; Muñoz Maniega, Susana; Murray, Catherine; Lutz, Michael W; Saunders, Ann M; Roses, Allen D; Valdés Hernández, Maria del C; Royle, Natalie A; Starr, John M; Porteous, David J; Wardlaw, Joanna M; Deary, Ian J

2014-06-01

Apolipoprotein E (APOE) ε genotype has previously been significantly associated with cognitive, brain imaging, and Alzheimer's disease-related phenotypes (e.g., age of onset). In the TOMM40 gene, the rs10524523 ("523") variable length poly-T repeat polymorphism has more recently been associated with similar ph/enotypes, although the allelic directions of these associations have varied between initial reports. Using diffusion magnetic resonance imaging tractography, the present study aimed to investigate whether there are independent effects of apolipoprotein E (APOE) and TOMM40 genotypes on human brain white matter integrity in a community-dwelling sample of older adults, the Lothian Birth Cohort 1936 (mean age = 72.70 years, standard deviation = 0.74, N approximately = 640-650; for most analyses). Some nominally significant effects were observed (i.e., covariate-adjusted differences between genotype groups at p < 0.05). For APOE, deleterious effects of ε4 "risk" allele presence (vs. absence) were found in the right ventral cingulum and left inferior longitudinal fasciculus. To test for biologically independent effects of the TOMM40 523 repeat, participants were stratified into APOE genotype subgroups, so that any significant effects could not be attributed to APOE variation. In participants with the APOE ε3/ε4 genotype, effects of TOMM40 523 status were found in the left uncinate fasciculus, left rostral cingulum, left ventral cingulum, and a general factor of white matter integrity. In all 4 of these tractography measures, carriers of the TOMM40 523 "short" allele showed lower white matter integrity when compared with carriers of the "long" and "very-long" alleles. Most of these effects survived correction for childhood intelligence test scores and vascular disease history, though only the effect of TOMM40 523 on the left ventral cingulum integrity survived correction for false discovery rate. The effects of APOE in this older population are more specific and restricted compared with those reported in previous studies, and the effects of TOMM40 on white matter integrity appear to be novel, although replication is required in large independent samples. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Disorder-Specific Alteration in White Matter Structural Property in Adults With Autism Spectrum Disorder Relative to Adults With ADHD and Adult Controls.

PubMed

Chiang, Huey-Ling; Chen, Yu-Jen; Lin, Hsiang-Yuan; Tseng, Wen-Yih Isaac; Gau, Susan Shur-Fen

2017-01-01

Autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) are not only often comorbid but also overlapped in behavioral and cognitive abnormalities. Little is known about whether these shared phenotypes are based on common or different underlying neuropathologies. Therefore, this study aims to examine the disorder-specific alterations in white matter (WM) structural property. The three comparison groups included 23 male adults with ASD (21.4 ± 3.1 years), 32 male adults with ADHD (23.4 ± 3.3 years), and 29 age-matched healthy male controls (22.4 ± 3.3 years). After acquisition of the diffusion spectrum imaging (DSI), whole brain tractography was reconstructed by a tract-based automatic analysis. Generalized fractional anisotropy (GFA) values were computed to indicate tract-specific WM property with adjusted P value < 0.05 for false discovery rate correction. Post hoc analyses revealed that men with ASD exhibited significant lower GFA values than men with ADHD and male controls in six identified fiber tracts: the right arcuate fasciculus, right cingulum (hippocampal part), anterior commissure, and three callosal fibers (ventrolateral prefrontal cortex part, precentral part, superior temporal part). There was no significant difference in the GFA values of any of the fiber tracts between men with ADHD and controls. In men with ASD, the GFA values of the right arcuate fasciculus and right cingulum (hippocampal part) were negatively associated with autistic social-deficit symptoms, and the anterior commissure GFA value was positively correlated with intelligence. This study highlights the disorder-specific alteration of the microstructural property of WM tracts in male adults with ASD. Hum Brain Mapp 38:384-395, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Avian-like breathing mechanics in maniraptoran dinosaurs

PubMed Central

Codd, Jonathan R; Manning, Phillip L; Norell, Mark A; Perry, Steven F

2007-01-01

In 1868 Thomas Huxley first proposed that dinosaurs were the direct ancestors of birds and subsequent analyses have identified a suite of ‘avian’ characteristics in theropod dinosaurs. Ossified uncinate processes are found in most species of extant birds and also occur in extinct non-avian maniraptoran dinosaurs. Their presence in these dinosaurs represents another morphological character linking them to Aves, and further supports the presence of an avian-like air-sac respiratory system in theropod dinosaurs, prior to the evolution of flight. Here we report a phylogenetic analysis of the presence of uncinate processes in Aves and non-avian maniraptoran dinosaurs indicating that these were homologous structures. Furthermore, recent work on Canada geese has demonstrated that uncinate processes are integral to the mechanics of avian ventilation, facilitating both inspiration and expiration. In extant birds, uncinate processes function to increase the mechanical advantage for movements of the ribs and sternum during respiration. Our study presents a mechanism whereby uncinate processes, in conjunction with lateral and ventral movements of the sternum and gastral basket, affected avian-like breathing mechanics in extinct non-avian maniraptoran dinosaurs. PMID:17986432

Hereditary spastic paraplegia: clinical principles and genetic advances.

PubMed

Fink, John K

2014-07-01

Hereditary spastic paraplegia (HSP) refers to inherited disorders in which spastic gait is either the only feature or is a major syndrome feature. There are more than 70 genetic types of HSP. Neuropathological studies, albeit limited to only a few genetic types of HSP, have identified axon degeneration involving the distal ends of the corticospinal tracts and fasciculus gracilis fibers. In this review, the author highlights the clinical and genetic features of HSP. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Immunohistochemical localization of luteinizing hormone-releasing hormone (LHRH) in the hypothalamus of adult female hamsters treated neonatally with monosodium glutamate or hypertonic saline.

PubMed

Lamperti, A A; Pickard, G E

1984-05-01

The immunohistochemical localization of luteinizing hormone-releasing hormone (LHRH) was studied in paraffin and vibratome-sectioned tissue from adult female hamsters that were treated neonatally with monosodium glutamate (MSG) or hypertonic saline. There appeared to be a reduction in LHRH-positive fibers in the median eminence of animals with an MSG-induced lesion of the arcuate nucleus in paraffin-embedded tissue. However, when unembedded tissue was cut on a vibratome, the distribution of LHRH-positive fibers and perikarya was similar in both groups of animals. Fibers were seen coursing through the periventricular area and lateral hypothalamus to the median eminence. In addition, LHRH-positive fibers were seen in the organum vasculosum of the lamina terminalis, subfornical organ, septal and preoptic areas, fasciculus retroflexus, habenular complex, and several regions in the basal forebrain. Animals that were pretreated with colchicine had LHRH-positive perikarya in the medial habenular nucleus, diagonal band of Broca, and the medial olfactory tract.

Verbal Memory in Parkinson’s Disease: A Combined DTI and fMRI Study

PubMed Central

Lucas-Jiménez, Olaia; Díez-Cirarda, María; Ojeda, Natalia; Peña, Javier; Cabrera-Zubizarreta, Alberto; Ibarretxe-Bilbao, Naroa

2015-01-01

Background: While significant progress has been made to determine the functional role of specific gray matter areas underlying verbal memory in Parkinson’s disease (PD), very little is known about the relationship between these regions and their underlying white matter structures. Objective: The objectives of this study were (1) to investigate verbal memory, fractional anisotropy and brain activation differences between PD patients and healthy controls (HC), (2) to explore the neuroanatomical and neurofunctional correlates of verbal memory in PD, and (3) to investigate the relationship between these neuroanatomical and neurofunctional verbal memory correlates in PD. Methods: Functional magnetic resonance imaging (fMRI) while performing a verbal memory paradigm and diffusion tensor imaging data (DTI), were acquired in 37 PD patients and 15 age-, sex-, and education-matched HC. Results: PD patients showed verbal recognition memory impairment, lower fractional anisotropy in the anterior cingulate tract, and lower brain activation in the inferior orbitofrontal cortex compared to HC. Brain activation in the inferior orbitofrontal cortex correlated significantly with verbal recognition memory impairment in PD patients. In addition, a relationship between brain activation in the inferior orbitofrontal cortex and fractional anisotropy of the uncinate fasciculus was found in PD. Conclusions: These results reveal that deficits in verbal memory in PD are accompanied by functional brain activation changes, but also have specific structural correlates related to white matter microstructural integrity. PMID:27070003

Recent-onset schizophrenia and adolescent cannabis use: MRI evidence for structural hyperconnectivity?

PubMed

Peters, Bart D; de Haan, Lieuwe; Vlieger, Erik-Jan; Majoie, Charles B; den Heeten, Gerard J; Linszen, Don H

2009-01-01

There is growing evidence that brain white matter abnormalities are implicated in the pathophysiology of schizophrenia. Cannabis use is an independent risk factor for schizophrenia.We tested the hypothesis that cannabis use during early adolescence is associated with white matter abnormalities in schizophrenia patients. Thirtyfive male recent-onset schizophrenia patients, with and without a history of cannabis use before age 17, and twenty-one matched healthy comparison men without illicit drug use were assessed with diffusion tensor imaging (DTI).White matter regions of interest were examined in co-registered DTI images. Compared to controls, patients with cannabis use before age 17 showed increased directional coherence in the bilateral uncinate fasciculus, anterior internal capsule and frontal white matter. These abnormalities were absent in patients without cannabis use before age 17. The abnormalities were not related to lifetime doses of cannabis or other illicit drugs.We could not exclude confounding effects of other illicit drugs. Recent-onset schizophrenia patients with start of cannabis use during early adolescence use may represent a subgroup of schizophrenia patients with increased white matter directional coherence, which may reflect structural hyperconnectivity. This is in contrast with most DTI studies in schizophrenia, which have produced evidence for hypoconnectivity. Further studies are necessary to assess the effect of adolescent cannabis and other illicit drug use on brain white matter in schizophrenia.

Never forget a name: white matter connectivity predicts person memory

PubMed Central

Metoki, Athanasia; Alm, Kylie H.; Wang, Yin; Ngo, Chi T.; Olson, Ingrid R.

2018-01-01

Through learning and practice, we can acquire numerous skills, ranging from the simple (whistling) to the complex (memorizing operettas in a foreign language). It has been proposed that complex learning requires a network of brain regions that interact with one another via white matter pathways. One candidate white matter pathway, the uncinate fasciculus (UF), has exhibited mixed results for this hypothesis: some studies have shown UF involvement across a range of memory tasks, while other studies report null results. Here, we tested the hypothesis that the UF supports associative memory processes and that this tract can be parcellated into subtracts that support specific types of memory. Healthy young adults performed behavioral tasks (two face-name learning tasks, one word pair memory task) and underwent a diffusion-weighted imaging scan. Our results revealed that variation in UF microstructure was significantly associated with individual differences in performance on both face-name tasks, as well as the word association memory task. A UF sub-tract, functionally defined by its connectivity between face-selective regions in the anterior temporal lobe and orbitofrontal cortex, selectively predicted face-name learning. In contrast, connectivity between the fusiform face patch and both anterior face patches had no predictive validity. These findings suggest that there is a robust and replicable relationship between the UF and associative learning and memory. Moreover, this large white matter pathway can be subdivided to reveal discrete functional profiles. PMID:28646241

99mTc-HYNIC-TOC increased uptake can mimic malignancy in the pancreas uncinate process at somatostatin receptor SPECT/CT.

PubMed

Yamaga, Lilian Yuri Itaya; Neto, Guilherme Campos Carvalho; da Cunha, Marcelo Livorsi; Osawa, Akemi; Oliveira, Julio Cesar Silveira; Fonseca, Ricardo Quartim; Nogueira, Solange Amorim; Wagner, Jairo; Funari, Marcelo Gusmão

2016-03-01

The aim of this study was to assess the occurrence and frequency of increased physiologic uptake of 99mTc-HYNIC-TOC by the uncinate process of the pancreas in SPECT/CT images. Forty-six scans of 41 patients were evaluated retrospectively. The uptake of 99mTc-HYNIC-TOC was considered to be physiologic in patients with normal findings at dedicated abdominal CT or MR and lack of neoplastic lesions in clinical follow-ups. The intensity of uncinate process uptake was compared to the uptake of the normal liver. Focal uptake was attributed to the presence of pancreatic NET in 5 patients. Among the 36 patients without any evidence of malignancy in CT, MR and follow-up, 7 (19.4 %) showed increased uptake in the uncinate process. The intensity of uptake was lesser in 3 (8.3 %), similar in 3 and greater than the normal liver in 1 (2.8 %) case. Increased 99mTc-HYNIC-TOC uptake occurred in 19.4 % of those subjects without any evidence of neuroendocrine tumor in the uncinate process.

White matter connectivity and Internet gaming disorder

PubMed Central

Jeong, Bum Seok; Han, Doug Hyun; Kim, Sun Mi; Lee, Sang Won; Renshaw, Perry F.

2017-01-01

Internet use and on-line game play stimulate corticostriatal-limbic circuitry in both healthy subjects and subjects with Internet gaming disorder (IGD). We hypothesized that increased fractional anisotropy (FA) with decreased radial diffusivity (RD) would be observed in IGD subjects, compared with healthy control subjects, and that these white matter indices would be associated with clinical variables including duration of illness and executive function. We screened 181 male patients in order to recruit a large number (n = 58) of IGD subjects without psychiatric co-morbidity as well as 26 male healthy comparison subjects. Multiple diffusion-weighted images were acquired using a 3.0 Tesla magnetic resonance imaging scanner. Tract-based spatial statistics was applied to compare group differences in diffusion tensor imaging (DTI) metrics between IGD and healthy comparison subjects. IGD subjects had increased FA values within forceps minor, right anterior thalamic radiation, right corticospinal tract, right inferior longitudinal fasciculus, right cingulum to hippocampus and right inferior fronto-occipital fasciculus (IFOF) as well as parallel decreases in RD value within forceps minor, right anterior thalamic radiation and IFOF relative to healthy control subjects. In addition, the duration of illness in IGD subjects was positively correlated with the FA values (integrity of white matter fibers) and negatively correlated with RD scores (diffusivity of axonal density) of whole brain white matter. In IGD subjects without psychiatric co-morbidity, our DTI results suggest that increased myelination (increased FA and decreased RD values) in right-sided frontal fiber tracts may be the result of extended game play. PMID:25899390

An unusual variation in the anatomy of the uncinate process in external dacryocystorhinostomy

PubMed Central

Puri, Nitin

2008-01-01

Variations in the bony components of the nose are often encountered. One such variation was found in a 49-year-old male who had undergone conventional external dacryocystorhinostomy for adult onset nasolacrimal duct blockage. Intraoperatively, a thick bar of bone was seen beneath and parallel to the lacrimal sac fossa after a complete osteotomy had been made. Another osteotomy had to be fashioned in this bone to reach the nasal cavity. Postoperative 3D computed tomographic scan revealed the bone to be an anatomical variation of the uncinate process of the ethmoidal bone which was rather anteriorly placed, much thicker than usual, and attached to the nasal roof. The uncinate process is thin, curved and its anterior edge may frequently overlap some part of the lacrimal fossa. However, to our knowledge, the presence of such a large and thick uncinate process necessitating an additional large osteotomy has not been reported. PMID:18711272

Normal uptake of 68Ga-DOTA-TOC by the pancreas uncinate process mimicking malignancy at somatostatin receptor PET.

PubMed

Jacobsson, Hans; Larsson, Patricia; Jonsson, Cathrine; Jussing, Emma; Grybäck, Per

2012-04-01

To characterize a commonly occurring increased uptake by the uncinate process of the pancreas at PET/CT using 68Ga-DOTA-d-Phe1-Tyr3-octreotide (68Ga-DOTA-TOC). This tracer has replaced In pentetreotide (OctreoScan®) for somatostatin receptor scintigraphy at our laboratory. Fifty of our first 74 PET/CT examinations with 68Ga-DOTA-TOC could be evaluated in retrospect. None of these patients had surgery or showed any pathology in the pancreas head at the concomitant CT. Thirty-five of the 50 examinations (70%) showed an uptake by the uncinate process sufficiently intense to be interpreted as pathologic and simulating a tumor. Mean SUVmax was 9.2. Mean SUVmean using an isoactivity cut-off of >75% and >50% was 7.8 and 6.0, respectively. Volume calculations of the uncinate process activity using these definitions gave 0.9 mL and 4.2 mL, respectively. There is a frequent physiological uptake of 68Ga-DOTA-TOC by the pancreas uncinate process. This may be caused by an accumulation of pancreatic polypeptide-containing cells expressing somatostatin receptors. If there is a normal finding at concomitant diagnostic CT, this uptake should be regarded as physiological.

Diffusion tensor imaging--arcuate fasciculus and the importance for the neurosurgeon.

PubMed

Hana, Ardian; Dooms, Georges; Boecher-Schwarz, Hans; Hertel, Frank

2015-05-01

Tumors in eloquent areas of the brain like Broca or Wernicke might have disastrous consequences for patients. We intended to visualize the arcuate fasciculus (AF) and to demonstrate his relation with the corticospinal tract and the visual pathway using diffusion tensor imaging (DTI). We depicted between 2012 and 2014 the AF in 71 patients. Men and women of all ages were included. Eleven patients had postoperative controls also. We used a 3DT1-sequence for the navigation. Furthermore T2- and DTI-sequences were performed. The FOV was 200 × 200 mm(2), slice thickness 2mm, and an acquisition matrix of 96 × 96 yielding nearly isotropic voxels of 2 × 2 × 2 mm. 3-Tesla-MRI was carried out strictly axial using 32 gradient directions and one b0-image. We used Echo-Planar-Imaging (EPI) and ASSET parallel imaging with an acceleration factor of 2. b-Value was 800 s/mm(2). Additional scanning time was less than 9 min. AF was portrayed in 63 patients bilaterally. In one glioblastoma patient it was impossible to visualize the left AF and in seven other patients we could not portray the right one. The lesions affected AF by disrupting or displacing the fibers. DTI might be a useful tool to portray AF. It is time-saving and can be used to preserve morbidity in patients with lesions in eloquent brain areas. It might give deeper insights of the white matter and the reorganization of AF-fibers postoperatively. Copyright © 2015 Elsevier B.V. All rights reserved.

Subcomponents and Connectivity of the Inferior Fronto-Occipital Fasciculus Revealed by Diffusion Spectrum Imaging Fiber Tracking

PubMed Central

Wu, Yupeng; Sun, Dandan; Wang, Yong; Wang, Yibao

2016-01-01

The definitive structure and functional role of the inferior fronto-occipital fasciculus (IFOF) are still controversial. In this study, we aimed to investigate the connectivity, asymmetry, and segmentation patterns of this bundle. High angular diffusion spectrum imaging (DSI) analysis was performed on 10 healthy adults and a 90-subject DSI template (NTU-90 Atlas). In addition, a new tractography approach based on the anatomic subregions and two regions of interest (ROI) was evaluated for the fiber reconstructions. More widespread anterior-posterior connections than previous “standard” definition of the IFOF were found. This distinct pathway demonstrated a greater inter-subjects connective variability with a maximum of 40% overlap in its central part. The statistical results revealed no asymmetry between the left and right hemispheres and no significant differences existed in distributions of the IFOF according to sex. In addition, five subcomponents within the IFOF were identified according to the frontal areas of originations. As the subcomponents passed through the anterior floor of the external capsule, the fibers radiated to the posterior terminations. The most common connection patterns of the subcomponents were as follows: IFOF-I, from frontal polar cortex to occipital pole, inferior occipital lobe, middle occipital lobe, superior occipital lobe, and pericalcarine; IFOF-II, from orbito-frontal cortex to occipital pole, inferior occipital lobe, middle occipital lobe, superior occipital lobe, and pericalcarine; IFOF-III, from inferior frontal gyrus to inferior occipital lobe, middle occipital lobe, superior occipital lobe, occipital pole, and pericalcarine; IFOF-IV, from middle frontal gyrus to occipital pole, and inferior occipital lobe; IFOF-V, from superior frontal gyrus to occipital pole, inferior occipital lobe, and middle occipital lobe. Our work demonstrates the feasibility of high resolution diffusion tensor tractography with sufficient sensitivity to elucidate more anatomical details of the IFOF. And we provides a new framework for subdividing the IFOF for better understanding its functional role in the human brain. PMID:27721745

Structural white-matter connections mediating distinct behavioral components of spatial neglect in right brain-damaged patients.

PubMed

Vaessen, Maarten J; Saj, Arnaud; Lovblad, Karl-Olof; Gschwind, Markus; Vuilleumier, Patrik

2016-04-01

Spatial neglect is a neuropsychological syndrome in which patients fail to perceive and orient to stimuli located in the space contralateral to the lesioned hemisphere. It is characterized by a wide heterogeneity in clinical symptoms which can be grouped into distinct behavioral components correlating with different lesion sites. Moreover, damage to white-matter (WM) fiber tracts has been suggested to disconnect brain networks that mediate different functions associated with spatial cognition and attention. However, it remains unclear what WM pathways are associated with functionally dissociable neglect components. In this study we examined nine patients with a focal right hemisphere stroke using a series of neuropsychological tests and diffusion tensor imaging (DTI) in order to disentangle the role of specific WM pathways in neglect symptoms. First, following previous work, the behavioral test scores of patients were factorized into three independent components reflecting perceptual, exploratory, and object-centered deficits in spatial awareness. We then examined the structural neural substrates of these components by correlating indices of WM integrity (fractional anisotropy) with the severity of deficits along each profile. Several locations in the right parietal and frontal WM correlated with neuropsychological scores. Fiber tracts projecting from these locations indicated that posterior parts of the superior longitudinal fasciculus (SLF), as well as nearby callosal fibers connecting ipsilateral and contralateral parietal areas, were associated with perceptual spatial deficits, whereas more anterior parts of SLF and inferior fronto-occipital fasciculus (IFOF) were predominantly associated with object-centered deficits. In addition, connections between frontal areas and superior colliculus were found to be associated with the exploratory deficits. Our results provide novel support to the view that neglect may result from disconnection lesions in distributed brain networks, but also extend these notions by highlighting the role of dissociable circuits in different functional components of the neglect syndrome. However these preliminary findings require replication with larger samples of patients. Copyright © 2016 Elsevier Ltd. All rights reserved.

White Matter Microstructural Integrity and Neurobehavioral Outcome of HIV-Exposed Uninfected Neonates.

PubMed

Tran, Linh T; Roos, Annerine; Fouche, Jean-Paul; Koen, Nastassja; Woods, Roger P; Zar, Heather J; Narr, Katherine L; Stein, Dan J; Donald, Kirsten A

2016-01-01

The successful implementation of prevention programs for mother-to-child human immunodeficiency virus (HIV) transmission has dramatically reduced the prevalence of infants infected with HIV while increasing that of HIV-exposed uninfected (HEU) children. Neuropsychological assessments indicate that HEU children may exhibit differences in neurodevelopment compared to unexposed children (HUU). Pathological mechanisms leading to such neurodevelopmental delays are not clear. In this observational birth cohort study we explored the integrity of regional white matter microstructure in HEU infants, shortly after birth. Microstructural changes in white matter associated with prenatal HIV exposure were evaluated in HEU infants (n = 15) and matched controls (n = 22) using diffusion tensor imaging and tract-based spatial statistics. Additionally, diffusion values were extracted and compared for white matter tracts of interest, and associations with clinical outcomes from the Dubowitz neonatal neurobehavioral tool were investigated. Higher fractional anisotropy in the middle cerebellar peduncles of HEU compared to HUU neonates was found after correction for age and gender. Scores on the Dubowitz abnormal neurological signs subscale were positively correlated with FA (r = 0.58, P = 0.038) in the left uncinate fasciculus in HEU infants. This is the first study to present data suggesting that prenatal HIV exposure without infection is associated with altered white matter microstructural integrity in the neonatal period. Longitudinal studies of HEU infants as their brains mature are necessary to understand further the significance of prenatal HIV and antiretroviral treatment exposure on white matter integrity and neurodevelopmental outcomes.

Surface-based brain morphometry and diffusion tensor imaging in schizoaffective disorder.

PubMed

Landin-Romero, Ramón; Canales-Rodríguez, Erick J; Kumfor, Fiona; Moreno-Alcázar, Ana; Madre, Mercè; Maristany, Teresa; Pomarol-Clotet, Edith; Amann, Benedikt L

2017-01-01

The profile of grey matter abnormalities and related white-matter pathology in schizoaffective disorder has only been studied to a limited extent. The aim of this study was to identify grey- and white-matter abnormalities in patients with schizoaffective disorder using complementary structural imaging techniques. Forty-five patients meeting Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition criteria and Research Diagnostic Criteria for schizoaffective disorder and 45 matched healthy controls underwent structural-T1 and diffusion magnetic resonance imaging to enable surface-based brain morphometry and diffusion tensor imaging analyses. Analyses were conducted to determine group differences in cortical volume, cortical thickness and surface area, as well as in fractional anisotropy and mean diffusivity. At a threshold of p = 0.05 corrected, all measures revealed significant differences between patients and controls at the group level. Spatial overlap of abnormalities was observed across the various structural neuroimaging measures. In grey matter, patients with schizoaffective disorder showed abnormalities in the frontal and temporal lobes, striatum, fusiform, cuneus, precuneus, lingual and limbic regions. White-matter abnormalities were identified in tracts connecting these areas, including the corpus callosum, superior and inferior longitudinal fasciculi, anterior thalamic radiation, uncinate fasciculus and cingulum bundle. The spatial overlap of abnormalities across the different imaging techniques suggests widespread and consistent brain pathology in schizoaffective disorder. The abnormalities were mainly detected in areas that have commonly been reported to be abnormal in schizophrenia, and to some extent in bipolar disorder, which may explain the clinical and aetiological overlap in these disorders.

GABA content within medial prefrontal cortex predicts the variability of fronto-limbic effective connectivity

PubMed Central

Pizzi, Stefano Delli; Chiacchieretta, Piero; Mantini, Dante; Bubbico, Giovanna; Edden, Richard A.; Onofrj, Marco; Ferretti, Antonio

2017-01-01

The amygdala-medial prefrontal cortex (mPFC) circuit plays a key role in social behavior. The amygdala and mPFC are bidirectionally connected, functionally and anatomically, via the uncinate fasciculus. Recent evidence suggests that GABA-ergic neurotransmission within the mPFC could be central to the regulation of amygdala activity related to emotions and anxiety processing. However, the functional and neurochemical interactions within amygdala-mPFC circuits are unclear. In the current study, multimodal magnetic resonance imaging techniques were combined to investigate effective connectivity within the amygdala-mPFC network and its relationship with mPFC neurotransmission in 22 healthy subjects aged between 41 and 88 years. Effective connectivity in the amygdala-mPFC circuit was assessed on resting-state functional magnetic resonance imaging data using spectral dynamic causal modelling. State and trait anxiety were also assessed. The mPFC was shown to be the target of incoming outputs from the amygdalae and the source of exciting inputs to the limbic system. The amygdalae were reciprocally connected by excitatory projections. About half of the variance relating to the strength of top–down endogenous connection between right amygdala and mPFC was explained by mPFC GABA levels. State anxiety was correlated with the strength of the endogenous connections between right amygdala and mPFC. We suggest that mPFC GABA content predicts variability in the effective connectivity within the mPFC-amygdala circuit, providing new insights on emotional physiology and the underlying functional and neurochemical interactions. PMID:28386778

Medial prefrontal aberrations in major depressive disorder revealed by cytoarchitectonically informed voxel-based morphometry

PubMed Central

Bludau, Sebastian; Bzdok, Danilo; Gruber, Oliver; Kohn, Nils; Riedl, Valentin; Sorg, Christian; Palomero-Gallagher, Nicola; Müller, Veronika I.; Hoffstaedter, Felix; Amunts, Katrin; Eickhoff, Simon B.

2017-01-01

Objective The heterogeneous human frontal pole has been identified as a node in the dysfunctional network of major depressive disorder. The contribution of the medial (socio-affective) versus lateral (cognitive) frontal pole to major depression pathogenesis is currently unclear. The present study performs morphometric comparison of the microstructurally informed subdivisions of human frontal pole between depressed patients and controls using both uni- and multivariate statistics. Methods Multi-site voxel- and region-based morphometric MRI analysis of 73 depressed patients and 73 matched controls without psychiatric history. Frontal pole volume was first compared between depressed patients and controls by subdivision-wise classical morphometric analysis. In a second approach, frontal pole volume was compared by subdivision-naive multivariate searchlight analysis based on support vector machines. Results Subdivision-wise morphometric analysis found a significantly smaller medial frontal pole in depressed patients with a negative correlation of disease severity and duration. Histologically uninformed multivariate voxel-wise statistics provided converging evidence for structural aberrations specific to the microstructurally defined medial area of the frontal pole in depressed patients. Conclusions Across disparate methods, we demonstrated subregion specificity in the left medial frontal pole volume in depressed patients. Indeed, the frontal pole was shown to structurally and functionally connect to other key regions in major depression pathology like the anterior cingulate cortex and the amygdala via the uncinate fasciculus. Present and previous findings consolidate the left medial portion of the frontal pole as particularly altered in major depression. PMID:26621569

Microstructural abnormalities in white and gray matter in obese adolescents with and without type 2 diabetes.

PubMed

Nouwen, Arie; Chambers, Alison; Chechlacz, Magdalena; Higgs, Suzanne; Blissett, Jacqueline; Barrett, Timothy G; Allen, Harriet A

2017-01-01

In adults, type 2 diabetes and obesity have been associated with structural brain changes, even in the absence of dementia. Some evidence suggested similar changes in adolescents with type 2 diabetes but comparisons with a non-obese control group have been lacking. The aim of the current study was to examine differences in microstructure of gray and white matter between adolescents with type 2 diabetes, obese adolescents and healthy weight adolescents. Magnetic resonance imaging data were collected from 15 adolescents with type 2 diabetes, 21 obese adolescents and 22 healthy weight controls. Volumetric differences in the gray matter between the three groups were examined using voxel based morphology, while tract based spatial statistics was used to examine differences in the microstructure of the white matter. Adolescents with type 2 diabetes and obese adolescents had reduced gray matter volume in the right hippocampus, left putamen and caudate, bilateral amygdala and left thalamus compared to healthy weight controls. Type 2 diabetes was also associated with significant regional changes in fractional anisotropy within the corpus callosum, fornix, left inferior fronto-occipital fasciculus, left uncinate, left internal and external capsule. Fractional anisotropy reductions within these tracts were explained by increased radial diffusivity, which may suggest demyelination of white matter tracts. Mean diffusivity and axial diffusivity did not differ between the groups. Our data shows that adolescent obesity alone results in reduced gray matter volume and that adolescent type 2 diabetes is associated with both white and gray matter abnormalities.

Tract-based analysis of white matter integrity in psychotic and nonpsychotic bipolar disorder.

PubMed

Ji, Andrew; Godwin, Douglass; Rutlin, Jerrel; Kandala, Sridhar; Shimony, Joshua S; Mamah, Daniel

2017-02-01

At least 50% of individuals with bipolar disorder (BD) present with psychosis during their lifetime. Psychotic symptoms have sometimes been linked to specific genetic and phenotypic markers. This study aims to explore potential differences between bipolar disorder subtypes by measuring white matter integrity of the brain and relationships with clinical measures. Diffusion tensor imaging and clinical measures were acquired from 102 participants, grouped as psychotic bipolar disorder (PBD) (n=48), non-psychotic bipolar disorder (NBD) (n=24), and healthy controls (n=30). We utilized a powerful, automated tool (TRACULA: Tracts Constrained by Underlying Anatomy) to analyze the fractional anisotropy (FA) and mean diffusivity (MD) of 18 white matter tracts. Decreased FA in numerous tracts was observed in bipolar disorder groups compared to healthy controls: bilateral cingulum-cingulate gyrus bundles, corticospinal tracts, and superior longitudinal fasciculi as well as the right hemisphere cingulum-angular bundle. Only left uncinate fasciculus FA differed between PBD and NPBD groups. We found no group differences in MD. Positive symptoms correlated with FA in the superior (inversely) and inferior (directly) longitudinal fasciculi. Negative symptoms directly correlated with mean FA of the corticospinal tract and cingulum-angular bundle. Neurotropic, mood-stabilizing medication prescribed for individuals with BD may interact with measures of white matter integrity in our BD participants. Our results indicate decreased white matter coherence in BD. Minimal differences in white matter FA between PBD and NPBD participants suggest related underlying neurobiology. Copyright © 2016 Elsevier B.V. All rights reserved.

Neuroanatomical correlates of negative emotionality-related traits: A systematic review and meta-analysis.

PubMed

Mincic, Adina M

2015-10-01

Two central traits present in the most influential models of personality characterize the response to positive and, respectively, negative emotional events. Negative emotionality (NE)-related traits are linked to vulnerability to mood and anxiety disorders; this has fuelled a special interest in examining stable differences in brain morphology associated to these traits. Structural imaging methods including voxel-based morphometry, cortical thickness analysis and diffusion tensor imaging (DTI) have yielded inconclusive and sometimes contradictory results. This review summarizes the findings reported to date through these methods and discusses them in relation to the functional imaging results. To detect topographic convergence between studies showing positive and, respectively, negative grey matter associations with NE-traits, activation likelihood estimation (ALE) meta-analyses of VBM studies were performed. Individuals scoring high on NE-related traits show consistent morphological differences in a left-lateralized circuit: higher grey matter volume (GMV) in amygdala and anterior parahippocampal gyrus and lower GMV in the orbitofrontal cortex extending into perigenual anterior cingulate cortex. Most DTI studies indicate reduced white matter integrity in various brain regions and tracts, particularly in the uncinate fasciculus and in cingulum bundle. These results show that the behavioural phenotype associated to NE traits is reflected in structural differences within the cortico-limbic system, suggesting alterations in information processing and transmission. The results are discussed from the perspective of neuron-glia interactions. Future directions are outlined based on recent developments in structural imaging techniques. Copyright © 2015 Elsevier Ltd. All rights reserved.

White matter correlates of sensory processing in autism spectrum disorders

PubMed Central

Pryweller, Jennifer R.; Schauder, Kimberly B.; Anderson, Adam W.; Heacock, Jessica L.; Foss-Feig, Jennifer H.; Newsom, Cassandra R.; Loring, Whitney A.; Cascio, Carissa J.

2014-01-01

Autism spectrum disorder (ASD) has been characterized by atypical socio-communicative behavior, sensorimotor impairment and abnormal neurodevelopmental trajectories. DTI has been used to determine the presence and nature of abnormality in white matter integrity that may contribute to the behavioral phenomena that characterize ASD. Although atypical patterns of sensory responding in ASD are well documented in the behavioral literature, much less is known about the neural networks associated with aberrant sensory processing. To address the roles of basic sensory, sensory association and early attentional processes in sensory responsiveness in ASD, our investigation focused on five white matter fiber tracts known to be involved in these various stages of sensory processing: superior corona radiata, centrum semiovale, inferior longitudinal fasciculus, posterior limb of the internal capsule, and splenium. We acquired high angular resolution diffusion images from 32 children with ASD and 26 typically developing children between the ages of 5 and 8. We also administered sensory assessments to examine brain-behavior relationships between white matter integrity and sensory variables. Our findings suggest a modulatory role of the inferior longitudinal fasciculus and splenium in atypical sensorimotor and early attention processes in ASD. Increased tactile defensiveness was found to be related to reduced fractional anisotropy in the inferior longitudinal fasciculus, which may reflect an aberrant connection between limbic structures in the temporal lobe and the inferior parietal cortex. Our findings also corroborate the modulatory role of the splenium in attentional orienting, but suggest the possibility of a more diffuse or separable network for social orienting in ASD. Future investigation should consider the use of whole brain analyses for a more robust assessment of white matter microstructure. PMID:25379451

Emerging Structure–Function Relations in the Developing Face Processing System

PubMed Central

Suzanne Scherf, K.; Thomas, Cibu; Doyle, Jaime; Behrmann, Marlene

2014-01-01

To evaluate emerging structure–function relations in a neural circuit that mediates complex behavior, we investigated age-related differences among cortical regions that support face recognition behavior and the fiber tracts through which they transmit and receive signals using functional neuroimaging and diffusion tensor imaging. In a large sample of human participants (aged 6–23 years), we derived the microstructural and volumetric properties of the inferior longitudinal fasciculus (ILF), the inferior fronto-occipital fasciculus, and control tracts, using independently defined anatomical markers. We also determined the functional characteristics of core face- and place-selective regions that are distributed along the trajectory of the pathways of interest. We observed disproportionately large age-related differences in the volume, fractional anisotropy, and mean and radial, but not axial, diffusivities of the ILF. Critically, these differences in the structural properties of the ILF were tightly and specifically linked with an age-related increase in the size of a key face-selective functional region, the fusiform face area. This dynamic association between emerging structural and functional architecture in the developing brain may provide important clues about the mechanisms by which neural circuits become organized and optimized in the human cortex. PMID:23765156

Anatomy and clinical significance of the uncinate process and uncovertebral joint: A comprehensive review.

PubMed

Hartman, Jeffrey

2014-04-01

The uncinate process and its associated uncovertebral articulation are features unique to the cervical spine. This review examines the morphology of these unique structures with particular emphasis on the regional anatomy, development and clinical significance. Five electronic databases were utilized in the literature search and additional relevant citations were retrieved from the references. A total of 74 citations were included for review. This literature review found that the uncinate processes and uncovertebral articulations are rudimentary at birth and develop and evolve with age. With degeneration they become clinically apparent with compression of related structures; most importantly affecting the spinal nerve root and vertebral artery. The articulations have also been found to precipitate torticollis when edematous and be acutely damaged in severe head and neck injuries. The uncinate processes are also important in providing stability and guiding the motion of the cervical spine. This review is intended to re-examine an often overlooked region of the cervical spine as not only an interesting anatomical feature but also a clinically relevant one. Copyright © 2014 Wiley Periodicals, Inc.

Trypanorhynch cestodes (Eutetrarhynchidae) from batoids along the coast of Argentina, including the description of new species in Dollfusiella Campbell et Beveridge, 1994 and Mecistobothrium Heinz et Dailey, 1974.

PubMed

Menoret, Adriana; Ivanov, Veronica A

2015-09-07

During a recent parasitological survey of elasmobranchs along the coast of Argentina, two new species of eutetrarhynchid cestodes of the genera Dollfusiella Campbell et Beveridge, 1994 and Mecistobothrium Heinz et Dailey, 1974 were collected from batoids. Dollfusiella acuta sp. n. was found in four arhynchobatid skates, i.e. Sympterygia acuta Garman (type host), Sympterygia bonapartii Müller et Henle, Atlantoraja castelnaui (Miranda Ribeiro) and Atlantoraja platana (Günther), and Mecistobothrium oblongum sp. n. in the eagle ray Myliobatis goodei Garman. Dollfusiella acuta sp. n. has a tentacular armature consisting of basal rows of uncinate hooks, a distinct basal swelling with uncinate, falcate and bill hooks, and a heteroacanthous metabasal armature with heteromorphous hooks (bothrial uncinate hooks and antibothrial falcate hooks), hooks 1(1') not separated, testes in two columns and an internal seminal vesicle. The tentacular armature of M. oblongum sp. n. is characterised by basal rows of uncinate hooks, a basal swelling with uncinate and falcate hooks, a typical heteroacanthous metabasal armature with heteromorphous hooks (uncinate and falcate to spiniform), and hooks 1(1') separated and of a constant size along the tentacle. It also possesses an elongate scolex, numerous testes arranged in 5-6 irregular columns, and an internal seminal vesicle. The discovery of M. oblongum in M. goodei represents the first record of species of Mecistobothrium in the southwestern Atlantic Ocean. An amended description of Dollfusiella cortezensis (Friggens et Duszynski, 2005) is also provided to clarify details of the scolex and tentacular armature. Members of Dollfusiella in the southwestern Atlantic are specific to a single host species or to a particular host family, while M. oblongum was found in a single host species. Although globally some plerocerci of eutetrarhynchids have been found in teleosts, extensive examination of teleosts off the coast of Argentina suggests that the transmission pathways of these species are exclusively based on invertebrates as intermediate or paratenic hosts.

Does the Left Inferior Longitudinal Fasciculus Play a Role in Language? A Brain Stimulation Study

ERIC Educational Resources Information Center

Mandonnet, Emmanuel; Nouet, Aurelien; Gatignol, Peggy; Capelle, Laurent; Duffau, Hugues

2007-01-01

Although advances in diffusion tensor imaging have enabled us to better study the anatomy of the inferior longitudinal fasciculus (ILF), its function remains poorly understood. Recently, it was suggested that the subcortical network subserving the language semantics could be constituted, in parallel with the inferior occipitofrontal fasciculus, by…

Vocabulary growth rate from preschool to school-age years is reflected in the connectivity of the arcuate fasciculus in 14-year-old children.

PubMed

Su, Mengmeng; Thiebaut de Schotten, Michel; Zhao, Jingjing; Song, Shuang; Zhou, Wei; Gong, Gaolang; McBride, Catherine; Ramus, Franck; Shu, Hua

2018-02-06

The acquisition of language involves the functional specialization of several cortical regions. Connectivity between these brain regions may also change with the development of language. Various studies have demonstrated that the arcuate fasciculus was essential for language function. Vocabulary learning is one of the most important skills in language acquisition. In the present longitudinal study, we explored the influence of vocabulary development on the anatomical properties of the arcuate fasciculus. Seventy-nine Chinese children participated in this study. Between age 4 and age 10, they were administered the same vocabulary task repeatedly. Following a previous study, children's vocabulary developmental trajectories were clustered into three subgroups (consistently good, catch-up, consistently poor). At age 14, diffusion tensor imaging data were collected. Using ROI-based tractography, the anterior, posterior and direct segments of the bilateral arcuate fasciculus were delineated in each child's native space. Group comparisons showed a significantly reduced fractional anisotropy in the left arcuate fasciculus of children in the consistently poor group, in particular in the posterior and direct segments of the arcuate fasciculus. No group differences were observed in the right hemisphere, nor in the left anterior segment. Further regression analyses showed that the rate of vocabulary development, rather than the initial vocabulary size, was a specific predictor of the left arcuate fasciculus connectivity. © 2018 John Wiley & Sons Ltd.

Importance of human right inferior frontoparietal network connected by inferior branch of superior longitudinal fasciculus tract in corporeal awareness of kinesthetic illusory movement.

PubMed

Amemiya, Kaoru; Naito, Eiichi

2016-05-01

It is generally believed that the human right cerebral hemisphere plays a dominant role in corporeal awareness, which is highly associated with conscious experience of the physical self. Prompted by our previous findings, we examined whether the right frontoparietal activations often observed when people experience kinesthetic illusory limb movement are supported by a large-scale brain network connected by a specific branch of the superior longitudinal fasciculus fiber tracts (SLF I, II, and III). We scanned brain activity with functional magnetic resonance imaging (MRI) while nineteen blindfolded healthy volunteers experienced illusory movement of the right stationary hand elicited by tendon vibration, which was replicated after the scanning. We also scanned brain activity when they executed and imagined right hand movement, and identified the active brain regions during illusion, execution, and imagery in relation to the SLF fiber tracts. We found that illusion predominantly activated the right inferior frontoparietal regions connected by SLF III, which were not substantially recruited during execution and imagery. Among these regions, activities in the right inferior parietal cortices and inferior frontal cortices showed right-side dominance and correlated well with the amount of illusion (kinesthetic illusory awareness) experienced by the participants. The results illustrated the predominant involvement of the right inferior frontoparietal network connected by SLF III when people recognize postural changes of their limb. We assume that the network bears a series of functions, specifically, monitoring the current status of the musculoskeletal system, and building-up and updating our postural model (body schema), which could be a basis for the conscious experience of the physical self. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Genetic Contributions to Changes of Fiber Tracts of Ventral Visual Stream in 22q11.2 Deletion Syndrome

PubMed Central

Kikinis, Zora; Makris, Nikos; Finn, Christine T.; Bouix, Sylvain; Lucia, Diandra; Coleman, Michael J.; Tworog-Dube, Erica; Kikinis, Ron; Kucherlapati, Raju; Shenton, Martha E.; Kubicki, Marek

2013-01-01

Patients with 22q11.2 deletion syndrome (22q11.2DS) represent a population at high risk for developing schizophrenia, as well as learning disabilities. Deficits in visuo-spatial memory are thought to underlie some of the cognitive disabilities. Neuronal substrates of visuo-spatial memory include the inferior fronto-occipital fasciculus (IFOF) and the inferior longitudinal fasciculus (ILF), two tracts that comprise the ventral visual stream. Diffusion Tensor Magnetic Resonance Imaging (DT-MRI) is an established method to evaluate white matter (WM) connections in vivo. DT-MRI scans of nine 22q11.2DS young adults and nine matched healthy subjects were acquired. Tractography of the IFOF and the ILF was performed. DT-MRI indices, including Fractional anisotropy (FA) (measure of WM changes), axial diffusivity (AD, measure of axonal changes) and radial diffusivity (RD, measure of myelin changes) of each of the tracts and each group were measured and compared. The 22q11.2DS group showed statistically significant reductions of FA in IFOF in the left hemisphere. Additionally, reductions of AD were found in the IFOF and the ILF in both hemispheres. These findings might be the consequence of axonal changes, which is possibly due to fewer, thinner, or less organized fibers. No changes in RD were detected in any of the tracts delineated, which is in contrast to findings in schizophrenia patients where increases in RD are believed to be indicative of demyelination. We conclude that reduced axonal changes may be key to understanding the underlying pathology of WM leading to the visuo-spatial phenotype in 22q11.2DS. PMID:23612843

Microsurgical and Tractographic Anatomy of the Supplementary Motor Area Complex in Humans.

PubMed

Bozkurt, Baran; Yagmurlu, Kaan; Middlebrooks, Erik H; Karadag, Ali; Ovalioglu, Talat Cem; Jagadeesan, Bharathi; Sandhu, Gauravjot; Tanriover, Necmettin; Grande, Andrew W

2016-11-01

To evaluate the microsurgical anatomy of the fiber tract connections of the supplementary motor area (SMA) and pre-SMA, and examine its potential functional role with reference to clinical trials in the literature. Ten postmortem formalin-fixed human brains (20 sides) and 1 cadaveric head were prepared following Klingler's method. The fiber dissection was performed in a stepwise fashion, from lateral to medial and also from medial to lateral, under an operating microscope, with 3D images captured at each stage. Our findings were supported by in vivo magnetic resonance imaging tractography in 2 healthy subjects. The connections of the SMA complex, composed of the pre-SMA and the SMA proper, are composed of short "U" association fibers and the superior longitudinal fasciculus I, cingulum, claustrocortical fibers, callosal fibers, corticospinal tract, frontal aslant tract, and frontostriatal tract. The claustrocortical fibers may play an important role in the integration of motor, language, and limbic functions of the SMA complex. The frontostriatal tract connects the pre-SMA to the putamen and caudate nucleus, and also forms parts of both the internal capsule and the dorsal external capsule. The SMA complex has numerous connections throughout the cerebrum. An understanding of these connections is important for presurgical planning for lesions in the frontal lobe and helps explain symptoms related to SMA injury. Copyright © 2016 Elsevier Inc. All rights reserved.

A Combined fMRI and DTI Examination of Functional Language Lateralization and Arcuate Fasciculus Structure: Effects of Degree versus Direction of Hand Preference

ERIC Educational Resources Information Center

Propper, Ruthe E.; O'Donnell, Lauren J.; Whalen, Stephen; Tie, Yanmei; Norton, Isaiah H.; Suarez, Ralph O.; Zollei, Lilla; Radmanesh, Alireza; Golby, Alexandra J.

2010-01-01

The present study examined the relationship between hand preference degree and direction, functional language lateralization in Broca's and Wernicke's areas, and structural measures of the arcuate fasciculus. Results revealed an effect of degree of hand preference on arcuate fasciculus structure, such that consistently-handed individuals,…

Involvement of the right hemisphere in reading comprehension: a DTI study

PubMed Central

Horowitz-Kraus, Tzipi; Wang, Yingying; Plante, Elena; Holland, Scott K.

2014-01-01

The Simple View of reading emphasizes the critical role of two factors in normal reading skills: word recognition and reading comprehension. The current study aims to identify the anatomical support for aspects of reading performance that fall within these two components. Fractional anisotropy (FA) values were obtained from Diffusion Tensor images in twenty-one typical adolescents and young adults using the Tract Based Spatial Statistics (TBSS) method. We focused on the Arcuate Fasciculus (AF) and Inferior Longitudinal Fasciculus (ILF) as fiber tracts that connect regions already implicated in the distributed cortical network for reading. Our results demonstrate dissociation between word-level and narrative-level reading skills: the FA values for both left and right ILF were correlated with measures of word reading, while only the left ILF correlated with reading comprehension scores. FA in the AF, however, correlated only with reading comprehension scores, bilaterally. Correlations with the right AF were particularly robust, emphasizing the contribution of the right hemisphere, especially the frontal lobe, to reading comprehension performance on the particular passage comprehension test used in this study. The anatomical dissociation between these reading skills is supported by the Simple View theory and may shed light on why these two skills dissociate in those with reading disorders. PMID:24909792

Sex differences in adolescent white matter architecture.

PubMed

Bava, Sunita; Boucquey, Veronique; Goldenberg, Diane; Thayer, Rachel E; Ward, Megan; Jacobus, Joanna; Tapert, Susan F

2011-02-23

Sex-specific trajectories in white matter development during adolescence may help explain cognitive and behavioral divergences between males and females. Knowledge of sex differences in typically developing adolescents can provide a basis for interpreting sexual dimorphisms in abilities and actions. We examined 58 healthy adolescents (12-14years of age) with diffusion tensor imaging (DTI). Diffusion parameters fractional anisotropy (FA), and mean (MD), radial (RD), and axial diffusivities (AD) were subjected to whole-brain voxel-wise group comparisons using tract-based spatial statistics. Sex differences in white matter microstructure were examined in relation to pubertal development. Early adolescent females (n=29) evidenced higher FA in the right superior corona radiata, higher FA and AD in bilateral corticospinal tracts (≥164μl, p<.01), and lower MD in the right inferior longitudinal fasciculus (ILF) and left forceps major (≥164μl, p<.01) than age-matched males (n=29). Males did not show any areas of higher FA or lower MD than females, but had higher AD in the right superior longitudinal fasciculus, ILF, and forceps minor (≥ 164μl, p<.01). Pubertal stage did not account for sex disparities. In early adolescence, females' motor tracts may reflect widespread changes, while males may undergo relatively more microstructural change in projection and association fibers. Copyright © 2010 Elsevier B.V. All rights reserved.

Pure alexia as a disconnection syndrome: new diffusion imaging evidence for an old concept.

PubMed

Epelbaum, Stéphane; Pinel, Philippe; Gaillard, Raphael; Delmaire, Christine; Perrin, Muriel; Dupont, Sophie; Dehaene, Stanislas; Cohen, Laurent

2008-09-01

Functional neuroimaging and studies of brain-damaged patients made it possible to delineate the main components of the cerebral system for word reading. However, the anatomical connections subtending the flow of information within this network are still poorly defined. Here we study the connectivity of the Visual Word Form Area (VWFA), a pivotal component of the reading network achieving the invariant identification of letter strings, and reproducibly located in the left lateral occipitotemporal sulcus. Diffusion images and functional imaging data were gathered in a patient who developed pure alexia following a small surgical lesion in the vicinity of his VWFA. We had a unique opportunity to compare images obtained before, early after, and late after surgery. Analysis of diffusion images with white matter tractography and voxel-based morphometry showed that the VWFA was mainly linked to the occipital cortex through the inferior longitudinal fasciculus (ILF), and to perisylvian language areas (supramarginal gyrus) through the arcuate fasciculus. After surgery, we observed the progressive and selective degeneration of the ILF, while the VWFA was anatomically intact. This allowed us to establish the critical causal role of this fiber tract in normal reading, and to show that its disruption is one pathophysiological mechanism of pure alexia, thus clarifying a long-standing debate on the role of disconnection in neurocognitive disorders.

White Matter Integrity Dissociates Verbal Memory and Auditory Attention Span in Emerging Adults with Congenital Heart Disease.

PubMed

Brewster, Ryan C; King, Tricia Z; Burns, Thomas G; Drossner, David M; Mahle, William T

2015-01-01

White matter disruptions have been identified in individuals with congenital heart disease (CHD). However, no specific theory-driven relationships between microstructural white matter disruptions and cognition have been established in CHD. We conducted a two-part study. First, we identified significant differences in fractional anisotropy (FA) of emerging adults with CHD using Tract-Based Spatial Statistics (TBSS). TBSS analyses between 22 participants with CHD and 18 demographically similar controls identified five regions of normal appearing white matter with significantly lower FA in CHD, and two higher. Next, two regions of lower FA in CHD were selected to examine theory-driven differential relationships with cognition: voxels along the left uncinate fasciculus (UF; a tract theorized to contribute to verbal memory) and voxels along the right middle cerebellar peduncle (MCP; a tract previously linked to attention). In CHD, a significant positive correlation between UF FA and memory was found, r(20)=.42, p=.049 (uncorrected). There was no correlation between UF and auditory attention span. A positive correlation between MCP FA and auditory attention span was found, r(20)=.47, p=.027 (uncorrected). There was no correlation between MCP and memory. In controls, no significant relationships were identified. These results are consistent with previous literature demonstrating lower FA in younger CHD samples, and provide novel evidence for disrupted white matter integrity in emerging adults with CHD. Furthermore, a correlational double dissociation established distinct white matter circuitry (UF and MCP) and differential cognitive correlates (memory and attention span, respectively) in young adults with CHD.

Frontotemporal correlates of impulsivity and machine learning in retired professional athletes with a history of multiple concussions.

PubMed

Goswami, R; Dufort, P; Tartaglia, M C; Green, R E; Crawley, A; Tator, C H; Wennberg, R; Mikulis, D J; Keightley, M; Davis, Karen D

2016-05-01

The frontotemporal cortical network is associated with behaviours such as impulsivity and aggression. The health of the uncinate fasciculus (UF) that connects the orbitofrontal cortex (OFC) with the anterior temporal lobe (ATL) may be a crucial determinant of behavioural regulation. Behavioural changes can emerge after repeated concussion and thus we used MRI to examine the UF and connected gray matter as it relates to impulsivity and aggression in retired professional football players who had sustained multiple concussions. Behaviourally, athletes had faster reaction times and an increased error rate on a go/no-go task, and increased aggression and mania compared to controls. MRI revealed that the athletes had (1) cortical thinning of the ATL, (2) negative correlations of OFC thickness with aggression and task errors, indicative of impulsivity, (3) negative correlations of UF axial diffusivity with error rates and aggression, and (4) elevated resting-state functional connectivity between the ATL and OFC. Using machine learning, we found that UF diffusion imaging differentiates athletes from healthy controls with significant classifiers based on UF mean and radial diffusivity showing 79-84 % sensitivity and specificity, and 0.8 areas under the ROC curves. The spatial pattern of classifier weights revealed hot spots at the orbitofrontal and temporal ends of the UF. These data implicate the UF system in the pathological outcomes of repeated concussion as they relate to impulsive behaviour. Furthermore, a support vector machine has potential utility in the general assessment and diagnosis of brain abnormalities following concussion.

Multimodal Neuroimaging of Frontolimbic Structure and Function Associated With Suicide Attempts in Adolescents and Young Adults With Bipolar Disorder.

PubMed

Johnston, Jennifer A Y; Wang, Fei; Liu, Jie; Blond, Benjamin N; Wallace, Amanda; Liu, Jiacheng; Spencer, Linda; Cox Lippard, Elizabeth T; Purves, Kirstin L; Landeros-Weisenberger, Angeli; Hermes, Eric; Pittman, Brian; Zhang, Sheng; King, Robert; Martin, Andrés; Oquendo, Maria A; Blumberg, Hilary P

2017-07-01

Bipolar disorder is associated with high risk for suicidal behavior that often develops in adolescence and young adulthood. Elucidation of involved neural systems is critical for prevention. This study of adolescents and young adults with bipolar disorder with and without a history of suicide attempts combines structural, diffusion tensor, and functional MR imaging methods to investigate implicated abnormalities in the morphology and structural and functional connectivity within frontolimbic systems. The study had 26 participants with bipolar disorder who had a prior suicide attempt (the attempter group) and 42 participants with bipolar disorder without a suicide attempt (the nonattempter group). Regional gray matter volume, white matter integrity, and functional connectivity during processing of emotional stimuli were compared between groups, and differences were explored for relationships between imaging modalities and associations with suicide-related symptoms and behaviors. Compared with the nonattempter group, the attempter group showed significant reductions in gray matter volume in the orbitofrontal cortex, hippocampus, and cerebellum; white matter integrity in the uncinate fasciculus, ventral frontal, and right cerebellum regions; and amygdala functional connectivity to the left ventral and right rostral prefrontal cortex. In exploratory analyses, among attempters, there was a significant negative correlation between right rostral prefrontal connectivity and suicidal ideation and between left ventral prefrontal connectivity and attempt lethality. Adolescent and young adult suicide attempters with bipolar disorder demonstrate less gray matter volume and decreased structural and functional connectivity in a ventral frontolimbic neural system subserving emotion regulation. Among attempters, reductions in amygdala-prefrontal functional connectivity may be associated with severity of suicidal ideation and attempt lethality.

Multimodal Neuroimaging of Fronto-limbic Structure and Function Associated with Suicide Attempts in Adolescents and Young Adults with Bipolar Disorder

PubMed Central

Johnston, Jennifer A. Y.; Wang, Fei; Liu, Jie; Blond, Benjamin N.; Wallace, Amanda; Liu, Jiacheng; Spencer, Linda; Cox Lippard, Elizabeth T.; Purves, Kirstin L.; Landeros-Weisenberger, Angeli; Hermes, Eric; Pittman, Brian; Zhang, Sheng; King, Robert; Martin, Andrés; Oquendo, Maria A.; Blumberg, Hilary P.

2018-01-01

Objective Bipolar disorder is associated with high risk for suicide behavior that often develops in adolescence/young adulthood. Elucidation of involved neural systems is critical for prevention. This study of adolescents/young adults with bipolar disorder with and without history of suicide attempts combines structural, diffusion tensor and functional magnetic resonance imaging methods to investigate implicated abnormalities in structural and functional connectivity within fronto-limbic systems. Method Participants with bipolar disorder included 26 with a prior suicide attempt and 42 without attempts. Regional gray matter volume, white matter integrity and functional connectivity during processing of emotional stimuli were compared between groups and differences were explored for relationships between imaging modalities and associations with suicide-related symptoms and behaviors. Results Compared to the non-attempter group, the attempter group showed reductions in gray matter volume in orbitofrontal cortex, hippocampus and cerebellum; white matter integrity in uncinate fasciculus, ventral frontal and right cerebellum regions; and amygdala functional connectivity to left ventral and right rostral prefrontal cortex (p<0.05, corrected). In exploratory analyses, among attempters, right rostral prefrontal connectivity was negatively correlated with suicidal ideation (p<0.05), and left ventral prefrontal connectivity was negatively correlated with attempt lethality (p<0.05). Conclusions Adolescent/young adult suicide attempters with bipolar disorder demonstrate less gray matter volume and decreased structural and functional connectivity in a ventral fronto-limbic neural system subserving emotion regulation. Among suicide attempters, reductions in amygdala-prefrontal functional connectivity may be associated with severity of suicide ideation and attempt lethality. PMID:28135845

Structural and functional neural correlates of self-reported attachment in healthy adults: evidence for an amygdalar involvement.

PubMed

Rigon, Arianna; Duff, Melissa C; Voss, Michelle W

2016-12-01

The concept of attachment in long-term interpersonal relationships has been linked to relationship outcome and social-emotional health. To date, no relationship between the structural properties of the human amygdala and attachment in romantic relationships (measured through self-reported attachment related anxiety and avoidance) has been described. The aim of the current study was to investigate the relationship between amygdala structure as well as amygdala structural and functional connectivity and attachment anxiety and avoidance. To this end, we collected self-report attachment data on a sample of female young adults. We then examined associations between attachment and mean diffusivity, fractional anisotropy and resting state functional connectivity MRI (rs-FC) of the amygdala and its white matter connections with the prefrontal cortex. We found that lower integrity of the left amygdala was linked with attachment avoidance (e.g., being less comfortable in seeking proximity with others and depending on others) and that greater structural integrity of the uncinate fasciculus was positively associated with avoidance. Lastly, we found that stronger rs-FC between the bilateral amygdala and medial prefrontal regions was linked with greater avoidance. Our findings are compatible with and expand previous results reported by studies that have taken a task-related fMRI approach, furthering our understanding of the neurobiological mechanisms of attachment, and in particular implicating the system formed by amygdala and prefrontal areas in the patterns of behavior that regulate emotional proximity in romantic relationships. These findings have the potential to further our understanding of the affective mechanisms underlying attachment behavior.

Profiles of White Matter Tract Pathology in Frontotemporal Dementia

PubMed Central

Mahoney, Colin J; Ridgway, Gerard R; Malone, Ian B; Downey, Laura E; Beck, Jonathan; Kinnunen, Kirsi M; Schmitz, Nicole; Golden, Hannah L; Rohrer, Jonathan D; Schott, Jonathan M; Rossor, Martin N; Ourselin, Sebastien; Mead, Simon; Fox, Nick C; Warren, Jason D

2014-01-01

Despite considerable interest in improving clinical and neurobiological characterisation of frontotemporal dementia and in defining the role of brain network disintegration in its pathogenesis, information about white matter pathway alterations in frontotemporal dementia remains limited. Here we investigated white matter tract damage using an unbiased, template-based diffusion tensor imaging (DTI) protocol in a cohort of 27 patients with the behavioral variant of frontotemporal dementia (bvFTD) representing both major genetic and sporadic forms, in relation both to healthy individuals and to patients with Alzheimer's disease. Widespread white matter tract pathology was identified in the bvFTD group compared with both healthy controls and Alzheimer's disease group, with prominent involvement of uncinate fasciculus, cingulum bundle and corpus callosum. Relatively discrete and distinctive white matter profiles were associated with genetic subgroups of bvFTD associated with MAPT and C9ORF72 mutations. Comparing diffusivity metrics, optimal overall separation of the bvFTD group from the healthy control group was signalled using radial diffusivity, whereas optimal overall separation of the bvFTD group from the Alzheimer's disease group was signalled using fractional anisotropy. Comparing white matter changes with regional grey matter atrophy (delineated using voxel based morphometry) in the bvFTD cohort revealed co-localisation between modalities particularly in the anterior temporal lobe, however white matter changes extended widely beyond the zones of grey matter atrophy. Our findings demonstrate a distributed signature of white matter alterations that is likely to be core to the pathophysiology of bvFTD and further suggest that this signature is modulated by underlying molecular pathologies. PMID:24510641

White matter tract integrity and intelligence in patients with mental retardation and healthy adults.

PubMed

Yu, Chunshui; Li, Jun; Liu, Yong; Qin, Wen; Li, Yonghui; Shu, Ni; Jiang, Tianzi; Li, Kuncheng

2008-05-01

It is well known that brain structures correlate with intelligence but the association between the integrity of brain white matter tracts and intelligence in patients with mental retardation (MR) and healthy adults remains unknown. The aims of this study are to investigate whether the integrity of corpus callosum (CC), cingulum, uncinate fasciculus (UF), optic radiation (OR) and corticospinal tract (CST) are damaged in patients with MR, and to determine the correlations between the integrity of these tracts and full scale intelligence quotient (FSIQ) in both patients and controls. Fifteen MR patients and 79 healthy controls underwent intelligence tests and diffusion tensor imaging examinations. According to the FSIQ, all healthy controls were divided into general intelligence (GI: FSIQ<120; n=42) and high intelligence (HI: FSIQ> or =120; n=37) groups. Intelligence was assessed by Chinese Revised Wechsler Adult Intelligence Scale, and white matter tract integrity was assessed by fractional anisotropy (FA). MR patients showed significantly lower FA than healthy controls in the CC, UF, OR and CST. However, GI subjects only demonstrated lower FA than HI subjects in the right UF. Partial correlation analysis controlling for age and sex showed that FSIQ scores were significantly correlated with the FA of the bilateral UF, genu and truncus of CC, bilateral OR and left CST. While FSIQ scores were only significantly correlated with the FA of the right UF when further controlling for group. This study indicate that MR patients show extensive damage in the integrity of the brain white matter tracts, and the right UF is an important neural basis of human intelligence.

Altered connections on the road to psychopathy.

PubMed

Craig, M C; Catani, M; Deeley, Q; Latham, R; Daly, E; Kanaan, R; Picchioni, M; McGuire, P K; Fahy, T; Murphy, D G M

2009-10-01

Psychopathy is strongly associated with serious criminal behaviour (for example, rape and murder) and recidivism. However, the biological basis of psychopathy remains poorly understood. Earlier studies suggested that dysfunction of the amygdala and/or orbitofrontal cortex (OFC) may underpin psychopathy. Nobody, however, has ever studied the white matter connections (such as the uncinate fasciculus (UF)) linking these structures in psychopaths. Therefore, we used in vivo diffusion tensor magnetic resonance imaging (DT-MRI) tractography to analyse the microstructural integrity of the UF in psychopaths (defined by a Psychopathy Checklist Revised (PCL-R) score of > or = 25) with convictions that included attempted murder, manslaughter, multiple rape with strangulation and false imprisonment. We report significantly reduced fractional anisotropy (FA) (P<0.003), an indirect measure of microstructural integrity, in the UF of psychopaths compared with age- and IQ-matched controls. We also found, within psychopaths, a correlation between measures of antisocial behaviour and anatomical differences in the UF. To confirm that these findings were specific to the limbic amygdala-OFC network, we also studied two 'non-limbic' control tracts connecting the posterior visual and auditory areas to the amygdala and the OFC, and found no significant between-group differences. Lastly, to determine that our findings in UF could not be totally explained by non-specific confounds, we carried out a post hoc comparison with a psychiatric control group with a past history of drug abuse and institutionalization. Our findings remained significant. Taken together, these results suggest that abnormalities in a specific amygdala-OFC limbic network underpin the neurobiological basis of psychopathy.

White matter tract signatures of impaired social cognition in frontotemporal lobar degeneration

PubMed Central

Downey, Laura E.; Mahoney, Colin J.; Buckley, Aisling H.; Golden, Hannah L.; Henley, Susie M.; Schmitz, Nicole; Schott, Jonathan M.; Simpson, Ivor J.; Ourselin, Sebastien; Fox, Nick C.; Crutch, Sebastian J.; Warren, Jason D.

2015-01-01

Impairments of social cognition are often leading features in frontotemporal lobar degeneration (FTLD) and likely to reflect large-scale brain network disintegration. However, the neuroanatomical basis of impaired social cognition in FTLD and the role of white matter connections have not been defined. Here we assessed social cognition in a cohort of patients representing two core syndromes of FTLD, behavioural variant frontotemporal dementia (bvFTD; n = 29) and semantic variant primary progressive aphasia (svPPA; n = 15), relative to healthy older individuals (n = 37) using two components of the Awareness of Social Inference Test, canonical emotion identification and sarcasm identification. Diffusion tensor imaging (DTI) was used to derive white matter tract correlates of social cognition performance and compared with the distribution of grey matter atrophy on voxel-based morphometry. The bvFTD and svPPA groups showed comparably severe deficits for identification of canonical emotions and sarcasm, and these deficits were correlated with distributed and overlapping white matter tract alterations particularly affecting frontotemporal connections in the right cerebral hemisphere. The most robust DTI associations were identified in white matter tracts linking cognitive and evaluative processing with emotional responses: anterior thalamic radiation, fornix (emotion identification) and uncinate fasciculus (sarcasm identification). DTI associations of impaired social cognition were more consistent than corresponding grey matter associations. These findings delineate a brain network substrate for the social impairment that characterises FTLD syndromes. The findings further suggest that DTI can generate sensitive and functionally relevant indexes of white matter damage in FTLD, with potential to transcend conventional syndrome boundaries. PMID:26236629

Kernel Regression Estimation of Fiber Orientation Mixtures in Diffusion MRI

PubMed Central

Cabeen, Ryan P.; Bastin, Mark E.; Laidlaw, David H.

2016-01-01

We present and evaluate a method for kernel regression estimation of fiber orientations and associated volume fractions for diffusion MR tractography and population-based atlas construction in clinical imaging studies of brain white matter. This is a model-based image processing technique in which representative fiber models are estimated from collections of component fiber models in model-valued image data. This extends prior work in nonparametric image processing and multi-compartment processing to provide computational tools for image interpolation, smoothing, and fusion with fiber orientation mixtures. In contrast to related work on multi-compartment processing, this approach is based on directional measures of divergence and includes data-adaptive extensions for model selection and bilateral filtering. This is useful for reconstructing complex anatomical features in clinical datasets analyzed with the ball-and-sticks model, and our framework’s data-adaptive extensions are potentially useful for general multi-compartment image processing. We experimentally evaluate our approach with both synthetic data from computational phantoms and in vivo clinical data from human subjects. With synthetic data experiments, we evaluate performance based on errors in fiber orientation, volume fraction, compartment count, and tractography-based connectivity. With in vivo data experiments, we first show improved scan-rescan reproducibility and reliability of quantitative fiber bundle metrics, including mean length, volume, streamline count, and mean volume fraction. We then demonstrate the creation of a multi-fiber tractography atlas from a population of 80 human subjects. In comparison to single tensor atlasing, our multi-fiber atlas shows more complete features of known fiber bundles and includes reconstructions of the lateral projections of the corpus callosum and complex fronto-parietal connections of the superior longitudinal fasciculus I, II, and III. PMID:26691524

Diffusion tensor imaging and diffusion tensor imaging-fibre tractograph depict the mechanisms of Broca-like and Wernicke-like conduction aphasia.

PubMed

Song, Xinjie; Dornbos, David; Lai, Zongli; Zhang, Yumei; Li, Tieshan; Chen, Hongyan; Yang, Zhonghua

2011-06-01

Conduction aphasia is usually considered a result of damage of the arcuate fasciculus, which is subjacent to the parietal portion of the supra-marginal gyrus and the upper part of the insula. It is important to stress that many features of conduction aphasia relate to a cortical deficit, more than a pure disconnection mechanism. In this study, we explore the mechanism of Broca-like and Wernicke-like conduction aphasia by using diffusion tensor imaging (DTI) and diffusion tensor imaging-fibre tractograph (DT-FT). We enrolled five Broca-like conduction aphasia cases, five Wernicke-like aphasia conduction cases and 10 healthy volunteers residing in Beijing and speaking Mandarin. All are right handed. We analyzed the arcuate fasciculus, Broca's areas and Wernicke's areas by DTI and measured fractional anisotrogy (FA). The results of left and right hemispheres were compared in both conduction aphasia cases and volunteers. Then the results of the conduction aphasia cases were compared with those of volunteers. The fibre construction of Broca's and Wernicke's areas was also compared by DTI-FT. The FA occupied by the identified connective pathways (Broca's area, Wernicke's area and the arcuate fasciculus) in the left hemisphere was larger than that in the right hemisphere in the control group (P<0.05). Among Broca-like conduction aphasia cases, the FA of the left Broca's area was smaller than that of the right mirror side (P<0.05), and the FA of the left anterior segment of the arcuate fasciculus was smaller than that of right mirror side (P<0.05). On the other hand, among Wernicke-like conduction aphasia patients, the FA of the left Wernicke's area was smaller than that of right mirror side (P<0.05), and the FA of left posterior segment of arcuate fasciculus was smaller than that of right mirror side (P<0.05). Conduction aphasia results from not only arcuate fasciculus destruction, but also from disruption of the associated cortical areas. Along different segments of the arcuate fasciculus, the characteristics of language disorders of conduction aphasia were different. A lesion involving Broca's area and the anterior segments of the arcuate fasciculus would lead to Broca-like conduction aphasia, whereas a lesion involved Wernicke's area and posterior segments of the arcuate fasciculus would lead to Wernicke-like conduction aphasia.

Perspective on basal ganglia connections as described by Nauta and Mehler in 1966: Where we were and how this paper effected where we are now.

PubMed

Haber, Suzanne

2016-08-15

The fiber degenerations resulting from variously located lesions of the lentiform nucleus were studied in the rhesus monkey by the aid of the Nauta-Gygax and Albrecht-Fernstrom techniques. The following observations were made. (1) Putaminofugal connections. Thin fibers originating in the putamen and composing Wilson's 'pencil' bundles traverse the globus pallidus, converging toward the medial point of the lentiform nucleus. The mjority of these fibers terminate in both segments of the globus pallidus, but a considerable number continue caudalward, perforating the cerebral peduncle as ventral components of Edinger's comb system, and terminate in lateral parts of the substantia nigra, pars reticulata. (2) Pallidofugal connections. The ansa lenticularis as defined by von Monakow originates exclusively from the globus pallidus. Its middle division, composed of fibers of medium calibre, arises in the external pallidal segment and traverses the cerebral peduncle as the dorsal component of the comb system to end in the subthalamic nucleus. The thick-fibered dorsal and ventral ansal divisions arise in the internal pallidal segment and combine to form the fasciculus lenticularis which represents the only apparent direct connection of the globus pallidus with the thalamus and the mesencephalic tegmentum. (a) Pallidothalamic fibers follow successively the lenticular and thalamic fasciculi and are distributed to the nuclei ventralis lateralis (subnuclei medialis and oralis of Olszewski and Baxter; none to Zone X and subnucleus caudalis) and ventralis anterior (except subnucleus VAmc). A considerable number of thinner fibers, possibly collaterals of those to VL and VA, terminate in the 'centre médian'; this connection appears to close a potential transthalamic circuit: putamen-globus pallidus-'centre médian'-putamen. (b) There is suggestive evidence of pallidofugal fibers following the stratum zonale thalami to the habenula. (c) Pallidohypothalamic connections could not be identified. Most, and possibly all, of the ansal fibers composing the so-called pallidohypothalamic tract loop back into Forel's fields after a shorter or longer descent into the hypothalamus. (d) Fibers of the fasciculus lenticularis by-passing the thalamus are distributed to the nucleus of Forel's field H (prerubral field). Longer fibers of the same category pass caudalward lateral and ventral to the red nucleus and terminate in the nucleus tegmenti pedunculopontinus, particularly in the latter's caudal subnucleus compactus (terminology of Olszewski and Baxter). A few such pallidomesencephalic fibers appear to end in a small circumscript caudal area of the substantia nigra, pars compacta. No evidence was obtained of pallidotegmental fibers extending caudally beyond the mesencephalon. (e) Pallidal efferents to the zona incerta could not be identified. Only sporadic pallidofugal fibers could be followed to the red nucleus, nucleus interstitialis, and nucleus of Darkschewitsch. The article, 'Projections of the lentiform nucleus in the monkey', by Walle J.H. Nauta and William R. Mehler used a relatively new anatomical tracing method that allowed visualization of degenerating myelin following carefully placed lesions to identify the efferent projections from the lentiform nucleus. While several of the basal ganglia pathways had been described or suspected, this publication validated many of these, resolved controversies regarding some connections, and demonstrated a few that had not previously been shown. This seminal paper became a main reference for basal ganglia connections until newer, more specific tracer techniques were developed. Several students and colleagues who worked closely with Nauta continued to use anatomical tracing methods to make key important contributions to delineating basal ganglia circuits and function. Collectively these studies have impacted greatly on our understanding of the role of the basal ganglia in normal behavior and in neurological and psychiatric disorders. This article is part of a Special Issue entitled SI:50th Anniversary Issue. Copyright © 2016. Published by Elsevier B.V.

Inter-individual differences in audio-motor learning of piano melodies and white matter fiber tract architecture.

PubMed

Engel, Annerose; Hijmans, Brenda S; Cerliani, Leonardo; Bangert, Marc; Nanetti, Luca; Keller, Peter E; Keysers, Christian

2014-05-01

Humans vary substantially in their ability to learn new motor skills. Here, we examined inter-individual differences in learning to play the piano, with the goal of identifying relations to structural properties of white matter fiber tracts relevant to audio-motor learning. Non-musicians (n = 18) learned to perform three short melodies on a piano keyboard in a pure audio-motor training condition (vision of their own fingers was occluded). Initial learning times ranged from 17 to 120 min (mean ± SD: 62 ± 29 min). Diffusion-weighted magnetic resonance imaging was used to derive the fractional anisotropy (FA), an index of white matter microstructural arrangement. A correlation analysis revealed that higher FA values were associated with faster learning of piano melodies. These effects were observed in the bilateral corticospinal tracts, bundles of axons relevant for the execution of voluntary movements, and the right superior longitudinal fasciculus, a tract important for audio-motor transformations. These results suggest that the speed with which novel complex audio-motor skills can be acquired may be determined by variability in structural properties of white matter fiber tracts connecting brain areas functionally relevant for audio-motor learning. Copyright © 2013 Wiley Periodicals, Inc.

A reliability assessment of constrained spherical deconvolution-based diffusion-weighted magnetic resonance imaging in individuals with chronic stroke.

PubMed

Snow, Nicholas J; Peters, Sue; Borich, Michael R; Shirzad, Navid; Auriat, Angela M; Hayward, Kathryn S; Boyd, Lara A

2016-01-15

Diffusion-weighted magnetic resonance imaging (DW-MRI) is commonly used to assess white matter properties after stroke. Novel work is utilizing constrained spherical deconvolution (CSD) to estimate complex intra-voxel fiber architecture unaccounted for with tensor-based fiber tractography. However, the reliability of CSD-based tractography has not been established in people with chronic stroke. Establishing the reliability of CSD-based DW-MRI in chronic stroke. High-resolution DW-MRI was performed in ten adults with chronic stroke during two separate sessions. Deterministic region of interest-based fiber tractography using CSD was performed by two raters. Mean fractional anisotropy (FA), apparent diffusion coefficient (ADC), tract number, and tract volume were extracted from reconstructed fiber pathways in the corticospinal tract (CST) and superior longitudinal fasciculus (SLF). Callosal fiber pathways connecting the primary motor cortices were also evaluated. Inter-rater and test-retest reliability were determined by intra-class correlation coefficients (ICCs). ICCs revealed excellent reliability for FA and ADC in ipsilesional (0.86-1.00; p<0.05) and contralesional hemispheres (0.94-1.00; p<0.0001), for CST and SLF fibers; and excellent reliability for all metrics in callosal fibers (0.85-1.00; p<0.05). ICC ranged from poor to excellent for tract number and tract volume in ipsilesional (-0.11 to 0.92; p≤0.57) and contralesional hemispheres (-0.27 to 0.93; p≤0.64), for CST and SLF fibers. Like other select DW-MRI approaches, CSD-based tractography is a reliable approach to evaluate FA and ADC in major white matter pathways, in chronic stroke. Future work should address the reproducibility and utility of CSD-based metrics of tract number and tract volume. Copyright © 2015 Elsevier B.V. All rights reserved.

The vertical occipital fasciculus: a century of controversy resolved by in vivo measurements.

PubMed

Yeatman, Jason D; Weiner, Kevin S; Pestilli, Franco; Rokem, Ariel; Mezer, Aviv; Wandell, Brian A

2014-12-02

The vertical occipital fasciculus (VOF) is the only major fiber bundle connecting dorsolateral and ventrolateral visual cortex. Only a handful of studies have examined the anatomy of the VOF or its role in cognition in the living human brain. Here, we trace the contentious history of the VOF, beginning with its original discovery in monkey by Wernicke (1881) and in human by Obersteiner (1888), to its disappearance from the literature, and recent reemergence a century later. We introduce an algorithm to identify the VOF in vivo using diffusion-weighted imaging and tractography, and show that the VOF can be found in every hemisphere (n = 74). Quantitative T1 measurements demonstrate that tissue properties, such as myelination, in the VOF differ from neighboring white-matter tracts. The terminations of the VOF are in consistent positions relative to cortical folding patterns in the dorsal and ventral visual streams. Recent findings demonstrate that these same anatomical locations also mark cytoarchitectonic and functional transitions in dorsal and ventral visual cortex. We conclude that the VOF is likely to serve a unique role in the communication of signals between regions on the ventral surface that are important for the perception of visual categories (e.g., words, faces, bodies, etc.) and regions on the dorsal surface involved in the control of eye movements, attention, and motion perception.

White matter anisotropy in the ventral language pathway predicts sound-to-word learning success

PubMed Central

Wong, Francis C. K.; Chandrasekaran, Bharath; Garibaldi, Kyla; Wong, Patrick C. M.

2011-01-01

According to the dual stream model of auditory language processing, the dorsal stream is responsible for mapping sound to articulation while the ventral stream plays the role of mapping sound to meaning. Most researchers agree that the arcuate fasciculus (AF) is the neuroanatomical correlate of the dorsal steam, however, less is known about what constitutes the ventral one. Nevertheless two hypotheses exist, one suggests that the segment of the AF that terminates in middle temporal gyrus corresponds to the ventral stream and the other suggests that it is the extreme capsule that underlies this sound to meaning pathway. The goal of this study is to evaluate these two competing hypotheses. We trained participants with a sound-to-word learning paradigm in which they learned to use a foreign phonetic contrast for signaling word meaning. Using diffusion tensor imaging (DTI), a brain imaging tool to investigate white matter connectivity in humans, we found that fractional anisotropy in the left parietal-temporal region positively correlated with the performance in sound-to-word learning. In addition, fiber tracking revealed a ventral pathway, composed of the extreme capsule and the inferior longitudinal fasciculus, that mediated auditory comprehension. Our findings provide converging evidence supporting the importance of the ventral steam, an extreme capsule system, in the frontal-temporal language network. Implications for current models of speech processing will also be discussed. PMID:21677162

Neuronavigation Based on Track Density Image Extracted from Deterministic High-Definition Fiber Tractography.

PubMed

Wei, Peng-Hu; Cong, Fei; Chen, Ge; Li, Ming-Chu; Yu, Xin-Guang; Bao, Yu-Hai

2017-02-01

Diffusion tensor imaging-based navigation is unable to resolve crossing fibers or to determine with accuracy the fanning, origin, and termination of fibers. It is important to improve the accuracy of localizing white matter fibers for improved surgical approaches. We propose a solution to this problem using navigation based on track density imaging extracted from high-definition fiber tractography (HDFT). A 28-year-old asymptomatic female patient with a left-lateral ventricle meningioma was enrolled in the present study. Language and visual tests, magnetic resonance imaging findings, both preoperative and postoperative HDFT, and the intraoperative navigation and surgery process are presented. Track density images were extracted from tracts derived using full q-space (514 directions) diffusion spectrum imaging (DSI) and integrated into a neuronavigation system. Navigation accuracy was verified via intraoperative records and postoperative DSI tractography, as well as a functional examination. DSI successfully represented the shape and range of the Meyer loop and arcuate fasciculus. Extracted track density images from the DSI were successfully integrated into the navigation system. The relationship between the operation channel and surrounding tracts was consistent with the postoperative findings, and the patient was functionally intact after the surgery. DSI-based TDI navigation allows for the visualization of anatomic features such as fanning and angling and helps to identify the range of a given tract. Moreover, our results show that our HDFT navigation method is a promising technique that preserves neural function. Copyright © 2016 Elsevier Inc. All rights reserved.

Night sleep influences white matter microstructure in bipolar depression.

PubMed

Benedetti, Francesco; Melloni, Elisa M T; Dallaspezia, Sara; Bollettini, Irene; Locatelli, Clara; Poletti, Sara; Colombo, Cristina

2017-08-15

Alteration of circadian rhythms and sleep disruption are prominent trait-like features of bipolar disorder (BD). Diffusion tensor imaging (DTI) measures suggest a widespread alteration of white matter (WM) microstructure in patients with BD. Sleep promotes myelination and oligodendrocyte precursor cells proliferation. We hypothesized a possible association between DTI measures of WM microstructure and sleep quantity measures in BD. We studied 69 inpatients affected by a depressive episode in course of type I BD. We used whole brain tract-based spatial statistics on DTI measures of WM microstructure: axial, radial, and mean diffusivity (AD, RD, MD), and fractional anisotropy (FA). Self-assessed measures of time asleep (TA) and total sleep time (TST) were extracted from the Pittsburgh Sleep Quality Index (PSQI). Actigraphic recordings were performed on a subsample of 23 patients. We observed a positive correlation of DTI measures of FA with actigraphic measures of TA and TST, and with PSQI measure of TA. DTI measures of RD inversely associated with actigraphic measure of TA, and with PSQI measures of TA and TST. Several WM tracts were involved, including corpus callosum, cyngulate gyrus, uncinate fasciculus, left superior and inferior longitudinal and fronto-occipital fasciculi, thalamic radiation, corona radiata, retrolenticular part of internal capsule and corticospinal tract. The study is correlational in nature, and no conclusion about a causal connection can be drawn. Reduced FA with increased RD and MD indicate higher water diffusivity associated with less organized myelin and/or axonal structures. Our findings suggest an association between sleep disruption and these measures of brain microstructure in specific tracts contributing to the functional connectivity in BD. Copyright © 2017 Elsevier B.V. All rights reserved.

Episodic memory function is associated with multiple measures of white matter integrity in cognitive aging

PubMed Central

Lockhart, Samuel N.; Mayda, Adriane B. V.; Roach, Alexandra E.; Fletcher, Evan; Carmichael, Owen; Maillard, Pauline; Schwarz, Christopher G.; Yonelinas, Andrew P.; Ranganath, Charan; DeCarli, Charles

2011-01-01

Previous neuroimaging research indicates that white matter injury and integrity, measured respectively by white matter hyperintensities (WMH) and fractional anisotropy (FA) obtained from diffusion tensor imaging (DTI), differ with aging and cerebrovascular disease (CVD) and are associated with episodic memory deficits in cognitively normal older adults. However, knowledge about tract-specific relationships between WMH, FA, and episodic memory in aging remains limited. We hypothesized that white matter connections between frontal cortex and subcortical structures as well as connections between frontal and temporo-parietal cortex would be most affected. In the current study, we examined relationships between WMH, FA and episodic memory in 15 young adults, 13 elders with minimal WMH and 15 elders with extensive WMH, using an episodic recognition memory test for object-color associations. Voxel-based statistics were used to identify voxel clusters where white matter measures were specifically associated with variations in episodic memory performance, and white matter tracts intersecting these clusters were analyzed to examine white matter-memory relationships. White matter injury and integrity measures were significantly associated with episodic memory in extensive regions of white matter, located predominantly in frontal, parietal, and subcortical regions. Template based tractography indicated that white matter injury, as measured by WMH, in the uncinate and inferior longitudinal fasciculi were significantly negatively associated with episodic memory performance. Other tracts such as thalamo-frontal projections, superior longitudinal fasciculus, and dorsal cingulum bundle demonstrated strong negative associations as well. The results suggest that white matter injury to multiple pathways, including connections of frontal and temporal cortex and frontal-subcortical white matter tracts, plays a critical role in memory differences seen in older individuals. PMID:22438841

Interactive effects of genetic polymorphisms and childhood adversity on brain morphologic changes in depression.

PubMed

Kim, Yong-Ku; Ham, Byung-Joo; Han, Kyu-Man

2018-03-10

The etiology of depression is characterized by the interplay of genetic and environmental factors and brain structural alteration. Childhood adversity is a major contributing factor in the development of depression. Interactions between childhood adversity and candidate genes for depression could affect brain morphology via the modulation of neurotrophic factors, serotonergic neurotransmission, or the hypothalamus-pituitary-adrenal (HPA) axis, and this pathway may explain the subsequent onset of depression. Childhood adversity is associated with structural changes in the hippocampus, amygdala, anterior cingulate cortex (ACC), and prefrontal cortex (PFC), as well as white matter tracts such as the corpus callosum, cingulum, and uncinate fasciculus. Childhood adversity showed an interaction with the brain-derived neurotrophic factor (BDNF) gene Val66Met polymorphism, serotonin transporter-linked promoter region (5-HTTLPR), and FK506 binding protein 51 (FKBP5) gene rs1360780 in brain morphologic changes in patients with depression and in a non-clinical population. Individuals with the Met allele of BDNF Val66Met and a history of childhood adversity had reduced volume in the hippocampus and its subfields, amygdala, and PFC and thinner rostral ACC in a study of depressed patients and healthy controls. The S allele of 5-HTTLPR combined with exposure to childhood adversity or a poorer parenting environment was associated with a smaller hippocampal volume and subsequent onset of depression. The FKBP5 gene rs160780 had a significant interaction with childhood adversity in the white matter integrity of brain regions involved in emotion processing. This review identified that imaging genetic studies on childhood adversity may deepen our understanding on the neurobiological background of depression by scrutinizing complicated pathways of genetic factors, early psychosocial environments, and the accompanying morphologic changes in emotion-processing neural circuitry. Copyright © 2018 Elsevier Inc. All rights reserved.

A framework for incorporating DTI Atlas Builder registration into Tract-Based Spatial Statistics and a simulated comparison to standard TBSS.

PubMed

Leming, Matthew; Steiner, Rachel; Styner, Martin

2016-02-27

Tract-based spatial statistics (TBSS) 6 is a software pipeline widely employed in comparative analysis of the white matter integrity from diffusion tensor imaging (DTI) datasets. In this study, we seek to evaluate the relationship between different methods of atlas registration for use with TBSS and different measurements of DTI (fractional anisotropy, FA, axial diffusivity, AD, radial diffusivity, RD, and medial diffusivity, MD). To do so, we have developed a novel tool that builds on existing diffusion atlas building software, integrating it into an adapted version of TBSS called DAB-TBSS (DTI Atlas Builder-Tract-Based Spatial Statistics) by using the advanced registration offered in DTI Atlas Builder 7 . To compare the effectiveness of these two versions of TBSS, we also propose a framework for simulating population differences for diffusion tensor imaging data, providing a more substantive means of empirically comparing DTI group analysis programs such as TBSS. In this study, we used 33 diffusion tensor imaging datasets and simulated group-wise changes in this data by increasing, in three different simulations, the principal eigenvalue (directly altering AD), the second and third eigenvalues (RD), and all three eigenvalues (MD) in the genu, the right uncinate fasciculus, and the left IFO. Additionally, we assessed the benefits of comparing the tensors directly using a functional analysis of diffusion tensor tract statistics (FADTTS 10 ). Our results indicate comparable levels of FA-based detection between DAB-TBSS and TBSS, with standard TBSS registration reporting a higher rate of false positives in other measurements of DTI. Within the simulated changes investigated here, this study suggests that the use of DTI Atlas Builder's registration enhances TBSS group-based studies.

Sex differences in white matter abnormalities after mild traumatic brain injury: localization and correlation with outcome.

PubMed

Fakhran, Saeed; Yaeger, Karl; Collins, Michael; Alhilali, Lea

2014-09-01

To evaluate sex differences in diffusion-tensor imaging (DTI) white matter abnormalities after mild traumatic brain injury (mTBI) using tract-based spatial statistics (TBSS) and to compare associated clinical outcomes. The institutional review board approved this study, with waiver of informed consent. DTI in 69 patients with mTBI (47 male and 22 female patients) and 21 control subjects (10 male and 11 female subjects) with normal conventional magnetic resonance (MR) images were retrospectively reviewed. Fractional anisotropy (FA) maps were generated as a measure of white matter integrity. Patients with mTBI underwent serial neurocognitive testing with Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT). Correlation between sex, white matter FA values, ImPACT scores, and time to symptom resolution (TSR) were analyzed with multivariate analysis and TBSS. No significant difference in age was seen between males and females (control subjects, P = .3; patients with mTBI, P = .34). No significant difference was seen in initial ImPACT symptom scores (P = .33) between male and female patients with mTBI. Male patients with mTBI had significantly decreased FA values in the uncinate fasciculus (UF) bilaterally (mean FA, 0.425; 95% confidence interval: 0.375, 0.476) compared with female patients with mTBI and control subjects (P < .05), with a significantly longer TSR (P = .04). Multivariate analysis showed sex and UF FA values independently correlated with TSR longer than 3 months (adjusted odds ratios, 2.27 and 2.38; P = .04 and P < .001, respectively), but initial symptom severity did not (adjusted odds ratio, 1.15; P = .35). Relative sparing of the UF is seen in female compared with male patients after mTBI, with sex and UF FA values as stronger predictors of TSR than initial symptom severity.

Effect of patient sex on white matter alterations in unilateral medial temporal lobe epilepsy with hippocampal sclerosis assessed by diffusion tensor imaging.

PubMed

Oguz, K K; Tezer, I; Sanverdi, E; Has, A C; Bilginer, B; Dolgun, A; Saygi, S

2013-05-01

Studies shows ictal behavior and symptoms are affected by patient sex in temporal lobe epilepsy. The purpose of our study was to determine whether alterations in the WM as assessed by DTI display different patterns in male and female patients with unilateral HS. Patients with unilateral HS were categorized as women with right HS (n=12), men with right HS (n=10), women with left HS (n=12), and men with left HS (n=10). DTI of the brain along 64 noncollinear directions was obtained from 44 patients and 37 sex-matched control participants. We used TBSS to analyze whole-brain WM. Regions with significant changes of FA and MD, and their mean FA, MD, total number of significant voxels, and asymmetry indices were determined for each group. All groups showed bilateral and extensive reductions of FA and elevated MD in the WM, more prominent ipsilateral to the affected hippocampus. The total number of voxels with decreased FA in patients compared with that of control participants was higher in women with right HS (24,727 vs 5,459) and in men with left HS (27,332 vs 14,013) than in their counterparts. Changes in MD associated with right HS were more extensive in both men and women (right vs left HS, women: 16,926 vs 5,458; men: 5,389 vs 4,764) than in those with left HS. In patients with right HS, the ipsilateral cingulum, uncinate fasciculus, internal and external capsules, and right acoustic radiation were involved extensively in women. Women and men showed different patterns in extent of WM alterations associated with HS.

Lower Activation in Frontal Cortex and Posterior Cingulate Cortex Observed during Sex Determination Test in Early-Stage Dementia of the Alzheimer Type

PubMed Central

Rajmohan, Ravi; Anderson, Ronald C.; Fang, Dan; Meyer, Austin G.; Laengvejkal, Pavis; Julayanont, Parunyou; Hannabas, Greg; Linton, Kitten; Culberson, John; Khan, Hafiz; De Toledo, John; Reddy, P. Hemachandra; O’Boyle, Michael W.

2017-01-01

Face-labeling refers to the ability to classify faces into social categories. This plays a critical role in human interaction as it serves to define concepts of socially acceptable interpersonal behavior. The purpose of the current study was to characterize, what, if any, impairments in face-labeling are detectable in participants with early-stage clinically diagnosed dementia of the Alzheimer type (CDDAT) through the use of the sex determination test (SDT). In the current study, four (1 female, 3 males) CDDAT and nine (4 females, 5 males) age-matched neurotypicals (NT) completed the SDT using chimeric faces while undergoing BOLD fMRI. It was expected that CDDAT participants would have poor verbal fluency, which would correspond to poor performance on the SDT. This could be explained by decreased activation and connectivity patterns within the fusiform face area (FFA) and anterior cingulate cortex (ACC). DTI was also performed to test the association of pathological deterioration of connectivity in the uncinate fasciculus (UF) and verbally-mediated performance. CDDAT showed lower verbal fluency test (VFT) performance, but VFT was not significantly correlated to SDT and no significant difference was seen between CDDAT and NT for SDT performance as half of the CDDAT performed substantially worse than NT while the other half performed similarly. BOLD fMRI of SDT displayed differences in the left superior frontal gyrus and posterior cingulate cortex (PCC), but not the FFA or ACC. Furthermore, although DTI showed deterioration of the right inferior and superior longitudinal fasciculi, as well as the PCC, it did not demonstrate significant deterioration of UF tracts. Taken together, early-stage CDDAT may represent a common emerging point for the loss of face labeling ability. PMID:28588478

Lower Activation in Frontal Cortex and Posterior Cingulate Cortex Observed during Sex Determination Test in Early-Stage Dementia of the Alzheimer Type.

PubMed

Rajmohan, Ravi; Anderson, Ronald C; Fang, Dan; Meyer, Austin G; Laengvejkal, Pavis; Julayanont, Parunyou; Hannabas, Greg; Linton, Kitten; Culberson, John; Khan, Hafiz; De Toledo, John; Reddy, P Hemachandra; O'Boyle, Michael W

2017-01-01

Face-labeling refers to the ability to classify faces into social categories. This plays a critical role in human interaction as it serves to define concepts of socially acceptable interpersonal behavior. The purpose of the current study was to characterize, what, if any, impairments in face-labeling are detectable in participants with early-stage clinically diagnosed dementia of the Alzheimer type (CDDAT) through the use of the sex determination test (SDT). In the current study, four (1 female, 3 males) CDDAT and nine (4 females, 5 males) age-matched neurotypicals (NT) completed the SDT using chimeric faces while undergoing BOLD fMRI. It was expected that CDDAT participants would have poor verbal fluency, which would correspond to poor performance on the SDT. This could be explained by decreased activation and connectivity patterns within the fusiform face area (FFA) and anterior cingulate cortex (ACC). DTI was also performed to test the association of pathological deterioration of connectivity in the uncinate fasciculus (UF) and verbally-mediated performance. CDDAT showed lower verbal fluency test (VFT) performance, but VFT was not significantly correlated to SDT and no significant difference was seen between CDDAT and NT for SDT performance as half of the CDDAT performed substantially worse than NT while the other half performed similarly. BOLD fMRI of SDT displayed differences in the left superior frontal gyrus and posterior cingulate cortex (PCC), but not the FFA or ACC. Furthermore, although DTI showed deterioration of the right inferior and superior longitudinal fasciculi, as well as the PCC, it did not demonstrate significant deterioration of UF tracts. Taken together, early-stage CDDAT may represent a common emerging point for the loss of face labeling ability.

Poorer frontolimbic white matter integrity is associated with chronic cannabis use, FAAH genotype, and increased depressive and apathy symptoms in adolescents and young adults.

PubMed

Shollenbarger, Skyler G; Price, Jenessa; Wieser, Jon; Lisdahl, Krista

2015-01-01

The heaviest period of cannabis use coincides with ongoing white matter (WM) maturation. Further, cannabis-related changes may be moderated by FAAH genotype (rs324420). We examined the association between cannabis use and FAAH genotype on frontolimbic WM integrity in adolescents and emerging adults. We then tested whether observed WM abnormalities were linked with depressive or apathy symptoms. Participants included 37 cannabis users and 37 healthy controls (33 female; ages 18-25). Multiple regressions examined the independent and interactive effects of variables on WM integrity. Regular cannabis users demonstrated reduced WM integrity in the bilateral uncinate fasciculus (UNC) (MD, right: p = .009 and left: p = .009; FA, right: p = .04 and left: p = .03) and forceps minor (fMinor) (MD, p = .03) compared to healthy controls. Marginally reduced WM integrity in the cannabis users was found in the left anterior thalamic radiation (ATR) (FA, p = .08). Cannabis group ∗ FAAH genotype interaction predicted WM integrity in bilateral ATR (FA, right: p = .05 and left: p = .001) and fMinor (FA, p = .02). In cannabis users, poorer WM integrity was correlated with increased symptoms of depression and apathy in bilateral ATR and UNC. Consistent with prior findings, cannabis use was associated with reduced frontolimbic WM integrity. WM integrity was also moderated by FAAH genotype, in that cannabis-using FAAH C/C carriers and A carrying controls had reduced WM integrity compared to control C/C carriers. Observed frontolimbic white matter abnormalities were linked with increased depressive and apathy symptoms in the cannabis users.

Poorer frontolimbic white matter integrity is associated with chronic cannabis use, FAAH genotype, and increased depressive and apathy symptoms in adolescents and young adults

PubMed Central

Shollenbarger, Skyler G.; Price, Jenessa; Wieser, Jon; Lisdahl, Krista

2015-01-01

Background The heaviest period of cannabis use coincides with ongoing white matter (WM) maturation. Further, cannabis-related changes may be moderated by FAAH genotype (rs324420). We examined the association between cannabis use and FAAH genotype on frontolimbic WM integrity in adolescents and emerging adults. We then tested whether observed WM abnormalities were linked with depressive or apathy symptoms. Methods Participants included 37 cannabis users and 37 healthy controls (33 female; ages 18–25). Multiple regressions examined the independent and interactive effects of variables on WM integrity. Results Regular cannabis users demonstrated reduced WM integrity in the bilateral uncinate fasciculus (UNC) (MD, right: p = .009 and left: p = .009; FA, right: p = .04 and left: p = .03) and forceps minor (fMinor) (MD, p = .03) compared to healthy controls. Marginally reduced WM integrity in the cannabis users was found in the left anterior thalamic radiation (ATR) (FA, p = .08). Cannabis group ∗ FAAH genotype interaction predicted WM integrity in bilateral ATR (FA, right: p = .05 and left: p = .001) and fMinor (FA, p = .02). In cannabis users, poorer WM integrity was correlated with increased symptoms of depression and apathy in bilateral ATR and UNC. Conclusions Consistent with prior findings, cannabis use was associated with reduced frontolimbic WM integrity. WM integrity was also moderated by FAAH genotype, in that cannabis-using FAAH C/C carriers and A carrying controls had reduced WM integrity compared to control C/C carriers. Observed frontolimbic white matter abnormalities were linked with increased depressive and apathy symptoms in the cannabis users. PMID:26106535

White matter microstructural changes as vulnerability factors and acquired signs of post-earthquake distress.

PubMed

Sekiguchi, Atsushi; Sugiura, Motoaki; Taki, Yasuyuki; Kotozaki, Yuka; Nouchi, Rui; Takeuchi, Hikaru; Araki, Tsuyoshi; Hanawa, Sugiko; Nakagawa, Seishu; Miyauchi, Carlos Makoto; Sakuma, Atsushi; Kawashima, Ryuta

2014-01-01

Many survivors of severe disasters need psychological support, even those not suffering post-traumatic stress disorder (PTSD). The critical issue in understanding the psychological response after experiencing severe disasters is to distinguish neurological microstructural underpinnings as vulnerability factors from signs of emotional distress acquired soon after the stressful life event. We collected diffusion-tensor magnetic resonance imaging (DTI) data from a group of healthy adolescents before the Great East Japan Earthquake and re-examined the DTIs and anxiety levels of 30 non-PTSD subjects from this group 3-4 months after the earthquake using voxel-based analyses in a longitudinal DTI study before and after the earthquake. We found that the state anxiety level after the earthquake was negatively associated with fractional anisotropy (FA) in the right anterior cingulum (Cg) before the earthquake (r = -0.61, voxel level p<0.0025, cluster level p<0.05 corrected), and positively associated with increased FA changes from before to after the earthquake in the left anterior Cg (r = 0.70, voxel level p<0.0025, cluster level p<0.05 corrected) and uncinate fasciculus (Uf) (r = 0.65, voxel level p<0.0025, cluster level p<0.05 corrected). The results demonstrated that lower FA in the right anterior Cg was a vulnerability factor and increased FA in the left anterior Cg and Uf was an acquired sign of state anxiety after the earthquake. We postulate that subjects with dysfunctions in processing fear and anxiety before the disaster were likely to have higher anxiety levels requiring frequent emotional regulation after the disaster. These findings provide new evidence of psychophysiological responses at the neural network level soon after a stressful life event and might contribute to the development of effective methods to prevent PTSD.

Microstructural White Matter Alterations in the Corpus Callosum of Girls With Conduct Disorder.

PubMed

Menks, Willeke Martine; Furger, Reto; Lenz, Claudia; Fehlbaum, Lynn Valérie; Stadler, Christina; Raschle, Nora Maria

2017-03-01

Diffusion tensor imaging (DTI) studies in adolescent conduct disorder (CD) have demonstrated white matter alterations of tracts connecting functionally distinct fronto-limbic regions, but only in boys or mixed-gender samples. So far, no study has investigated white matter integrity in girls with CD on a whole-brain level. Therefore, our aim was to investigate white matter alterations in adolescent girls with CD. We collected high-resolution DTI data from 24 girls with CD and 20 typically developing control girls using a 3T magnetic resonance imaging system. Fractional anisotropy (FA) and mean diffusivity (MD) were analyzed for whole-brain as well as a priori-defined regions of interest, while controlling for age and intelligence, using a voxel-based analysis and an age-appropriate customized template. Whole-brain findings revealed white matter alterations (i.e., increased FA) in girls with CD bilaterally within the body of the corpus callosum, expanding toward the right cingulum and left corona radiata. The FA and MD results in a priori-defined regions of interest were more widespread and included changes in the cingulum, corona radiata, fornix, and uncinate fasciculus. These results were not driven by age, intelligence, or attention-deficit/hyperactivity disorder comorbidity. This report provides the first evidence of white matter alterations in female adolescents with CD as indicated through white matter reductions in callosal tracts. This finding enhances current knowledge about the neuropathological basis of female CD. An increased understanding of gender-specific neuronal characteristics in CD may influence diagnosis, early detection, and successful intervention strategies. Copyright © 2017 American Academy of Child and Adolescent Psychiatry. Published by Elsevier Inc. All rights reserved.

Neuroimaging abnormalities in clade C HIV are independent of Tat genetic diversity.

PubMed

Paul, Robert H; Phillips, Sarah; Hoare, Jacqueline; Laidlaw, David H; Cabeen, Ryan; Olbricht, Gayla R; Su, Yuqing; Stein, Dan J; Engelbrecht, Susan; Seedat, Soraya; Salminen, Lauren E; Baker, Laurie M; Heaps, Jodi; Joska, John

2017-04-01

Controversy remains regarding the neurotoxicity of clade C human immunodeficiency virus (HIV-C). When examined in preclinical studies, a cysteine to serine substitution in the C31 dicysteine motif of the HIV-C Tat protein (C31S) results in less severe brain injury compared to other viral clades. By contrast, patient cohort studies identify significant neuropsychological impairment among HIV-C individuals independent of Tat variability. The present study clarified this discrepancy by examining neuroimaging markers of brain integrity among HIV-C individuals with and without the Tat substitution. Thirty-seven HIV-C individuals with the Tat C31S substitution, 109 HIV-C individuals without the Tat substitution (C31C), and 34 HIV- controls underwent 3T structural magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI). Volumes were determined for the caudate, putamen, thalamus, corpus callosum, total gray matter, and total white matter. DTI metrics included fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD). Tracts of interest included the anterior thalamic radiation (ATR), cingulum bundle (CING), uncinate fasciculus (UNC), and corpus callosum (CC). HIV+ individuals exhibited smaller volumes in subcortical gray matter, total gray matter and total white matter compared to HIV- controls. HIV+ individuals also exhibited DTI abnormalities across multiple tracts compared to HIV- controls. By contrast, neither volumetric nor diffusion indices differed significantly between the Tat C31S and C31C groups. Tat C31S status is not a sufficient biomarker of HIV-related brain integrity in patient populations. Clinical attention directed at brain health is warranted for all HIV+ individuals, independent of Tat C31S or clade C status.

Physiological expression of pancreatic somatostatin receptors in 99mTc-HYNIC-TOC scintigraphy.

PubMed

de la Cueva, L; Lloro, P; Sangrós, M J; López Vélez, L; Navarro, P; Sarria, L; Álvarez, S; Abós, D

2017-07-01

To describe the frequency of head and/or pancreas uncinate process uptake of 99mTc-HYNIC-TOC, to study its nature, and analyze its diagnostic value. Retrospective evaluation of 47 consecutive 99mTc-HYNIC-TOC examinations was conducted. Head and/or pancreas uncinate process uptake was considered to be physiological in patients with normal CT at the same episode and in follow-up. It was analyzed if age or diabetes mellitus was justifying the existence or not of uptake. 32.5% patients showed uptake; 73% of them were mild. 84.6% patients with uptake have no pathology and 4% had neuroendocrine pancreatic disease at CT. Neither the age nor the diabetes mellitus established differences in patients without lesion. Near one-third of patients show physiological uptake by head and/or pancreas uncinate process at 99mTc-HYNIC-TOC scintigraphy. It seems that neither the diabetes nor the ages are factors that determine this physiological uptake.

Bilingualism modulates the white matter structure of language-related pathways.

PubMed

Hämäläinen, Sini; Sairanen, Viljami; Leminen, Alina; Lehtonen, Minna

2017-05-15

Learning and speaking a second language (L2) may result in profound changes in the human brain. Here, we investigated local structural differences along two language-related white matter trajectories, the arcuate fasciculus and the inferior fronto-occipital fasciculus (IFOF), between early simultaneous bilinguals and late sequential bilinguals. We also examined whether early exposure to two languages might lead to a more bilateral structural organization of the arcuate fasciculus. Fractional anisotropy, mean and radial diffusivities (FA, MD, and RD respectively) were extracted to analyse tract-specific changes. Additionally, global voxel-wise effects were investigated with Tract-Based Spatial Statistics (TBSS). We found that relative to late exposure, early exposure to L2 leads to increased FA along a phonology-related segment of the arcuate fasciculus, but induces no modulations along the IFOF, associated to semantic processing. Late sequential bilingualism, however, was associated with decreased MD along the bilateral IFOF. Our results suggest that early vs. late bilingualism may lead to qualitatively different kind of changes in the structural language-related network. Furthermore, we show that early bilingualism contributes to the structural laterality of the arcuate fasciculus, leading to a more bilateral organization of these perisylvian language-related tracts. Copyright © 2017 Elsevier Inc. All rights reserved.

A review on functional and structural brain connectivity in numerical cognition

PubMed Central

Moeller, Korbinian; Willmes, Klaus; Klein, Elise

2015-01-01

Only recently has the complex anatomo-functional system underlying numerical cognition become accessible to evaluation in the living brain. We identified 27 studies investigating brain connectivity in numerical cognition. Despite considerable heterogeneity regarding methodological approaches, populations investigated, and assessment procedures implemented, the results provided largely converging evidence regarding the underlying brain connectivity involved in numerical cognition. Analyses of both functional/effective as well as structural connectivity have consistently corroborated the assumption that numerical cognition is subserved by a fronto-parietal network including (intra)parietal as well as (pre)frontal cortex sites. Evaluation of structural connectivity has indicated the involvement of fronto-parietal association fibers encompassing the superior longitudinal fasciculus dorsally and the external capsule/extreme capsule system ventrally. Additionally, commissural fibers seem to connect the bilateral intraparietal sulci when number magnitude information is processed. Finally, the identification of projection fibers such as the superior corona radiata indicates connections between cortex and basal ganglia as well as the thalamus in numerical cognition. Studies on functional/effective connectivity further indicated a specific role of the hippocampus. These specifications of brain connectivity augment the triple-code model of number processing and calculation with respect to how gray matter areas associated with specific number-related representations may work together. PMID:26029075

White Matter Integrity, Substance Use, and Risk Taking in Adolescence

PubMed Central

Jacobus, Joanna; Thayer, Rachel E.; Trim, Ryan S.; Bava, Sunita; Frank, Lawrence R.; Tapert, Susan F.

2012-01-01

White matter development is important for efficient communication between brain regions, higher order cognitive functioning, and complex behaviors. Adolescents have a higher propensity for engaging in risky behaviors, yet few studies have explored associations between white matter integrity and risk taking directly. Altered white matter integrity in mid-adolescence was hypothesized to predict subsequent risk taking behaviors 1.5 years later. Adolescent substance users (predominantly alcohol and marijuana, n=47) and demographically similar non-users (n=49) received diffusion tensor imaging at baseline (ages 16–19), and risk taking measures at both baseline and an 18-month follow-up (i.e., at ages 17–20). Brain regions of interest were: fornix, superior corona radiata, superior longitudinal fasciculus, and superior fronto-occipital fasciculus. In substance using youth (n=47), lower white matter integrity at baseline in the fornix and superior corona radiata predicted follow-up substance use (ΔR2 =10–12%, ps < .01), and baseline fornix integrity predicted follow-up delinquent behaviors (ΔR2 = 10%, p < .01) 1.5 years later. Poorer fronto-limbic white matter integrity was linked to a greater propensity for future risk taking behaviors among youth who initiated heavy substance use by mid-adolescence. Most notable were relationships between projection and limbic system fibers and future substance use frequency. Subcortical white matter coherence along with an imbalance between the maturation levels in cognitive control and reward systems may disadvantage the resistance to engage in risk taking behaviors during adolescence. PMID:22564204

White matter microstructure within the superior longitudinal fasciculus modulates the degree of response conflict indexed by N2 in healthy adults.

PubMed

Gao, Shudan; Liu, Peng; Guo, Jialu; Zhu, Yuanqiang; Liu, Peng; Sun, Jinbo; Yang, Xuejuan; Qin, Wei

2017-12-01

Response conflict can be induced by priming multiple responses competing for control of action in trials. The N2 is one functionally-related cognitive control index for response conflict. And yet the underlying whiter matter neural substrates of inter-individual difference in conflict N2 remain unclear. So the aim of present study was to address the white matter microstructure of the N2 responsible for conflict by directly relating the amplitude cost of the event-related potential (ERP) N2 component to diffusion tensor imaging (DTI) indices in healthy subjects. Thirty healthy subjects underwent DTI scanning and electrophysiology recording during a modified Flanker task. N2 was a stimulus-locked negative ERP component. Fractional anisotropy (FA) was calculated based on DTI measures and was assumed to reflect the integrity of myelinate fiber bundles. Therefore, we tested the relationship between N2 amplitude and FA in brain white matter. Results showed that FA, an index for white matter characteristics, in the right superior longitudinal fasciculus (SLF) was significantly positively associated with N2 amplitude cost. The N2 amplitude cost also predicted response time (RT) cost in the Flanker task. Higher FA was associated with larger N2 amplitude cost, suggesting that changes in white matter integrity in the SLF may account for changes in efficient transmission of fronto-parietal modulatory conflict signals. Copyright © 2017 Elsevier B.V. All rights reserved.

White matter integrity, substance use, and risk taking in adolescence.

PubMed

Jacobus, Joanna; Thayer, Rachel E; Trim, Ryan S; Bava, Sunita; Frank, Lawrence R; Tapert, Susan F

2013-06-01

White matter development is important for efficient communication between brain regions, higher order cognitive functioning, and complex behaviors. Adolescents have a higher propensity for engaging in risky behaviors, yet few studies have explored associations between white matter integrity and risk taking directly. Altered white matter integrity in mid-adolescence was hypothesized to predict subsequent risk taking behaviors 1.5 years later. Adolescent substance users (predominantly alcohol and marijuana, n = 47) and demographically similar nonusers (n = 49) received diffusion tensor imaging at baseline (ages 16-19), and risk taking measures at both baseline and an 18-month follow-up (i.e., at ages 17-20). Brain regions of interest were the fornix, superior corona radiata, superior longitudinal fasciculus, and superior fronto-occipital fasciculus. In substance-using youth (n = 47), lower white matter integrity at baseline in the fornix and superior corona radiata predicted follow-up substance use (ΔR2 = 10-12%, ps < .01), and baseline fornix integrity predicted follow-up delinquent behaviors (ΔR2 = 10%, p < .01) 1.5 years later. Poorer fronto-limbic white matter integrity was linked to a greater propensity for future risk taking behaviors among youth who initiated heavy substance use by mid-adolescence. Most notable were relationships between projection and limbic-system fibers and future substance-use frequency. Subcortical white matter coherence, along with an imbalance between the maturation levels in cognitive control and reward systems, may disadvantage the resistance to engage in risk taking behaviors during adolescence. 2013 APA, all rights reserved

Development of Tract-Specific White Matter Pathways During Early Reading Development in At-Risk Children and Typical Controls.

PubMed

Wang, Yingying; Mauer, Meaghan V; Raney, Talia; Peysakhovich, Barbara; Becker, Bryce L C; Sliva, Danielle D; Gaab, Nadine

2017-04-01

Developmental dyslexia is a neurodevelopmental disorder with a strong genetic basis. Previous studies observed white matter alterations in the left posterior brain regions in adults and school-age children with dyslexia. However, no study yet has examined the development of tract-specific white matter pathways from the pre-reading to the fluent reading stage in children at familial risk for dyslexia (FHD+) versus controls (FHD-). This study examined white matter integrity at pre-reading, beginning, and fluent reading stages cross-sectionally ( n = 78) and longitudinally (n = 45) using an automated fiber-tract quantification method. Our findings depict white matter alterations and atypical lateralization of the arcuate fasciculus at the pre-reading stage in FHD+ versus FHD- children. Moreover, we demonstrate faster white matter development in subsequent good versus poor readers and a positive association between white matter maturation and reading development using a longitudinal design. Additionally, the combination of white matter maturation, familial risk, and psychometric measures best predicted later reading abilities. Furthermore, within FHD+ children, subsequent good readers exhibited faster white matter development in the right superior longitudinal fasciculus compared with subsequent poor readers, suggesting a compensatory mechanism. Overall, our findings highlight the importance of white matter pathway maturation in the development of typical and atypical reading skills. Published by Oxford University Press 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.

The lateralized arcuate fasciculus in developmental pitch disorders among mandarin amusics: left for speech and right for music.

PubMed

Chen, Xizhuo; Zhao, Yanxin; Zhong, Suyu; Cui, Zaixu; Li, Jiaqi; Gong, Gaolang; Dong, Qi; Nan, Yun

2018-05-01

The arcuate fasciculus (AF) is a neural fiber tract that is critical to speech and music development. Although the predominant role of the left AF in speech development is relatively clear, how the AF engages in music development is not understood. Congenital amusia is a special neurodevelopmental condition, which not only affects musical pitch but also speech tone processing. Using diffusion tensor tractography, we aimed at understanding the role of AF in music and speech processing by examining the neural connectivity characteristics of the bilateral AF among thirty Mandarin amusics. Compared to age- and intelligence quotient (IQ)-matched controls, amusics demonstrated increased connectivity as reflected by the increased fractional anisotropy in the right posterior AF but decreased connectivity as reflected by the decreased volume in the right anterior AF. Moreover, greater fractional anisotropy in the left direct AF was correlated with worse performance in speech tone perception among amusics. This study is the first to examine the neural connectivity of AF in the neurodevelopmental condition of amusia as a result of disrupted music pitch and speech tone processing. We found abnormal white matter structural connectivity in the right AF for the amusic individuals. Moreover, we demonstrated that the white matter microstructural properties of the left direct AF is modulated by lexical tone deficits among the amusic individuals. These data support the notion of distinctive pitch processing systems between music and speech.

Abnormal white matter tractography of visual pathways detected by high-angular-resolution diffusion imaging (HARDI) corresponds to visual dysfunction in cortical/cerebral visual impairment

PubMed Central

Bauer, Corinna M.; Heidary, Gena; Koo, Bang-Bon; Killiany, Ronald J.; Bex, Peter; Merabet, Lotfi B.

2014-01-01

Cortical (cerebral) visual impairment (CVI) is characterized by visual dysfunction associated with damage to the optic radiations and/or visual cortex. Typically it results from pre- or perinatal hypoxic damage to postchiasmal visual structures and pathways. The neuroanatomical basis of this condition remains poorly understood, particularly with regard to how the resulting maldevelopment of visual processing pathways relates to observations in the clinical setting. We report our investigation of 2 young adults diagnosed with CVI and visual dysfunction characterized by difficulties related to visually guided attention and visuospatial processing. Using high-angular-resolution diffusion imaging (HARDI), we characterized and compared their individual white matter projections of the extrageniculo-striate visual system with a normal-sighted control. Compared to a sighted control, both CVI cases revealed a striking reduction in association fibers, including the inferior frontal-occipital fasciculus as well as superior and inferior longitudinal fasciculi. This reduction in fibers associated with the major pathways implicated in visual processing may provide a neuroanatomical basis for the visual dysfunctions observed in these patients. PMID:25087644

The Role of the Arcuate Fasciculus in Conduction Aphasia

ERIC Educational Resources Information Center

Bernal, Byron; Ardila, Alfredo

2009-01-01

In aphasia literature, it has been considered that a speech repetition defect represents the main constituent of conduction aphasia. Conduction aphasia has frequently been interpreted as a language impairment due to lesions of the arcuate fasciculus (AF) that disconnect receptive language areas from expressive ones. Modern neuroradiological…

Anatomical Properties of the Arcuate Fasciculus Predict Phonological and Reading Skills in Children

ERIC Educational Resources Information Center

Yeatman, Jason D.; Dougherty, Robert F.; Rykhlevskaia, Elena; Sherbondy, Anthony J.; Deutsch, Gayle K.; Wandell, Brian A.; Ben-Shachar, Michal

2011-01-01

For more than a century, neurologists have hypothesized that the arcuate fasciculus carries signals that are essential for language function; however, the relevance of the pathway for particular behaviors is highly controversial. The primary objective of this study was to use diffusion tensor imaging to examine the relationship between individual…

Alterations in the inferior longitudinal fasciculus in autism and associations with visual processing: a diffusion-weighted MRI study.

PubMed

Boets, Bart; Van Eylen, Lien; Sitek, Kevin; Moors, Pieter; Noens, Ilse; Steyaert, Jean; Sunaert, Stefan; Wagemans, Johan

2018-01-01

One of the most reported neural features of autism spectrum disorder (ASD) is the alteration of multiple long-range white matter fiber tracts, as assessed by diffusion-weighted imaging and indexed by reduced fractional anisotropy (FA). Recent methodological advances, however, have shown that this same pattern of reduced FA may be an artifact resulting from excessive head motion and poorer data quality and that aberrant structural connectivity in children with ASD is confined to the right inferior longitudinal fasciculus (ILF). This study aimed at replicating the observation of reduced FA along the right ILF in ASD, while controlling for group differences in head motion and data quality. In addition, we explored associations between reduced FA in the right ILF and quantitative ASD characteristics, and the involvement of the right ILF in visual processing, which is known to be altered in ASD. Global probabilistic tractography was performed on diffusion-weighted imaging data of 17 adolescent boys with ASD and 17 typically developing boys, matched for age, performance IQ, handedness, and data quality. Four tasks were administered to measure various aspects of visual information processing, together with questionnaires assessing ASD characteristics. Group differences were examined and the neural data were integrated with previously published findings using Bayesian statistics to quantify evidence for replication and to pool data and thus increase statistical power. (Partial) correlations were calculated to investigate associations between measures. The ASD group showed consistently reduced FA only in the right ILF and slower performance on the visual search task. Bayesian statistics pooling data across studies confirmed that group differences in FA were confined to the right ILF only, with the evidence for altered FA in the left ILF being indecisive. Lower FA in the right ILF tended to covary with slower visual search and a more fragmented part-oriented processing style. Individual differences in FA of the right ILF were not reliably associated with the severity of ASD traits after controlling for clinical status. Our findings support the growing evidence for reduced FA along a specific fiber tract in ASD, the right ILF.

Neurocomputational Consequences of Evolutionary Connectivity Changes in Perisylvian Language Cortex.

PubMed

Schomers, Malte R; Garagnani, Max; Pulvermüller, Friedemann

2017-03-15

The human brain sets itself apart from that of its primate relatives by specific neuroanatomical features, especially the strong linkage of left perisylvian language areas (frontal and temporal cortex) by way of the arcuate fasciculus (AF). AF connectivity has been shown to correlate with verbal working memory-a specifically human trait providing the foundation for language abilities-but a mechanistic explanation of any related causal link between anatomical structure and cognitive function is still missing. Here, we provide a possible explanation and link, by using neurocomputational simulations in neuroanatomically structured models of the perisylvian language cortex. We compare networks mimicking key features of cortical connectivity in monkeys and humans, specifically the presence of relatively stronger higher-order "jumping links" between nonadjacent perisylvian cortical areas in the latter, and demonstrate that the emergence of working memory for syllables and word forms is a functional consequence of this structural evolutionary change. We also show that a mere increase of learning time is not sufficient, but that this specific structural feature, which entails higher connectivity degree of relevant areas and shorter sensorimotor path length, is crucial. These results offer a better understanding of specifically human anatomical features underlying the language faculty and their evolutionary selection advantage. SIGNIFICANCE STATEMENT Why do humans have superior language abilities compared to primates? Recently, a uniquely human neuroanatomical feature has been demonstrated in the strength of the arcuate fasciculus (AF), a fiber pathway interlinking the left-hemispheric language areas. Although AF anatomy has been related to linguistic skills, an explanation of how this fiber bundle may support language abilities is still missing. We use neuroanatomically structured computational models to investigate the consequences of evolutionary changes in language area connectivity and demonstrate that the human-specific higher connectivity degree and comparatively shorter sensorimotor path length implicated by the AF entail emergence of verbal working memory, a prerequisite for language learning. These results offer a better understanding of specifically human anatomical features for language and their evolutionary selection advantage. Copyright © 2017 Schomers et al.

Diffusion Tensor Imaging of Incentive Effects in Prospective Memory after Pediatric Traumatic Brain Injury

PubMed Central

Wilde, Elisabeth A.; Bigler, Erin D.; Chu, Zili; Yallampalli, Ragini; Oni, Margaret B.; Wu, Trevor C.; Ramos, Marco A.; Pedroza, Claudia; Vásquez, Ana C.; Hunter, Jill V.; Levin, Harvey S.

2011-01-01

Abstract Few studies exist investigating the brain-behavior relations of event-based prospective memory (EB-PM) impairments following traumatic brain injury (TBI). To address this, children with moderate-to-severe TBI performed an EB-PM test with two motivational enhancement conditions and underwent concurrent diffusion tensor imaging (DTI) at 3 months post-injury. Children with orthopedic injuries (OI; n = 37) or moderate-to-severe TBI (n = 40) were contrasted. Significant group differences were found for fractional anisotropy (FA) and apparent diffusion coefficient for orbitofrontal white matter (WM), cingulum bundles, and uncinate fasciculi. The FA of these WM structures in children with TBI significantly correlated with EB-PM performance in the high, but not the low motivation condition. Regression analyses within the TBI group indicated that the FA of the left cingulum bundle (p = 0.003), left orbitofrontal WM (p < 0.02), and left (p < 0.02) and right (p < 0.008) uncinate fasciculi significantly predicted EB-PM performance in the high motivation condition. We infer that the cingulum bundles, orbitofrontal WM, and uncinate fasciculi are important WM structures mediating motivation-based EB-PM responses following moderate-to-severe TBI in children. PMID:21250917

68Ga-DOTA-TOC uptake in neuroendocrine tumour and healthy tissue: differentiation of physiological uptake and pathological processes in PET/CT.

PubMed

Kroiss, A; Putzer, D; Decristoforo, C; Uprimny, C; Warwitz, B; Nilica, B; Gabriel, M; Kendler, D; Waitz, D; Widmann, G; Virgolini, I J

2013-04-01

We wanted to establish the range of (68)Ga-DOTA-TOC uptake in liver and bone metastases of patients with neuroendocrine tumours (NET) and to establish the range of its uptake in pancreatic NET. This would allow differentiation between physiological uptake and tumour-related somatostatin receptor expression in the pancreas (including the uncinate process), liver and bone. Finally, we wanted to test for differences in patients with NET, either treated or not treated with peptide receptor radionuclide therapy (PRRT). In 249 patients, 390 (68)Ga-DOTA-TOC PET/CT studies were performed. The clinical indications for PET/CT were gastroenteropancreatic NET (194 studies), nongastroenteropancreatic NET (origin in the lung and rectum; 46 studies), NET of unknown primary (111 studies), phaeochromocytoma/glomus tumours (18 studies), and radioiodine-negative metastatic thyroid carcinoma (21 studies). SUVmax (mean ± standard deviation) values of (68)Ga-DOTA-TOC were 29.8 ± 16.5 in 162 liver metastases, 19.8 ± 18.8 in 89 bone metastases and 34.6 ± 17.1 in 43 pancreatic NET (33.6 ± 14.3 in 30 tumours of the uncinate process and 36.3 ± 21.5 in 13 tumours of the pancreatic tail). A significant difference in SUVmax (p < 0.02) was found in liver metastases of NET patients treated with PRRT. There were significant differences in SUVmax between nonmalignant and malignant tissue for both bone and liver metastases and for pancreatic NET including the uncinate process (p < 0.0001). At a cut-off value of 17.1 the specificity and sensitivity of SUVmax for differentiating tumours in the uncinate process were 93.6 % and 90.0 %, respectively (p < 0.0001). (68)Ga-DOTA-TOC is an excellent tracer for the imaging of tumours expressing somatostatin receptors on the tumour cell surface, facilitating the detection of even small tumour lesions. The noninvasive PET/CT approach by measurement of regional SUVmax can offer important clinical information to distinguish between physiological and pathological somatostatin receptor expression, especially in the uncinate process. PRRT does not significantly influence SUVmax, except in liver metastases of patients with NET.

Lower Working Memory Performance in Overweight and Obese Adolescents Is Mediated by White Matter Microstructure

PubMed Central

Alarcón, Gabriela; Ray, Siddharth; Nagel, Bonnie J.

2017-01-01

Objectives Elevated body mass index (BMI) is associated with deficits in working memory, reduced gray matter volume in frontal and parietal lobes, as well as changes in white matter (WM) microstructure. The current study examined whether BMI was related to working memory performance and blood oxygen level dependent (BOLD) activity, as well as WM microstructure during adolescence. Methods Linear regressions with BMI and (1) verbal working memory BOLD signal, (2) spatial working memory BOLD signal, and (3) fractional anisotropy (FA), a measure of WM microstructure, were conducted in a sample of 152 healthy adolescents ranging in BMI. Results BMI was inversely related to IQ and verbal and spatial working memory accuracy; however, there was no significant relationship between BMI and BOLD response for either verbal or spatial working memory. Furthermore, BMI was negatively correlated with FA in the left superior longitudinal fasciculus (SLF) and left inferior longitudinal fasciculus (ILF). ILF FA and IQ significantly mediated the relationship between BMI and verbal working memory performance, whereas SLF FA, but not IQ, significantly mediated the relationship between BMI and accuracy of both verbal and spatial working memory. Conclusions These findings indicate that higher BMI is associated with decreased FA in WM fibers connecting brain regions that support working memory, and that WM microstructural deficits may underlie inferior working memory performance in youth with higher BMI. Of interest, BMI did not show the same relationship with working memory BOLD activity, which may indicate that changes in brain structure precede changes in function. PMID:26708324

Words are not enough: nonword repetition as an indicator of arcuate fasciculus integrity during brain tumor resection.

PubMed

Sierpowska, Joanna; Gabarrós, Andreu; Fernandez-Coello, Alejandro; Camins, Àngels; Castañer, Sara; Juncadella, Montserrat; Morís, Joaquín; Rodríguez-Fornells, Antoni

2017-02-01

OBJECTIVE Subcortical electrical stimulation during brain surgery may allow localization of functionally crucial white matter fibers and thus tailoring of the tumor resection according to its functional limits. The arcuate fasciculus (AF) is a white matter bundle connecting frontal, temporal, and parietal cortical areas that is often disrupted by left brain lesions. It plays a critical role in several cognitive functions related to phonological processing, but current intraoperative monitoring methods do not yet allow mapping of this tract with sufficient precision. In the present study the authors aimed to test a new paradigm for the intraoperative monitoring of the AF. METHODS In this report, the authors studied 12 patients undergoing awake brain surgery for tumor resection with a related risk of AF damage. To preserve AF integrity and the cognitive processes sustained by this tract in the intraoperative context, the authors used real word repetition (WR) and nonword repetition (NWR) tasks as complements to standard picture naming. RESULTS Compared with the errors identified by WR or picture naming, the NWR task allowed the detection of subtle errors possibly related to AF alterations. Moreover, only 3 patients demonstrated phonological paraphasias in standard picture naming, and in 2 of these patients the paraphasias co-occurred with the total loss of WR and NWR ability. Before surgery, lesion volume predicted a patient's NWR performance. CONCLUSIONS The authors suggest that monitoring NWR intraoperatively may complement the standard naming tasks and could permit better preservation of the important language production functions subserved by the AF.

An exploratory analysis linking neuropsychological testing to quantification of tractography using High Definition Fiber Tracking (HDFT) in military TBI.

PubMed

Presson, Nora; Beers, Sue R; Morrow, Lisa; Wagener, Lauren M; Bird, William A; Van Eman, Gina; Krishnaswamy, Deepa; Penderville, Joshua; Borrasso, Allison J; Benso, Steven; Puccio, Ava; Fissell, Catherine; Okonkwo, David O; Schneider, Walter

2015-09-01

To realize the potential value of tractography in traumatic brain injury (TBI), we must identify metrics that provide meaningful information about functional outcomes. The current study explores quantitative metrics describing the spatial properties of tractography from advanced diffusion imaging (High Definition Fiber Tracking, HDFT). In a small number of right-handed males from military TBI (N = 7) and civilian control (N = 6) samples, both tract homologue symmetry and tract spread (proportion of brain mask voxels contacted) differed for several tracts among civilian controls and extreme groups in the TBI sample (high scorers and low scorers) for verbal recall, serial reaction time, processing speed index, and trail-making. Notably, proportion of voxels contacted in the arcuate fasciculus distinguished high and low performers on the CVLT-II and PSI, potentially reflecting linguistic task demands, and GFA in the left corticospinal tract distinguished high and low performers in PSI and Trail Making Test Part A, potentially reflecting right hand motor response demands. The results suggest that, for advanced diffusion imaging, spatial properties of tractography may add analytic value to measures of tract anisotropy.

Prefrontal vulnerabilities and whole brain connectivity in aging and depression.

PubMed

Lamar, Melissa; Charlton, Rebecca A; Ajilore, Olusola; Zhang, Aifeng; Yang, Shaolin; Barrick, Thomas R; Rhodes, Emma; Kumar, Anand

2013-07-01

Studies exploring the underpinnings of age-related neurodegeneration suggest fronto-limbic alterations that are increasingly vulnerable in the presence of disease including late life depression. Less work has assessed the impact of this specific vulnerability on widespread brain circuitry. Seventy-nine older adults (healthy controls=45; late life depression=34) completed translational tasks shown in non-human primates to rely on fronto-limbic networks involving dorsolateral (Self-Ordered Pointing Task) or orbitofrontal (Object Alternation Task) cortices. A sub-sample of participants also completed diffusion tensor imaging for white matter tract quantification (uncinate and cingulum bundle; n=58) and whole brain tract-based spatial statistics (n=62). Despite task associations to specific white matter tracts across both groups, only healthy controls demonstrated significant correlations between widespread tract integrity and cognition. Thus, increasing Object Alternation Task errors were associated with decreasing fractional anisotropy in the uncinate in late life depression; however, only in healthy controls was the uncinate incorporated into a larger network of white matter vulnerability associating fractional anisotropy with Object Alternation Task errors using whole brain tract-based spatial statistics. It appears that the whole brain impact of specific fronto-limbic vulnerabilities in aging may be eclipsed in the presence of disease-specific neuropathology like that seen in late life depression. Copyright © 2013 Elsevier Ltd. All rights reserved.

Discriminating Schizophrenia and Bipolar Disorder by Fusing FMRI and DTI in A Multimodal CCA+ Joint ICA Model

PubMed Central

Sui, Jing; Pearlson, Godfrey; Adali, Tülay; Kiehl, Kent A.; Caprihan, Arvind; Liu, Jingyu; Yamamoto, Jeremy; Calhoun, Vince D.

2011-01-01

Diverse structural and functional brain alterations have been identified in both schizophrenia and bipolar disorder, but with variable replicability, significant overlap and often in limited number of subjects. In this paper, we aimed to clarify differences between bipolar disorder and schizophrenia by combining fMRI (collected during an auditory oddball task) and diffusion tensor imaging (DTI) data. We proposed a fusion method, “multimodal CCA+ joint ICA’, which increases flexibility in statistical assumptions beyond existing approaches and can achieve higher estimation accuracy. The data collected from 164 participants (62 healthy controls, 54 schizophrenia and 48 bipolar) were extracted into “features” (contrast maps for fMRI and fractional anisotropy (FA) for DTI) and analyzed in multiple facets to investigate the group differences for each pair-wised groups and each modality. Specifically, both patient groups shared significant dysfunction in dorsolateral prefrontal cortex and thalamus, as well as reduced white matter (WM) integrity in anterior thalamic radiation and uncinate fasciculus. Schizophrenia and bipolar subjects were separated by functional differences in medial frontal and visual cortex, as well as WM tracts associated with occipital and frontal lobes. Both patients and controls showed similar spatial distributions in motor and parietal regions, but exhibited significant variations in temporal lobe. Furthermore, there were different group trends for age effects on loading parameters in motor cortex and multiple WM regions, suggesting brain dysfunction and WM disruptions occurred in identified regions for both disorders. Most importantly, we can visualize an underlying function-structure network by evaluating the joint components with strong links between DTI and fMRI. Our findings suggest that although the two patient groups showed several distinct brain patterns from each other and healthy controls, they also shared common abnormalities in prefrontal thalamic WM integrity and in frontal brain mechanisms. PMID:21640835

Frontal networks in adults with autism spectrum disorder

PubMed Central

Catani, Marco; Dell’Acqua, Flavio; Budisavljevic, Sanja; Howells, Henrietta; Thiebaut de Schotten, Michel; Froudist-Walsh, Seán; D’Anna, Lucio; Thompson, Abigail; Sandrone, Stefano; Bullmore, Edward T.; Suckling, John; Baron-Cohen, Simon; Lombardo, Michael V.; Wheelwright, Sally J.; Chakrabarti, Bhismadev; Lai, Meng-Chuan; Ruigrok, Amber N. V.; Leemans, Alexander; Ecker, Christine; Consortium, MRC AIMS; Craig, Michael C.

2016-01-01

Abstract It has been postulated that autism spectrum disorder is underpinned by an ‘atypical connectivity’ involving higher-order association brain regions. To test this hypothesis in a large cohort of adults with autism spectrum disorder we compared the white matter networks of 61 adult males with autism spectrum disorder and 61 neurotypical controls, using two complementary approaches to diffusion tensor magnetic resonance imaging. First, we applied tract-based spatial statistics, a ‘whole brain’ non-hypothesis driven method, to identify differences in white matter networks in adults with autism spectrum disorder. Following this we used a tract-specific analysis, based on tractography, to carry out a more detailed analysis of individual tracts identified by tract-based spatial statistics. Finally, within the autism spectrum disorder group, we studied the relationship between diffusion measures and autistic symptom severity. Tract-based spatial statistics revealed that autism spectrum disorder was associated with significantly reduced fractional anisotropy in regions that included frontal lobe pathways. Tractography analysis of these specific pathways showed increased mean and perpendicular diffusivity, and reduced number of streamlines in the anterior and long segments of the arcuate fasciculus, cingulum and uncinate—predominantly in the left hemisphere. Abnormalities were also evident in the anterior portions of the corpus callosum connecting left and right frontal lobes. The degree of microstructural alteration of the arcuate and uncinate fasciculi was associated with severity of symptoms in language and social reciprocity in childhood. Our results indicated that autism spectrum disorder is a developmental condition associated with abnormal connectivity of the frontal lobes. Furthermore our findings showed that male adults with autism spectrum disorder have regional differences in brain anatomy, which correlate with specific aspects of autistic symptoms. Overall these results suggest that autism spectrum disorder is a condition linked to aberrant developmental trajectories of the frontal networks that persist in adult life. PMID:26912520

The neural markers of MRI to differentiate depression and panic disorder.

PubMed

Lai, Chien-Han

2018-04-27

Depression and panic disorder (PD) share the common pathophysiology from the perspectives of neurotransmitters. The relatively high comorbidity between depression and PD contributes to the substantial obstacles to differentiate from depression and PD, especially for the brain pathophysiology. There are significant differences in the diagnostic criteria between depression and PD. However, the paradox of similar pathophysiology and different diagnostic criteria in these two disorders were still the issues needing to be addressed. Therefore the clarification of potential difference in the field of neuroscience and pathophysiology between depression and PD can help the clinicians and scientists to understand more comprehensively about significant differences between depression and PD. The researchers should be curious about the underlying difference of pathophysiology beneath the significant distinction of clinical symptoms. In this review article, I tried to find some evidences for the differences between depression and PD, especially for neural markers revealed by magnetic resonance imaging (MRI). The distinctions of structural and functional alterations in depression and PD are reviewed. From the structural perspectives, PD seems to have less severe gray matter alterations in frontal and temporal lobes than depression. The study of white matter microintegrity reveals more widespread alterations in fronto-limbic circuit of depression patients than PD patients, such as the uncinate fasciculus and anterior thalamic radiation. PD might have a more restrictive pattern of structural alterations when compared to depression. For the functional perspectives, the core site of depression pathophysiology is the anterior subnetwork of resting-state network, such as anterior cingulate cortex, which is not significantly altered in PD. A possibly emerging pattern of fronto-limbic distinction between depression and PD has been revealed by these explorative reports. The future trend for machine learning and pattern recognition might confirm the differentiation pattern between depression and PD based on the explorative results. Copyright © 2018 Elsevier Inc. All rights reserved.

White Matter Microstructural Changes as Vulnerability Factors and Acquired Signs of Post-Earthquake Distress

PubMed Central

Sekiguchi, Atsushi; Sugiura, Motoaki; Taki, Yasuyuki; Kotozaki, Yuka; Nouchi, Rui; Takeuchi, Hikaru; Araki, Tsuyoshi; Hanawa, Sugiko; Nakagawa, Seishu; Miyauchi, Carlos Makoto; Sakuma, Atsushi; Kawashima, Ryuta

2014-01-01

Many survivors of severe disasters need psychological support, even those not suffering post-traumatic stress disorder (PTSD). The critical issue in understanding the psychological response after experiencing severe disasters is to distinguish neurological microstructural underpinnings as vulnerability factors from signs of emotional distress acquired soon after the stressful life event. We collected diffusion-tensor magnetic resonance imaging (DTI) data from a group of healthy adolescents before the Great East Japan Earthquake and re-examined the DTIs and anxiety levels of 30 non-PTSD subjects from this group 3–4 months after the earthquake using voxel-based analyses in a longitudinal DTI study before and after the earthquake. We found that the state anxiety level after the earthquake was negatively associated with fractional anisotropy (FA) in the right anterior cingulum (Cg) before the earthquake (r = −0.61, voxel level p<0.0025, cluster level p<0.05 corrected), and positively associated with increased FA changes from before to after the earthquake in the left anterior Cg (r = 0.70, voxel level p<0.0025, cluster level p<0.05 corrected) and uncinate fasciculus (Uf) (r = 0.65, voxel level p<0.0025, cluster level p<0.05 corrected). The results demonstrated that lower FA in the right anterior Cg was a vulnerability factor and increased FA in the left anterior Cg and Uf was an acquired sign of state anxiety after the earthquake. We postulate that subjects with dysfunctions in processing fear and anxiety before the disaster were likely to have higher anxiety levels requiring frequent emotional regulation after the disaster. These findings provide new evidence of psychophysiological responses at the neural network level soon after a stressful life event and might contribute to the development of effective methods to prevent PTSD. PMID:24400079

White matter damage in primary progressive aphasias: a diffusion tensor tractography study.

PubMed

Galantucci, Sebastiano; Tartaglia, Maria Carmela; Wilson, Stephen M; Henry, Maya L; Filippi, Massimo; Agosta, Federica; Dronkers, Nina F; Henry, Roland G; Ogar, Jennifer M; Miller, Bruce L; Gorno-Tempini, Maria Luisa

2011-10-01

Primary progressive aphasia is a clinical syndrome that encompasses three major phenotypes: non-fluent/agrammatic, semantic and logopenic. These clinical entities have been associated with characteristic patterns of focal grey matter atrophy in left posterior frontoinsular, anterior temporal and left temporoparietal regions, respectively. Recently, network-level dysfunction has been hypothesized but research to date has focused largely on studying grey matter damage. The aim of this study was to assess the integrity of white matter tracts in the different primary progressive aphasia subtypes. We used diffusion tensor imaging in 48 individuals: nine non-fluent, nine semantic, nine logopenic and 21 age-matched controls. Probabilistic tractography was used to identify bilateral inferior longitudinal (anterior, middle, posterior) and uncinate fasciculi (referred to as the ventral pathway); and the superior longitudinal fasciculus segmented into its frontosupramarginal, frontoangular, frontotemporal and temporoparietal components, (referred to as the dorsal pathway). We compared the tracts' mean fractional anisotropy, axial, radial and mean diffusivities for each tract in the different diagnostic categories. The most prominent white matter changes were found in the dorsal pathways in non-fluent patients, in the two ventral pathways and the temporal components of the dorsal pathways in semantic variant, and in the temporoparietal component of the dorsal bundles in logopenic patients. Each of the primary progressive aphasia variants showed different patterns of diffusion tensor metrics alterations: non-fluent patients showed the greatest changes in fractional anisotropy and radial and mean diffusivities; semantic variant patients had severe changes in all metrics; and logopenic patients had the least white matter damage, mainly involving diffusivity, with fractional anisotropy altered only in the temporoparietal component of the dorsal pathway. This study demonstrates that both careful dissection of the main language tracts and consideration of all diffusion tensor metrics are necessary to characterize the white matter changes that occur in the variants of primary progressive aphasia. These results highlight the potential value of diffusion tensor imaging as a new tool in the multimodal diagnostic evaluation of primary progressive aphasia.

Brain MRI fiber-tracking reveals white matter alterations in hypertensive patients without damage at conventional neuroimaging.

PubMed

Carnevale, Lorenzo; D'Angelosante, Valentina; Landolfi, Alessandro; Grillea, Giovanni; Selvetella, Giulio; Storto, Marianna; Lembo, Giuseppe; Carnevale, Daniela

2018-06-12

Hypertension is one of the main risk factor for dementia. The subtle damage provoked by chronic high blood pressure in the brain is usually evidenced by conventional magnetic resonance imaging (MRI), in terms of white matter (WM) hyperintensities or cerebral atrophy. However, it is clear that by the time brain damage is visible, it may be too late hampering neurodegeneration. Aim of this study was to characterize a signature of early brain damage induced by hypertension, before the neurodegenerative injury manifests. This work was conducted on hypertensive and normotensive subjects with no sign of structural damage at conventional neuroimaging and no diagnosis of dementia revealed by neuropsychological assessment. All individuals underwent cardiological clinical examination in order to define the hypertensive status and the related target organ damage. Additionally, patients were subjected to DTI-MRI scan to identify microstructural damage of WM by probabilistic fiber-tracking. To gain insights in the neurocognitive profile of patients a specific battery of tests was administered. As primary outcome of the study we aimed at finding any specific signature of fiber-tracts alterations in hypertensive patients, associated with an impairment of the related cognitive functions. Hypertensive patients showed significant alterations in three specific WM fiber-tracts: the anterior thalamic radiation, the superior longitudinal fasciculus and the forceps minor. Hypertensive patients also scored significantly worse in the cognitive domains ascribable to brain regions connected through those WM fiber-tracts, showing decreased performances in executive functions, processing speed, memory, and paired associative learning tasks. Overall, WM fiber-tracking on MRI evidenced an early signature of damage in hypertensive patients when otherwise undetectable by conventional neuroimaging. In perspective, this approach could allow identifying those patients that are in initial stages of brain damage and could benefit of therapies aimed at limiting the transition to dementia and neurodegeneration.

White matter tracts of speech and language.

PubMed

Smits, Marion; Jiskoot, Lize C; Papma, Janne M

2014-10-01

Diffusion tensor imaging (DTI) has been used to investigate the white matter (WM) tracts underlying the perisylvian cortical regions known to be associated with language function. The arcuate fasciculus is composed of 3 segments (1 long and 2 short) whose separate functions correlate with traditional models of conductive and transcortical motor or sensory aphasia, respectively. DTI mapping of language fibers is useful in presurgical planning for patients with dominant hemisphere tumors, particularly when combined with functional magnetic resonance imaging. DTI has found damage to language networks in stroke patients and has the potential to influence poststroke rehabilitation and treatment. Assessment of the WM tracts involved in the default mode network has been found to correlate with mild cognitive impairment, potentially explaining language deficits in patients with apparently mild small vessel ischemic disease. Different patterns of involvement of language-related WM structures appear to correlate with different clinical subtypes of primary progressive aphasias. Copyright © 2014 Elsevier Inc. All rights reserved.

A review of conduction aphasia.

PubMed

Ardila, Alfredo

2010-11-01

In this paper, a historical overview of the interpretation of conduction aphasia is initially presented. It is emphasized that the name conduction aphasia was proposed by Wernicke and was interpreted as a disconnection between the temporal and frontal brain language areas; this interpretation was re-taken by Geschwind, attributing the arcuate fasciculus the main role in speech repetition disturbances and resulting in the so-called Wernicke-Geschwind model of language. With the introduction of contemporary neuroimaging techniques, this interpretation of conduction aphasia as a disconnection syndrome due to an impairment of the arcuate fasciculus has been challenged. It has been disclosed that the arcuate fasciculus does not really connect Wernicke's and Broca's areas, but Wernicke's and motor/premotor frontal areas. Furthermore, conduction aphasia can be found in cases of cortical damage without subcortical extension. It is concluded that conduction aphasia remains a controversial topic not only from the theoretic point of view, but also from the understanding of its neurologic foundations.

Diffusion Tensor Fractional Anisotropy in the Superior Longitudinal Fasciculus Correlates with Functional Independence Measure Cognition Scores in Patients with Cerebral Infarction.

PubMed

Koyama, Tetsuo; Domen, Kazuhisa

2017-08-01

This study aimed to determine the relationship between fiber tract degeneration measured by diffusion-tensor imaging (DTI) and outcome of patients after cerebral infarction. Fractional anisotropy (FA) maps were generated by DTI in patients 14-21 days after the first infarction and were analyzed by tract-based spatial statistics (TBSS). Mean FA values within the corticospinal tract (CST) and the superior longitudinal fasciculus (SLF) were extracted from individual TBSS data. Relationships between FA ratios (rFAs, lesioned to non-lesioned hemisphere) and outcomes assessed by Brunnstrom stage (BRS) and Functional Independence Measure (FIM) motor and cognition scores were examined using Spearman's rank correlation test. Forty patients (21 left and 19 right hemisphere lesions) were entered into an analytical database. BRS ranged from 1 to 6 (median, 5) for shoulder, elbow, or forearm; from 2 to 6 (median, 4.5) for hand or finger; and from 3 to 6 (median, 5) for lower extremity. FIM motor ranged from 51 to 91 (median, 79.5), and FIM cognition ranged from 16 to 35 (median, 29). rFA values in the CST ranged from .692 to 1.053 (median, .933), and those in the SLF ranged from .778 to 1.076 (median, .965). Mann-Whitney U test (P <.05) revealed no significant differences between the left and the right hemisphere lesion groups. Individual rFA values in the CST correlated with BRS scores (r = .585-0.654), whereas those in the SLF correlated with FIM cognition scores (r = .409, P <.05). DTI-FA values in the SLF and CST may be useful for outcome prediction of cognitive function and extremity function, respectively. Copyright © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Lithium and GSK3-β Promoter Gene Variants Influence White Matter Microstructure in Bipolar Disorder

PubMed Central

Benedetti, Francesco; Bollettini, Irene; Barberi, Ignazio; Radaelli, Daniele; Poletti, Sara; Locatelli, Clara; Pirovano, Adele; Lorenzi, Cristina; Falini, Andrea; Colombo, Cristina; Smeraldi, Enrico

2013-01-01

Lithium is the mainstay for the treatment of bipolar disorder (BD) and inhibits glycogen synthase kinase 3-β (GSK3-β). The less active GSK3-β promoter gene variants have been associated with less detrimental clinical features of BD. GSK3-β gene variants and lithium can influence brain gray matter structure in psychiatric conditions. Diffusion tensor imaging (DTI) measures of white matter (WM) integrity showed widespred disruption of WM structure in BD. In a sample of 70 patients affected by a major depressive episode in course of BD, we investigated the effect of ongoing long-term lithium treatment and GSK3-β promoter rs334558 polymorphism on WM microstructure, using DTI and tract-based spatial statistics with threshold-free cluster enhancement. We report that the less active GSK3-β rs334558*C gene-promoter variants, and the long-term administration of the GSK3-β inhibitor lithium, were associated with increases of DTI measures of axial diffusivity (AD) in several WM fiber tracts, including corpus callosum, forceps major, anterior and posterior cingulum bundle (bilaterally including its hippocampal part), left superior and inferior longitudinal fasciculus, left inferior fronto-occipital fasciculus, left posterior thalamic radiation, bilateral superior and posterior corona radiata, and bilateral corticospinal tract. AD reflects the integrity of axons and myelin sheaths. We suggest that GSK3-β inhibition and lithium could counteract the detrimental influences of BD on WM structure, with specific benefits resulting from effects on specific WM tracts contributing to the functional integrity of the brain and involving interhemispheric, limbic, and large frontal, parietal, and fronto-occipital connections. PMID:22990942

A comprehensive tractography study of patients with bipolar disorder and their unaffected siblings.

PubMed

Sprooten, Emma; Barrett, Jennifer; McKay, D Reese; Knowles, Emma E; Mathias, Samuel R; Winkler, Anderson M; Brumbaugh, Margaret S; Landau, Stefanie; Cyr, Lindsay; Kochunov, Peter; Glahn, David C

2016-10-01

Diffusion tensor imaging studies show reductions in fractional anisotropy (FA) in individuals with bipolar disorder and their unaffected siblings. However, the use of various analysis methods is an important source of between-study heterogeneity. Using tract-based spatial statistics, we previously demonstrated widespread FA reductions in patients and unaffected relatives. To better interpret the neuroanatomical pattern of this previous finding and to assess the influence of methodological heterogeneity, we here applied tractography to the same sample. Diffusion-weighted images were acquired for 96 patients, 69 unaffected siblings and 56 controls. We applied TRACULA, an extension of a global probabilistic tractography algorithm, to automatically segment 18 major fiber tracts. Average FA within each tract and at each cross-section along each tract was compared between groups. Patients had reduced FA compared to healthy controls and their unaffected siblings in general, and in particular in the parietal part of the superior longitudinal fasciculus. In unaffected siblings, FA was nominally reduced compared to controls in the corpus callosum. Point-wise analyses indicated that similar effects were present along extended sections, but with variable effect sizes. Current symptom severity negatively correlated with FA in several fronto-limbic association tracts. The differential sensitivity of analysis techniques likely explains between-study heterogeneity in anatomical localization of FA reductions. The present tractography analysis confirms the presence of overall FA reductions in patients with bipolar disorder, which are most pronounced in the superior longitudinal fasciculus. Unaffected siblings may display similar, albeit more subtle and anatomically restricted FA reductions. Hum Brain Mapp 37:3474-3485, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

White Matter Microstructure Correlates of Narrative Production in Typically Developing Children and Children with High Functioning Autism

PubMed Central

Mills, Brian; Lai, Janie; Brown, Timothy T.; Erhart, Matthew; Halgren, Eric; Reilly, Judy; Dale, Anders; Appelbaum, Mark; Moses, Pamela

2013-01-01

This study investigated the relationship between white matter microstructure and the development of morphosyntax in a spoken narrative in typically developing children (TD) and in children with high functioning autism (HFA). Autism is characterized by language and communication impairments, yet the relationship between morphosyntactic development in spontaneous discourse contexts and neural development is not well understood in either this population or typical development. Diffusion tensor imaging (DTI) was used to assess multiple parameters of diffusivity as indicators of white matter tract integrity in language-related tracts in children between 6 and 13 years of age. Children were asked to spontaneously tell a story about at time when someone made them sad, mad, or angry. The story was evaluated for morphological accuracy and syntactic complexity. Analysis of the relationship between white matter microstructure and language performance in TD children showed that diffusivity correlated with morphosyntax production in the superior longitudinal fasciculus (SLF), a fiber tract traditionally associated with language. At the anatomical level, the HFA group showed abnormal diffusivity in the right inferior longitudinal fasciculus (ILF) relative to the TD group. Within the HFA group, children with greater white matter integrity in the right ILF displayed greater morphological accuracy during their spoken narrative. Overall, the current study shows an association between white matter structure in a traditional language pathway and narrative performance in TD children. In the autism group, associations were only found in the ILF, suggesting that during real world language use, children with HFA rely less on typical pathways and instead rely on alternative ventral pathways that possibly mediate visual elements of language. PMID:23810972

Toward a functional neuroanatomy of semantic aphasia: A history and ten new cases.

PubMed

Dragoy, Olga; Akinina, Yulia; Dronkers, Nina

2017-12-01

Almost 70 years ago, Alexander Luria incorporated semantic aphasia among his aphasia classifications by demonstrating that deficits in linking the logical relationships of words in a sentence could co-occur with non-linguistic disorders of calculation, spatial gnosis and praxis deficits. In line with his comprehensive approach to the assessment of language and other cognitive functions, he argued that deficits in understanding semantically reversible sentences and prepositional phrases, for example, were in line with a single neuropsychological factor of impaired spatial analysis and synthesis, since understanding such grammatical relationships would also draw on their spatial relationships. Critically, Luria demonstrated the neural underpinnings of this syndrome with the critical implication of the cortex of the left temporal-parietal-occipital (TPO) junction. In this study, we report neuropsychological and lesion profiles of 10 new cases of semantic aphasia. Modern neuroimaging techniques provide support for the relevance of the left TPO area for semantic aphasia, but also extend Luria's neuroanatomical model by taking into account white matter pathways. Our findings suggest that tracts with parietal connectivity - the arcuate fasciculus (long and posterior segments), the inferior fronto-occipital fasciculus, the inferior longitudinal fasciculus, the superior longitudinal fasciculus II and III, and the corpus callosum - are implicated in the linguistic and non-linguistic deficits of patients with semantic aphasia. Copyright © 2016 Elsevier Ltd. All rights reserved.

Diffusion tensor MRI tractography reveals increased fractional anisotropy (FA) in arcuate fasciculus following music-cued motor training.

PubMed

Moore, Emma; Schaefer, Rebecca S; Bastin, Mark E; Roberts, Neil; Overy, Katie

2017-08-01

Auditory cues are frequently used to support movement learning and rehabilitation, but the neural basis of this behavioural effect is not yet clear. We investigated the microstructural neuroplasticity effects of adding musical cues to a motor learning task. We hypothesised that music-cued, left-handed motor training would increase fractional anisotropy (FA) in the contralateral arcuate fasciculus, a fibre tract connecting auditory, pre-motor and motor regions. Thirty right-handed participants were assigned to a motor learning condition either with (Music Group) or without (Control Group) musical cues. Participants completed 20minutes of training three times per week over four weeks. Diffusion tensor MRI and probabilistic neighbourhood tractography identified FA, axial (AD) and radial (RD) diffusivity before and after training. Results revealed that FA increased significantly in the right arcuate fasciculus of the Music group only, as hypothesised, with trends for AD to increase and RD to decrease, a pattern of results consistent with activity-dependent increases in myelination. No significant changes were found in the left ipsilateral arcuate fasciculus of either group. This is the first evidence that adding musical cues to movement learning can induce rapid microstructural change in white matter pathways in adults, with potential implications for therapeutic clinical practice. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Tract-based spatial statistics analysis of white matter changes in children with anisometropic amblyopia.

PubMed

Li, Qian; Zhai, Liying; Jiang, Qinying; Qin, Wen; Li, Qingji; Yin, Xiaohui; Guo, Mingxia

2015-06-15

Amblyopia is a neurological disorder of vision that follows abnormal binocular interaction or visual deprivation during early life. Previous studies have reported multiple functional or structural cortical alterations. Although white matter was also studied, it still cannot be clarified clearly which fasciculus was affected by amblyopia. In the present study, tract-based spatial statistics analysis was applied to diffusion tensor imaging (DTI) to investigate potential diffusion changes of neural tracts in anisometropic amblyopia. Fractional anisotropy (FA) value was calculated and compared between 20 amblyopic children and 18 healthy age-matched controls. In contrast to the controls, significant decreases in FA values were found in right optic radiation (OR), left inferior longitudinal fasciculus/inferior fronto-occipital fasciculus (ILF/IFO) and right superior longitudinal fasciculus (SLF) in the amblyopia. Furthermore, FA values of these identified tracts showed positive correlation with visual acuity. It can be inferred that abnormal visual input not only hinders OR from well developed, but also impairs fasciculi associated with dorsal and ventral visual pathways, which may be responsible for the amblyopic deficiency in object discrimination and stereopsis. Increased FA was detected in right posterior part of corpus callosum (CC) with a medium effect size, which may be due to compensation effect. DTI with subsequent measurement of FA is a useful tool for investigating neuronal tract involvement in amblyopia. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Mnemonic function in small vessel disease and associations with white matter tract microstructure.

PubMed

Metoki, Athanasia; Brookes, Rebecca L; Zeestraten, Eva; Lawrence, Andrew J; Morris, Robin G; Barrick, Thomas R; Markus, Hugh S; Charlton, Rebecca A

2017-09-01

Cerebral small vessel disease (SVD) is associated with deficits in working memory, with a relative sparing of long-term memory; function may be influenced by white matter microstructure. Working and long-term memory were examined in 106 patients with SVD and 35 healthy controls. Microstructure was measured in the uncinate fasciculi and cingula. Working memory was more impaired than long-term memory in SVD, but both abilities were reduced compared to controls. Regression analyses found that having SVD explained the variance in memory functions, with additional variance explained by the cingula (working memory) and uncinate (long-term memory). Performance can be explained in terms of integrity loss in specific white matter tract associated with mnemonic functions. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Neuronal substrates of Corsi Block span: Lesion symptom mapping analyses in relation to attentional competition and spatial bias.

PubMed

Chechlacz, Magdalena; Rotshtein, Pia; Humphreys, Glyn W

2014-11-01

Spatial working memory problems are frequently reported following brain damage within both left and right hemispheres but with the severity often being grater in individuals with right hemisphere lesions. Clinically, deficits in spatial working memory have also been noted in patients with visuospatial disorders such as unilateral neglect. Here, we examined neural substrates of short-term memory for spatial locations based on the Corsi Block tapping task and the relationship with the visuospatial deficits of neglect and extinction in a group of chronic neuropsychological patients. Principal Component Analysis (PCA) was used to distinguish shared and dissociate functional components. The neural substrates of spatial short-term memory deficits and the components identified by PCA were examined using whole brain voxel-based morphometry and tract-wise lesion deficits analyses. We found that bilateral lesions within occipital cortex (middle occipital gyrus) and right posterior parietal cortex, along with disconnection of the right parieto-temporal segment of arcuate fasciculus, were associated with low spatial memory span. A single component revealed by PCA accounted for over half of the variance and was linked to damage to right posterior brain regions (temporo-parietal junction, the inferior parietal lobule and middle temporal gyrus extending into middle occipital gyrus). We also found link to disconnections within several association pathways including the superior longitudinal fasciculus, arcuate fasciculus, inferior fronto-occipital fasciculus and inferior longitudinal fasciculus. These results indicate that different visuospatial deficits converge into a single component mapped within posterior parietal areas and fronto-parietal white matter pathways. Furthermore, the data presented here fit with the role of posterior parietal cortex/temporo-parietal junction in maintaining a map of salient locations in space, with Corsi Block performance being impaired when the spatial map is damaged. Copyright © 2014 Elsevier Ltd. All rights reserved.

Maternal Interleukin-6 concentration during pregnancy is associated with variation in frontolimbic white matter and cognitive development in early life.

PubMed

Rasmussen, Jerod M; Graham, Alice M; Entringer, Sonja; Gilmore, John H; Styner, Martin; Fair, Damien A; Wadhwa, Pathik D; Buss, Claudia

2018-04-11

Maternal inflammation during pregnancy can alter the trajectory of fetal brain development and increase risk for offspring psychiatric disorders. However, the majority of relevant research to date has been conducted in animal models. Here, in humans, we focus on the structural connectivity of frontolimbic circuitry as it is both critical for socioemotional and cognitive development, and commonly altered in a range of psychiatric disorders associated with intrauterine inflammation. Specifically, we test the hypothesis that elevated maternal concentration of the proinflammatory cytokine interleukin-6 (IL-6) during pregnancy will be associated with variation in microstructural properties of this circuitry in the neonatal period and across the first year of life. Pregnant mothers were recruited in early pregnancy and maternal blood samples were obtained for assessment of maternal IL-6 concentrations in early (12.6 ± 2.8 weeks [S.D.]), mid (20.4 ± 1.5 weeks [S.D.]) and late (30.3 ± 1.3 weeks [S.D.]) gestation. Offspring brain MRI scans were acquired shortly after birth (N = 86, scan age = 3.7 ± 1.7 weeks [S.D.]) and again at 12-mo age (N = 32, scan age = 54.0 ± 3.1 weeks [S.D.]). Diffusion Tensor Imaging (DTI) was used to characterize fractional anisotropy (FA) along the left and right uncinate fasciculus (UF), representing the main frontolimbic fiber tract. In N = 30 of the infants with serial MRI data at birth and 12-mo age, cognitive and socioemotional developmental status was characterized using the Bayley Scales of Infant Development. All analyses tested for potentially confounding influences of household income, prepregnancy Body-Mass-Index, obstetric risk, smoking during pregnancy, and infant sex, and outcomes at 12-mo age were additionally adjusted for the quality of the postnatal caregiving environment. Maternal IL-6 concentration (averaged across pregnancy) was prospectively and inversely associated with FA (suggestive of reduced integrity under high inflammatory conditions) in the newborn offspring (bi-lateral, p < 0.01) in the central portion of the UF proximal to the amygdala. Furthermore, maternal IL-6 concentration was positively associated with rate of FA increase across the first year of life (bi-lateral, p < 0.05), resulting in a null association between maternal IL-6 and UF FA at 12-mo age. Maternal IL-6 was also inversely associated with offspring cognition at 12-mo age, and this association was mediated by FA growth across the first year of postnatal life. Findings from the current study support the premise that susceptibility for cognitive impairment and potentially psychiatric disorders may be affected in utero, and that maternal inflammation may constitute an intrauterine condition of particular importance in this context. Copyright © 2018 Elsevier Inc. All rights reserved.

Current knowledge on the sensitivity of the (68)Ga-somatostatin receptor positron emission tomography and the SUVmax reference range for management of pancreatic neuroendocrine tumours.

PubMed

Virgolini, Irene; Gabriel, Michael; Kroiss, Alexander; von Guggenberg, Elisabeth; Prommegger, Rupert; Warwitz, Boris; Nilica, Bernhard; Roig, Llanos Geraldo; Rodrigues, Margarida; Uprimny, Christian

2016-10-01

Physiologically increased pancreatic uptake at the head/uncinate process is observed in more than one-third of patients after injection of one of the three (68)Ga-labelled octreotide-based peptides used for somatostatin (sst) receptor (r) imaging. There are minor differences between these (68)Ga-sstr-binding peptides in the imaging setting. On (68)Ga-sstr-imaging the physiological uptake can be diffuse or focal and usually remains stable over time. Differences in the maximal standardised uptake values (SUVmax) reported for the normal pancreas as well as for pancreatic neuroendocrine tumour (PNET) lesions may be related to several factors, including (a) differences in the peptide binding affinities as well as differences in sstr subtype expression of pancreatic α- and β-cells, and heterogeneity / density of tumour cells, (b) differences in scanner resolution, image reconstruction techniques and acquisition protocols, (c) mostly retrospective study designs, (d) mixed patient populations, or (e) interference with medications such as treatment with long-acting sst analogues. The major limitation in most of the studies lies in the lack of histopathological confirmation of abnormal findings. There is a significant overlap between the calculated SUVmax-values for physiological pancreas and PNET-lesions of the head/uncinate process that do not favour the use of quantitative parameters in the clinical setting. Anecdotal long-term follow-up studies have even indicated that increased uptake in the head/uncinate process still can turn out to be malignant over years of follow up. SUVmax-data for the pancreatic body and tail are limited. Therefore, any visible focal tracer uptake in the pancreas must be considered as suspicious for malignancy irrespective of quantitative parameters. In general, sstr-PET/CT has significant implications for the management of NET patients leading to a change in treatment decision in about one-third of patients. Therefore, follow-up with (68)Ga-sstr-PET/CT is mandatory in the clinical setting if uptake in the head/uncinate process is observed.

Higher integrity of the motor and visual pathways in long-term video game players.

PubMed

Zhang, Yang; Du, Guijin; Yang, Yongxin; Qin, Wen; Li, Xiaodong; Zhang, Quan

2015-01-01

Long term video game players (VGPs) exhibit superior visual and motor skills compared with non-video game control subjects (NVGCs). However, the neural basis underlying the enhanced behavioral performance remains largely unknown. To clarify this issue, the present study compared the whiter matter integrity within the corticospinal tracts (CST), the superior longitudinal fasciculus (SLF), the inferior longitudinal fasciculus (ILF), and the inferior fronto-occipital fasciculus (IFOF) between the VGPs and the NVGCs using diffusion tensor imaging. Compared with the NVGCs, voxel-wise comparisons revealed significantly higher fractional anisotropy (FA) values in some regions within the left CST, left SLF, bilateral ILF, and IFOF in VGPs. Furthermore, higher FA values in the left CST at the level of cerebral peduncle predicted a faster response in visual attention tasks. These results suggest that higher white matter integrity in the motor and higher-tier visual pathways is associated with long-term video game playing, which may contribute to the understanding on how video game play influences motor and visual performance.

Higher integrity of the motor and visual pathways in long-term video game players

PubMed Central

Du, Guijin; Yang, Yongxin; Qin, Wen; Li, Xiaodong; Zhang, Quan

2015-01-01

Long term video game players (VGPs) exhibit superior visual and motor skills compared with non-video game control subjects (NVGCs). However, the neural basis underlying the enhanced behavioral performance remains largely unknown. To clarify this issue, the present study compared the whiter matter integrity within the corticospinal tracts (CST), the superior longitudinal fasciculus (SLF), the inferior longitudinal fasciculus (ILF), and the inferior fronto-occipital fasciculus (IFOF) between the VGPs and the NVGCs using diffusion tensor imaging. Compared with the NVGCs, voxel-wise comparisons revealed significantly higher fractional anisotropy (FA) values in some regions within the left CST, left SLF, bilateral ILF, and IFOF in VGPs. Furthermore, higher FA values in the left CST at the level of cerebral peduncle predicted a faster response in visual attention tasks. These results suggest that higher white matter integrity in the motor and higher-tier visual pathways is associated with long-term video game playing, which may contribute to the understanding on how video game play influences motor and visual performance. PMID:25805981

ON THE EFFECT OF COMPLETE ANEMIA OF THE CENTRAL NERVOUS SYSTEM IN DOGS RESUSCITATED AFTER RELATIVE DEATH

PubMed Central

Crile, George; Dolley, David H.

1908-01-01

To determine the limits of recovery after a total anemia of the central nervous system, a series of thirty dogs was killed by chloroform and resuscitated after varying times from three to fourteen minutes. Under five minutes the recovery of function was rapid and strikingly free from the after effects which characterized longer periods. Of seven animals between the periods of five and six and one-half minutes, only one died apparently as a direct result of the anemia, but of twelve between the periods of seven minutes and eight and one-half minutes, only one, after seven and one-half minutes recovered. The remaining dogs all died. Further corroborative data are drawn from the previously published paper on the technique of resuscitation. Histological examination both of presumptive recoveries and fatal cases was made by ordinary methods and those of Nissl and Marchi. The neurocytes of the fatal cases uniformly presented the greatest change, not merely chromolytic but here and there definitely indicative of cell death. Marchi's method further supported these findings by proving the existence of fiber degeneration. Finally, showing the narrowness of the escape, the animal with best result in recovery, seven and one-half minutes in time, which at the end of four weeks had apparently entirely returned to a normal state, by the Marchi method had a degeneration of a number of fibers localized in the pyramidal fasciculi which were traced from the cord to the cortex, and in Flechsig's fasciculus, as well as a more sparsely scattered degeneration of both ascending and descending fibers elsewhere. PMID:19867163

Brain white matter structure and COMT gene are linked to second-language learning in adults

PubMed Central

Mamiya, Ping C.; Richards, Todd L.; Coe, Bradley P.; Eichler, Evan E.; Kuhl, Patricia K.

2016-01-01

Adult human brains retain the capacity to undergo tissue reorganization during second-language learning. Brain-imaging studies show a relationship between neuroanatomical properties and learning for adults exposed to a second language. However, the role of genetic factors in this relationship has not been investigated. The goal of the current study was twofold: (i) to characterize the relationship between brain white matter fiber-tract properties and second-language immersion using diffusion tensor imaging, and (ii) to determine whether polymorphisms in the catechol-O-methyltransferase (COMT) gene affect the relationship. We recruited incoming Chinese students enrolled in the University of Washington and scanned their brains one time. We measured the diffusion properties of the white matter fiber tracts and correlated them with the number of days each student had been in the immersion program at the time of the brain scan. We found that higher numbers of days in the English immersion program correlated with higher fractional anisotropy and lower radial diffusivity in the right superior longitudinal fasciculus. We show that fractional anisotropy declined once the subjects finished the immersion program. The relationship between brain white matter fiber-tract properties and immersion varied in subjects with different COMT genotypes. Subjects with the Methionine (Met)/Valine (Val) and Val/Val genotypes showed higher fractional anisotropy and lower radial diffusivity during immersion, which reversed immediately after immersion ended, whereas those with the Met/Met genotype did not show these relationships. Statistical modeling revealed that subjects’ grades in the language immersion program were best predicted by fractional anisotropy and COMT genotype. PMID:27298360

Brain white matter structure and COMT gene are linked to second-language learning in adults.

PubMed

Mamiya, Ping C; Richards, Todd L; Coe, Bradley P; Eichler, Evan E; Kuhl, Patricia K

2016-06-28

Adult human brains retain the capacity to undergo tissue reorganization during second-language learning. Brain-imaging studies show a relationship between neuroanatomical properties and learning for adults exposed to a second language. However, the role of genetic factors in this relationship has not been investigated. The goal of the current study was twofold: (i) to characterize the relationship between brain white matter fiber-tract properties and second-language immersion using diffusion tensor imaging, and (ii) to determine whether polymorphisms in the catechol-O-methyltransferase (COMT) gene affect the relationship. We recruited incoming Chinese students enrolled in the University of Washington and scanned their brains one time. We measured the diffusion properties of the white matter fiber tracts and correlated them with the number of days each student had been in the immersion program at the time of the brain scan. We found that higher numbers of days in the English immersion program correlated with higher fractional anisotropy and lower radial diffusivity in the right superior longitudinal fasciculus. We show that fractional anisotropy declined once the subjects finished the immersion program. The relationship between brain white matter fiber-tract properties and immersion varied in subjects with different COMT genotypes. Subjects with the Methionine (Met)/Valine (Val) and Val/Val genotypes showed higher fractional anisotropy and lower radial diffusivity during immersion, which reversed immediately after immersion ended, whereas those with the Met/Met genotype did not show these relationships. Statistical modeling revealed that subjects' grades in the language immersion program were best predicted by fractional anisotropy and COMT genotype.

A combinatorial optogenetic approach to medial habenula function

NASA Astrophysics Data System (ADS)

Turner, Eric E.; Hsu, Yun-Wei; Wang, Si; Morton, Glenn; Zeng, Hongkui

2013-03-01

The habenula is a brain region found in all vertebrate species. It consists of medial and lateral subnuclei which make complex descending connections to the brainstem. Although the medial habenula (MHb) and its projection, the fasciculus retroflexus (FR), have been recognized for decades, their function remains obscure. The small size of the MHb in rodents, and the cellular and molecular complexity of this region, have made it difficult to study the function of this region with high specificity. Here we describe a Cre-mediated genetic system for expressing the microbial opsin channelrhodopsin (ChR2) specifically in the dorsal (dMHb) and ventral (vMHb) medial habenula. Genetically targeted expression of ChR2 allows MHb neurons to be selectively activated with light in acute brain slices with electrophysiological readouts, and in vivo by means of custom-built fiber optic cannulas. These tools will allow highly specific studies of MHb circuitry and the role of the MHb in behaviors related to addiction and mood regulation.

Cortico-subcortical organization of language networks in the right hemisphere: an electrostimulation study in left-handers.

PubMed

Duffau, Hugues; Leroy, Marianne; Gatignol, Peggy

2008-12-01

We have studied the configuration of the cortico-subcortical language networks within the right hemisphere (RH) in nine left-handers, being operated on while awake for a cerebral glioma. Intraoperatively, language was mapped using cortico-subcortical electrostimulation, to avoid permanent deficit. In frontal regions, cortical stimulation elicited articulatory disorders (ventral premotor cortex), anomia (dorsal premotor cortex), speech arrest (pars opercularis), and semantic paraphasia (dorsolateral prefrontal cortex). Insular stimulation generated dysarthria, parietal stimulation phonemic paraphasias, and temporal stimulation semantic paraphasias. Subcortically, the superior longitudinal fasciculus (inducing phonological disturbances when stimulated), inferior occipito-frontal fasciculus (eliciting semantic disturbances during stimulation), subcallosal fasciculus (generating control disturbances when stimulated), and common final pathway (inducing articulatory disorders during stimulation) were identified. These cortical and subcortical structures were preserved, avoiding permanent aphasia, despite a transient immediate postoperative language worsening. Both intraoperative results and postsurgical transitory dysphasia support the major role of the RH in language in left-handers, and provide new insights into the anatomo-functional cortico-subcortical organization of the language networks in the RH-suggesting a "mirror" configuration in comparison to the left hemisphere.

Sex differences in associations between white matter microstructure and gonadal hormones in children and adolescents with prenatal alcohol exposure.

PubMed

Uban, K A; Herting, M M; Wozniak, J R; Sowell, E R

2017-09-01

Despite accumulating evidence from animal models demonstrating that prenatal alcohol exposure (PAE) results in life-long neuroendocrine dysregulation, very little is known on this topic among humans with fetal alcohol spectrum disorders (FASD). We expected that alterations in gonadal hormones might interfere with the typical development of white matter (WM) myelination, and in a sex-dependent manner, in human adolescents with FASD. In order to investigate this hypothesis, we used diffusion tensor imaging (DTI) to assess: 1) whether or not sex moderates the impact of PAE on WM microstructure; and 2) how gonadal hormones relate to alterations in WM microstructure in children and adolescents affected by PAE. 61 youth (9 to 16 yrs.; 49% girls; 50% PAE) participated as part of the Collaborative Initiative on Fetal Alcohol Spectrum Disorders (CIFASD). DTI scans and passive drool samples were obtained to examine neurodevelopmental associations with testosterone (T) and dehydroepiandrosterone (DHEA) levels in boys and girls, and estradiol (E2) and progesterone (P) levels in girls. Tract-based spatial statistics were utilized to generate fractional anisotropy (FA) and mean diffusivity (MD) for 9 a priori WM regions of interest (ROIs). As predicted, alterations in FA were observed in adolescents with PAE relative to controls, and these differences varied by sex. Girls with PAE exhibited lower FA (Inferior fronto-occipital and Uncinate fasciculi) while boys with PAE exhibited higher FA (Callosal body, Cingulum, Corticospinal tract, Optic radiation, Superior longitudinal fasciculus) relative to age-matched controls. When gonadal hormone levels were examined in relation to DTI measures, additional group differences in FA were revealed, demonstrating that neuroendocrine factors are associated with PAE-related brain alterations. These findings provide human evidence that PAE relates to sex-specific differences in WM microstructure, and underlying alterations in gonadal hormone function may, in part, contribute to these effects. Determining PAE-effects on neuroendocrine function among humans is an essential first step towards developing novel clinical (e.g., assessment or intervention) tools that target hormone systems to improve on-going brain development among children and adolescents with FASD. Copyright © 2017 Elsevier Ltd. All rights reserved.

White matter damage in primary progressive aphasias: a diffusion tensor tractography study

PubMed Central

Galantucci, Sebastiano; Tartaglia, Maria Carmela; Wilson, Stephen M.; Henry, Maya L.; Filippi, Massimo; Agosta, Federica; Dronkers, Nina F.; Henry, Roland G.; Ogar, Jennifer M.; Miller, Bruce L.

2011-01-01

Primary progressive aphasia is a clinical syndrome that encompasses three major phenotypes: non-fluent/agrammatic, semantic and logopenic. These clinical entities have been associated with characteristic patterns of focal grey matter atrophy in left posterior frontoinsular, anterior temporal and left temporoparietal regions, respectively. Recently, network-level dysfunction has been hypothesized but research to date has focused largely on studying grey matter damage. The aim of this study was to assess the integrity of white matter tracts in the different primary progressive aphasia subtypes. We used diffusion tensor imaging in 48 individuals: nine non-fluent, nine semantic, nine logopenic and 21 age-matched controls. Probabilistic tractography was used to identify bilateral inferior longitudinal (anterior, middle, posterior) and uncinate fasciculi (referred to as the ventral pathway); and the superior longitudinal fasciculus segmented into its frontosupramarginal, frontoangular, frontotemporal and temporoparietal components, (referred to as the dorsal pathway). We compared the tracts’ mean fractional anisotropy, axial, radial and mean diffusivities for each tract in the different diagnostic categories. The most prominent white matter changes were found in the dorsal pathways in non-fluent patients, in the two ventral pathways and the temporal components of the dorsal pathways in semantic variant, and in the temporoparietal component of the dorsal bundles in logopenic patients. Each of the primary progressive aphasia variants showed different patterns of diffusion tensor metrics alterations: non-fluent patients showed the greatest changes in fractional anisotropy and radial and mean diffusivities; semantic variant patients had severe changes in all metrics; and logopenic patients had the least white matter damage, mainly involving diffusivity, with fractional anisotropy altered only in the temporoparietal component of the dorsal pathway. This study demonstrates that both careful dissection of the main language tracts and consideration of all diffusion tensor metrics are necessary to characterize the white matter changes that occur in the variants of primary progressive aphasia. These results highlight the potential value of diffusion tensor imaging as a new tool in the multimodal diagnostic evaluation of primary progressive aphasia. PMID:21666264

Mapping the "Depression Switch" During Intraoperative Testing of Subcallosal Cingulate Deep Brain Stimulation.

PubMed

Choi, Ki Sueng; Riva-Posse, Patricio; Gross, Robert E; Mayberg, Helen S

2015-11-01

The clinical utility of monitoring behavioral changes during intraoperative testing of subcallosal cingulate deep brain stimulation is unknown. To characterize the structural connectivity correlates of deep brain stimulation-evoked behavioral effects using probabilistic tractography in depression. Categorization of acute behavioral effects was conducted in 9 adults undergoing deep brain stimulation implantation surgery for chronic treatment-resistant depression in a randomized and blinded testing session at Emory University. Patients were studied from September 1, 2011, through June 30, 2013. Post hoc analyses of the structural tractography patterns mediating distinct categories of evoked behavioral effects were defined, including the best response overall. Data analyses were performed from May 1 through July 1, 2015. Categorization of stimulation-induced transient behavioral effects and delineation of the shared white matter tracts mediating response subtypes. Among the 9 patients, 72 active and 36 sham trials were recorded. The following stereotypical behavior patterns were identified: changes in interoceptive (noted changes in body state in 30 of 72 active and 4 of 36 sham trials) and in exteroceptive (shift in attention from patient to others in 9 of 72 active and 0 sham trials) awareness. The best response was a combination of exteroceptive and interoceptive changes at a single left contact for all 9 patients. Structural connectivity showed that the best response contacts had a pattern of connections to the bilateral ventromedial frontal cortex (via forceps minor and left uncinate fasciculus) and to the cingulate cortex (via left cingulum bundle), whereas behaviorally salient but nonbest contacts had only cingulate involvement. The involvement of the 3 white matter bundles during stimulation of the best contacts suggests a mechanism for the observed transient "depression switch." This analysis of transient behavior changes during intraoperative deep brain stimulation of the subcallosal cingulate and the subsequent identification of unique connectivity patterns may provide a biomarker of a rapid-onset depression switch to guide surgical implantation and to refine and optimize algorithms for the selection of contacts in long-term stimulation for treatment-resistant depression.

Normal development of human brain white matter from infancy to early adulthood: a diffusion tensor imaging study.

PubMed

Uda, Satoshi; Matsui, Mie; Tanaka, Chiaki; Uematsu, Akiko; Miura, Kayoko; Kawana, Izumi; Noguchi, Kyo

2015-01-01

Diffusion tensor imaging (DTI), which measures the magnitude of anisotropy of water diffusion in white matter, has recently been used to visualize and quantify parameters of neural tracts connecting brain regions. In order to investigate the developmental changes and sex and hemispheric differences of neural fibers in normal white matter, we used DTI to examine 52 healthy humans ranging in age from 2 months to 25 years. We extracted the following tracts of interest (TOIs) using the region of interest method: the corpus callosum (CC), cingulum hippocampus (CGH), inferior longitudinal fasciculus (ILF), and superior longitudinal fasciculus (SLF). We measured fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD), and radial diffusivity (RD). Approximate values and changes in growth rates of all DTI parameters at each age were calculated and analyzed using LOESS (locally weighted scatterplot smoothing). We found that for all TOIs, FA increased with age, whereas ADC, AD and RD values decreased with age. The turning point of growth rates was at approximately 6 years. FA in the CC was greater than that in the SLF, ILF and CGH. Moreover, FA, ADC and AD of the splenium of the CC (sCC) were greater than in the genu of the CC (gCC), whereas the RD of the sCC was lower than the RD of the gCC. The FA of right-hemisphere TOIs was significantly greater than that of left-hemisphere TOIs. In infants, growth rates of both FA and RD were larger than those of AD. Our data show that developmental patterns differ by TOIs and myelination along with the development of white matter, which can be mainly expressed as an increase in FA together with a decrease in RD. These findings clarify the long-term normal developmental characteristics of white matter microstructure from infancy to early adulthood. © 2015 S. Karger AG, Basel.

Altered white matter microstructure in adolescent substance users.

PubMed

Bava, Sunita; Frank, Lawrence R; McQueeny, Tim; Schweinsburg, Brian C; Schweinsburg, Alecia D; Tapert, Susan F

2009-09-30

Chronic marijuana use during adolescence is frequently comorbid with heavy alcohol consumption and associated with CNS alterations, yet the influence of early cannabis and alcohol use on microstructural white matter integrity is unclear. Building on evidence that cannabinoid receptors are present in myelin precursors and affect glial cell processing, and that excessive ethanol exposure is associated with persistently impaired myelination, we used diffusion tensor imaging (DTI) to characterize white matter integrity in heavy substance using and non-using adolescents. We evaluated 36 marijuana and alcohol-using (MJ+ALC) adolescents (ages 16-19) and 36 demographically similar non-using controls with DTI. The diffusion parameters fractional anisotropy (FA) and mean diffusivity (MD) were subjected to whole-brain voxelwise group comparisons using tract-based spatial statistics (Smith, S.M., Jenkinson, M., Johansen-Berg, H., Rueckert, D., Nichols, T.E., Mackay, C.E., Watkins, K.E., Ciccarelli, O., Cader, M.Z., Matthews, P.M., Behrens, T.E., 2006. Tract-based spatial statistics: voxelwise analysis of multi-subject diffusion data. Neuroimage 31, 1487-1505). MJ+ALC teens had significantly lower FA than controls in 10 regions, including left superior longitudinal fasciculus (SLF), left postcentral gyrus, bilateral crus cerebri, and inferior frontal and temporal white matter tracts. These diminutions occurred in the context of increased FA in right occipital, internal capsule, and SLF regions. Changes in MD were less distributed, but increased MD was evident in the right occipital lobe, whereas the left inferior longitudinal fasciculus showed lower MD in MJ+ALC users. Findings suggest that fronto-parietal circuitry may be particularly impacted in adolescent users of the most prevalent intoxicants: marijuana and alcohol. Disruptions to white matter in this young group could indicate aberrant axonal and myelin maturation with resultant compromise of fiber integrity. Findings of increased anisotropic diffusion in alternate brain regions suggest possible neuroadaptive processes and can be examined in future studies of connectivity to determine how aberrancies in specific tracts might influence efficient cognitive processing.

Double-letter processing in surface dyslexia and dysgraphia following a left temporal lesion: A multimodal neuroimaging study.

PubMed

Tomasino, Barbara; Marin, Dario; Maieron, Marta; D'Agostini, Serena; Fabbro, Franco; Skrap, Miran; Luzzatti, Claudio

2015-12-01

Neuropsychological data about acquired impairments in reading and writing provide a strong basis for the theoretical framework of the dual-route models. The present study explored the functional neuroanatomy of the reading and spelling processing system. We describe the reading and writing performance of patient CF, an Italian native speaker who developed an extremely selective reading and spelling deficit (his spontaneous speech, oral comprehension, repetition and oral picture naming were almost unimpaired) in processing double letters associated with surface dyslexia and dysgraphia, following a tumor in the left temporal lobe. In particular, the majority of CF's errors in spelling were phonologically plausible substitutions, errors concerning letter numerosity of consonants, and syllabic phoneme-to-grapheme conversion (PGC) errors. A similar pattern of impairment also emerged in his reading behavior, with a majority of lexical stress errors (the only possible type of surface reading errors in the Italian language, due the extreme regularity of print-to-sound correspondence). CF's neuropsychological profile was combined with structural neuroimaging data, fiber tracking, and functional maps and compared to that of healthy control participants. We related CF's deficit to a dissociation between impaired ventral/lexical route (as evidenced by a fractional anisotropy - FA decrease along the inferior fronto-occipital fasciculus - IFOF) and relatively preserved dorsal/phonological route (as evidenced by a rather full integrity of the superior longitudinal fasciculus - SLF). In terms of functional processing, the lexical-semantic ventral route network was more activated in controls than in CF, while the network supporting the dorsal route was shared by CF and the control participants. Our results are discussed within the theoretical framework of dual-route models of reading and spelling, emphasize the importance of the IFOF both in lexical reading and spelling, and offer a better comprehension of the neurological and functional substrates involved in written language and, in particular, in surface dyslexia and dysgraphia and in doubling/de-doubling consonant sounds and letters. Copyright © 2015 Elsevier Ltd. All rights reserved.

Enkephalin neurons in the guinea pig proximal colon: an immunocytochemical study using an antiserum to methionine-enkephalin-Arg6-Gly7-Leu8.

PubMed

Kobayashi, S; Suzuki, M; Yanaihara, N

1985-02-01

The distribution and structure of the neurons containing opioid peptide-like immunoreactivity (enkephalin neurons) in the antimesenteric border of the guinea pig proximal colon were immunocytochemically investigated using an antiserum for methionine-enkephalin-Arg6-Gly7-Leu8 (R-0171). Whole-mount preparations of the different layers of the intestine perfusion-fixed with Bouin's fluid were immunostained by peroxidase-antiperoxidase techniques. Immunopositive nerve fibers were apparent in the longitudinal muscle layer, myenteric plexus, circular muscle layer and submucosa. Immunopositive perikarya of the ganglionic cells were found in the myenteric plexus. A Golgi-type panoramic view was obtained in the intensely-immunostained enkephalin neurons. Distinct immunoreactivity was shown in the many Dogiel type 1 neurons, characterized by short broad processes (winglets or alulae) and one long axon-like process, as well as a few type 2, characterized by several tapering processes, and type 3 neurons, characterized by dendrite-like processes. Many twig-like processes originated from the free margin of the winglet of the enkephalin neurons (wing-ramuli). A part of them entered the intramuscular fasciculus, while the rest remained inside the ganglion. There were transitional forms between these wing-ramuli and the tapering processes of the type 2 neurons or the dendrite-like processes of the type 3 neurons. The axon-like processes sent out branches (axon-ramuli) along their courses or into the intramuscular fasciculus. At the origin of these axon-ramuli, there was a nodulous or humped swelling of the axon-like process (nodulus or crista). In the myenteric ganglion, the axon-ramuli formed varicose terminals. In the guinea pig proximal colon, many axon-like processes of the enkephalin neurons ran in the oral direction. This polarity of neuronic processes may have a functional significance in the neuronal control of the antiperistalsis.

DTI measures identify mild and moderate TBI cases among patients with complex health problems: A receiver operating characteristic analysis of U.S. veterans.

PubMed

Main, Keith L; Soman, Salil; Pestilli, Franco; Furst, Ansgar; Noda, Art; Hernandez, Beatriz; Kong, Jennifer; Cheng, Jauhtai; Fairchild, Jennifer K; Taylor, Joy; Yesavage, Jerome; Wesson Ashford, J; Kraemer, Helena; Adamson, Maheen M

2017-01-01

Standard MRI methods are often inadequate for identifying mild traumatic brain injury (TBI). Advances in diffusion tensor imaging now provide potential biomarkers of TBI among white matter fascicles (tracts). However, it is still unclear which tracts are most pertinent to TBI diagnosis. This study ranked fiber tracts on their ability to discriminate patients with and without TBI. We acquired diffusion tensor imaging data from military veterans admitted to a polytrauma clinic (Overall n  = 109; Age: M  = 47.2, SD  = 11.3; Male: 88%; TBI: 67%). TBI diagnosis was based on self-report and neurological examination. Fiber tractography analysis produced 20 fiber tracts per patient. Each tract yielded four clinically relevant measures (fractional anisotropy, mean diffusivity, radial diffusivity, and axial diffusivity). We applied receiver operating characteristic (ROC) analyses to identify the most diagnostic tract for each measure. The analyses produced an optimal cutpoint for each tract. We then used kappa coefficients to rate the agreement of each cutpoint with the neurologist's diagnosis. The tract with the highest kappa was most diagnostic. As a check on the ROC results, we performed a stepwise logistic regression on each measure using all 20 tracts as predictors. We also bootstrapped the ROC analyses to compute the 95% confidence intervals for sensitivity, specificity, and the highest kappa coefficients. The ROC analyses identified two fiber tracts as most diagnostic of TBI: the left cingulum (LCG) and the left inferior fronto-occipital fasciculus (LIF). Like ROC, logistic regression identified LCG as most predictive for the FA measure but identified the right anterior thalamic tract (RAT) for the MD, RD, and AD measures. These findings are potentially relevant to the development of TBI biomarkers. Our methods also demonstrate how ROC analysis may be used to identify clinically relevant variables in the TBI population.

Coexpression of high-voltage-activated ion channels Kv3.4 and Cav1.2 in pioneer axons during pathfinding in the developing rat forebrain.

PubMed

Huang, Chia-Yi; Chu, Dachen; Hwang, Wei-Chao; Tsaur, Meei-Ling

2012-11-01

Precise axon pathfinding is crucial for establishment of the initial neuronal network during development. Pioneer axons navigate without the help of preexisting axons and pave the way for follower axons that project later. Voltage-gated ion channels make up the intrinsic electrical activity of pioneer axons and regulate axon pathfinding. To elucidate which channel molecules are present in pioneer axons, immunohistochemical analysis was performed to examine 14 voltage-gated ion channels (Kv1.1-Kv1.3, Kv3.1-Kv3.4, Kv4.3, Cav1.2, Cav1.3, Cav2.2, Nav1.2, Nav1.6, and Nav1.9) in nine axonal tracts in the developing rat forebrain, including the optic nerve, corpus callosum, corticofugal fibers, thalamocortical axons, lateral olfactory tract, hippocamposeptal projection, anterior commissure, hippocampal commissure, and medial longitudinal fasciculus. We found A-type K⁺ channel Kv3.4 in both pioneer axons and early follower axons and L-type Ca²⁺ channel Cav1.2 in pioneer axons and early and late follower axons. Spatially, Kv3.4 and Cav1.2 were colocalized with markers of pioneer neurons and pioneer axons, such as deleted in colorectal cancer (DCC), in most fiber tracts examined. Temporally, Kv3.4 and Cav1.2 were expressed abundantly in most fiber tracts during axon pathfinding but were downregulated beginning in synaptogenesis. By contrast, delayed rectifier Kv channels (e.g., Kv1.1) and Nav channels (e.g., Nav1.2) were absent from these fiber tracts (except for the corpus callosum) during pathfinding of pioneer axons. These data suggest that Kv3.4 and Cav1.2, two high-voltage-activated ion channels, may act together to control Ca²⁺ -dependent electrical activity of pioneer axons and play important roles during axon pathfinding. Copyright © 2012 Wiley Periodicals, Inc.

Cortical and subcortical mapping of language areas: correlation of functional MRI and tractography in a 3T scanner with intraoperative cortical and subcortical stimulation in patients with brain tumors located in eloquent areas.

PubMed

Jiménez de la Peña, M; Gil Robles, S; Recio Rodríguez, M; Ruiz Ocaña, C; Martínez de Vega, V

2013-01-01

To describe the detection of cortical areas and subcortical pathways involved in language observed in MRI activation studies and tractography in a 3T MRI scanner and to correlate the findings of these functional studies with direct intraoperative cortical and subcortical stimulation. We present a series of 14 patients with focal brain tumors adjacent to eloquent brain areas. All patients underwent neuropsychological evaluation before and after surgery. All patients underwent MRI examination including structural sequences, perfusion imaging, spectroscopy, functional imaging to determine activation of motor and language areas, and 3D tractography. All patients underwent cortical mapping through cortical and subcortical stimulation during the operation to resect the tumor. Postoperative follow-up studies were done 24 hours after surgery. The correlation of motor function and of the corticospinal tract determined by functional MRI and tractography with intraoperative mapping of cortical and subcortical motor areas was complete. The eloquent brain areas of language expression and reception were strongly correlated with intraoperative cortical mapping in all but two cases (a high grade infiltrating glioma and a low grade glioma located in the frontal lobe). 3D tractography identified the arcuate fasciculus, the lateral part of the superior longitudinal fasciculus, the subcallosal fasciculus, the inferior fronto-occipital fasciculus, and the optic radiations, which made it possible to mark the limits of the resection. The correlation with the subcortical mapping of the anatomic arrangement of the fasciculi with respect to the lesions was complete. The best treatment for brain tumors is maximum resection without associated deficits, so high quality functional studies are necessary for preoperative planning. Copyright © 2011 SERAM. Published by Elsevier Espana. All rights reserved.

Pathways of the inferior frontal occipital fasciculus in overt speech and reading.

PubMed

Rollans, Claire; Cheema, Kulpreet; Georgiou, George K; Cummine, Jacqueline

2017-11-19

In this study, we examined the relationship between tractography-based measures of white matter integrity (ex. fractional anisotropy [FA]) from diffusion tensor imaging (DTI) and five reading-related tasks, including rapid automatized naming (RAN) of letters, digits, and objects, and reading of real words and nonwords. Twenty university students with no reported history of reading difficulties were tested on all five tasks and their performance was correlated with diffusion measures extracted through DTI tractography. A secondary analysis using whole-brain Tract-Based Spatial Statistics (TBSS) was also used to find clusters showing significant negative correlations between reaction time and FA. Results showed a significant relationship between the left inferior fronto-occipital fasciculus FA and performance on the RAN of objects task, as well as a strong relationship to nonword reading, which suggests a role for this tract in slower, non-automatic and/or resource-demanding speech tasks. There were no significant relationships between FA and the faster, more automatic speech tasks (RAN of letters and digits, and real word reading). These findings provide evidence for the role of the inferior fronto-occipital fasciculus in tasks that are highly demanding of orthography-phonology translation (e.g., nonword reading) and semantic processing (e.g., RAN object). This demonstrates the importance of the inferior fronto-occipital fasciculus in basic naming and suggests that this tract may be a sensitive predictor of rapid naming performance within the typical population. We discuss the findings in the context of current models of reading and speech production to further characterize the white matter pathways associated with basic reading processes. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Hemispheric asymmetries in dorsal language pathway white-matter tracts: A magnetic resonance imaging tractography and functional magnetic resonance imaging study.

PubMed

Silva, Guilherme; Citterio, Alberto

2017-10-01

Introduction Previous studies have shown that the arcuate fasciculus has a leftward asymmetry in right-handers that could be correlated with the language lateralisation defined by functional magnetic resonance imaging. Nonetheless, information about the asymmetry of the other fibres that constitute the dorsal language pathway is scarce. Objectives This study investigated the asymmetry of the white-matter tracts involved in the dorsal language pathway through the diffusion tensor imaging (DTI) technique, in relation to language hemispheric dominance determined by task-dependent functional magnetic resonance imaging (fMRI). Methods We selected 11 patients (10 right-handed) who had been studied with task-dependent fMRI for language areas and DTI and who had no language impairment or structural abnormalities that could compromise magnetic resonance tractography of the fibres involved in the dorsal language pathway. Laterality indices (LI) for fMRI and for the volumes of each tract were calculated. Results In fMRI, all the right-handers had left hemispheric lateralisation, and the ambidextrous subject presented right hemispheric dominance. The arcuate fasciculus LI was strongly correlated with fMRI LI ( r = 0.739, p = 0.009), presenting the same lateralisation of fMRI in seven subjects (including the right hemispheric dominant). It was not asymmetric in three cases and had opposite lateralisation in one case. The other tracts presented predominance for rightward lateralisation, especially superior longitudinal fasciculus (SLF) II/III (nine subjects), but their LI did not correlate (directly or inversely) with fMRI LI. Conclusion The fibres that constitute the dorsal language pathway have an asymmetric distribution in the cerebral hemispheres. Only the asymmetry of the arcuate fasciculus is correlated with fMRI language lateralisation.

Age Related Changes in Topological Properties of Brain Functional Network and Structural Connectivity.

PubMed

Shah, Chandan; Liu, Jia; Lv, Peilin; Sun, Huaiqiang; Xiao, Yuan; Liu, Jieke; Zhao, Youjin; Zhang, Wenjing; Yao, Li; Gong, Qiyong; Lui, Su

2018-01-01

Introduction: There are still uncertainties about the true nature of age related changes in topological properties of the brain functional network and its structural connectivity during various developmental stages. In this cross- sectional study, we investigated the effects of age and its relationship with regional nodal properties of the functional brain network and white matter integrity. Method: DTI and fMRI data were acquired from 458 healthy Chinese participants ranging from age 8 to 81 years. Tractography was conducted on the DTI data using FSL. Graph Theory analyses were conducted on the functional data yielding topological properties of the functional network using SPM and GRETNA toolbox. Two multiple regressions were performed to investigate the effects of age on nodal topological properties of the functional brain network and white matter integrity. Result: For the functional studies, we observed that regional nodal characteristics such as node betweenness were decreased while node degree and node efficiency was increased in relation to increasing age. Perversely, we observed that the relationship between nodal topological properties and fasciculus structures were primarily positive for nodal betweenness but negative for nodal degree and nodal efficiency. Decrease in functional nodal betweenness was primarily located in superior frontal lobe, right occipital lobe and the global hubs. These brain regions also had both direct and indirect anatomical relationships with the 14 fiber bundles. A linear age related decreases in the Fractional anisotropy (FA) value was found in the callosum forceps minor. Conclusion: These results suggests that age related differences were more pronounced in the functional than in structural measure indicating these measures do not have direct one-to-one mapping. Our study also indicates that the fiber bundles with longer fibers exhibited a more pronounced effect on the properties of functional network.

'For the benefit of the people': the Dutch translation of the Fasciculus medicinae, Antwerp 1512.

PubMed

Coppens, Christian

2009-01-01

The article deals with the Dutch translation of the Fasciculus medicinae based on the Latin edition, Venice 1495, with the famous woodcuts created in 1494 for the Italian translation of the original Latin edition of 1491. The woodcuts are compared with the Venetian model. New features in the Antwerp edition include the Skeleton and the Zodiac Man, bot originally based on German models. The text also deals with other woodcuts in the Low Countries based on these Venetian illustrations. The Appendices provide a short title catalog of all the editions and translations based on the Venetian edition and a stemma.

[Medial longitudinal fasciculus (MLF) syndrome in a patient with giant cell arteritis].

PubMed

Uenaka, Takeshi; Hamaguchi, Hirotoshi; Sekiguchi, Kenji; Kowa, Hisatomo; Kanda, Fumio; Toda, Tatsushi

2015-01-01

A 76-year-old female was referred to our department because of diplopia for two months and intermittent claudication for five months. She showed medial longitudinal fasciculus (MLF) syndrome. Brain MRI (T2WI) showed multiple infarctions in the right pontine tegmentum and left paramedian midbrain. A biopsy of superficial temporal artery showed the characteristic findings of glanulomatous inflammation indicative of giant cell arteritis. We thought the mechanism of this cerebral infarction as artery to artery embolization or intracranial arteritis. Treatment with oral prednisolone (1 mg/kg/day) improved her limb claudication and normalized serum C-reactive protein level.

Increased brain white matter axial diffusivity associated with fatigue, pain and hyperalgesia in Gulf War illness.

PubMed

Rayhan, Rakib U; Stevens, Benson W; Timbol, Christian R; Adewuyi, Oluwatoyin; Walitt, Brian; VanMeter, John W; Baraniuk, James N

2013-01-01

Gulf War exposures in 1990 and 1991 have caused 25% to 30% of deployed personnel to develop a syndrome of chronic fatigue, pain, hyperalgesia, cognitive and affective dysfunction. Gulf War veterans (n = 31) and sedentary veteran and civilian controls (n = 20) completed fMRI scans for diffusion tensor imaging. A combination of dolorimetry, subjective reports of pain and fatigue were correlated to white matter diffusivity properties to identify tracts associated with symptom constructs. Gulf War Illness subjects had significantly correlated fatigue, pain, hyperalgesia, and increased axial diffusivity in the right inferior fronto-occipital fasciculus. ROC generated thresholds and subsequent binary regression analysis predicted CMI classification based upon axial diffusivity in the right inferior fronto-occipital fasciculus. These correlates were absent for controls in dichotomous regression analysis. The right inferior fronto-occipital fasciculus may be a potential biomarker for Gulf War Illness. This tract links cortical regions involved in fatigue, pain, emotional and reward processing, and the right ventral attention network in cognition. The axonal neuropathological mechanism(s) explaining increased axial diffusivity may account for the most prominent symptoms of Gulf War Illness.

Developmental dyscalculia: a dysconnection syndrome?

PubMed

Kucian, Karin; Ashkenazi, Simone Schwizer; Hänggi, Jürgen; Rotzer, Stephanie; Jäncke, Lutz; Martin, Ernst; von Aster, Michael

2014-09-01

Numerical understanding is important for everyday life. For children with developmental dyscalculia (DD), numbers and magnitudes present profound problems which are thought to be based upon neuronal impairments of key regions for numerical understanding. The aim of the present study was to investigate possible differences in white matter fibre integrity between children with DD and controls using diffusion tensor imaging. White matter integrity and behavioural measures were evaluated in 15 children with developmental dyscalculia aged around 10 years and 15 matched controls. The main finding, obtained by a whole brain group comparison, revealed reduced fractional anisotropy in the superior longitudinal fasciculus in children with developmental dyscalculia. In addition, a region of interest analysis exhibited prominent deficits in fibres of the superior longitudinal fasciculus adjacent to the intraparietal sulcus, which is thought to be the core region for number processing. To conclude, our results outline deficient fibre projection between parietal, temporal and frontal regions in children with developmental dyscalculia, and therefore raise the question of whether dyscalculia can be seen as a dysconnection syndrome. Since the superior longitudinal fasciculus is involved in the integration and control of distributed brain processes, the present results highlight the importance of considering broader domain-general mechanisms in the diagnosis and therapy of dyscalculia.

Associations Between White Matter Microstructure and Infants’ Working Memory

PubMed Central

Short, Sarah J.; Elison, Jed T.; Goldman, Barbara Davis; Styner, Martin; Gu, Hongbin; Connelly, Mark; Maltbie, Eric; Woolson, Sandra; Lin, Weili; Gerig, Guido; Reznick, J. Steven; Gilmore, John H.

2013-01-01

Working memory emerges in infancy and plays a privileged role in subsequent adaptive cognitive development. The neural networks important for the development of working memory during infancy remain unknown. We used diffusion tensor imaging (DTI) and deterministic fiber tracking to characterize the microstructure of white matter fiber bundles hypothesized to support working memory in 12-month-old infants (n=73). Here we show robust associations between infants’ visuospatial working memory performance and microstructural characteristics of widespread white matter. Significant associations were found for white matter tracts that connect brain regions known to support working memory in older children and adults (genu, anterior and superior thalamic radiations, anterior cingulum, arcuate fasciculus, and the temporal-parietal segment). Better working memory scores were associated with higher FA and lower RD values in these selected white matter tracts. These tract-specific brain-behavior relationships accounted for a significant amount of individual variation above and beyond infants’ gestational age and developmental level, as measured with the Mullen Scales of Early Learning. Working memory was not associated with global measures of brain volume, as expected, and few associations were found between working memory and control white matter tracts. To our knowledge, this study is among the first demonstrations of brain-behavior associations in infants using quantitative tractography. The ability to characterize subtle individual differences in infant brain development associated with complex cognitive functions holds promise for improving our understanding of normative development, biomarkers of risk, experience-dependent learning and neuro-cognitive periods of developmental plasticity. PMID:22989623

Evidence for Plasticity in White Matter Tracts of Chronic Aphasic Patients Undergoing Intense Intonation-based Speech Therapy

PubMed Central

Schlaug, Gottfried; Marchina, Sarah; Norton, Andrea

2009-01-01

Recovery from aphasia can be achieved through recruitment of either peri-lesional brain regions in the affected hemisphere or homologous language regions in the non-lesional hemisphere. For patients with large left-hemisphere lesions, recovery through the right hemisphere may be the only possible path. The right hemisphere regions most likely to play a role in this recovery process are the superior temporal lobe (important for auditory feedback control), premotor regions/posterior inferior frontal gyrus (important for planning and sequencing of motor actions and for auditory-motor mapping) and the primary motor cortex (important for execution of vocal motor actions). These regions are connected reciprocally via a major fiber tract called the arcuate fasciculus (AF), but this tract is usually not as well developed in the non-dominant right hemisphere. We tested whether an intonation-based speech therapy (i.e., Melodic Intonation Therapy) which is typically administered in an intense fashion with 75–80 daily therapy sessions, would lead to changes in white matter tracts, particularly the AF. Using diffusion tensor imaging (DTI), we found a significant increase in the number of AF fibers and AF volume comparing post with pre-treatment assessments in 6 patients that could not be attributed to scan-to-scan variability. This suggests that intense, long-term Melodic Intonation Therapy leads to remodeling of the right AF and may provide an explanation for the sustained therapy effects that were seen in these 6 patients. PMID:19673813

Development of tectal connectivity across metamorphosis in the bullfrog (Rana catesbeiana).

PubMed

Horowitz, Seth S; Simmons, Andrea Megela

2010-01-01

In the bullfrog (Rana catesbeiana), the process of metamorphosis culminates in the appearance of new visual and visuomotor behaviors reflective of the emergence of binocular vision and visually-guided prey capture behaviors as the animal transitions to life on land. Using several different neuroanatomical tracers, we examined the substrates that may underlie these behavioral changes by tracing the afferent and efferent connectivity of the midbrain optic tectum across metamorphic development. Intratectal, tectotoral, tectotegmental, tectobulbar, and tecto-thalamic tracts exhibit similar trajectories of neurobiotin fiber label across the developmental span from early larval tadpoles to adults. Developmental variability was apparent primarily in intensity and distribution of cell and puncta label in target nuclei. Combined injections of cholera toxin subunit β and Phaseolus vulgaris leucoagglutinin consistently label cell bodies, puncta, or fiber segments bilaterally in midbrain targets including the pretectal gray, laminar nucleus of the torus semicircularis, and the nucleus of the medial longitudinal fasciculus. Developmentally stable label was observed bilaterally in medullary targets including the medial vestibular nucleus, lateral vestibular nucleus, and reticular gray, and in forebrain targets including the posterior and ventromedial nuclei of the thalamus. The nucleus isthmi, cerebellum, lateral line nuclei, medial septum, ventral striatum, and medial pallium show more developmentally variable patterns of connectivity. Our results suggest that even during larval development, the optic tectum contains substrates for integration of visual with auditory, vestibular, and somatosensory cues, as well as for guidance of motivated behaviors. Copyright © 2011 S. Karger AG, Basel.

Cerebral correlates of visuospatial neglect: a direct cerebral stimulation study.

PubMed

Vallar, Giuseppe; Bello, Lorenzo; Bricolo, Emanuela; Castellano, Antonella; Casarotti, Alessandra; Falini, Andrea; Riva, Marco; Fava, Enrica; Papagno, Costanza

2014-04-01

To assess the role of the superior longitudinal fascicle, the inferior fronto-occipital fascicle, and the posterior parietal lobe in visuospatial attention in humans during awake brain surgery. Seven patients with hemispheric gliomas (six in the right hemisphere) entered the study. During surgery in asleep/awake anesthesia, guided by Diffusion Tensor Imaging Fiber Tractography, visuospatial neglect was assessed during direct electrical stimulation by computerized line bisection. A rightward deviation, indicating left visuospatial neglect, was induced in six of seven patients by stimulation of the parietofrontal connections, in a location consistent with the trajectory of the second branch of the superior longitudinal fascicle. Stimulation of the medial and dorsal white matter of the superior parietal lobule (corresponding to the first branch of the superior longitudinal fascicle), of the ventral and lateral white matter of the supramarginal gyrus (corresponding to the third branch of the superior longitudinal fascicle), and of the inferior occipitofrontal fasciculus, was largely ineffective. Stimulation of the superior parietal lobule (Brodmann's area 7) caused a marked rightward deviation in all of the six assessed patients, while stimulation of Brodmann's areas 5 and 19 was ineffective. The parietofrontal connections of the dorso-lateral fibers of the superior longitudinal fascicle (i.e., the second branch of the fascicle), and the posterior superior parietal lobe (Brodmann's area 7) are involved in the orientation of spatial attention. Spatial neglect should be assessed systematically during awake brain surgery, particularly when the right parietal lobe may be involved by the neurosurgical procedure. Copyright © 2013 Wiley Periodicals, Inc.

Correlations of diffusion tensor imaging values and symptom scores in patients with schizophrenia.

PubMed

Michael, Andrew M; Calhoun, Vince D; Pearlson, Godfrey D; Baum, Stefi A; Caprihan, Arvind

2008-01-01

Abnormalities in white matter (WM) brain regions are attributed as a possible biomarker for schizophrenia (SZ). Diffusion tensor imaging (DTI) is used to capture WM tracts. Psychometric tests that evaluate the severity of symptoms of SZ are clinically used in the diagnosis process. In this study we investigate the correlates of scalar DTI measures, such as fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity with behavioral test scores. The correlations were found by different schemes: mean correlation with WM atlas regions and multiple regression of DTI values with test scores. The corpus callosum, superior longitudinal fasciculus right and inferior longitudinal fasciculus left were found to be having high correlations with test scores.

Global and Targeted Pathway Impact of Gliomas on White Matter Integrity Based on Lobar Localization.

PubMed

Ormond, David R; D'Souza, Shawn; Thompson, John A

2017-09-07

Primary brain tumors comprise 28% of all tumors and 80% of malignant tumors. Pathophysiology of high-grade gliomas includes significant distortion of white matter architecture, necrosis, the breakdown of the blood brain barrier, and increased intracranial pressure. Diffusion tensor imaging (DTI), a diffusion weighted imaging technique, can be used to assess white matter architecture. Use of DTI as a non-invasive pathophysiological tool to analyze glioma impact on white matter microstructure has yet to be fully explored. Preliminary assessment of DTI tractography was done as a measure of intracranial tumor impact on white matter architecture. Specifically, we addressed three questions: 1) whether glioma differentially affects local white matter structure compared to metastasis, 2) whether glioma affects tract integrity of major white matter bundles, 3) whether glioma lobe localization affects tract integrity of different white matter bundles. In this study, we retrospectively investigated preoperative DTI scans from 24 patients undergoing tumor resection. Fiber tractography was estimated using a deterministic fiber tracking algorithm in DSI (diffusion spectrum imaging) Studio. The automatic anatomical labeling (AAL) atlas was used to define the left and right (L/R)   hemisphere regions of interest (ROI). In addition, the John Hopkins University (JHU) White Matter Atlas was used to auto-segment major white matter bundle ROIs. For all tracts derived from ROI seed targets, we computed the following parameters: tract number, tract length, fractional anisotropy (FA), axial diffusivity (AD), mean diffusivity (MD), and radial diffusivity (RD). The DTI tractography analysis revealed that white matter integrity in the hemisphere ipsilateral to intracranial tumor was significantly compromised compared to the control contralateral hemisphere. No differences were observed between high vs low-grade gliomas, however, gliomas induced significantly greater white matter degradation than metastases. In addition, targeted analysis of major white matter bundles important for sensory/motor function (i.e., corticospinal tract and superior longitudinal fasciculus) revealed tract-parameter specific susceptibility due to the presence of the tumor. Finally, major tract bundles were differentially affected based on lobar localization of the glioma. These DTI-based tractographic analyses complement findings from gross histopathological examination of glioma impact on neural tissue. Global and focal white matter architecture, ipsilateral to glioma, shows higher rates of degradation or edema - based on DTI tractographic metrics - in comparison to normal brain or metastases. Gliomas, which arise in the parietal lobe, also have a higher negative impact (potentially due to increased edema) on white matter integrity of the superior longitudinal fasciculus(SLF) than those which arise in the frontal lobe. Future studies will focus on using preoperative and postoperative tractography to predict functional deficits following resective surgery.

Il Fasciculo di Medicina of 1493: medical culture through the eyes of the artist.

PubMed

DiMaio, Salvatore; Discepola, Federico; Del Maestro, Rolando F

2006-01-01

THE FASCICULUS MEDICINA, printed in 1491, is considered the first illustrated medical book. The Latin essays and illustrations in this volume provide insight into the medical knowledge of Western Europe and, in the Italian edition published in 1493, glimpses into the medical culture of the late 15th century. We outline the scientific and social environments into which the Fasciculus Medicinae of 1491 was introduced and the transition that occurred with the publication of the 1493 Italian edition. The artist of the 1493 Fasciculo witnessed a paradigm shift occurring. In four woodcuts, the artist captured four themes: the relevance of knowledge-based medicine, the emergence of laboratory medicine, the Hippocratic lessons of patient observation, and the emerging revolution in anatomy.

Microstructural Correlates of Emotional Attribution Impairment in Non-Demented Patients with Amyotrophic Lateral Sclerosis.

PubMed

Crespi, Chiara; Cerami, Chiara; Dodich, Alessandra; Canessa, Nicola; Iannaccone, Sandro; Corbo, Massimo; Lunetta, Christian; Falini, Andrea; Cappa, Stefano F

2016-01-01

Impairments in the ability to recognize and attribute emotional states to others have been described in amyotrophic lateral sclerosis patients and linked to the dysfunction of key nodes of the emotional empathy network. Microstructural correlates of such disorders are still unexplored. We investigated the white-matter substrates of emotional attribution deficits in a sample of amyotrophic lateral sclerosis patients without cognitive decline. Thirteen individuals with either probable or definite amyotrophic lateral sclerosis and 14 healthy controls were enrolled in a Diffusion Tensor Imaging study and administered the Story-based Empathy Task, assessing the ability to attribute mental states to others (i.e., Intention and Emotion attribution conditions). As already reported, a significant global reduction of empathic skills, mainly driven by a failure in Emotion Attribution condition, was found in amyotrophic lateral sclerosis patients compared to healthy subjects. The severity of this deficit was significantly correlated with fractional anisotropy along the forceps minor, genu of corpus callosum, right uncinate and inferior fronto-occipital fasciculi. The involvement of frontal commissural fiber tracts and right ventral associative fronto-limbic pathways is the microstructural hallmark of the impairment of high-order processing of socio-emotional stimuli in amyotrophic lateral sclerosis. These results support the notion of the neurofunctional and neuroanatomical continuum between amyotrophic lateral sclerosis and frontotemporal dementia.

Microstructural Correlates of Emotional Attribution Impairment in Non-Demented Patients with Amyotrophic Lateral Sclerosis

PubMed Central

Cerami, Chiara; Dodich, Alessandra; Canessa, Nicola; Iannaccone, Sandro; Corbo, Massimo; Lunetta, Christian; Falini, Andrea; Cappa, Stefano F.

2016-01-01

Impairments in the ability to recognize and attribute emotional states to others have been described in amyotrophic lateral sclerosis patients and linked to the dysfunction of key nodes of the emotional empathy network. Microstructural correlates of such disorders are still unexplored. We investigated the white-matter substrates of emotional attribution deficits in a sample of amyotrophic lateral sclerosis patients without cognitive decline. Thirteen individuals with either probable or definite amyotrophic lateral sclerosis and 14 healthy controls were enrolled in a Diffusion Tensor Imaging study and administered the Story-based Empathy Task, assessing the ability to attribute mental states to others (i.e., Intention and Emotion attribution conditions). As already reported, a significant global reduction of empathic skills, mainly driven by a failure in Emotion Attribution condition, was found in amyotrophic lateral sclerosis patients compared to healthy subjects. The severity of this deficit was significantly correlated with fractional anisotropy along the forceps minor, genu of corpus callosum, right uncinate and inferior fronto-occipital fasciculi. The involvement of frontal commissural fiber tracts and right ventral associative fronto-limbic pathways is the microstructural hallmark of the impairment of high-order processing of socio-emotional stimuli in amyotrophic lateral sclerosis. These results support the notion of the neurofunctional and neuroanatomical continuum between amyotrophic lateral sclerosis and frontotemporal dementia. PMID:27513746

Bipolar disorder and neurophysiologic mechanisms.

PubMed

McCrea, Simon M

2008-12-01

Recent studies have suggested that some variants of bipolar disorder (BD) may be due to hyperconnectivity between orbitofrontal (OFC) and temporal pole (TP) structures in the dominant hemisphere. Some initial MRI studies noticed that there were corpus callosum abnormalities within specific regional areas and it was hypothesized that developmentally this could result in functional or effective connectivity changes within the orbitofrontal-basal ganglia-thalamocortical circuits. Recent diffusion tensor imaging (DTI) white matter fiber tractography studies may well be superior to region of interest (ROI) DTI in understanding BD. A "ventral semantic stream" has been discovered connecting the TP and OFC through the uncinate and inferior longitudinal fasciculi and the elusive TP is known to be involved in theory of mind and complex narrative understanding tasks. The OFC is involved in abstract valuation in goal and sub-goal structures and the TP may be critical in binding semantic memory with person-emotion linkages associated with narrative. BD patients have relative attenuation of performance on visuoconstructional praxis consistent with an atypical localization of cognitive functions. Multiple lines of evidence suggest that some BD alleles are being selected for which could explain the enhanced creativity in higher-ability probands. Associations between ROI's that are not normally connected could explain the higher incidence of artistic aptitude, writing ability, and scientific achievements among some mood disorder subjects.

Is there a correlation between the clinical findings and the radiological findings in chronic maxillary sinus atelectasis?

PubMed

Eyigör, Hülya; Çekiç, Bülent; Turgut Çoban, Deniz; Selçuk, Ömer Tarık; Renda, Levent; Şimşek, Emine Handan; Yılmaz, Mustafa Deniz

2016-07-01

Silent sinus syndrome (SSS) is a clinical syndrome that occurs as a result of chronic maxillary sinus atelectasis (CMA) and is seen with progressive enophthalmos and hypoglobus. The aim of this study was to investigate the correlation between radiological findings and clinical findings in patients with radiologically asymmetrical reduced maxillary sinus volume. A comparison was made of patients with CMA through evaluation of paranasal sinus computed tomography, magnetic resonance imaging examination of maxillary sinus volume of the CMA side and the contralateral side, thickness of the retroantral fat tissue, infraorbital bone curve, uncinate process lateralisation measurement, middle concha diameter, and calculation of the change in location of the inferior rectus muscle. The study included 16 patients. Although a statistically significant difference was determined between the healthy and the pathological sides in respect to maxillary sinus volume, thickness of the retroantral fat tissue, infraorbital bone curve, uncinate process lateralisation measurement, and middle concha diameter (p = 0.00, p = 0.002, p = 0.020, p = 0.020, p = 0.007), no significant difference was determined in respect to the change in location of the inferior rectus muscle (p = 0.154). A positive correlation was determined between the increase in sulcus depth and maxillary sinus volume and inferior orbital bone curve (p < 0.05). In CMA patients suspected of having SSS, radiological maxillary sinus volume analysis, determination of retroantral fat thickness, measurement of the infraorbital bone curve, and measurement of the uncinate process lateralisation can be used as objective tests. However, it should be kept in mind that radiological findings may not always be compatible with the ophthalmological examination findings. Copyright © 2016 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Decision-making deficit of a patient with axonal damage after traumatic brain injury.

PubMed

Yasuno, Fumihiko; Matsuoka, Kiwamu; Kitamura, Soichiro; Kiuchi, Kuniaki; Kosaka, Jun; Okada, Koji; Tanaka, Syohei; Shinkai, Takayuki; Taoka, Toshiaki; Kishimoto, Toshifumi

2014-02-01

Patients with traumatic brain injury (TBI) were reported to have difficulty making advantageous decisions, but the underlying deficits of the network of brain areas involved in this process were not directly examined. We report a patient with TBI who demonstrated problematic behavior in situations of risk and complexity after cerebral injury from a traffic accident. The Iowa gambling task (IGT) was used to reveal his deficits in the decision-making process. To examine underlying deficits of the network of brain areas, we examined T1-weighted structural MRI, diffusion tensor imaging (DTI) and Tc-ECD SPECT in this patient. The patient showed abnormality in IGT. DTI-MRI results showed a significant decrease in fractional anisotropy (FA) in the fasciculus between the brain stem and cortical regions via the thalamus. He showed significant decrease in gray matter volumes in the bilateral insular cortex, hypothalamus, and posterior cingulate cortex, possibly reflecting Wallerian degeneration secondary to the fasciculus abnormalities. SPECT showed significant blood flow decrease in the broad cortical areas including the ventromedial prefrontal cortex (VM). Our study showed that the patient had dysfunctional decision-making process. Microstructural abnormality in the fasciculus, likely from the traffic accident, caused reduced afferent feedback to the brain, resulting in less efficient decision-making. Our findings support the somatic-marker hypothesis (SMH), where somatic feedback to the brain influences the decision-making process. Copyright © 2013 Elsevier Inc. All rights reserved.

Diffuse alterations in grey and white matter associated with cognitive impairment in Shwachman–Diamond syndrome: Evidence from a multimodal approach

PubMed Central

Perobelli, Sandra; Alessandrini, Franco; Zoccatelli, Giada; Nicolis, Elena; Beltramello, Alberto; Assael, Baroukh M.; Cipolli, Marco

2015-01-01

Shwachman–Diamond syndrome is a rare recessive genetic disease caused by mutations in SBDS gene, at chromosome 7q11. Phenotypically, the syndrome is characterized by exocrine pancreatic insufficiency, bone marrow dysfunction, skeletal dysplasia and variable cognitive impairments. Structural brain abnormalities (smaller head circumference and decreased brain volume) have also been reported. No correlation studies between brain abnormalities and neuropsychological features have yet been performed. In this study we investigate neuroanatomical findings, neurofunctional pathways and cognitive functioning of Shwachman–Diamond syndrome subjects compared with healthy controls. To be eligible for inclusion, participants were required to have known SBDS mutations on both alleles, no history of cranial trauma or any standard contraindication to magnetic resonance imaging. Appropriate tests were used to assess cognitive functions. The static images were acquired on a 3 × 0 T magnetic resonance scanner and blood oxygen level-dependent functional magnetic resonance imaging data were collected both during the execution of the Stroop task and at rest. Diffusion tensor imaging was used to assess brain white matter. The Tract-based Spatial Statistics package and probabilistic tractography were used to characterize white matter pathways. Nine participants (5 males), half of all the subjects aged 9–19 years included in the Italian Shwachman–Diamond Syndrome Registry, were evaluated and compared with nine healthy subjects, matched for sex and age. The patients performed less well than norms and controls on cognitive tasks (p = 0.0002). Overall, cortical thickness was greater in the patients, both in the left (+10%) and in the right (+15%) hemisphere, significantly differently increased in the temporal (left and right, p = 0.04), and right parietal (p = 0.03) lobes and in Brodmann area 44 (p = 0.04) of the right frontal lobe. The greatest increases were observed in the left limbic-anterior cingulate cortex (≥43%, p < 0.0004). Only in Broca's area in the left hemisphere did the patients show a thinner cortical thickness than that of controls (p = 0.01). Diffusion tensor imaging showed large, significant difference increases in both fractional anisotropy (+37%, p < 0.0001) and mean diffusivity (+35%, p < 0.005); the Tract-based Spatial Statistics analysis identified six abnormal clusters of white matter fibres in the fronto-callosal, right fronto-external capsulae, left fronto-parietal, right pontine, temporo-mesial and left anterior–medial–temporal regions. Brain areas activated during the Stroop task and those active during the resting state, are different, fewer and smaller in patients and correlate with worse performance (p = 0.002). Cognitive impairment in Shwachman–Diamond syndrome subjects is associated with diffuse brain anomalies in the grey matter (verbal skills with BA44 and BA20 in the right hemisphere; perceptual skills with BA5, 37, 20, 21, 42 in the left hemisphere) and white matter connectivity (verbal skills with alterations in the fronto-occipital fasciculus and with the inferior-longitudinal fasciculus; perceptual skills with the arcuate fasciculus, limbic and ponto-cerebellar fasciculus; memory skills with the arcuate fasciculus; executive functions with the anterior cingulated and arcuate fasciculus). PMID:25844324

Diffuse alterations in grey and white matter associated with cognitive impairment in Shwachman-Diamond syndrome: evidence from a multimodal approach.

PubMed

Perobelli, Sandra; Alessandrini, Franco; Zoccatelli, Giada; Nicolis, Elena; Beltramello, Alberto; Assael, Baroukh M; Cipolli, Marco

2015-01-01

Shwachman-Diamond syndrome is a rare recessive genetic disease caused by mutations in SBDS gene, at chromosome 7q11. Phenotypically, the syndrome is characterized by exocrine pancreatic insufficiency, bone marrow dysfunction, skeletal dysplasia and variable cognitive impairments. Structural brain abnormalities (smaller head circumference and decreased brain volume) have also been reported. No correlation studies between brain abnormalities and neuropsychological features have yet been performed. In this study we investigate neuroanatomical findings, neurofunctional pathways and cognitive functioning of Shwachman-Diamond syndrome subjects compared with healthy controls. To be eligible for inclusion, participants were required to have known SBDS mutations on both alleles, no history of cranial trauma or any standard contraindication to magnetic resonance imaging. Appropriate tests were used to assess cognitive functions. The static images were acquired on a 3 × 0 T magnetic resonance scanner and blood oxygen level-dependent functional magnetic resonance imaging data were collected both during the execution of the Stroop task and at rest. Diffusion tensor imaging was used to assess brain white matter. The Tract-based Spatial Statistics package and probabilistic tractography were used to characterize white matter pathways. Nine participants (5 males), half of all the subjects aged 9-19 years included in the Italian Shwachman-Diamond Syndrome Registry, were evaluated and compared with nine healthy subjects, matched for sex and age. The patients performed less well than norms and controls on cognitive tasks (p = 0.0002). Overall, cortical thickness was greater in the patients, both in the left (+10%) and in the right (+15%) hemisphere, significantly differently increased in the temporal (left and right, p = 0.04), and right parietal (p = 0.03) lobes and in Brodmann area 44 (p = 0.04) of the right frontal lobe. The greatest increases were observed in the left limbic-anterior cingulate cortex (≥43%, p < 0.0004). Only in Broca's area in the left hemisphere did the patients show a thinner cortical thickness than that of controls (p = 0.01). Diffusion tensor imaging showed large, significant difference increases in both fractional anisotropy (+37%, p < 0.0001) and mean diffusivity (+35%, p < 0.005); the Tract-based Spatial Statistics analysis identified six abnormal clusters of white matter fibres in the fronto-callosal, right fronto-external capsulae, left fronto-parietal, right pontine, temporo-mesial and left anterior-medial-temporal regions. Brain areas activated during the Stroop task and those active during the resting state, are different, fewer and smaller in patients and correlate with worse performance (p = 0.002). Cognitive impairment in Shwachman-Diamond syndrome subjects is associated with diffuse brain anomalies in the grey matter (verbal skills with BA44 and BA20 in the right hemisphere; perceptual skills with BA5, 37, 20, 21, 42 in the left hemisphere) and white matter connectivity (verbal skills with alterations in the fronto-occipital fasciculus and with the inferior-longitudinal fasciculus; perceptual skills with the arcuate fasciculus, limbic and ponto-cerebellar fasciculus; memory skills with the arcuate fasciculus; executive functions with the anterior cingulated and arcuate fasciculus).

Topical dura mater application of CFA induces enhanced expression of c-fos and glutamate in rat trigeminal nucleus caudalis: attenuated by KYNA derivate (SZR72).

PubMed

Lukács, M; Warfvinge, K; Tajti, J; Fülöp, F; Toldi, J; Vécsei, L; Edvinsson, L

2017-12-01

Migraine is a debilitating neurological disorder where trigeminovascular activation plays a key role. We have previously reported that local application of Complete Freund's Adjuvant (CFA) onto the dura mater caused activation in rat trigeminal ganglion (TG) which was abolished by a systemic administration of kynurenic acid (KYNA) derivate (SZR72). Here, we hypothesize that this activation may extend to the trigeminal complex in the brainstem and is attenuated by treatment with SZR72. Activation in the trigeminal nucleus caudalis (TNC) and the trigeminal tract (Sp5) was achieved by application of CFA onto the dural parietal surface. SZR72 was given intraperitoneally (i.p.), one dose prior CFA deposition and repeatedly daily for 7 days. Immunohistochemical studies were performed for mapping glutamate, c-fos, PACAP, substance P, IL-6, IL-1β and TNFα in the TNC/Sp5 and other regions of the brainstem and at the C 1 -C 2 regions of the spinal cord. We found that CFA increased c-fos and glutamate immunoreactivity in TNC and C 1 -C 2 neurons. This effect was mitigated by SZR72. PACAP positive fibers were detected in the fasciculus cuneatus and gracilis. Substance P, TNFα, IL-6 and IL-1β immunopositivity were detected in fibers of Sp5 and neither of these molecules showed any change in immunoreactivity following CFA administration. This is the first study demonstrating that dural application of CFA increases the expression of c-fos and glutamate in TNC neurons. Treatment with the KYNA analogue prevented this expression.

Abnormal white matter integrity in chronic users of codeine-containing cough syrups: a tract-based spatial statistics study.

PubMed

Qiu, Y-W; Su, H-H; Lv, X-F; Jiang, G-H

2015-01-01

Codeine-containing cough syrups have become one of the most popular drugs of abuse in young people in the world. Chronic codeine-containing cough syrup abuse is related to impairments in a broad range of cognitive functions. However, the potential brain white matter impairment caused by chronic codeine-containing cough syrup abuse has not been reported previously. Our aim was to investigate abnormalities in the microstructure of brain white matter in chronic users of codeine-containing syrups and to determine whether these WM abnormalities are related to the duration of the use these syrups and clinical impulsivity. Thirty chronic codeine-containing syrup users and 30 matched controls were evaluated. Diffusion tensor imaging was performed by using a single-shot spin-echo-planar sequence. Whole-brain voxelwise analysis of fractional anisotropy was performed by using tract-based spatial statistics to localize abnormal WM regions. The Barratt Impulsiveness Scale 11 was surveyed to assess participants' impulsivity. Volume-of-interest analysis was used to detect changes of diffusivity indices in regions with fractional anisotropy abnormalities. Abnormal fractional anisotropy was extracted and correlated with clinical impulsivity and the duration of codeine-containing syrup use. Chronic codeine-containing syrup users had significantly lower fractional anisotropy in the inferior fronto-occipital fasciculus of the bilateral temporo-occipital regions, right frontal region, and the right corona radiata WM than controls. There were significant negative correlations among fractional anisotropy values of the right frontal region of the inferior fronto-occipital fasciculus and the right superior corona radiata WM and Barratt Impulsiveness Scale total scores, and between the right frontal region of the inferior fronto-occipital fasciculus and nonplan impulsivity scores in chronic codeine-containing syrup users. There was also a significant negative correlation between fractional anisotropy values of the right frontal region of the inferior fronto-occipital fasciculus and the duration of codeine-containing syrup use in chronic users. Chronic codeine-containing syrup abuse may be associated with disruptions in brain WM integrity. These WM microstructural deficits may be linked to higher impulsivity in chronic codeine-containing syrup users. © 2015 by American Journal of Neuroradiology.

The arcuate fasciculus and the disconnection theme in language and aphasia: History and current state

PubMed Central

Catani, Marco; Mesulam, Marsel

2009-01-01

Few themes have been more central to neurological models of aphasia than the disconnection paradigm and the role of the arcuate fasciculus. Introduced by luminaries of 19th Century neurology and resurrected by the charismatic work of Norman Geschwind, the disconnection theme has triggered spectacular advances of modern understanding of language and aphasia. But the disconnection paradigm had alternate fortunes, ranging from irrational exuberance to benign neglect, and its followers have not always shared the same view on its functional consequences and anatomical correlates. Our goal in this paper is, first, to survey the 19th Century roots of the connectionist approach to aphasia and, second, to describe emerging imaging technologies based on diffusion tensor imaging (DTI) that promise to consolidate and expand the disconnection approach to language and its disorders. PMID:18614162

The arcuate fasciculus and the disconnection theme in language and aphasia: history and current state.

PubMed

Catani, Marco; Mesulam, Marsel

2008-09-01

Few themes have been more central to neurological models of aphasia than the disconnection paradigm and the role of the arcuate fasciculus. Introduced by luminaries of 19th Century neurology and resurrected by the charismatic work of Norman Geschwind, the disconnection theme has triggered spectacular advances of modern understanding of language and aphasia. But the disconnection paradigm had alternate fortunes, ranging from irrational exuberance to benign neglect, and its followers have not always shared the same view on its functional consequences and anatomical correlates. Our goal in this paper is, first, to survey the 19th Century roots of the connectionist approach to aphasia and, second, to describe emerging imaging technologies based on diffusion tensor imaging (DTI) that promise to consolidate and expand the disconnection approach to language and its disorders.

Is the term "fasciculus opticus cerebralis" more justifiable than the term "optic nerve"?

PubMed

Vojniković, Bojo; Bajek, Snjezana; Bajek, Goran; Strenja-Linić, Ines; Grubesić, Aron

2013-04-01

The terminology of the optic nerve had already been changed three times, since 1895 until 1955 when the term "nervus opticus" was introduced in the "Terminologia Anatomica". Following our study we claim that, from the aspect of phylogenetic evolution of binocular vision development as well as optical embryogenesis where opticus is evidently presented as a product of diencephalic structures, the addition of the term "nervus" to opticus is not adequate and justified. From the clinical aspect the term "nervus opticus" is also inadequate, both as a "nerve" that has no functional regenerative properties, unlike other cranial nerves, as well as from a pedagogical and didactical aspect of educating future physicians. We suggest that the term "Fasciculus Opticus Cerebralis" should be used as it much better explains the origin as well as its affiliation to the central nervous system.

Functional evidence for a direct excitatory projection from the lateral habenula to the ventral tegmental area in the rat

PubMed Central

Shepard, Paul D.

2016-01-01

The lateral habenula, a phylogenetically conserved epithalamic structure, is activated by aversive stimuli and reward omission. Excitatory efferents from the lateral habenula predominately inhibit midbrain dopamine neuronal firing through a disynaptic, feedforward inhibitory mechanism involving the rostromedial tegmental nucleus. However, the lateral habenula also directly targets dopamine neurons within the ventral tegmental area, suggesting that opposing actions may result from increased lateral habenula activity. In the present study, we tested the effect of habenular efferent stimulation on dopamine and nondopamine neurons in the ventral tegmental area of Sprague-Dawley rats using a parasagittal brain slice preparation. Single pulse stimulation of the fasciculus retroflexus excited 48% of dopamine neurons and 51% of nondopamine neurons in the ventral tegmental area of rat pups. These proportions were not altered by excision of the rostromedial tegmental nucleus and were evident in both cortical- and striatal-projecting dopamine neurons. Glutamate receptor antagonists blocked this excitation, and fasciculus retroflexus stimulation elicited evoked excitatory postsynaptic potentials with a nearly constant onset latency, indicative of a monosynaptic, glutamatergic connection. Comparison of responses in rat pups and young adults showed no significant difference in the proportion of neurons excited by fasciculus retroflexus stimulation. Our data indicate that the well-known, indirect inhibitory effect of lateral habenula activation on midbrain dopamine neurons is complemented by a significant, direct excitatory effect. This pathway may contribute to the role of midbrain dopamine neurons in processing aversive stimuli and salience. PMID:27358317

Involuntary switching into the native language induced by electrocortical stimulation of the superior temporal gyrus: a multimodal mapping study.

PubMed

Tomasino, Barbara; Marin, Dario; Canderan, Cinzia; Maieron, Marta; Budai, Riccardo; Fabbro, Franco; Skrap, Miran

2014-09-01

We describe involuntary language switching from L2 to L1 evoked by electro-stimulation in the superior temporal gyrus in a 30-year-old right-handed Serbian (L1) speaker who was also a late Italian learner (L2). The patient underwent awake brain surgery. Stimulation of other portions of the exposed cortex did not cause language switching as did not stimulation of the left inferior frontal gyrus, where we evoked a speech arrest. Stimulation effects on language switching were selective, namely, interfered with counting behaviour but not with object naming. The coordinates of the positive site were combined with functional and fibre tracking (DTI) data. Results showed that the language switching site belonged to a significant fMRI cluster in the left superior temporal gyrus/supramarginal gyrus found activated for both L1 and L2, and for both the patient and controls, and did not overlap with the inferior fronto-occipital fasciculus (IFOF), the inferior longitudinal fasciculus (ILF) and the superior longitudinal fasciculus (SLF). This area, also known as Stp, has a role in phonological processing. Language switching phenomenon we observed can be partly explained by transient dysfunction of the feed-forward control mechanism hypothesized by the DIVA (Directions Into Velocities of Articulators) model (Golfinopoulos, E., Tourville, J. A., & Guenther, F. H. (2010). The integration of large-scale neural network modeling and functional brain imaging in speech motor control. Copyright © 2014 Elsevier Ltd. All rights reserved.

Functional evidence for a direct excitatory projection from the lateral habenula to the ventral tegmental area in the rat.

PubMed

Brown, P Leon; Shepard, Paul D

2016-09-01

The lateral habenula, a phylogenetically conserved epithalamic structure, is activated by aversive stimuli and reward omission. Excitatory efferents from the lateral habenula predominately inhibit midbrain dopamine neuronal firing through a disynaptic, feedforward inhibitory mechanism involving the rostromedial tegmental nucleus. However, the lateral habenula also directly targets dopamine neurons within the ventral tegmental area, suggesting that opposing actions may result from increased lateral habenula activity. In the present study, we tested the effect of habenular efferent stimulation on dopamine and nondopamine neurons in the ventral tegmental area of Sprague-Dawley rats using a parasagittal brain slice preparation. Single pulse stimulation of the fasciculus retroflexus excited 48% of dopamine neurons and 51% of nondopamine neurons in the ventral tegmental area of rat pups. These proportions were not altered by excision of the rostromedial tegmental nucleus and were evident in both cortical- and striatal-projecting dopamine neurons. Glutamate receptor antagonists blocked this excitation, and fasciculus retroflexus stimulation elicited evoked excitatory postsynaptic potentials with a nearly constant onset latency, indicative of a monosynaptic, glutamatergic connection. Comparison of responses in rat pups and young adults showed no significant difference in the proportion of neurons excited by fasciculus retroflexus stimulation. Our data indicate that the well-known, indirect inhibitory effect of lateral habenula activation on midbrain dopamine neurons is complemented by a significant, direct excitatory effect. This pathway may contribute to the role of midbrain dopamine neurons in processing aversive stimuli and salience. Copyright © 2016 the American Physiological Society.

Design fluency and neuroanatomical correlates in 54 neurosurgical patients with lesions to the right hemisphere.

PubMed

Marin, Dario; Madotto, Eleonora; Fabbro, Franco; Skrap, Miran; Tomasino, Barbara

2017-10-01

We addressed the neuroanatomical correlates of 54 right-brain-damaged neurosurgical patients on visuo-spatial design fluency, which is a measure of the ability to generate/plan a series of new abstract combinations in a flexible way. 22.2% of the patients were impaired. They failed the task because they did not use strategic behavior, in particular they used rotational strategy to a significantly lower extent and produced a significantly higher rate of perseverative errors. Overall performance did not correlate with neuropsychological tests, suggesting that proficient performance was independent of other cognitive domains. Performance significantly correlated with use of rotational strategy. Tasks related to executive functions such as psychomotor speed and capacity to shift were positively correlated to the number of strategies used to solve the task. Lesion analysis showed that the maximum density of the patients' lesions-obtained by subtracting the overlap of lesions of spared patients from the overlap of lesions of impaired patients-overlaps with the precentral gyrus, rolandic operculum/insula, superior/middle temporal gyrus/hippocampus and, at subcortical level, with part of the superior longitudinal fasciculus, external capsule, retrolenticular part of the internal capsule and sagittal stratum (inferior longitudinal fasciculus and inferior fronto-occipital fasciculus). These areas are part of the fronto-parietal-temporal network known to be involved in top-down control of visuo-spatial attention, suggesting that the mechanisms and the strategies needed for proficient performance are essentially visuo-spatial in nature.

[Tourette syndrome and reading disorder in a boy with left parietofrontal tract disruption].

PubMed

Martín Fernández-Mayoralas, D; Fernández-Jaén, A; Gómez Herrera, J J; Jiménez de la Peña, M

2014-01-01

We present the case of a nine-year-old boy with Tourette syndrome and reading disorder with a history of a severe infectious process in the late neonatal period. Brain MRI showed a left parietal malacotic cavity and diffusion tensor imaging and tractography showed a striking disruption of the white matter bundle that joins the left parietal region with the ipsilateral frontal region with involvement of the left superior longitudinal fasciculus and of the left arcuate fasciculus. Although Tourette syndrome and reading disorder are fundamentally hereditary neuropsychiatric disorders, they can also occur secondary to cerebral alterations like those existing in this boy. The introduction of modern neuroimaging techniques in patients with neuropsychiatric disorders (or the risk of developing them) can be very useful in the diagnosis and prognosis in the future. Copyright © 2011 SERAM. Published by Elsevier Espana. All rights reserved.

Individual differences in children's global motion sensitivity correlate with TBSS-based measures of the superior longitudinal fasciculus.

PubMed

Braddick, Oliver; Atkinson, Janette; Akshoomoff, Natacha; Newman, Erik; Curley, Lauren B; Gonzalez, Marybel Robledo; Brown, Timothy; Dale, Anders; Jernigan, Terry

2017-12-01

Reduced global motion sensitivity, relative to global static form sensitivity, has been found in children with many neurodevelopmental disorders, leading to the "dorsal stream vulnerability" hypothesis (Braddick et al., 2003). Individual differences in typically developing children's global motion thresholds have been shown to be associated with variations in specific parietal cortical areas (Braddick et al., 2016). Here, in 125 children aged 5-12years, we relate individual differences in global motion and form coherence thresholds to fractional anisotropy (FA) in the superior longitudinal fasciculus (SLF), a major fibre tract communicating between parietal lobe and anterior cortical areas. We find a positive correlation between FA of the right SLF and individual children's sensitivity to global motion coherence, while FA of the left SLF shows a negative correlation. Further analysis of parietal cortical area data shows that this is also asymmetrical, showing a stronger association with global motion sensitivity in the left hemisphere. None of these associations hold for an analogous measure of global form sensitivity. We conclude that a complex pattern of structural asymmetry, including the parietal lobe and the superior longitudinal fasciculus, is specifically linked to the development of sensitivity to global visual motion. This pattern suggests that individual differences in motion sensitivity are primarily linked to parietal brain areas interacting with frontal systems in making decisions on integrated motion signals, rather than in the extra-striate visual areas that perform the initial integration. The basis of motion processing deficits in neurodevelopmental disorders may depend on these same structures. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bone chip-induced rhinosinusitis.

PubMed

Reilly, Brian K; Conley, David B

2009-12-01

This case report describes both the pathophysiology and management of chronic rhinosinusitis (CRS). Specifically, we report a case of chronic maxillary rhinosinusitis with a free-floating maxillary sinus calcification (bone chip). After obtaining the computed tomography scan, the patient underwent endoscopic sinus surgery, with removal of the uncinate, enlargement of the diseased natural ostium of the maxillary sinus, and removal of the diseased bone chip. This eliminated the nidus for infection, ultimately restoring mucociliary flow.

The robotic Whipple: operative strategy and technical considerations.

PubMed

MacKenzie, Shawn; Kosari, Kambiz; Sielaff, Timothy; Johnson, Eric

2011-03-01

Advances in robotic surgery have allowed the frontiers of minimally invasive pancreatic surgery to expand. We present a step-by-step approach to the robotic Whipple procedure. The discussion includes port setting and robotic docking, kocherization and superior mesenteric vein identification, portal dissection, releasing the ligament of Treitz, uncinate dissection, and reconstruction. A brief report of our initial 2-year experience with the robotic Whipple procedure is also presented.

White matter microstructure in boys with persistent depressive disorder.

PubMed

Vilgis, Veronika; Vance, Alasdair; Cunnington, Ross; Silk, Timothy J

2017-10-15

Persistent depressive symptoms in children and adolescents are considered a risk factor for the development of major depressive disorder (MDD) later in life. Previous research has shown alterations in white matter microstructure in pediatric MDD but discrepancies exist as to the specific tracts affected. The current study aimed to improve upon previous methodology and address the question whether previous findings of lower fractional anisotropy (FA) replicate in a sample of children with persistent depressive disorder characterized by mild but more chronic symptoms of depression. White matter microstructure was examined in 25 boys with persistent depressive disorder and 25 typically developing children. Tract specific analysis implemented with the Diffusion Tensor Imaging - ToolKit (DTI-TK) was used to probe fractional anisotropy (FA) in eleven major white matter tracts. Clusters within the left uncinate, inferior fronto-occipital and cerebrospinal tracts showed lower FA in the clinical group. FA in the left uncinate showed a negative association with self-reported symptoms of depression. The results demonstrate lower FA in several white matter tracts in children with persistent depressive disorder. These findings support the contention that early onset depression is associated with altered white matter microstructure, which may contribute to the maintenance and recurrence of symptoms. Copyright © 2017. Published by Elsevier B.V.

Impaired functional but preserved structural connectivity in limbic white matter tracts in youth with conduct disorder or oppositional defiant disorder plus psychopathic traits.

PubMed

Finger, Elizabeth Carrie; Marsh, Abigail; Blair, Karina Simone; Majestic, Catherine; Evangelou, Iordanis; Gupta, Karan; Schneider, Marguerite Reid; Sims, Courtney; Pope, Kayla; Fowler, Katherine; Sinclair, Stephen; Tovar-Moll, Fernanda; Pine, Daniel; Blair, Robert James

2012-06-30

Youths with conduct disorder or oppositional defiant disorder and psychopathic traits (CD/ODD+PT) are at high risk of adult antisocial behavior and psychopathy. Neuroimaging studies demonstrate functional abnormalities in orbitofrontal cortex and the amygdala in both youths and adults with psychopathic traits. Diffusion tensor imaging in psychopathic adults demonstrates disrupted structural connectivity between these regions (uncinate fasiculus). The current study examined whether functional neural abnormalities present in youths with CD/ODD+PT are associated with similar white matter abnormalities. Youths with CD/ODD+PT and comparison participants completed 3.0 T diffusion tensor scans and functional magnetic resonance imaging scans. Diffusion tensor imaging did not reveal disruption in structural connections within the uncinate fasiculus or other white matter tracts in youths with CD/ODD+PT, despite the demonstration of disrupted amygdala-prefrontal functional connectivity in these youths. These results suggest that disrupted amygdala-frontal white matter connectivity as measured by fractional anisotropy is less sensitive than imaging measurements of functional perturbations in youths with psychopathic traits. If white matter tracts are intact in youths with this disorder, childhood may provide a critical window for intervention and treatment, before significant structural brain abnormalities solidify. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Effects of vocal training in a musicophile with congenital amusia.

PubMed

Wilbiks, Jonathan M P; Vuvan, Dominique T; Girard, Pier-Yves; Peretz, Isabelle; Russo, Frank A

2016-12-01

Congenital amusia is a condition in which an individual suffers from a deficit of musical pitch perception and production. Individuals suffering from congenital amusia generally tend to abstain from musical activities. Here, we present the unique case of Tim Falconer, a self-described musicophile who also suffers from congenital amusia. We describe and assess Tim's attempts to train himself out of amusia through a self-imposed 18-month program of formal vocal training and practice. We tested Tim with respect to music perception and vocal production across seven sessions including pre- and post-training assessments. We also obtained diffusion-weighted images of his brain to assess connectivity between auditory and motor planning areas via the arcuate fasciculus (AF). Tim's behavioral and brain data were compared to that of normal and amusic controls. While Tim showed temporary gains in his singing ability, he did not reach normal levels, and these gains faded when he was not engaged in regular lessons and practice. Tim did show some sustained gains with respect to the perception of musical rhythm and meter. We propose that Tim's lack of improvement in pitch perception and production tasks is due to long-standing and likely irreversible reduction in connectivity along the AF fiber tract.

Left hemisphere fractional anisotropy increase in noise-induced tinnitus: a diffusion tensor imaging (DTI) study of white matter tracts in the brain.

PubMed

Benson, Randall R; Gattu, Ramtilak; Cacace, Anthony T

2014-03-01

Diffusion tensor imaging (DTI) is a contemporary neuroimaging modality used to study connectivity patterns and microstructure of white matter tracts in the brain. The use of DTI in the study of tinnitus is a relatively unexplored methodology with no studies focusing specifically on tinnitus induced by noise exposure. In this investigation, participants were two groups of adults matched for etiology, age, and degree of peripheral hearing loss, but differed by the presence or absence (+/-) of tinnitus. It is assumed that matching individuals on the basis of peripheral hearing loss, allows for differentiating changes in white matter microstructure due to hearing loss from changes due to the effects of chronic tinnitus. Alterations in white matter tracts, using the fractional anisotropy (FA) metric, which measures directional diffusion of water, were quantified using tract-based spatial statistics (TBSS) with additional details provided by in vivo probabilistic tractography. Our results indicate that 10 voxel clusters differentiated the two groups, including 9 with higher FA in the group with tinnitus. A decrease in FA was found for a single cluster in the group with tinnitus. However, seven of the 9 clusters with higher FA were in left hemisphere thalamic, frontal, and parietal white matter. These foci were localized to the anterior thalamic radiations and the inferior and superior longitudinal fasciculi. The two right-sided clusters with increased FA were located in the inferior fronto-occipital fasciculus and superior longitudinal fasciculus. The only decrease in FA for the tinnitus-positive group was found in the superior longitudinal fasciculus of the left parietal lobe. Copyright © 2013 Elsevier B.V. All rights reserved.

Lower white matter microstructure in the superior longitudinal fasciculus is associated with increased response time variability in adults with attention-deficit/ hyperactivity disorder.

PubMed

Wolfers, Thomas; Onnink, A Marten H; Zwiers, Marcel P; Arias-Vasquez, Alejandro; Hoogman, Martine; Mostert, Jeanette C; Kan, Cornelis C; Slaats-Willemse, Dorine; Buitelaar, Jan K; Franke, Barbara

2015-09-01

Response time variability (RTV) is consistently increased in patients with attention-deficit/hyperactivity disorder (ADHD). A right-hemispheric frontoparietal attention network model has been implicated in these patients. The 3 main connecting fibre tracts in this network, the superior longitudinal fasciculus (SLF), inferior longitudinal fasciculus (ILF) and the cingulum bundle (CB), show microstructural abnormalities in patients with ADHD. We hypothesized that the microstructural integrity of the 3 white matter tracts of this network are associated with ADHD and RTV. We examined RTV in adults with ADHD by modelling the reaction time distribution as an exponentially modified Gaussian (ex-Gaussian) function with the parameters μ, σ and τ, the latter of which has been attributed to lapses of attention. We assessed adults with ADHD and healthy controls using a sustained attention task. Diffusion tensor imaging-derived fractional anisotropy (FA) values were determined to quantify bilateral microstructural integrity of the tracts of interest. We included 100 adults with ADHD and 96 controls in our study. Increased τ was associated with ADHD diagnosis and was linked to symptoms of inattention. An inverse correlation of τ with mean FA was seen in the right SLF of patients with ADHD, but no direct association between the mean FA of the 6 regions of interest with ADHD could be observed. Regions of interest were defined a priori based on the attentional network model for ADHD and thus we might have missed effects in other networks. This study suggests that reduced microstructural integrity of the right SLF is associated with elevated τ in patients with ADHD.

Trail Making Test Elucidates Neural Substrates of Specific Poststroke Executive Dysfunctions.

PubMed

Muir, Ryan T; Lam, Benjamin; Honjo, Kie; Harry, Robin D; McNeely, Alicia A; Gao, Fu-Qiang; Ramirez, Joel; Scott, Christopher J M; Ganda, Anoop; Zhao, Jiali; Zhou, X Joe; Graham, Simon J; Rangwala, Novena; Gibson, Erin; Lobaugh, Nancy J; Kiss, Alex; Stuss, Donald T; Nyenhuis, David L; Lee, Byung-Chul; Kang, Yeonwook; Black, Sandra E

2015-10-01

Poststroke cognitive impairment is typified by prominent deficits in processing speed and executive function. However, the underlying neuroanatomical substrates of executive deficits are not well understood, and further elucidation is needed. There may be utility in fractionating executive functions to delineate neural substrates. One test amenable to fine delineation is the Trail Making Test (TMT), which emphasizes processing speed (TMT-A) and set shifting (TMT-B-A difference, proportion, quotient scores, and TMT-B set-shifting errors). The TMT was administered to 2 overt ischemic stroke cohorts from a multinational study: (1) a chronic stroke cohort (N=61) and (2) an acute-subacute stroke cohort (N=45). Volumetric quantification of ischemic stroke and white matter hyperintensities was done on magnetic resonance imaging, along with ratings of involvement of cholinergic projections, using the previously published cholinergic hyperintensities projections scale. Damage to the superior longitudinal fasciculus, which colocalizes with some cholinergic projections, was also documented. Multiple linear regression analyses were completed. Although larger infarcts (β=0.37, P<0.0001) were associated with slower processing speed, cholinergic hyperintensities projections scale severity (β=0.39, P<0.0001) was associated with all metrics of set shifting. Left superior longitudinal fasciculus damage, however, was only associated with the difference score (β=0.17, P=0.03). These findings were replicated in both cohorts. Patients with ≥2 TMT-B set-shifting errors also had greater cholinergic hyperintensities projections scale severity. In this multinational stroke cohort study, damage to lateral cholinergic pathways and the superior longitudinal fasciculus emerged as significant neuroanatomical correlates for executive deficits in set shifting. © 2015 American Heart Association, Inc.

Lower white matter microstructure in the superior longitudinal fasciculus is associated with increased response time variability in adults with attention-deficit/hyperactivity disorder

PubMed Central

Wolfers, Thomas; Onnink, A. Marten H.; Zwiers, Marcel P.; Arias-Vasquez, Alejandro; Hoogman, Martine; Mostert, Jeanette C.; Kan, Cornelis C.; Slaats-Willemse, Dorine; Buitelaar, Jan K.; Franke, Barbara

2015-01-01

Background Response time variability (RTV) is consistently increased in patients with attention-deficit/hyperactivity disorder (ADHD). A right-hemispheric frontoparietal attention network model has been implicated in these patients. The 3 main connecting fibre tracts in this network, the superior longitudinal fasciculus (SLF), inferior longitudinal fasciculus (ILF) and the cingulum bundle (CB), show microstructural abnormalities in patients with ADHD. We hypothesized that the microstructural integrity of the 3 white matter tracts of this network are associated with ADHD and RTV. Methods We examined RTV in adults with ADHD by modelling the reaction time distribution as an exponentially modified Gaussian (ex-Gaussian) function with the parameters μ, σ and τ, the latter of which has been attributed to lapses of attention. We assessed adults with ADHD and healthy controls using a sustained attention task. Diffusion tensor imaging–derived fractional anisotropy (FA) values were determined to quantify bilateral microstructural integrity of the tracts of interest. Results We included 100 adults with ADHD and 96 controls in our study. Increased τ was associated with ADHD diagnosis and was linked to symptoms of inattention. An inverse correlation of τ with mean FA was seen in the right SLF of patients with ADHD, but no direct association between the mean FA of the 6 regions of interest with ADHD could be observed. Limitations Regions of interest were defined a priori based on the attentional network model for ADHD and thus we might have missed effects in other networks. Conclusion This study suggests that reduced microstructural integrity of the right SLF is associated with elevated τ in patients with ADHD. PMID:26079698

Diffusion Tensor Imaging Studies on Arcuate Fasciculus in Stroke Patients: A Review

PubMed Central

Jang, Sung Ho

2013-01-01

Aphasia is one of the most common and devastating sequelae of stroke. The arcuate fasciculus (AF), an important neural tract for language function, connects Broca’s and Wernicke’s areas. In this review article, previous diffusion tensor imaging (DTI) studies on the AF in stroke patients were reviewed with regard to the usefulness for diagnosis (seven studies), prediction of prognosis (two studies), and recovery of aphasia (three studies). Although scant studies on this topic have been conducted in stroke patients, DTI for the AF appears to provide useful information on the presence or severity of injury of the AF, prognosis prediction of aphasia, and recovery mechanisms of aphasia in stroke patients. Therefore, further DTI studies on these topics should be encouraged, especially studies on prognosis prediction and recovery mechanisms of aphasia. In addition, research on other neural tracts known to be involved in aphasia as well as the AF in both hemispheres should be encouraged. PMID:24198780

Anatomy is strategy: Skilled reading differences associated with structural connectivity differences in the reading network

PubMed Central

Graves, William W.; Binder, Jeffrey R.; Desai, Rutvik H.; Humphries, Colin; Stengel, Benjamin C.; Seidenberg, Mark S.

2014-01-01

Are there multiple ways to be a skilled reader? To address this longstanding, unresolved question, we hypothesized that individual variability in using semantic information in reading aloud would be associated with neuroanatomical variation in pathways linking semantics and phonology. Left-hemisphere regions of interest for diffusion tensor imaging analysis were defined based on fMRI results, including two regions linked with semantic processing – angular gyrus (AG) and inferior temporal sulcus (ITS) – and two linked with phonological processing – posterior superior temporal gyrus (pSTG) and posterior middle temporal gyrus (pMTG). Effects of imageability (a semantic measure) on response times varied widely among individuals and covaried with the volume of pathways through the ITS and pMTG, and through AG and pSTG, partially overlapping the inferior longitudinal fasciculus and the posterior branch of the arcuate fasciculus. These results suggest strategy differences among skilled readers associated with structural variation in the neural reading network. PMID:24735993

Microsurgical anatomy of the central core of the brain.

PubMed

Ribas, Eduardo Carvalhal; Yağmurlu, Kaan; de Oliveira, Evandro; Ribas, Guilherme Carvalhal; Rhoton, Albert

2017-12-22

OBJECTIVE The purpose of this study was to describe in detail the cortical and subcortical anatomy of the central core of the brain, defining its limits, with particular attention to the topography and relationships of the thalamus, basal ganglia, and related white matter pathways and vessels. METHODS The authors studied 19 cerebral hemispheres. The vascular systems of all of the specimens were injected with colored silicone, and the specimens were then frozen for at least 1 month to facilitate identification of individual fiber tracts. The dissections were performed in a stepwise manner, locating each gray matter nucleus and white matter pathway at different depths inside the central core. The course of fiber pathways was also noted in relation to the insular limiting sulci. RESULTS The insular surface is the most superficial aspect of the central core and is divided by a central sulcus into an anterior portion, usually containing 3 short gyri, and a posterior portion, with 2 long gyri. It is bounded by the anterior limiting sulcus, the superior limiting sulcus, and the inferior limiting sulcus. The extreme capsule is directly underneath the insular surface and is composed of short association fibers that extend toward all the opercula. The claustrum lies deep to the extreme capsule, and the external capsule is found medial to it. Three fiber pathways contribute to form both the extreme and external capsules, and they lie in a sequential anteroposterior disposition: the uncinate fascicle, the inferior fronto-occipital fascicle, and claustrocortical fibers. The putamen and the globus pallidus are between the external capsule, laterally, and the internal capsule, medially. The internal capsule is present medial to almost all insular limiting sulci and most of the insular surface, but not to their most anteroinferior portions. This anteroinferior portion of the central core has a more complex anatomy and is distinguished in this paper as the "anterior perforated substance region." The caudate nucleus and thalamus lie medial to the internal capsule, as the most medial structures of the central core. While the anterior half of the central core is related to the head of the caudate nucleus, the posterior half is related to the thalamus, and hence to each associated portion of the internal capsule between these structures and the insular surface. The central core stands on top of the brainstem. The brainstem and central core are connected by several white matter pathways and are not separated from each other by any natural division. The authors propose a subdivision of the central core into quadrants and describe each in detail. The functional importance of each structure is highlighted, and surgical approaches are suggested for each quadrant of the central core. CONCLUSIONS As a general rule, the internal capsule and its vascularization should be seen as a parasagittal barrier with great functional importance. This is of particular importance in choosing surgical approaches within this region.

Safety and efficacy of LigaSure usage in pancreaticoduodenectomy.

PubMed

Eng, Oliver S; Goswami, Julie; Moore, Dirk; Chen, Chunxia; Brumbaugh, Jennifer; Gannon, Christopher J; August, David A; Carpizo, Darren R

2013-10-01

Over recent years, use of the LigaSure™ vessel sealing device has increased in major abdominal surgery to include pancreaticoduodenectomy (PD). LigaSure™ use during PD has expanded to include all steps of the procedure, including the division of the uncinate margin. This introduces the potential for thermal major vascular injury or margin positivity. The aim of the present study was to evaluate the safety and efficacy of LigaSure™ usage in PD in comparison to established dissection techniques. One hundred and forty-eight patients who underwent PD from 2007 to 2012 at Robert Wood Johnson University Hospital were identified from a retrospective database. Two groups were recognized: those in which the LigaSure™ device was used (N = 114), and in those it was not (N = 34). Peri-operative outcomes were compared. Vascular intra-operative complications directly caused by thermal injury from LigaSure™ use occurred in 1.8% of patients. Overall vascular intra-operative complications, uncinate margin positivity, blood loss, length of stay, and complication severity were not significantly different between groups. The mean operative time was 77 min less (P < 0.010) in the LigaSure™ group. Savings per case where the LigaSure™ was used amounted to $1776.73. LigaSure™ usage during PD is safe and effective. It is associated with decreased operative times, which may decrease operative costs in PD. © 2013 International Hepato-Pancreato-Biliary Association.

Safety and efficacy of LigaSure usage in pancreaticoduodenectomy

PubMed Central

Eng, Oliver S; Goswami, Julie; Moore, Dirk; Chen, Chunxia; Brumbaugh, Jennifer; Gannon, Christopher J; August, David A; Carpizo, Darren R

2013-01-01

Background Over recent years, use of the LigaSure™ vessel sealing device has increased in major abdominal surgery to include pancreaticoduodenectomy (PD). LigaSure™ use during PD has expanded to include all steps of the procedure, including the division of the uncinate margin. This introduces the potential for thermal major vascular injury or margin positivity. The aim of the present study was to evaluate the safety and efficacy of LigaSure™ usage in PD in comparison to established dissection techniques. Methods One hundred and forty-eight patients who underwent PD from 2007 to 2012 at Robert Wood Johnson University Hospital were identified from a retrospective database. Two groups were recognized: those in which the LigaSure™ device was used (N = 114), and in those it was not (N = 34). Peri-operative outcomes were compared. Results Vascular intra-operative complications directly caused by thermal injury from LigaSure™ use occurred in 1.8% of patients. Overall vascular intra-operative complications, uncinate margin positivity, blood loss, length of stay, and complication severity were not significantly different between groups. The mean operative time was 77 min less (P < 0.010) in the LigaSure™ group. Savings per case where the LigaSure™ was used amounted to $1776.73. Conclusion LigaSure™ usage during PD is safe and effective. It is associated with decreased operative times, which may decrease operative costs in PD. PMID:23782268

Beyond the Arcuate Fasciculus: Consensus and Controversy in the Connectional Anatomy of Language

ERIC Educational Resources Information Center

Dick, Anthony Steven; Tremblay, Pascale

2012-01-01

The growing consensus that language is distributed into large-scale cortical and subcortical networks has brought with it an increasing focus on the connectional anatomy of language, or how particular fibre pathways connect regions within the language network. Understanding connectivity of the language network could provide critical insights into…

A Tractography Study in Dyslexia: Neuroanatomic Correlates of Orthographic, Phonological and Speech Processing

ERIC Educational Resources Information Center

Vandermosten, Maaike; Boets, Bart; Poelmans, Hanne; Sunaert, Stefan; Wouters, Jan; Ghesquiere, Pol

2012-01-01

Diffusion tensor imaging tractography is a structural magnetic resonance imaging technique allowing reconstruction and assessment of the integrity of three dimensional white matter tracts, as indexed by their fractional anisotropy. It is assumed that the left arcuate fasciculus plays a crucial role for reading development, as it connects two…

The Plasticity of the Superior Longitudinal Fasciculus as a Function of Musical Expertise: A Diffusion Tensor Imaging Study

PubMed Central

Oechslin, Mathias S.; Imfeld, Adrian; Loenneker, Thomas; Meyer, Martin; Jäncke, Lutz

2009-01-01

Previous neuroimaging studies have demonstrated that musical expertise leads to functional alterations in language processing. We utilized diffusion tensor imaging (DTI) to investigate white matter plasticity in musicians with absolute pitch (AP), relative pitch and non-musicians. Using DTI, we analysed the fractional anisotropy (FA) of the superior longitudinal fasciculus (SLF), which is considered the most primary pathway for processing and production of speech and music. In association with different levels of musical expertise, we found that AP is characterized by a greater left than right asymmetry of FA in core fibres of the SLF. A voxel-based analysis revealed three clusters within the left hemisphere SLF that showed significant positive correlations with error rates only for AP-musicians in an AP-test, but not for musicians without AP. We therefore conclude that the SLF architecture in AP musicians is related to AP acuity. In order to reconcile our observations with general aspects of development of fibre bundles, we introduce the Pioneer Axon Thesis, a theoretical approach to formalize axonal arrangements of major white matter pathways. PMID:20161812

Disorders of emotional processing in amyotrophic lateral sclerosis.

PubMed

Sedda, Anna

2014-12-01

Amyotrophic lateral sclerosis (ALS) is a degenerative brain disease characterized by motor, behavioural and cognitive deficits. Only recently, emotional processing disorders have been shown in this disease. The interest in affective processing in ALS is growing given that basic emotion impairments could impact copying strategies and mood. Studies explore both basic emotion recognition and social cognition. Results are congruent on arousal and valence detection impairments, independently from the stimulus modality (verbal or visual). Further, recognition of facial expressions of anger, sadness and disgust is impaired in ALS, even when cognition is preserved. Clinical features such as type of onset and severity of the disease could be the cause of the heterogeneity in emotional deficits profiles between patients. Finally, a study employing diffusion tensor imaging showed that emotional dysfunctions in ALS are related to right hemispheric connective bundles impairments, involving the inferior longitudinal fasciculus and the inferior frontal occipital fasciculus. Research on emotional processing in ALS is still in its infancy and results are mixed. Future research including more detailed clinical profiles of patients and measures of brain connectivity will provide useful information to understand heterogeneity of results in ALS.

Exploratory analysis of diffusion tensor imaging in children with attention deficit hyperactivity disorder: evidence of abnormal white matter structure.

PubMed

Pastura, Giuseppe; Doering, Thomas; Gasparetto, Emerson Leandro; Mattos, Paulo; Araújo, Alexandra Prüfer

2016-06-01

Abnormalities in the white matter microstructure of the attentional system have been implicated in the aetiology of attention deficit hyperactivity disorder (ADHD). Diffusion tensor imaging (DTI) is a promising magnetic resonance imaging (MRI) technology that has increasingly been used in studies of white matter microstructure in the brain. The main objective of this work was to perform an exploratory analysis of white matter tracts in a sample of children with ADHD versus typically developing children (TDC). For this purpose, 13 drug-naive children with ADHD of both genders underwent MRI using DTI acquisition methodology and tract-based spatial statistics. The results were compared to those of a sample of 14 age- and gender-matched TDC. Lower fractional anisotropy was observed in the splenium of the corpus callosum, right superior longitudinal fasciculus, bilateral retrolenticular part of the internal capsule, bilateral inferior fronto-occipital fasciculus, left external capsule and posterior thalamic radiation (including right optic radiation). We conclude that white matter tracts in attentional and motor control systems exhibited signs of abnormal microstructure in this sample of drug-naive children with ADHD.

Diffusion-weighted MRI measures suggest increased white-matter integrity in Internet gaming disorder: Evidence from the comparison with recreational Internet game users.

PubMed

Dong, Guangheng; Wu, Lingdan; Wang, Ziliang; Wang, Yifan; Du, Xiaoxia; Potenza, Marc N

2018-06-01

Several studies have suggested that Internet gaming disorder (IGD) is related to altered brain white matter integrity. However, seeming inconsistencies exist and may reflect comparison groups not matched well for certain gaming characteristics. In order to address this possible concern, we recruited in the present study individuals with recreational Internet game use (RGU) comprised of individuals who spend similar amounts of time as IGD subjects playing online games without developing IGD. Diffusion tensor imaging data were collected from 42 IGD and 44 RGU subjects. Whole-brain comparisons showed that IGD subjects demonstrated increased fractional anisotropy (FA) in the bilateral anterior thalamic radiation, anterior limb of the internal capsule, bilateral corticospinal tract, bilateral inferior fronto-occipital fasciculus, corpus callosum, and bilateral inferior longitudinal fasciculus. In addition, Internet-addiction severity was positively correlated with FA values. Taken together, we conclude that IGD is associated with measures of increased white-matter integrity in tracts linking reward circuitry and sensory and motor control systems. Copyright © 2018 Elsevier Ltd. All rights reserved.

White matter tract integrity predicts visual search performance in young and older adults.

PubMed

Bennett, Ilana J; Motes, Michael A; Rao, Neena K; Rypma, Bart

2012-02-01

Functional imaging research has identified frontoparietal attention networks involved in visual search, with mixed evidence regarding whether different networks are engaged when the search target differs from distracters by a single (elementary) versus multiple (conjunction) features. Neural correlates of visual search, and their potential dissociation, were examined here using integrity of white matter connecting the frontoparietal networks. The effect of aging on these brain-behavior relationships was also of interest. Younger and older adults performed a visual search task and underwent diffusion tensor imaging (DTI) to reconstruct 2 frontoparietal (superior and inferior longitudinal fasciculus; SLF and ILF) and 2 midline (genu, splenium) white matter tracts. As expected, results revealed age-related declines in conjunction, but not elementary, search performance; and in ILF and genu tract integrity. Importantly, integrity of the superior longitudinal fasciculus, ILF, and genu tracts predicted search performance (conjunction and elementary), with no significant age group differences in these relationships. Thus, integrity of white matter tracts connecting frontoparietal attention networks contributes to search performance in younger and older adults. Copyright © 2012 Elsevier Inc. All rights reserved.

A Brain Network Processing the Age of Faces

PubMed Central

Homola, György A.; Jbabdi, Saad; Beckmann, Christian F.; Bartsch, Andreas J.

2012-01-01

Age is one of the most salient aspects in faces and of fundamental cognitive and social relevance. Although face processing has been studied extensively, brain regions responsive to age have yet to be localized. Using evocative face morphs and fMRI, we segregate two areas extending beyond the previously established face-sensitive core network, centered on the inferior temporal sulci and angular gyri bilaterally, both of which process changes of facial age. By means of probabilistic tractography, we compare their patterns of functional activation and structural connectivity. The ventral portion of Wernicke's understudied perpendicular association fasciculus is shown to interconnect the two areas, and activation within these clusters is related to the probability of fiber connectivity between them. In addition, post-hoc age-rating competence is found to be associated with high response magnitudes in the left angular gyrus. Our results provide the first evidence that facial age has a distinct representation pattern in the posterior human brain. We propose that particular face-sensitive nodes interact with additional object-unselective quantification modules to obtain individual estimates of facial age. This brain network processing the age of faces differs from the cortical areas that have previously been linked to less developmental but instantly changeable face aspects. Our probabilistic method of associating activations with connectivity patterns reveals an exemplary link that can be used to further study, assess and quantify structure-function relationships. PMID:23185334

Properties and connections of cat fastigiospinal neurons.

PubMed

Wilson, V J; Uchino, Y; Maunz, R A; Susswein, A; Fukushima, K

1978-05-12

1. Neurons in the cat fastigial nucleus that project to the upper cervical spinal segments (fastigiospinal neurons) were fired by antidromic stimulation of the contralateral spinal cord. Dye ejection from the recording electrode was used to show that most neurons were in the rostral half of the fastigial nucleus. 2. Fastigiospinal neurons can be excited and/or inhibited by stimulation of forelimb and hindlimb nerves and by stimulation of the vestibular nerve. These inputs converge on many neurons. 3. Antidromic microstimulation was used to trace fastigiospinal axons to the vicinity of motor nuclei in in C2-C3. 4. The rostral fastigial nucleus was stimulated in preparations with the medial longitudinal fasciculus transected by a wide lesion that impinged on the medial reticular formation in the caudal medulla, to eliminate some potential axon reflexes. Short-latency EPSPs were recorded in some trapezius and biventer-cervicis motoneurons. In many cases there was little or no occlusion between these EPSPs and others evoked by stimulation of the vestibular nerve ipsilateral to the motoneurons. 5. Movement of the stimulating electrode and placement of this electrode lateral to the fastigial nucleus show that the zone from which low threshold EPSPs can be evoked is localized. 6. Latency measurements and lack of temporal facilitation with double shocks suggest that the EPSPs are monosynaptic. The evidence suggests that they are caused by fastigiospinal fibers terminating on motoneurons.

White matter hyperintensity burden and disability in older adults: is chronic pain a contributor?

PubMed

Buckalew, Neilly; Haut, Marc W; Aizenstein, Howard; Rosano, Caterina; Edelman, Kathryn Dunfee; Perera, Subashan; Marrow, Lisa; Tadic, Stasa; Venkatraman, Vijay; Weiner, Debra

2013-06-01

To primarily explore differences in global and regional white matter hyperintensities (WMH) in older adults with self-reported disabling and nondisabling chronic low back pain (CLBP) and to examine the association of WMH with gait speed in all participants with CLBP. To secondarily compare WMH of the participants with CLBP with the pain-free controls. A cross-sectional, case-control study. University of Pittsburgh. Twenty-four community-dwelling older adults: 8 with self-reported disabling CLBP, 8 with nondisabling CLBP, and 8 were pain-free. Exclusions were psychiatric or neurologic disorders (either central or peripheral), substance abuse, opioid use, or diabetes mellitus. All participants underwent structural brain magnetic resonance imaging, and all participants with CLBP underwent the 4-m walk test. All the participants were assessed for both global and regional WMH by using an automated localization and segmentation method, and gait speed of participants with CLBP. The disabled group demonstrated statistically significant regional WMH in a number of left hemispheric tracts: anterior thalamic radiation (P = .0391), lower cingulate (P = .0336), inferior longitudinal fasciculus (P = .0367), superior longitudinal fasciculus (P = .0011), and the superior longitudinal fasciculus branch to the temporal lobe (P = .0072). Also, there was a statistically significant negative association (rs = -0.57; P = .0225) between the left lower cingulate WMH and the gait speed in all the participants with CLBP. There was a statistical difference in global WMH burden (P = .0014) and nearly all regional tracts (both left and right hemispheres) when comparing CLBP with pain-free participants. Our findings suggest that WMH is associated with, and hence, may be accelerated by chronic pain manifesting as perceived disability, given the self-reported disabled CLBP patients had the greatest burden, and the pain free the least, and manifesting as measurable disability, given increasing WMH was associated with decreasing gait speed in all chronic pain participants. Copyright © 2013 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Projections of the nucleus of the optic tract to the nucleus reticularis tegmenti pontis and prepositus hypoglossi nucleus in the pigmented rat as demonstrated by anterograde and retrograde transport methods.

PubMed

Korp, B G; Blanks, R H; Torigoe, Y

1989-01-01

The visual pathways from the nucleus of the optic tract (NOT) to the nucleus reticularis tegmenti pontis (NRTP) and prepositus hypoglossi nucleus (ph) were studied following injections of tritiated leucine into the NOT of pigmented rats. The cell bodies of origin of the pretectal-NRTP, NRTP-ph, and pretectal-ph projections were determined using retrograde horseradish peroxidase (HRP) technique. The pretectum projects strongly to the rostral two-thirds of the central and pericentral subdivisions of the NRTP and sends a remarkably smaller projection to the ph. Both are entirely ipsilateral. The fibers destined for the ph travel with the NOT-NRTP bundle, pass through the NRTP, traverse the medial longitudinal fasciculus, and are distributed to the rostral one-half of the ph. The retrograde HRP studies confirm these pathways. The pretectal projections to the NRTP arise from neurons in the rostromedial NOT; those to the ph are located primarily in the rostral NOT although small numbers are found within the anterior, posterior, and olivary pretectal nuclei. Of major importance is the fact that the ph injections retrogradely label neurons within the NRTP and the adjacent paramedian pontine reticular formation. This NRTP-ph projection is entirely bilateral and arises from parts of both subdivisions of the nucleus targeted by NOT afferents. Both the direct NOT-ph and indirect NOT-NRTP-ph connections provide the anatomical basis for the relay of visual (optokinetic) information to the perihypoglossal complex and, presumably, by virtue of reciprocal ph-vestibular nuclear connections, to the vestibular nuclei itself. Such pathways confirm previous physiological studies in rat and, in particular, clarify the contrasting effects of electrolytic lesions of NRTP in rat which completely abolishes optokinetic nystagmus (OKN) (Cazin et al., 1980a) vs kainic acid lesions which produce only minor effects on OKN slow velocity (Hess et al., 1988). Given these differential effects, one concludes that the critical pathway for OKN passes in relation to, but is not significantly relayed by, the neurons of the NRTP or adjacent pontine tegmentum. The present studies suggest that one such fiber system is the NOT-ph bundle. How this relatively small projection compares to other possible fiber of passage systems remains to be determined electrophysiologically.

Reading Impairment in a Patient with Missing Arcuate Fasciculus

ERIC Educational Resources Information Center

Rauschecker, Andreas M.; Deutsch, Gayle K.; Ben-Shachar, Michal; Schwartzman, Armin; Perry, Lee M.; Dougherty, Robert F.

2009-01-01

We describe the case of a child ("S") who was treated with radiation therapy at age 5 for a recurrent malignant brain tumor. Radiation successfully abolished the tumor but caused radiation-induced tissue necrosis, primarily affecting cerebral white matter. "S" was introduced to us at age 15 because of her profound dyslexia. We assessed cognitive…

Executive deficits, not processing speed relates to abnormalities in distinct prefrontal tracts in amyotrophic lateral sclerosis.

PubMed

Pettit, Lewis D; Bastin, Mark E; Smith, Colin; Bak, Thomas H; Gillingwater, Thomas H; Abrahams, Sharon

2013-11-01

Cognitive impairment in amyotrophic lateral sclerosis is characterized by deficits on tests of executive function; however, the contribution of abnormal processing speed is unknown. Methods are confounded by tasks that depend on motor speed in patients with physical disability. Structural and functional magnetic resonance imaging studies have revealed multi-system cerebral involvement, with evidence of reduced white matter volume and integrity in predominant frontotemporal regions. The current study has two aims. First, to investigate whether cognitive impairments in amyotrophic lateral sclerosis are due to executive dysfunction or slowed processing speed using methodology that accommodates motor disability. This is achieved using a dual-task paradigm and tasks that manipulate stimulus presentation times and do not rely on response motor speed. Second, to identify relationships between specific cognitive impairments and the integrity of distinct white matter tracts. Thirty patients with amyotrophic lateral sclerosis and 30 age- and education-matched control subjects were administered an experimental dual-task procedure that combined a visual inspection time task and digit recall. In addition, measures of executive function (including letter fluency) and processing speed (visual inspection time and rapid serial letter identification) were administered. Integrity of white matter tracts was determined using region of interest analyses of diffusion tensor magnetic resonance imaging data. Patients with amyotrophic lateral sclerosis did not show impairments on tests of processing speed, but executive deficits were revealed once visual inspection time was combined with digit recall (dual-task) and in letter fluency. In addition to the corticospinal tracts, significant differences in fractional anisotropy and mean diffusivity were found between groups in a number of prefrontal and temporal white matter tracts including the anterior cingulate, anterior thalamic radiation, uncinate fasciculus and hippocampal portion of the cingulum bundles. Significant differences also emerged in the anterior corona radiata as well as in white matter underlying the superior, medial and inferior frontal gyri and the temporal gyri. Dual-task performance significantly correlated with fractional anisotropy measures in the middle frontal gyrus white matter and anterior corona radiata. Letter fluency indices significantly correlated with fractional anisotropy measures of the inferior frontal gyrus white matter and corpus callosum in addition to the corticospinal tracts and mean diffusivity measures in the white matter of the superior frontal gyrus. The current study demonstrates that cognitive impairment in amyotrophic lateral sclerosis is not due to generic slowing of processing speed. Moreover, different executive deficits are related to distinct prefrontal tract involvement in amyotrophic lateral sclerosis with dual-task impairment associating with dorsolateral prefrontal dysfunction and letter fluency showing greater dependence on inferolateral prefrontal dysfunction.

Distinct contributions of the fornix and inferior longitudinal fasciculus to episodic and semantic autobiographical memory.

PubMed

Hodgetts, Carl J; Postans, Mark; Warne, Naomi; Varnava, Alice; Lawrence, Andrew D; Graham, Kim S

2017-09-01

Autobiographical memory (AM) is multifaceted, incorporating the vivid retrieval of contextual detail (episodic AM), together with semantic knowledge that infuses meaning and coherence into past events (semantic AM). While neuropsychological evidence highlights a role for the hippocampus and anterior temporal lobe (ATL) in episodic and semantic AM, respectively, it is unclear whether these constitute dissociable large-scale AM networks. We used high angular resolution diffusion-weighted imaging and constrained spherical deconvolution-based tractography to assess white matter microstructure in 27 healthy young adult participants who were asked to recall past experiences using word cues. Inter-individual variation in the microstructure of the fornix (the main hippocampal input/output pathway) related to the amount of episodic, but not semantic, detail in AMs - independent of memory age. Conversely, microstructure of the inferior longitudinal fasciculus, linking occipitotemporal regions with ATL, correlated with semantic, but not episodic, AMs. Further, these significant correlations remained when controlling for hippocampal and ATL grey matter volume, respectively. This striking correlational double dissociation supports the view that distinct, large-scale distributed brain circuits underpin context and concepts in AM. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Frequency Mapping of Rat Spinal Cord at 7T

NASA Astrophysics Data System (ADS)

Chen, Evan; Rauscher, Alexander; Kozlowski, Piotr; Yung, Andrew

2012-10-01

The spinal cord is an integral part of the nervous system responsible for sensory, motor, and reflex control crucial to all bodily function. Due to its non-invasive nature, MRI is well matched for characterizing and imaging of spinal cord, and is used extensively for clinical applications. Recent developments in magnetic resonance imaging (MRI) at high field (7T) using phase represents a new approach of characterizing spinal cord myelin. Theory suggests that microstructure differences in myelinated white matter (WM) and non-myelinated gray matter (GM) affect MR phase, measurable frequency shifts. Data from pilot experiments using a multi-gradient echo (MGE) sequence to image rat spinal cords placed parallel to main magnetic field B0 has shown frequency shifts between not only between WM and GM, but also between specific WM tracts of the dorsal column, including the fasciculus gracilis, fasciculus cuneatus, and corticospinal tract. Using MGE, frequency maps at multiple echo times (TE) between 4ms and 22ms show a non-linear relationship between WM frequency, contrary to what was previously expected. These results demonstrate the effectiveness of MGE in revealing new information about spinal cord tissue microstructure, and lays important groundwork for in-vivo and human studies.

Language, aging, and cognition: frontal aslant tract and superior longitudinal fasciculus contribute toward working memory performance in older adults.

PubMed

Rizio, Avery A; Diaz, Michele T

2016-06-15

Previous research has documented change in white matter tract integrity with increasing age. Both interhemispheric and intrahemispheric tracts that underlie language processing are susceptible to these age-related changes. The aim of the current study was to explore age and white matter integrity in language-related tracts as predictors of cognitive task performance in younger and older adults. To this end, we carried out principal component analyses of white matter tracts and confirmatory factor analysis of neuropsychological measures. We next carried out a series of regression analyses that used white matter components to predict scores on each of the neuropsychological components. For both younger and older adults, age was a significant predictor of processing speed and working memory. However, white matter integrity did not contribute independently toward these models. In older adults only, both age and a white matter component that included the bilateral frontal aslant tract and left superior longitudinal fasciculus were significant predictors of working memory. Taken together, these results extend our understanding of the contributions of language-related white matter structure to cognitive processing and highlight the effects of age-related differences in both frontal and dorsal tracts.

Lifelong Bilingualism Contributes to Cognitive Reserve against White Matter Integrity Declines in Aging

PubMed Central

Gold, Brian T.; Johnson, Nathan F.; Powell, David K.

2013-01-01

Recent evidence suggests that lifelong bilingualism may contribute to cognitive reserve (CR) in normal aging. However, there is currently no neuroimaging evidence to suggest that lifelong bilinguals can retain normal cognitive functioning in the face of age-related neurodegeneration. Here we explored this issue by comparing white matter (WM) integrity and gray matter (GM) volumetric patterns of older adult lifelong bilinguals (N = 20) and monolinguals (N = 20). The groups were matched on a range of relevant cognitive test scores and on the established CR variables of education, socioeconomic status and intelligence. Participants underwent high-resolution structural imaging for assessment of GM volume and diffusion tensor imaging (DTI) for assessment of WM integrity. Results indicated significantly lower microstructural integrity in the bilingual group in several WM tracts. In particular, compared to their monolingual peers, the bilingual group showed lower fractional anisotropy and/or higher radial diffusivity in the inferior longitudinal fasciculus/inferior fronto-occipital fasciculus bilaterally, the fornix, and multiple portions of the corpus callosum. There were no group differences in GM volume. Our results suggest that lifelong bilingualism contributes to CR against WM integrity declines in aging. PMID:24103400

Analysis of alterations in white matter integrity of adult patients with comitant exotropia.

PubMed

Li, Dan; Li, Shenghong; Zeng, Xianjun

2018-05-01

Objective This study was performed to investigate structural abnormalities of the white matter in patients with comitant exotropia using the tract-based spatial statistics (TBSS) method. Methods Diffusion tensor imaging data from magnetic resonance images of the brain were collected from 20 patients with comitant exotropia and 20 age- and sex-matched healthy controls. The FMRIB Software Library was used to compute the diffusion measures, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD). These measures were obtained using voxel-wise statistics with threshold-free cluster enhancement. Results The FA values in the right inferior fronto-occipital fasciculus (IFO) and right inferior longitudinal fasciculus were significantly higher and the RD values in the bilateral IFO, forceps minor, left anterior corona radiata, and left anterior thalamic radiation were significantly lower in the comitant exotropia group than in the healthy controls. No significant differences in the MD or AD values were found between the two groups. Conclusions Alterations in FA and RD values may indicate the underlying neuropathologic mechanism of comitant exotropia. The TBSS method can be a useful tool to investigate neuronal tract participation in patients with this disease.

White matter microstructure and volitional motor activity in schizophrenia: A diffusion kurtosis imaging study.

PubMed

Docx, Lise; Emsell, Louise; Van Hecke, Wim; De Bondt, Timo; Parizel, Paul M; Sabbe, Bernard; Morrens, Manuel

2017-02-28

Avolition is a core feature of schizophrenia and may arise from altered brain connectivity. Here we used diffusion kurtosis imaging (DKI) to investigate the association between white matter (WM) microstructure and volitional motor activity. Multi-shell diffusion MRI and 24-h actigraphy data were obtained from 20 right-handed patients with schizophrenia and 16 right-handed age and gender matched healthy controls. We examined correlations between fractional anisotropy (FA), mean diffusivity (MD), mean kurtosis (MK), and motor activity level, as well as group differences in these measures. In the patient group, increasing motor activity level was positively correlated with MK in the inferior, medial and superior longitudinal fasciculus, the corpus callosum, the posterior fronto-occipital fasciculus and the posterior cingulum. This association was not found in control subjects or in DTI measures. These results show that a lack of volitional motor activity in schizophrenia is associated with potentially altered WM microstructure in posterior brain regions associated with cognitive function and motivation. This could reflect both illness related dysconnectivity which through altered cognition, manifests as reduced volitional motor activity, and/or the effects of reduced physical activity on brain WM. Copyright © 2016. Published by Elsevier B.V.

Neural systems for speech and song in autism

PubMed Central

Pantazatos, Spiro P.; Schneider, Harry

2012-01-01

Despite language disabilities in autism, music abilities are frequently preserved. Paradoxically, brain regions associated with these functions typically overlap, enabling investigation of neural organization supporting speech and song in autism. Neural systems sensitive to speech and song were compared in low-functioning autistic and age-matched control children using passive auditory stimulation during functional magnetic resonance and diffusion tensor imaging. Activation in left inferior frontal gyrus was reduced in autistic children relative to controls during speech stimulation, but was greater than controls during song stimulation. Functional connectivity for song relative to speech was also increased between left inferior frontal gyrus and superior temporal gyrus in autism, and large-scale connectivity showed increased frontal–posterior connections. Although fractional anisotropy of the left arcuate fasciculus was decreased in autistic children relative to controls, structural terminations of the arcuate fasciculus in inferior frontal gyrus were indistinguishable between autistic and control groups. Fractional anisotropy correlated with activity in left inferior frontal gyrus for both speech and song conditions. Together, these findings indicate that in autism, functional systems that process speech and song were more effectively engaged for song than for speech and projections of structural pathways associated with these functions were not distinguishable from controls. PMID:22298195

Spatial coherence of oriented white matter microstructure: Applications to white matter regions associated with genetic similarity.

PubMed

Hallgrímsson, Haraldur T; Cieslak, Matthew; Foschini, Luca; Grafton, Scott T; Singh, Ambuj K

2018-05-15

We present a method to discover differences between populations with respect to the spatial coherence of their oriented white matter microstructure in arbitrarily shaped white matter regions. This method is applied to diffusion MRI scans of a subset of the Human Connectome Project dataset: 57 pairs of monozygotic and 52 pairs of dizygotic twins. After controlling for morphological similarity between twins, we identify 3.7% of all white matter as being associated with genetic similarity (35.1 k voxels, p<10 -4 , false discovery rate 1.5%), 75% of which spatially clusters into twenty-two contiguous white matter regions. Furthermore, we show that the orientation similarity within these regions generalizes to a subset of 47 pairs of non-twin siblings, and show that these siblings are on average as similar as dizygotic twins. The regions are located in deep white matter including the superior longitudinal fasciculus, the optic radiations, the middle cerebellar peduncle, the corticospinal tract, and within the anterior temporal lobe, as well as the cerebellum, brain stem, and amygdalae. These results extend previous work using undirected fractional anisotrophy for measuring putative heritable influences in white matter. Our multidirectional extension better accounts for crossing fiber connections within voxels. This bottom up approach has at its basis a novel measurement of coherence within neighboring voxel dyads between subjects, and avoids some of the fundamental ambiguities encountered with tractographic approaches to white matter analysis that estimate global connectivity. Copyright © 2018 Elsevier Inc. All rights reserved.

[Functional neuro-navigation and intraoperative magnetic resonance imaging for the resection of gliomas involving eloquent language structures].

PubMed

Chen, Xiao-lei; Xu, Bai-nan; Wang, Fei; Meng, Xiang-hui; Zhang, Jun; Jiang, Jin-li; Yu, Xin-guang; Zhou, Ding-biao

2011-08-01

To explore the clinical value of functional neuro-navigation and high-field-strength intraoperative magnetic resonance imaging (iMRI) for the resection of intracerebral gliomas involving eloquent language structures. From April 2009 to April 2010, 48 patients with intracerebral gliomas involving eloquent language structures, were operated with functional neuro-navigation and iMRI. Blood oxygen level dependent functional MRI (BOLD-fMRI) was used to depict both Broca and Wernicke cortex, while diffusion tensor imaging (DTI) based fiber tracking was used to delineate arcuate fasciculus. The reconstructed language structures were integrated into a navigation system, so that intra-operative microscopic-based functional neuro-navigation could be achieved. iMRI was used to update the images for both language structures and residual tumors. All patients were evaluated for language function pre-operatively and post-operatively upon short-term and long-term follow-up. In all patients, functional neuro-navigation and iMRI were successfully achieved. In 38 cases (79.2%), gross total resection was accomplished, while in the rest 10 cases (20.8%), subtotal resection was achieved. Only 1 case (2.1%) developed long-term (more than 3 months) new language function deficits at post-operative follow-up. No peri-operative mortality was recorded. With functional neuro-navigation and iMRI, the eloquent structures for language can be precisely located, while the resection size can be accurately evaluated intra-operatively. This technique is safe and helpful for preservation of language function.

Age-Related Differences and Heritability of the Perisylvian Language Networks.

PubMed

Budisavljevic, Sanja; Dell'Acqua, Flavio; Rijsdijk, Frühling V; Kane, Fergus; Picchioni, Marco; McGuire, Philip; Toulopoulou, Timothea; Georgiades, Anna; Kalidindi, Sridevi; Kravariti, Eugenia; Murray, Robin M; Murphy, Declan G; Craig, Michael C; Catani, Marco

2015-09-16

Acquisition of language skills depends on the progressive maturation of specialized brain networks that are usually lateralized in adult population. However, how genetic and environmental factors relate to the age-related differences in lateralization of these language pathways is still not known. We recruited 101 healthy right-handed subjects aged 9-40 years to investigate age-related differences in the anatomy of perisylvian language pathways and 86 adult twins (52 monozygotic and 34 dizygotic) to understand how heritability factors influence language anatomy. Diffusion tractography was used to dissect and extract indirect volume measures from the three segments of the arcuate fasciculus connecting Wernicke's to Broca's region (i.e., long segment), Broca's to Geschwind's region (i.e., anterior segment), and Wernicke's to Geschwind's region (i.e., posterior segment). We found that the long and anterior arcuate segments are lateralized before adolescence and their lateralization remains stable throughout adolescence and early adulthood. Conversely, the posterior segment shows right lateralization in childhood but becomes progressively bilateral during adolescence, driven by a reduction in volume in the right hemisphere. Analysis of the twin sample showed that genetic and shared environmental factors influence the anatomy of those segments that lateralize earlier, whereas specific environmental effects drive the variability in the volume of the posterior segment that continues to change in adolescence and adulthood. Our results suggest that the age-related differences in the lateralization of the language perisylvian pathways are related to the relative contribution of genetic and environmental effects specific to each segment. Our study shows that, by early childhood, frontotemporal (long segment) and frontoparietal (anterior segment) connections of the arcuate fasciculus are left and right lateralized, respectively, and remain lateralized throughout adolescence and early adulthood. In contrast, temporoparietal (posterior segment) connections are right lateralized in childhood, but become progressively bilateral during adolescence. Preliminary twin analysis suggested that lateralization of the arcuate fasciculus is a heterogeneous process that depends on the interplay between genetic and environment factors specific to each segment. Tracts that exhibit higher age effects later in life (i.e., posterior segment) appear to be influenced more by specific environmental factors. Copyright © 2015 Budisavljevic et al.

Age-Related Differences and Heritability of the Perisylvian Language Networks

PubMed Central

Dell'Acqua, Flavio; Rijsdijk, Frühling V.; Kane, Fergus; Picchioni, Marco; McGuire, Philip; Toulopoulou, Timothea; Georgiades, Anna; Kalidindi, Sridevi; Kravariti, Eugenia; Murray, Robin M.; Murphy, Declan G.; Craig, Michael C.

2015-01-01

Acquisition of language skills depends on the progressive maturation of specialized brain networks that are usually lateralized in adult population. However, how genetic and environmental factors relate to the age-related differences in lateralization of these language pathways is still not known. We recruited 101 healthy right-handed subjects aged 9–40 years to investigate age-related differences in the anatomy of perisylvian language pathways and 86 adult twins (52 monozygotic and 34 dizygotic) to understand how heritability factors influence language anatomy. Diffusion tractography was used to dissect and extract indirect volume measures from the three segments of the arcuate fasciculus connecting Wernicke's to Broca's region (i.e., long segment), Broca's to Geschwind's region (i.e., anterior segment), and Wernicke's to Geschwind's region (i.e., posterior segment). We found that the long and anterior arcuate segments are lateralized before adolescence and their lateralization remains stable throughout adolescence and early adulthood. Conversely, the posterior segment shows right lateralization in childhood but becomes progressively bilateral during adolescence, driven by a reduction in volume in the right hemisphere. Analysis of the twin sample showed that genetic and shared environmental factors influence the anatomy of those segments that lateralize earlier, whereas specific environmental effects drive the variability in the volume of the posterior segment that continues to change in adolescence and adulthood. Our results suggest that the age-related differences in the lateralization of the language perisylvian pathways are related to the relative contribution of genetic and environmental effects specific to each segment. SIGNIFICANCE STATEMENT Our study shows that, by early childhood, frontotemporal (long segment) and frontoparietal (anterior segment) connections of the arcuate fasciculus are left and right lateralized, respectively, and remain lateralized throughout adolescence and early adulthood. In contrast, temporoparietal (posterior segment) connections are right lateralized in childhood, but become progressively bilateral during adolescence. Preliminary twin analysis suggested that lateralization of the arcuate fasciculus is a heterogeneous process that depends on the interplay between genetic and environment factors specific to each segment. Tracts that exhibit higher age effects later in life (i.e., posterior segment) appear to be influenced more by specific environmental factors. PMID:26377454

Distinct white matter injury associated with medial temporal lobe atrophy in Alzheimer's versus semantic dementia.

PubMed

Bejanin, Alexandre; Desgranges, Béatrice; La Joie, Renaud; Landeau, Brigitte; Perrotin, Audrey; Mézenge, Florence; Belliard, Serge; de La Sayette, Vincent; Eustache, Francis; Chételat, Gaël

2017-04-01

This study aims at further understanding the distinct vulnerability of brain networks in Alzheimer's disease (AD) versus semantic dementia (SD) investigating the white matter injury associated with medial temporal lobe (MTL) atrophy in both conditions. Twenty-six AD patients, twenty-one SD patients, and thirty-nine controls underwent a high-resolution T1-MRI scan allowing to obtain maps of grey matter volume and white matter density. A statistical conjunction approach was used to identify MTL regions showing grey matter atrophy in both patient groups. The relationship between this common grey matter atrophy and white matter density maps was then assessed within each patient group. Patterns of grey matter atrophy were distinct in AD and SD but included a common region in the MTL, encompassing the hippocampus and amygdala. This common atrophy was associated with alterations in different white matter areas in AD versus SD, mainly including the cingulum and corpus callosum in AD, while restricted to the temporal lobe - essentially the uncinate and inferior longitudinal fasciculi - in SD. Complementary analyses revealed that these relationships remained significant when controlling for global atrophy or disease severity. Overall, this study provides the first evidence that atrophy of the same MTL region is related to damage in distinct white matter fibers in AD and SD. These different patterns emphasize the vulnerability of distinct brain networks related to the MTL in these two disorders, which might underlie the discrepancy in their symptoms. These results further suggest differences between AD and SD in the neuropathological processes occurring in the MTL. Hum Brain Mapp 38:1791-1800, 2017. © 2017 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Recovery of injured arcuate fasciculus in the dominant hemisphere in a patient with an intracerebral hemorrhage.

PubMed

Jang, Sung Ho; Lee, Han Do

2014-12-01

This study reports on a patient with an intracerebral hemorrhage who showed recovery of an injured arcuate fasciculus (AF) in the dominant hemisphere, using follow-up diffusion tensor tractography. A 43-year-old right-handed man presented with severe aphasia and hemiparesis resulting from a spontaneous intracerebral hemorrhage in the left parietotemporal lobes. The patient showed severe aphasia at 1 month after onset, with an aphasia quotient of 5% on the Korean-Western Aphasia Battery. He underwent comprehensive rehabilitative therapy until 22 months after onset and his aphasia showed improvement, with an aphasia quotient of 58% on the Korean-Western Aphasia Battery. On 1-month diffusion tensor tractography, only the thin ascending part of the left AF from the Wernicke area remained. In contrast, on 16-month diffusion tensor tractography, the injured left AF was thickened and elongated to around the left Broca area; however, discontinuation of the left AF was observed around the left Broca area, and this continuation was elongated to the left Broca area on 22-month diffusion tensor tractography. This study reports on a patient who showed recovery from injury of the left AF along with improvement of aphasia. Recovery of the injured AF in the dominant hemisphere appears to be one of the mechanisms for recovery from aphasia.

Longitudinal changes in white matter microstructure after heavy cannabis use

PubMed Central

Becker, Mary P.; Collins, Paul F.; Lim, Kelvin O.; Muetzel, R.L.; Luciana, M.

2015-01-01

Diffusion tensor imaging (DTI) studies of cannabis users report alterations in brain white matter microstructure, primarily based on cross-sectional research, and etiology of the alterations remains unclear. We report findings from longitudinal voxelwise analyses of DTI data collected at baseline and at a 2-year follow-up on 23 young adult (18-20 years old at baseline) regular cannabis users and 23 age-, sex-, and IQ-matched non-using controls with limited substance use histories. Onset of cannabis use was prior to age 17. Cannabis users displayed reduced longitudinal growth in fractional anisotropy in the central and parietal regions of the right and left superior longitudinal fasciculus, in white matter adjacent to the left superior frontal gyrus, in the left corticospinal tract, and in the right anterior thalamic radiation lateral to the genu of the corpus callosum, along with less longitudinal reduction of radial diffusion in the right central/posterior superior longitudinal fasciculus, corticospinal tract, and posterior cingulum. Greater amounts of cannabis use were correlated with reduced longitudinal growth in FA as was relatively impaired performance on a measure of verbal learning. These findings suggest that continued heavy cannabis use during adolescence and young adulthood alters ongoing development of white matter microstructure, contributing to functional impairment. PMID:26602958

White matter abnormalities and their impact on attentional performance in adult attention-deficit/hyperactivity disorder.

PubMed

Konrad, Andreas; Dielentheis, Thomas F; El Masri, Dschamil; Dellani, Paulo R; Stoeter, Peter; Vucurevic, Goran; Winterer, Georg

2012-06-01

Inattention is the most important behavioral feature of adult patients with attention-deficit/hyperactivity disorder (ADHD). Neuroimaging studies in ADHD have demonstrated abnormalities primarily in the frontostriatal circuitry and were mostly conducted in children. We investigated white matter (WM) integrity in adult ADHD patients and the correlation of WM microstructure and neuropsychological parameters in 37 (21 men) never-medicated adult ADHD patients and 34 age- and gender-matched healthy controls. All subjects underwent clinical interviews, rating scales, and neuropsychological tests of attentional performance. Diffusion tensor imaging (DTI) was acquired, and 12 WM regions-of-interest (ROIs) within the attentional network were chosen. Group differences of mean fractional anisotropy (FA) and mean diffusivity (MD) values were calculated for each ROI, and patients' DTI measures were then correlated with measures of attentional performance. FA values in ADHD patients were significantly reduced in the left inferior longitudinal fasciculus (ILF), while MD values were significantly increased in ADHD patients in the frontal portion of the left frontooccipital fasciculus (IFO). In ADHD patients, MD values were negatively correlated with attentional performance in the left ILF. Our findings provide further support for disturbed frontostriatal structural connectivity and also point to an involvement of the left temporal white matter with an impact on attentional performance.

Sex differences in white matter development during adolescence: a DTI study.

PubMed

Wang, Yingying; Adamson, Chris; Yuan, Weihong; Altaye, Mekibib; Rajagopal, Akila; Byars, Anna W; Holland, Scott K

2012-10-10

Adolescence is a complex transitional period in human development, composing physical maturation, cognitive and social behavioral changes. The objective of this study is to investigate sex differences in white matter development and the associations between intelligence and white matter microstructure in the adolescent brain using diffusion tensor imaging (DTI) and tract-based spatial statistics (TBSS). In a cohort of 16 typically-developing adolescents aged 13 to 17 years, longitudinal DTI data were recorded from each subject at two time points that were one year apart. We used TBSS to analyze the diffusion indices including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD). Our results suggest that boys (13-18 years) continued to demonstrate white matter maturation, whereas girls appeared to reach mature levels earlier. In addition, we identified significant positive correlations between FA and full-scale intelligence quotient (IQ) in the right inferior fronto-occipital fasciculus when both sexes were looked at together. Only girls showed significant positive correlations between FA and verbal IQ in the left cortico-spinal tract and superior longitudinal fasciculus. The preliminary evidence presented in this study supports that boys and girls have different developmental trajectories in white matter microstructure. Copyright © 2012 Elsevier B.V. All rights reserved.

Comparison of 3 mm versus 4 mm rigid endoscope in diagnostic nasal endoscopy.

PubMed

Neel, Gregory S; Kau, Ryan L; Bansberg, Stephen F; Lal, Devyani

2017-03-01

Compare nasal endoscopy with 3 mm versus conventional 4 mm rigid 30° endoscopes for visualization, patient comfort, and examiner ease. Ten adults with no previous sinus surgery underwent bilateral nasal endoscopy with both 4 mm and 3 mm endoscopes (resulting in 20 paired nasal endoscopies). Visualization, patient discomfort and examiner's difficulty were assessed with every endoscopy. Sino-nasal structures were checked on a list if visualized satisfactorily. Patients rated discomfort on a standardized numerical pain scale (0-10). Examiners rated difficulty of examination on a scale of 1-5 (1 = easiest). Visualization with 3 mm endoscope was superior for the sphenoid ostium ( P  = 0.002), superior turbinate ( P  = 0.007), spheno-ethmoid recess ( P  = 0.006), uncinate process ( P  = 0.002), cribriform area ( P  = 0.007), and Valve of Hasner ( P  = 0.002). Patient discomfort was not significantly different for 3 mm vs. 4 mm endoscopes but correlated with the examiners' assessment of difficulty ( r  = 0.73). The examiner rated endoscopy with 4 mm endoscopes more difficult ( P  = 0.027). The 3 mm endoscope was superior in visualizing the sphenoid ostium, superior turbinate, spheno-ethmoid recess, uncinate process, cribriform plate, and valve of Hasner. It therefore may be useful in assessment of spheno-ethmoid recess, nasolacrimal duct, and cribriform area pathologies. Overall, patients tolerated nasal endoscopy well. Though patient discomfort was not significantly different between the endoscopes, most discomfort with 3 mm endoscopes was noted while examining structures difficult to visualize with the 4 mm endoscope. Patients' discomfort correlated with the examiner's assessment of difficulty.

Mild Traumatic Brain Injury and Conduction Aphasia from a Close Proximity Blast Resulting in Arcuate Fasciculus Damage Diagnosed on DTI Tractography

DTIC Science & Technology

2009-11-01

communication which are described below as conduction aphasia and neurogenic stuttering secondary to the aphasia. Also, his family felt that his personality... stuttering , and “mumbling” speech. In continued evaluation, estimated premorbid intellectual ability was at least in the average range. Speech...language production resulted in mild neurogenic stuttering . There was also some evidence of visuoconstructional dysfunction. In addition there was

Microstructure of frontoparietal connections predicts individual resistance to sleep deprivation.

PubMed

Cui, Jiaolong; Tkachenko, Olga; Gogel, Hannah; Kipman, Maia; Preer, Lily A; Weber, Mareen; Divatia, Shreya C; Demers, Lauren A; Olson, Elizabeth A; Buchholz, Jennifer L; Bark, John S; Rosso, Isabelle M; Rauch, Scott L; Killgore, William D S

2015-02-01

Sleep deprivation (SD) can degrade cognitive functioning, but growing evidence suggests that there are large individual differences in the vulnerability to this effect. Some evidence suggests that baseline differences in the responsiveness of a fronto-parietal attention system that is activated during working memory (WM) tasks may be associated with the ability to sustain vigilance during sleep deprivation. However, the neurocircuitry underlying this network remains virtually unexplored. In this study, we employed diffusion tensor imaging (DTI) to investigate the association between the microstructure of the axonal pathway connecting the frontal and parietal regions--i.e., the superior longitudinal fasciculus (SLF)--and individual resistance to SD. Thirty healthy participants (15 males) aged 20-43 years underwent functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) at rested wakefulness prior to a 28-hour period of SD. Task-related fronto-parietal fMRI activation clusters during a Sternberg WM Task were localized and used as seed regions for probabilistic fiber tractography. DTI metrics, including fractional anisotropy, mean diffusivity, axial and radial diffusivity were measured in the SLF. The psychomotor vigilance test (PVT) was used to evaluate resistance to SD. We found that activation in the left inferior parietal lobule (IPL) and dorsolateral prefrontal cortex (DLPFC) positively correlated with resistance. Higher fractional anisotropy of the left SLF comprising the primary axons connecting IPL and DLPFC was also associated with better resistance. These findings suggest that individual differences in resistance to SD are associated with the functional responsiveness of a fronto-parietal attention system and the microstructural properties of the axonal interconnections. Copyright © 2014 Elsevier Inc. All rights reserved.

Diffusion abnormalities in adolescents and young adults with a history of heavy cannabis use.

PubMed

Ashtari, Manzar; Cervellione, Kelly; Cottone, John; Ardekani, Babak A; Sevy, Serge; Kumra, Sanjiv

2009-01-01

There is growing evidence that adolescence is a key period for neuronal maturation. Despite the high prevalence of marijuana use among adolescents and young adults in the United States and internationally, very little is known about its impact on the developing brain. Based on neuroimaging literature on normal brain developmental during adolescence, we hypothesized that individuals with heavy cannabis use (HCU) would have brain structure abnormalities in similar brain regions that undergo development during late adolescence, particularly the fronto-temporal connection. Fourteen young adult males in residential treatment for cannabis dependence and 14 age-matched healthy male control subjects were recruited. Patients had a history of HCU throughout adolescence; 5 had concurrent alcohol abuse. Subjects underwent structural and diffusion tensor magnetic resonance imaging. White matter integrity was compared between subject groups using voxelwise and fiber tractography analysis. Voxelwise and tractography analyses revealed that adolescents with HCU had reduced fractional anisotropy, increased radial diffusivity, and increased trace in the homologous areas known to be involved in ongoing development during late adolescence, particularly in the fronto-temporal connection via arcuate fasciculus. Our results support the hypothesis that heavy cannabis use during adolescence may affect the trajectory of normal brain maturation. Due to concurrent alcohol consumption in five HCU subjects, conclusions from this study should be considered preliminary, as the DTI findings reported here may be reflective of the combination of alcohol and marijuana use. Further research in larger samples, longitudinal in nature, and controlling for alcohol consumption is needed to better understand the pathophysiology of the effect of cannabis on the developing brain.

Plasticity of left perisylvian white-matter tracts is associated with individual differences in math learning.

PubMed

Jolles, Dietsje; Wassermann, Demian; Chokhani, Ritika; Richardson, Jennifer; Tenison, Caitlin; Bammer, Roland; Fuchs, Lynn; Supekar, Kaustubh; Menon, Vinod

2016-04-01

Plasticity of white matter tracts is thought to be essential for cognitive development and academic skill acquisition in children. However, a dearth of high-quality diffusion tensor imaging (DTI) data measuring longitudinal changes with learning, as well as methodological difficulties in multi-time point tract identification have limited our ability to investigate plasticity of specific white matter tracts. Here, we examine learning-related changes of white matter tracts innervating inferior parietal, prefrontal and temporal regions following an intense 2-month math tutoring program. DTI data were acquired from 18 third grade children, both before and after tutoring. A novel fiber tracking algorithm based on a White Matter Query Language (WMQL) was used to identify three sections of the superior longitudinal fasciculus (SLF) linking frontal and parietal (SLF-FP), parietal and temporal (SLF-PT) and frontal and temporal (SLF-FT) cortices, from which we created child-specific probabilistic maps. The SLF-FP, SLF-FT, and SLF-PT tracts identified with the WMQL method were highly reliable across the two time points and showed close correspondence to tracts previously described in adults. Notably, individual differences in behavioral gains after 2 months of tutoring were specifically correlated with plasticity in the left SLF-FT tract. Our results extend previous findings of individual differences in white matter integrity, and provide important new insights into white matter plasticity related to math learning in childhood. More generally, our quantitative approach will be useful for future studies examining longitudinal changes in white matter integrity associated with cognitive skill development.

Right hemisphere structures predict poststroke speech fluency.

PubMed

Pani, Ethan; Zheng, Xin; Wang, Jasmine; Norton, Andrea; Schlaug, Gottfried

2016-04-26

We sought to determine via a cross-sectional study the contribution of (1) the right hemisphere's speech-relevant white matter regions and (2) interhemispheric connectivity to speech fluency in the chronic phase of left hemisphere stroke with aphasia. Fractional anisotropy (FA) of white matter regions underlying the right middle temporal gyrus (MTG), precentral gyrus (PreCG), pars opercularis (IFGop) and triangularis (IFGtri) of the inferior frontal gyrus, and the corpus callosum (CC) was correlated with speech fluency measures. A region within the superior parietal lobule (SPL) was examined as a control. FA values of regions that significantly predicted speech measures were compared with FA values from healthy age- and sex-matched controls. FA values for the right MTG, PreCG, and IFGop significantly predicted speech fluency, but FA values of the IFGtri and SPL did not. A multiple regression showed that combining FA of the significant right hemisphere regions with the lesion load of the left arcuate fasciculus-a previously identified biomarker of poststroke speech fluency-provided the best model for predicting speech fluency. FA of CC fibers connecting left and right supplementary motor areas (SMA) was also correlated with speech fluency. FA of the right IFGop and PreCG was significantly higher in patients than controls, while FA of a whole CC region of interest (ROI) and the CC-SMA ROI was significantly lower in patients. Right hemisphere white matter integrity is related to speech fluency measures in patients with chronic aphasia. This may indicate premorbid anatomical variability beneficial for recovery or be the result of poststroke remodeling. © 2016 American Academy of Neurology.

Image Registration to Compensate for EPI Distortion in Patients with Brain Tumors: An Evaluation of Tract-Specific Effects.

PubMed

Albi, Angela; Meola, Antonio; Zhang, Fan; Kahali, Pegah; Rigolo, Laura; Tax, Chantal M W; Ciris, Pelin Aksit; Essayed, Walid I; Unadkat, Prashin; Norton, Isaiah; Rathi, Yogesh; Olubiyi, Olutayo; Golby, Alexandra J; O'Donnell, Lauren J

2018-03-01

Diffusion magnetic resonance imaging (dMRI) provides preoperative maps of neurosurgical patients' white matter tracts, but these maps suffer from echo-planar imaging (EPI) distortions caused by magnetic field inhomogeneities. In clinical neurosurgical planning, these distortions are generally not corrected and thus contribute to the uncertainty of fiber tracking. Multiple image processing pipelines have been proposed for image-registration-based EPI distortion correction in healthy subjects. In this article, we perform the first comparison of such pipelines in neurosurgical patient data. Five pipelines were tested in a retrospective clinical dMRI dataset of 9 patients with brain tumors. Pipelines differed in the choice of fixed and moving images and the similarity metric for image registration. Distortions were measured in two important tracts for neurosurgery, the arcuate fasciculus and corticospinal tracts. Significant differences in distortion estimates were found across processing pipelines. The most successful pipeline used dMRI baseline and T2-weighted images as inputs for distortion correction. This pipeline gave the most consistent distortion estimates across image resolutions and brain hemispheres. Quantitative results of mean tract distortions on the order of 1-2 mm are in line with other recent studies, supporting the potential need for distortion correction in neurosurgical planning. Novel results include significantly higher distortion estimates in the tumor hemisphere and greater effect of image resolution choice on results in the tumor hemisphere. Overall, this study demonstrates possible pitfalls and indicates that care should be taken when implementing EPI distortion correction in clinical settings. Copyright © 2018 by the American Society of Neuroimaging.

Shared neuroanatomical substrates of impaired phonological working memory across reading disability and autism

PubMed Central

Lu, Chunming; Qi, Zhenghan; Harris, Adrianne; Weil, Lisa Wisman; Han, Michelle; Halverson, Kelly; Perrachione, Tyler K.; Kjelgaard, Margaret; Wexler, Kenneth; Tager-Flusberg, Helen; Gabrieli, John D. E.

2015-01-01

Background Individuals with reading disability or individuals with autism spectrum disorder (ASD) are characterized, respectively, by their difficulties in reading or social communication, but both groups often have impaired phonological working memory (PWM). It is not known whether the impaired PWM reflects distinct or shared neuroanatomical abnormalities in these two diagnostic groups. Methods White-matter structural connectivity via diffusion weighted imaging was examined in sixty-four children, ages 5-17 years, with reading disability, ASD, or typical development (TD), who were matched in age, gender, intelligence, and diffusion data quality. Results Children with reading disability and children with ASD exhibited reduced PWM compared to children with TD. The two diagnostic groups showed altered white-matter microstructure in the temporo-parietal portion of the left arcuate fasciculus (AF) and in the temporo-occipital portion of the right inferior longitudinal fasciculus (ILF), as indexed by reduced fractional anisotropy and increased radial diffusivity. Moreover, the structural integrity of the right ILF was positively correlated with PWM ability in the two diagnostic groups, but not in the TD group. Conclusions These findings suggest that impaired PWM is transdiagnostically associated with shared neuroanatomical abnormalities in ASD and reading disability. Microstructural characteristics in left AF and right ILF may play important roles in the development of PWM. The right ILF may support a compensatory mechanism for children with impaired PWM. PMID:26949750

Shared neuroanatomical substrates of impaired phonological working memory across reading disability and autism.

PubMed

Lu, Chunming; Qi, Zhenghan; Harris, Adrianne; Weil, Lisa Wisman; Han, Michelle; Halverson, Kelly; Perrachione, Tyler K; Kjelgaard, Margaret; Wexler, Kenneth; Tager-Flusberg, Helen; Gabrieli, John D E

2016-03-01

Individuals with reading disability or individuals with autism spectrum disorder (ASD) are characterized, respectively, by their difficulties in reading or social communication, but both groups often have impaired phonological working memory (PWM). It is not known whether the impaired PWM reflects distinct or shared neuroanatomical abnormalities in these two diagnostic groups. White-matter structural connectivity via diffusion weighted imaging was examined in sixty-four children, ages 5-17 years, with reading disability, ASD, or typical development (TD), who were matched in age, gender, intelligence, and diffusion data quality. Children with reading disability and children with ASD exhibited reduced PWM compared to children with TD. The two diagnostic groups showed altered white-matter microstructure in the temporo-parietal portion of the left arcuate fasciculus (AF) and in the temporo-occipital portion of the right inferior longitudinal fasciculus (ILF), as indexed by reduced fractional anisotropy and increased radial diffusivity. Moreover, the structural integrity of the right ILF was positively correlated with PWM ability in the two diagnostic groups, but not in the TD group. These findings suggest that impaired PWM is transdiagnostically associated with shared neuroanatomical abnormalities in ASD and reading disability. Microstructural characteristics in left AF and right ILF may play important roles in the development of PWM. The right ILF may support a compensatory mechanism for children with impaired PWM.

White matter abnormalities in major depressive disorder with melancholic and atypical features: A diffusion tensor imaging study.

PubMed

Ota, Miho; Noda, Takamasa; Sato, Noriko; Hattori, Kotaro; Hori, Hiroaki; Sasayama, Daimei; Teraishi, Toshiya; Nagashima, Anna; Obu, Satoko; Higuchi, Teruhiko; Kunugi, Hiroshi

2015-06-01

The DSM-IV recognizes some subtypes of major depressive disorder (MDD). It is known that the effectiveness of antidepressants differs among the MDD subtypes, and thus the differentiation of the subtypes is important. However, little is known as to structural brain changes in MDD with atypical features (aMDD) in comparison with MDD with melancholic features (mMDD), which prompted us to examine possible differences in white matter integrity assessed with diffusion tensor imaging (DTI) between these two subtypes. Subjects were 21 patients with mMDD, 24 with aMDD, and 37 age- and sex-matched healthy volunteers whose DTI data were obtained by 1.5 tesla magnetic resonance imaging. We compared fractional anisotropy and mean diffusivity value derived from DTI data on a voxel-by-voxel basis among the two diagnostic groups and healthy subjects. There were significant decreases of fractional anisotropy and increases of mean diffusivity in patients with MDD compared with healthy subjects in the corpus callosum, inferior fronto-occipital fasciculus, and left superior longitudinal fasciculus. However, we detected no significant difference in any brain region between mMDD and aMDD. Our results suggest that patients with MDD had reduced white matter integrity in some regions; however, there was no major difference between aMDD and mMDD. © 2014 The Authors. Psychiatry and Clinical Neurosciences © 2014 Japanese Society of Psychiatry and Neurology.

White matter injury induced by diabetes in acute stroke is clinically relevant: A preliminary study.

PubMed

Yu, Xinfeng; Song, Ruirui; Jiaerken, Yerfan; Yuan, Lixia; Huang, Peiyu; Lou, Min; Jiang, Quan; Zhang, Minming

2017-01-01

The importance of white matter injury induced by diabetes in stroke severity and prognosis is largely unknown. We aimed to investigate the relationship between diabetes-related white matter injury beyond stroke lesions with acute neurological deficits and clinical outcome after stroke. In total, 36 stroke patients within 3-7 days after onset were enrolled. Neurological deficits on admission were assessed by National Institute of Health Stroke Score, and poor outcome at 3 months was defined as modified Rankin score >2. White matter tracts were compared between patients with diabetic and non-diabetic stroke using fractional anisotropy from diffusion tensor imaging. Regional white matter abnormality with decreased fractional anisotropy was observed in diabetic patients (n = 18) when compared to non-diabetic patients (n = 18). Decreased fractional anisotropy in ipsilesional distal corticospinal tract was independently associated with higher National Institute of Health Stroke Score motor component score (β = -0.444, p = 0.005), and decreased fractional anisotropy in contralesional superior longitudinal fasciculus I was independently related to poor outcome (odds ratio, 0.900; p = 0.033). Our findings suggested that only white matter injury induced by diabetes in specific tracts like corticospinal tract and superior longitudinal fasciculus beyond stroke lesions has clinically relevant, providing insight into the mechanism of stroke recovery under the diabetic condition. © The Author(s) 2016.

Lateralization of the arcuate fasciculus and its differential correlation with reading ability between young learners and experienced readers: a diffusion tensor tractography study in a Chinese cohort.

PubMed

Qiu, Deqiang; Tan, Li-Hai; Siok, Wai-Ting; Zhou, Ke; Khong, Pek-Lan

2011-12-01

As Chinese reading engages a different neural network from alphabetic language reading, we investigate whether leftward lateralization of the arcuate fasciculus (AF), as observed in the Western population, is also present in the Chinese population and if it does, whether it is associated with better reading ability. Diffusion tensor tractography analysis on 75 Chinese subjects of three age groups (first graders, fourth graders, and college students) showed that 70-83% of them had leftward lateralization of the AF. The pattern of lateralization did not differ significantly among the three groups, suggesting that lateralization of the AF is formed at an early age and before one enters first grade. Among the first graders, who had just started to learn to read, subjects with strongly leftward lateralized AF scored significantly higher than those with other defined lateralization patterns in Chinese (P = 0.001) and English (P = 0.036) reading tasks. This association was not observed among the fourth graders and college students who were experienced Chinese readers. Among the fourth graders, females were found to obtain significantly higher Chinese (P = 0.033) and English reading scores than males (P = 0.002). Our study suggests a differential effect of leftward lateralization of the AF on reading ability at different stages of reading development in the Chinese population. Copyright © 2011 Wiley Periodicals, Inc.

Autoradiographic labeling of the cholinergic habenulo-interpeduncular projection.

PubMed

Villani, L; Contestabile, A; Fonnum, F

1983-12-11

The transmitter-specific autoradiographic method has been used to retrogradely trace the habenulo-interpeduncular cholinergic projection. [3H]Choline injection in the interpeduncular nucleus resulted in remarkable labeling of the fasciculus retroflexus and in very strong accumulation of silver grains in the medial habenula. Brainstem nuclei sending non-cholinergic projections to the interpeduncular nucleus were not labeled. The present findings strongly support the notion of a cholinergic medial habenula-interpeduncular nucleus projection in agreement with recent immunohistochemical evidence, but in contrast to previous immunocytochemical and pharmacohistochemical results.

Solitary chemosensory cells and bitter taste receptor signaling in human sinonasal mucosa.

PubMed

Barham, Henry P; Cooper, Sarah E; Anderson, Catherine B; Tizzano, Marco; Kingdom, Todd T; Finger, Tom E; Kinnamon, Sue C; Ramakrishnan, Vijay R

2013-06-01

Solitary chemosensory cells (SCCs) are specialized cells in the respiratory epithelium that respond to noxious chemicals including bacterial signaling molecules. SCCs express components of bitter taste transduction including the taste receptor type 2 (TAS2R) bitter taste receptors and downstream signaling effectors: α-Gustducin, phospholipase Cβ2 (PLCβ2), and transient receptor potential cation channel subfamily M member 5 (TRPM5). When activated, SCCs evoke neurogenic reflexes, resulting in local inflammation. The purpose of this study was to test for the presence SCCs in human sinonasal epithelium, and to test for a correlation with inflammatory disease processes such as allergic rhinitis and chronic rhinosinusitis. Patient demographics and biopsies of human sinonasal mucosa were obtained from control patients (n = 7) and those with allergic rhinitis and/or chronic rhinosinusitis (n = 15). Reverse transcription polymerase chain reaction (RT-PCR), quantitative PCR (qPCR), and immunohistochemistry were used to determine whether expression of signaling effectors was altered in diseased patients. RT-PCR demonstrated that bitter taste receptors TAS2R4, TAS2R14, and TAS2R46, and downstream signaling effectors α-Gustducin, PLCβ2, and TRPM5 are expressed in the inferior turbinate, middle turbinate, septum, and uncinate of both control and diseased patients. PLCβ2/TRPM5-immunoreactive SCCs were identified in the sinonasal mucosa of both control and diseased patients. qPCR showed similar expression of α-Gustducin and TRPM5 in the uncinate process of control and diseased groups, and there was no correlation between level of expression and 22-item Sino-Nasal Outcomes Test (SNOT-22) or pain scores. SCCs are present in human sinonasal mucosa in functionally relevant areas. Expression level of signaling effectors was similar in control and diseased patients and did not correlate with measures of pain and inflammation. Further study into these pathways may provide insight into nasal inflammatory diseases and may offer potential therapeutic targets. © 2013 ARS-AAOA, LLC.

Structural modifications of the brain in acclimatization to high-altitude.

PubMed

Zhang, Jiaxing; Yan, Xiaodan; Shi, Jinfu; Gong, Qiyong; Weng, Xuchu; Liu, Yijun

2010-07-06

Adaptive changes in respiratory and cardiovascular responses at high altitude (HA) have been well clarified. However, the central mechanisms underlying HA acclimatization remain unclear. Using voxel-based morphometry (VBM) and diffusion tensor imaging (DTI) with fractional anisotropy (FA) calculation, we investigated 28 Han immigrant residents (17-22 yr) born and raised at HA of 2616-4200 m in Qinghai-Tibetan Plateau for at least 17 years and who currently attended college at sea-level (SL). Their family migrated from SL to HA 2-3 generations ago and has resided at HA ever since. Control subjects were matched SL residents. HA residents (vs. SL) showed decreased grey matter volume in the bilateral anterior insula, right anterior cingulate cortex, bilateral prefrontal cortex, left precentral cortex, and right lingual cortex. HA residents (vs. SL) had significantly higher FA mainly in the bilateral anterior limb of internal capsule, bilateral superior and inferior longitudinal fasciculus, corpus callosum, bilateral superior corona radiata, bilateral anterior external capsule, right posterior cingulum, and right corticospinal tract. Higher FA values in those regions were associated with decreased or unchanged radial diffusivity coinciding with no change of longitudinal diffusivity in HA vs. SL group. Conversely, HA residents had lower FA in the left optic radiation and left superior longitudinal fasciculus. Our data demonstrates that HA acclimatization is associated with brain structural modifications, including the loss of regional cortical grey matter accompanied by changes in the white matter, which may underlie the physiological adaptation of residents at HA.

Aerobic Exercise Intervention Alters Executive Function and White Matter Integrity in Deaf Children: A Randomized Controlled Study

PubMed Central

Xiong, Xuan; Zhu, Li-Na; Dong, Xiao-xiao; Wang, Wei; Yan, Jun

2018-01-01

This study examined the effects of an 11-week aerobic exercise intervention on executive function (EF) and white matter integrity (WMI). In total, 28 deaf children (aged 9–13 years) were randomly assigned to either an 11-week exercise intervention or the control group. All the children had behavioral assessment and diffusion tensor imaging prior to and following the exercise intervention. The behavioral performance results demonstrated that EF was enhanced by exercise. Relative to the control group, WMI of the exercise intervention group showed (1) lower fractional anisotropy (FA) in the pontine crossing tract (PCT) and right cingulum (hippocampus) (CH), genu of the corpus callosum (gCC), right inferior cerebellar peduncle (ICP), left superior corona radiata (SCR), and left superior frontooccipital fasciculus (SFOF); (2) higher mean diffusivity (MD) in the gCC, right CH, right inferior frontooccipital fasciculus (IFOF), and left anterior limb of the internal capsule (ALIC); and (3) lower MD in the left ICP and left tapetum (TAP). Furthermore, the lower FA in gCC showed a significant negative correlation with improvement in behavioral performance, but the correlation was not significant after FDR correction. These results suggest that exercise can effectively improve deaf children's EF and reshape the WMI in deaf children. The improved EF by exercise is not related to a reshaping of WMI, but more studies on the relationship between EF and WMI by exercise may be needed. PMID:29853843

Gestures, vocalizations, and memory in language origins.

PubMed

Aboitiz, Francisco

2012-01-01

THIS ARTICLE DISCUSSES THE POSSIBLE HOMOLOGIES BETWEEN THE HUMAN LANGUAGE NETWORKS AND COMPARABLE AUDITORY PROJECTION SYSTEMS IN THE MACAQUE BRAIN, IN AN ATTEMPT TO RECONCILE TWO EXISTING VIEWS ON LANGUAGE EVOLUTION: one that emphasizes hand control and gestures, and the other that emphasizes auditory-vocal mechanisms. The capacity for language is based on relatively well defined neural substrates whose rudiments have been traced in the non-human primate brain. At its core, this circuit constitutes an auditory-vocal sensorimotor circuit with two main components, a "ventral pathway" connecting anterior auditory regions with anterior ventrolateral prefrontal areas, and a "dorsal pathway" connecting auditory areas with parietal areas and with posterior ventrolateral prefrontal areas via the arcuate fasciculus and the superior longitudinal fasciculus. In humans, the dorsal circuit is especially important for phonological processing and phonological working memory, capacities that are critical for language acquisition and for complex syntax processing. In the macaque, the homolog of the dorsal circuit overlaps with an inferior parietal-premotor network for hand and gesture selection that is under voluntary control, while vocalizations are largely fixed and involuntary. The recruitment of the dorsal component for vocalization behavior in the human lineage, together with a direct cortical control of the subcortical vocalizing system, are proposed to represent a fundamental innovation in human evolution, generating an inflection point that permitted the explosion of vocal language and human communication. In this context, vocal communication and gesturing have a common history in primate communication.

Spinal cord magnetic resonance imaging demonstrates sensory neuronal involvement and clinical severity in neuronopathy associated with Sjögren's syndrome

PubMed Central

Mori, K; Koike, H; Misu, K; Hattori, N; Ichimura, M; Sobue, G

2001-01-01

OBJECTIVES—To determine spinal cord MRI findings in neuronopathy associated with Sjögren's syndrome and their correlation with severity of sensory impairment.
METHODS—Clinical and electrophysiological features, pathological findings in the sural nerve, and hyperintensity on T2* weighted MRI in the spinal dorsal columns were evaluated in 14 patients with neuronopathy associated with Sjögren's syndrome.
RESULTS—Of 14 patients, 12 showed high intensity by T2* weighted MRI in the posterior columns of the cervical cord. High intensity areas were seen in both the fasciculus cuneatus and gracilis in nine patients, who showed severe and widespread sensory deficits in the limbs and trunk; these patients also had a high frequency of autonomic symptoms. Somatosensory evoked potentials often could not be elicited. Hyperintensity restricted to the fasciculus gracilis was seen in three patients, who showed sensory deficits restricted to lower limbs without trunk involvement, or with only partial limb involvement; no autonomic symptoms were noted. The two patients who did not show high intensity areas in the dorsal columns showed restricted sensory involvement in the limbs. All patients showed axonal loss predominantly affecting large fibres, without axonal sprouting.
CONCLUSIONS—High intensity areas on T2* weighted MRI in the spinal dorsal columns reflect the degree of sensory neuronal involvement in neuronopathy associated with Sjögren's syndrome; this finding could also be a helpful marker for estimating severity of this neuronopathy.

 PMID:11561032

Right is not always wrong: DTI and fMRI evidence for the reliance of reading comprehension on language-comprehension networks in the right hemisphere.

PubMed

Horowitz-Kraus, Tzipi; Grainger, Molly; DiFrancesco, Mark; Vannest, Jennifer; Holland, Scott K

2015-03-01

The Simple View theory suggests that reading comprehension relies on automatic recognition of words combined with language comprehension. The goal of the current study was to examine the structural and functional connectivity in networks supporting reading comprehension and their relationship with language comprehension within 7-9 year old children using Diffusion Tensor Imaging (DTI) and fMRI during a Sentence Picture Matching task. Fractional Anisotropy (FA) values in the left and right Inferior Longitudinal Fasciculus (ILF) and Superior Longitudinal Fasciculus (SLF), known language-related tracts, were correlated from DTI data with scores from the Woodcock-Johnson III (WJ-III) Passage Comprehension sub-test. Brodmann areas most proximal to white-matter regions with significant correlation to Passage Comprehension scores were chosen as Regions-of-Interest (ROIs) and used as seeds in a functional connectivity analysis using the Sentence Picture Matching task. The correlation between percentile scores for the WJ-III Passage Comprehension subtest and the FA values in the right and left ILF and SLF indicated positive correlation in language-related ROIs, with greater distribution in the right hemisphere, which in turn showed strong connectivity in the fMRI data from the Sentence Picture Matching task. These results support the participation of the right hemisphere in reading comprehension and may provide physiologic support for a distinction between different types of reading comprehension deficits vs difficulties in technical reading.

Joint source based morphometry identifies linked gray and white matter group differences.

PubMed

Xu, Lai; Pearlson, Godfrey; Calhoun, Vince D

2009-02-01

We present a multivariate approach called joint source based morphometry (jSBM), to identify linked gray and white matter regions which differ between groups. In jSBM, joint independent component analysis (jICA) is used to decompose preprocessed gray and white matter images into joint sources and statistical analysis is used to determine the significant joint sources showing group differences and their relationship to other variables of interest (e.g. age or sex). The identified joint sources are groupings of linked gray and white matter regions with common covariation among subjects. In this study, we first provide a simulation to validate the jSBM approach. To illustrate our method on real data, jSBM is then applied to structural magnetic resonance imaging (sMRI) data obtained from 120 chronic schizophrenia patients and 120 healthy controls to identify group differences. JSBM identified four joint sources as significantly associated with schizophrenia. Linked gray-white matter regions identified in each of the joint sources included: 1) temporal--corpus callosum, 2) occipital/frontal--inferior fronto-occipital fasciculus, 3) frontal/parietal/occipital/temporal--superior longitudinal fasciculus and 4) parietal/frontal--thalamus. Age effects on all four joint sources were significant, but sex effects were significant only for the third joint source. Our findings demonstrate that jSBM can exploit the natural linkage between gray and white matter by incorporating them into a unified framework. This approach is applicable to a wide variety of problems to study linked gray and white matter group differences.

White matter microstructural alterations in clinically isolated syndrome and multiple sclerosis.

PubMed

Huang, Jing; Liu, Yaou; Zhao, Tengda; Shu, Ni; Duan, Yunyun; Ren, Zhuoqiong; Sun, Zheng; Liu, Zheng; Chen, Hai; Dong, Huiqing; Li, Kuncheng

2018-07-01

This study aims to determine whether and how diffusion alteration occurs in the earliest stage of multiple sclerosis (MS) and the differences in diffusion metrics between CIS and MS by using the tract-based spatial statistics (TBSS) method based on diffusion tensor imaging (DTI). Thirty-six CIS patients (mean age ± SD: 34.0 years ± 12.6), 36 relapsing-remitting multiple sclerosis (RRMS) patients (mean age ± SD: 35.0 years ± 9.4) and 36 age- and gender-matched normal controls (NCs) were included in this study. Voxel-wise analyses were performed with TBSS using multiple diffusion metrics, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (λ 1 ) and radial diffusivity (λ 23 ). In the CIS patients, TBSS analyses revealed diffusion alterations in a few white matter (WM) regions including the anterior thalamic radiation, corticospinal tract, inferior fronto-occipital fasciculus, superior longitudinal fasciculus, body and splenium of the corpus callosum, internal capsule, external capsule, and cerebral peduncle. MS patients showed more widespread diffusion changes (decreased FA, increased λ 1 , λ 23 and MD) than CIS. Exploratory analyses also revealed the possible associations between WM diffusion metrics and clinical variables (Expanded Disability Status Scale and disease duration) in the patients. This study provided imaging evidence for DTI abnormalities in CIS and MS and suggested that DTI can improve our knowledge of the path physiology of CIS and MS and clinical progression. Copyright © 2018 Elsevier Ltd. All rights reserved.

Combined DTI Tractography and Functional MRI Study of the Language Connectome in Healthy Volunteers: Extensive Mapping of White Matter Fascicles and Cortical Activations.

PubMed

Vassal, François; Schneider, Fabien; Boutet, Claire; Jean, Betty; Sontheimer, Anna; Lemaire, Jean-Jacques

2016-01-01

Despite a better understanding of brain language organization into large-scale cortical networks, the underlying white matter (WM) connectivity is still not mastered. Here we combined diffusion tensor imaging (DTI) fiber tracking (FT) and language functional magnetic resonance imaging (fMRI) in twenty healthy subjects to gain new insights into the macroscopic structural connectivity of language. Eight putative WM fascicles for language were probed using a deterministic DTI-FT technique: the arcuate fascicle (AF), superior longitudinal fascicle (SLF), uncinate fascicle (UF), temporo-occipital fascicle, inferior fronto-occipital fascicle (IFOF), middle longitudinal fascicle (MdLF), frontal aslant fascicle and operculopremotor fascicle. Specific measurements (i.e. volume, length, fractional anisotropy) and precise cortical terminations were derived for each WM fascicle within both hemispheres. Connections between these WM fascicles and fMRI activations were studied to determine which WM fascicles are related to language. WM fascicle volumes showed asymmetries: leftward for the AF, temporoparietal segment of SLF and UF, and rightward for the frontoparietal segment of the SLF. The lateralization of the AF, IFOF and MdLF extended to differences in patterns of anatomical connections, which may relate to specific hemispheric abilities. The leftward asymmetry of the AF was correlated to the leftward asymmetry of fMRI activations, suggesting that the lateralization of the AF is a structural substrate of hemispheric language dominance. We found consistent connections between fMRI activations and terminations of the eight WM fascicles, providing a detailed description of the language connectome. WM fascicle terminations were also observed beyond fMRI-confirmed language areas and reached numerous cortical areas involved in different functional brain networks. These findings suggest that the reported WM fascicles are not exclusively involved in language and might be related to other cognitive functions such as visual recognition, spatial attention, executive functions, memory, and processing of emotional and behavioral aspects.

The brain anatomy of attention-deficit/hyperactivity disorder in young adults - a magnetic resonance imaging study.

PubMed

Gehricke, Jean-G; Kruggel, Frithjof; Thampipop, Tanyaporn; Alejo, Sharina Dyan; Tatos, Erik; Fallon, James; Muftuler, L Tugan

2017-01-01

This is one of the first studies to examine the structural brain anatomy and connectivity associated with an ADHD diagnosis and child as well as adult ADHD symptoms in young adults. It was hypothesized that an adult ADHD diagnosis and in particular childhood symptoms, are associated with widespread changes in the brain macro- and microstructure, which can be used to develop a morphometric biomarker for ADHD. Voxel-wise linear regression models were used to examine structural and diffusion-weighted MRI data in 72 participants (31 young adults with ADHD and 41 controls without ADHD) in relation to diagnosis and the number of self-reported child and adult symptoms. Findings revealed significant associations between ADHD diagnosis and widespread changes to the maturation of white matter fiber bundles and gray matter density in the brain, such as structural shape changes (incomplete maturation) of the middle and superior temporal gyrus, and fronto-basal portions of both frontal lobes. ADHD symptoms in childhood showed the strongest association with brain macro- and microstructural abnormalities. At the brain circuitry level, the superior longitudinal fasciculus (SLF) and cortico-limbic areas are dysfunctional in individuals with ADHD. The morphometric findings predicted an ADHD diagnosis correctly up to 83% of all cases. An adult ADHD diagnosis and in particular childhood symptoms are associated with widespread micro- and macrostructural changes. The SLF and cortico-limbic findings suggest complex audio-visual, motivational, and emotional dysfunctions associated with ADHD in young adults. The sensitivity of the morphometric findings in predicting an ADHD diagnosis was sufficient, which indicates that MRI-based assessments are a promising strategy for the development of a biomarker.

An autopsy case of minamata disease (methylmercury poisoning)--pathological viewpoints of peripheral nerves.

PubMed

Eto, Komyo; Tokunaga, Hidehiro; Nagashima, Kazuo; Takeuchi, Tadao

2002-01-01

The outbreak of methylmercury poisoning in the geographic areas around Minamata Bay, Kumamoto, Japan in the 1950s has become known as Minamata disease. Based on earlier reports and extensive pathological studies on autopsied cases at the Kumamoto University School of Medicine, destructive lesions in the anterior portion of the calcarine cortex and depletion predominantly of granular cells in the cerebellar cortex came to be recognized as the hallmark and diagnostic yardstick of methylmercury poisoning in humans. As the number of autopsy cases of Minamata disease increased, it became apparent that the cerebral lesion was not restricted to the calcarine cortex but was relatively widespread. Less severe lesions, believed to be responsible for the motor symptoms of Minamata patients, were often found in the precentral, postcentral, and lateral temporal cortices. These patients also frequently presented with signs of sensory neuropathy affecting the distal extremities. Because of few sufficiently comprehensive studies, peripheral nerve degeneration has not been universally accepted as a cause of the sensory disturbances in Minamata patients. The present paper describes both biopsy and autopsy findings of the peripheral nerves in a male fisherman who died at the age of 64 years and showed the characteristic central nervous system lesions of Minamata disease at autopsy. A sural nerve biopsy with electron microscopy performed 1 month prior to his death showed endoneurial fibrosis and regenerated myelin sheaths. At autopsy the dorsal roots and sural nerve showed endoneurial fibrosis, loss of nerve fibers, and presence of Büngner's bands. The spinal cord showed Wallerian degeneration of the fasciculus gracilis (Goll's tract) with relative preservation of neurons in sensory ganglia. These findings support the contention that there is peripheral nerve degeneration in Minamata patients due to toxic injury from methylmercury.

Unique white matter microstructural patterns in ADHD presentations-a diffusion tensor imaging study.

PubMed

Svatkova, Alena; Nestrasil, Igor; Rudser, Kyle; Goldenring Fine, Jodene; Bledsoe, Jesse; Semrud-Clikeman, Margaret

2016-09-01

Attention-deficit/hyperactivity disorder predominantly inattentive (ADHD-PI) and combined (ADHD-C) presentations are likely distinct disorders that differ neuroanatomically, neurochemically, and neuropsychologically. However, to date, little is known about specific white matter (WM) regions differentiating ADHD presentations. This study examined differences in WM microstructure using diffusion tensor imaging (DTI) data from 20 ADHD-PI, 18 ADHD-C, and 27 typically developed children. Voxel-wise analysis of DTI measurements in major fiber bundles was carried out using tract-based spatial statistics (TBSS). Clusters showing diffusivity abnormalities were used as regions of interest for regression analysis between fractional anisotropy (FA) and neuropsychological outcomes. Compared to neurotypicals, ADHD-PI children showed higher FA in the anterior thalamic radiations (ATR), bilateral inferior longitudinal fasciculus (ILF), and in the left corticospinal tract (CST). In contrast, the ADHD-C group exhibited higher FA in the bilateral cingulum bundle (CB). In the ADHD-PI group, differences in FA in the left ILF and ATR were accompanied by axial diffusivity (AD) abnormalities. In addition, the ADHD-PI group exhibited atypical mean diffusivity in the forceps minor (FMi) and left ATR and AD differences in right CB compared to healthy subjects. Direct comparison between ADHD presentations demonstrated radial diffusivity differences in FMi. WM clusters with FA irregularities in ADHD were associated with neurobehavioral performance across groups. In conclusion, differences in WM microstructure in ADHD presentations strengthen the theory that ADHD-PI and ADHD-C are two distinct disorders. Regions with WM irregularity seen in both ADHD presentations might serve as predictors of executive and behavioral functioning across groups. Hum Brain Mapp 37:3323-3336, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

White matter microstructural abnormalities in girls with chromosome 22q11.2 deletion syndrome, Fragile X or Turner syndrome as evidenced by diffusion tensor imaging

PubMed Central

Villalon, Julio; Jahanshad, Neda; Beaton, Elliott; Toga, Arthur W.; Thompson, Paul M.; Simon, Tony J.

2014-01-01

Children with chromosome 22q11.2 Deletion Syndrome (22q11.2DS), Fragile X Syndrome (FXS), or Turner Syndrome (TS) are considered to belong to distinct genetic groups, as each disorder is caused by separate genetic alterations. Even so, they have similar cognitive and behavioral dysfunctions, particularly in visuospatial and numerical abilities. To assess evidence for common underlying neural microstructural alterations, we set out to determine whether these groups have partially overlapping white matter abnormalities, relative to typically developing controls. We scanned 101 female children between 7 and 14 years old: 25 with 22q11.2DS, 18 with FXS, 17 with TS, and 41 aged-matched controls using diffusion tensor imaging (DTI). Anisotropy and diffusivity measures were calculated and all brain scans were nonlinearly aligned to population and site-specific templates. We performed voxel-based statistical comparisons of the DTI-derived metrics between each disease group and the controls, while adjusting for age. Girls with 22q11.2DS showed lower fractional anisotropy (FA) than controls in the association fibers of the superior and inferior longitudinal fasciculi, the splenium of the corpus callosum, and the corticospinal tract. FA was abnormally lower in girls with FXS in the posterior limbs of the internal capsule, posterior thalami, and precentral gyrus. Girls with TS had lower FA in the inferior longitudinal fasciculus, right internal capsule and left cerebellar peduncle. Partially overlapping neurodevelopmental anomalies were detected in all three neurogenetic disorders. Altered white matter integrity in the superior and inferior longitudinal fasciculi and thalamic to frontal tracts may contribute to the behavioral characteristics of all of these disorders. PMID:23602925

Serum S100B Protein is Specifically Related to White Matter Changes in Schizophrenia

PubMed Central

Milleit, Berko; Smesny, Stefan; Rothermundt, Matthias; Preul, Christoph; Schroeter, Matthias L.; von Eiff, Christof; Ponath, Gerald; Milleit, Christine; Sauer, Heinrich; Gaser, Christian

2016-01-01

Background: Schizophrenia can be conceptualized as a form of dysconnectivity between brain regions.To investigate the neurobiological foundation of dysconnectivity, one approach is to analyze white matter structures, such as the pathology of fiber tracks. S100B is considered a marker protein for glial cells, in particular oligodendrocytes and astroglia, that passes the blood brain barrier and is detectable in peripheral blood. Earlier Studies have consistently reported increased S100B levels in schizophrenia. In this study, we aim to investigate associations between S100B and structural white matter abnormalities. Methods: We analyzed data of 17 unmedicated schizophrenic patients (first and recurrent episode) and 22 controls. We used voxel based morphometry (VBM) to detect group differences of white matter structures as obtained from T1-weighted MR-images and considered S100B serum levels as a regressor in an age-corrected interaction analysis. Results: S100B was increased in both patient subgroups. Using VBM, we found clusters indicating significant differences of the association between S100B concentration and white matter. Involved anatomical structures are the posterior cingulate bundle and temporal white matter structures assigned to the superior longitudinal fasciculus. Conclusions: S100B-associated alterations of white matter are shown to be existent already at time of first manifestation of psychosis and are distinct from findings in recurrent episode patients. This suggests involvement of S100B in an ongoing and dynamic process associated with structural brain changes in schizophrenia. However, it remains elusive whether increased S100B serum concentrations in psychotic patients represent a protective response to a continuous pathogenic process or if elevated S100B levels are actively involved in promoting structural brain damage. PMID:27013967

The nucleus of the optic tract (NOT) and the dorsal terminal nucleus (DTN) of opossums (Didelphis marsupialis aurita).

PubMed

Vargas, C D; Volchan, E; Nasi, J P; Bernardes, R F; Rocha-Miranda, C E

1996-01-01

Wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) was injected unilaterally into the pretectocollicular region of opossums (Didelphis marsupialis aurita), primarily to investigate the existence of a commissural subcortical pathway but also to reveal afferents and efferents of the nucleus of the optic tract (NOT) and dorsal terminal nucleus (DTN) in this species. Labelled cells and terminals were observed in the contralateral NOT-DTN. Furthermore, HRP was injected bilaterally in the region of the inferior olive (IO) to verify if the distribution of labelled cells in the NOT-DTN overlapped the region of commissural labelled cells. The two subpopulations of retrogradely labelled cells coincided, being distributed within the retinal terminal field attributed to the NOT-DTN, as revealed by contralateral eye injections of HRP. The commissural cells were located slightly more ventral than the olivary cells in the optic tract. The pretectocollicular WGA-HRP injections also labelled cells and terminals bilaterally in the lateral terminal nucleus (LTN), interstitial nucleus of the superior fasciculus, posterior fibers (INSFp), ventral lateral geniculate nucleus (vLGN), and superior colliculus (SC) and ipsilaterally in the medial terminal nucleus (MTN). In addition, further caudally, labelled cells and terminals were observed bilaterally in the nuclei prepositus hypoglossi (PH) and in the medial (MVN) and lateral (LVN) vestibular nuclei. Labelled terminals were found in the ipsilateral nucleus reticularis tegmenti pontis (NRTP) and in the IO with ipsilateral predominance. This study allowed an anatomical delimitation of the NOT-DTN in this opossum species, as defined by the olivary and commissural subpopulations, as well as a hodological evaluation of this region. The existence of some common anatomical aspects with other mammalian species is discussed.

The brain anatomy of attention-deficit/hyperactivity disorder in young adults – a magnetic resonance imaging study

PubMed Central

Kruggel, Frithjof; Thampipop, Tanyaporn; Alejo, Sharina Dyan; Tatos, Erik; Fallon, James; Muftuler, L. Tugan

2017-01-01

Background This is one of the first studies to examine the structural brain anatomy and connectivity associated with an ADHD diagnosis and child as well as adult ADHD symptoms in young adults. It was hypothesized that an adult ADHD diagnosis and in particular childhood symptoms, are associated with widespread changes in the brain macro- and microstructure, which can be used to develop a morphometric biomarker for ADHD. Methods Voxel-wise linear regression models were used to examine structural and diffusion-weighted MRI data in 72 participants (31 young adults with ADHD and 41 controls without ADHD) in relation to diagnosis and the number of self-reported child and adult symptoms. Results Findings revealed significant associations between ADHD diagnosis and widespread changes to the maturation of white matter fiber bundles and gray matter density in the brain, such as structural shape changes (incomplete maturation) of the middle and superior temporal gyrus, and fronto-basal portions of both frontal lobes. ADHD symptoms in childhood showed the strongest association with brain macro- and microstructural abnormalities. At the brain circuitry level, the superior longitudinal fasciculus (SLF) and cortico-limbic areas are dysfunctional in individuals with ADHD. The morphometric findings predicted an ADHD diagnosis correctly up to 83% of all cases. Conclusion An adult ADHD diagnosis and in particular childhood symptoms are associated with widespread micro- and macrostructural changes. The SLF and cortico-limbic findings suggest complex audio-visual, motivational, and emotional dysfunctions associated with ADHD in young adults. The sensitivity of the morphometric findings in predicting an ADHD diagnosis was sufficient, which indicates that MRI-based assessments are a promising strategy for the development of a biomarker. PMID:28406942

Regional vulnerability of longitudinal cortical association connectivity: Associated with structural network topology alterations in preterm children with cerebral palsy.

PubMed

Ceschin, Rafael; Lee, Vince K; Schmithorst, Vince; Panigrahy, Ashok

2015-01-01

Preterm born children with spastic diplegia type of cerebral palsy and white matter injury or periventricular leukomalacia (PVL), are known to have motor, visual and cognitive impairments. Most diffusion tensor imaging (DTI) studies performed in this group have demonstrated widespread abnormalities using averaged deterministic tractography and voxel-based DTI measurements. Little is known about structural network correlates of white matter topography and reorganization in preterm cerebral palsy, despite the availability of new therapies and the need for brain imaging biomarkers. Here, we combined novel post-processing methodology of probabilistic tractography data in this preterm cohort to improve spatial and regional delineation of longitudinal cortical association tract abnormalities using an along-tract approach, and compared these data to structural DTI cortical network topology analysis. DTI images were acquired on 16 preterm children with cerebral palsy (mean age 5.6 ± 4) and 75 healthy controls (mean age 5.7 ± 3.4). Despite mean tract analysis, Tract-Based Spatial Statistics (TBSS) and voxel-based morphometry (VBM) demonstrating diffusely reduced fractional anisotropy (FA) reduction in all white matter tracts, the along-tract analysis improved the detection of regional tract vulnerability. The along-tract map-structural network topology correlates revealed two associations: (1) reduced regional posterior-anterior gradient in FA of the longitudinal visual cortical association tracts (inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, optic radiation, posterior thalamic radiation) correlated with reduced posterior-anterior gradient of intra-regional (nodal efficiency) metrics with relative sparing of frontal and temporal regions; and (2) reduced regional FA within frontal-thalamic-striatal white matter pathways (anterior limb/anterior thalamic radiation, superior longitudinal fasciculus and cortical spinal tract) correlated with alteration in eigenvector centrality, clustering coefficient (inter-regional) and participation co-efficient (inter-modular) alterations of frontal-striatal and fronto-limbic nodes suggesting re-organization of these pathways. Both along tract and structural topology network measurements correlated strongly with motor and visual clinical outcome scores. This study shows the value of combining along-tract analysis and structural network topology in depicting not only selective parietal occipital regional vulnerability but also reorganization of frontal-striatal and frontal-limbic pathways in preterm children with cerebral palsy. These finding also support the concept that widespread, but selective posterior-anterior neural network connectivity alterations in preterm children with cerebral palsy likely contribute to the pathogenesis of neurosensory and cognitive impairment in this group.

A migratory mantle plume on Venus: Implications for Earth?

USGS Publications Warehouse

Chapman, M.G.; Kirk, R.L.

1996-01-01

A spatially fixed or at least internally rigid hotspot reference frame has been assumed for determining relative plate motions on Earth. Recent 1:5,000,000 scale mapping of Venus, a planet without terrestrial-style plate tectonics and ocean cover, reveals a systematic age and dimensional progression of corona-like arachnoids occurring in an uncinate chain. The nonrandom associations between arachnoids indicate they likely formed from a deep-seated mantle plume in a manner similar to terrestrial hotspot features. However, absence of expected convergent "plate" margin deformation suggests that the arachnoids are the surface expression of a migratory mantle plume beneath a stationary surface. If mantle plumes are not stationary on Venus, what if any are the implications for Earth?

Leonardo da Vinci and Kethem-Kiveris vena.

PubMed

Dolezal, Antonín; Skorepova-Honzlova, Zita; Jelen, Karel

2012-01-01

In the drawing of coitus by Leonardo da Vinci are pictured the contemporary hypotheses regarding this act. The authors analyze the mamillaruteral connection depicted by the artist and grow up to believe that this is a hypothetical kiveris vena, female vein described by Anatomist Master Nicolai Physicus from the Salerno School. The Hebrew roots were found in the name. The connection is described also by Mondino in The Anathomia. The same connection can be found in the picture of the pregnant woman in Fasciculus Medicinæ by Johannes De Ketham.

Investigating Musical Disorders with Diffusion Tensor Imaging: a Comparison of Imaging Parameters

PubMed Central

Loui, Psyche; Schlaug, Gottfried

2009-01-01

The Arcuate Fasciculus (AF) is a bundle of white matter traditionally thought to be responsible for language function. However, its role in music is not known. Here we investigate the connectivity of the AF using Diffusion Tensor Imaging (DTI) and show that musically tone-deaf individuals, who show impairments in pitch discrimination, have reduced connectivity in the AF relative to musically normal-functioning control subjects. Results were robust to variations in imaging parameters and emphasize the importance of brain connectivity in para-linguistic processes such as music. PMID:19673766

Structural Variability within Frontoparietal Networks and Individual Differences in Attentional Functions: An Approach Using the Theory of Visual Attention.

PubMed

Chechlacz, Magdalena; Gillebert, Celine R; Vangkilde, Signe A; Petersen, Anders; Humphreys, Glyn W

2015-07-29

Visuospatial attention allows us to select and act upon a subset of behaviorally relevant visual stimuli while ignoring distraction. Bundesen's theory of visual attention (TVA) (Bundesen, 1990) offers a quantitative analysis of the different facets of attention within a unitary model and provides a powerful analytic framework for understanding individual differences in attentional functions. Visuospatial attention is contingent upon large networks, distributed across both hemispheres, consisting of several cortical areas interconnected by long-association frontoparietal pathways, including three branches of the superior longitudinal fasciculus (SLF I-III) and the inferior fronto-occipital fasciculus (IFOF). Here we examine whether structural variability within human frontoparietal networks mediates differences in attention abilities as assessed by the TVA. Structural measures were based on spherical deconvolution and tractography-derived indices of tract volume and hindrance-modulated orientational anisotropy (HMOA). Individual differences in visual short-term memory (VSTM) were linked to variability in the microstructure (HMOA) of SLF II, SLF III, and IFOF within the right hemisphere. Moreover, VSTM and speed of information processing were linked to hemispheric lateralization within the IFOF. Differences in spatial bias were mediated by both variability in microstructure and volume of the right SLF II. Our data indicate that the microstructural and macrostrucutral organization of white matter pathways differentially contributes to both the anatomical lateralization of frontoparietal attentional networks and to individual differences in attentional functions. We conclude that individual differences in VSTM capacity, processing speed, and spatial bias, as assessed by TVA, link to variability in structural organization within frontoparietal pathways. Copyright © 2015 Chechlacz et al.

Differential susceptibility of white matter tracts to inflammatory mediators in schizophrenia: an integrated DTI study.

PubMed

Prasad, Konasale M; Upton, Catherine H; Nimgaonkar, Vishwajit L; Keshavan, Matcheri S

2015-01-01

The pathophysiological underpinnings of impaired anatomical and functional connectivity are not precisely known. Emerging data suggest that immune mediators may underlie such dysconnectivity. We examined anatomical brain connections using diffusion tensor imaging (DTI) data in relation to interleukin-6 (IL-6) and C-reactive protein (CRP) levels among early-course clinically stable schizophrenia subjects compared to healthy controls (HC). DTI data were acquired in 30 directions with 2 averages. Fractional anisotropy (FA) and radial diffusivity (RD) maps were separately processed using FSL4.1.9 and Tract-Based Spatial Statistics (TBSS). Threshold free cluster enhancements (TFCE) were examined employing familywise error (FWE) corrections for multiple testing within linear regression models including age, sex and socioeconomic status as covariates. IL-6 and CRP were assayed using highly sensitive and specific sandwich immunosorbent assays. The groups did not differ in age and sex as well as in the IL-6 and CRP levels. IL-6 levels were negatively correlated with the FA and positively correlated with RD among schizophrenia subjects but not HC. The voxel clusters that showed significant correlations were localized to the forceps major, the inferior longitudinal fasciculus and the inferior fronto-occipital fasciculus. CRP levels showed similar pattern except for lack of correlation with RD on any cluster that corresponded to the forceps major. Our results suggest that the IL-6 and CRP contribute to impaired anisotropy of water diffusion in selected pathways that have been previously associated with schizophrenia suggesting differential susceptibility of selected neural pathways to immune mediators. Copyright © 2014 Elsevier B.V. All rights reserved.

Reduced Volume of the Arcuate Fasciculus in Adults with High-Functioning Autism Spectrum Conditions

PubMed Central

Moseley, Rachel L.; Correia, Marta M.; Baron-Cohen, Simon; Shtyrov, Yury; Pulvermüller, Friedemann; Mohr, Bettina

2016-01-01

Atypical language is a fundamental feature of autism spectrum conditions (ASC), but few studies have examined the structural integrity of the arcuate fasciculus, the major white matter tract connecting frontal and temporal language regions, which is usually implicated as the main transfer route used in processing linguistic information by the brain. Abnormalities in the arcuate have been reported in young children with ASC, mostly in low-functioning or non-verbal individuals, but little is known regarding the structural properties of the arcuate in adults with ASC or, in particular, in individuals with ASC who have intact language, such as those with high-functioning autism or Asperger syndrome. We used probabilistic tractography of diffusion-weighted imaging to isolate and scrutinize the arcuate in a mixed-gender sample of 18 high-functioning adults with ASC (17 Asperger syndrome) and 14 age- and IQ-matched typically developing controls. Arcuate volume was significantly reduced bilaterally with clearest differences in the right hemisphere. This finding remained significant in an analysis of all male participants alone. Volumetric reduction in the arcuate was significantly correlated with the severity of autistic symptoms as measured by the Autism-Spectrum Quotient. These data reveal that structural differences are present even in high-functioning adults with ASC, who presented with no clinically manifest language deficits and had no reported developmental language delay. Arcuate structural integrity may be useful as an index of ASC severity and thus as a predictor and biomarker for ASC. Implications for future research are discussed. PMID:27242478

Disrupted white matter connectivity underlying developmental dyslexia: A machine learning approach.

PubMed

Cui, Zaixu; Xia, Zhichao; Su, Mengmeng; Shu, Hua; Gong, Gaolang

2016-04-01

Developmental dyslexia has been hypothesized to result from multiple causes and exhibit multiple manifestations, implying a distributed multidimensional effect on human brain. The disruption of specific white-matter (WM) tracts/regions has been observed in dyslexic children. However, it remains unknown if developmental dyslexia affects the human brain WM in a multidimensional manner. Being a natural tool for evaluating this hypothesis, the multivariate machine learning approach was applied in this study to compare 28 school-aged dyslexic children with 33 age-matched controls. Structural magnetic resonance imaging (MRI) and diffusion tensor imaging were acquired to extract five multitype WM features at a regional level: white matter volume, fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity. A linear support vector machine (LSVM) classifier achieved an accuracy of 83.61% using these MRI features to distinguish dyslexic children from controls. Notably, the most discriminative features that contributed to the classification were primarily associated with WM regions within the putative reading network/system (e.g., the superior longitudinal fasciculus, inferior fronto-occipital fasciculus, thalamocortical projections, and corpus callosum), the limbic system (e.g., the cingulum and fornix), and the motor system (e.g., the cerebellar peduncle, corona radiata, and corticospinal tract). These results were well replicated using a logistic regression classifier. These findings provided direct evidence supporting a multidimensional effect of developmental dyslexia on WM connectivity of human brain, and highlighted the involvement of WM tracts/regions beyond the well-recognized reading system in dyslexia. Finally, the discriminating results demonstrated a potential of WM neuroimaging features as imaging markers for identifying dyslexic individuals. © 2016 Wiley Periodicals, Inc.

Frontotemporal neural systems supporting semantic processing in Alzheimer's disease.

PubMed

Peelle, Jonathan E; Powers, John; Cook, Philip A; Smith, Edward E; Grossman, Murray

2014-03-01

We hypothesized that semantic memory for object concepts involves both representations of visual feature knowledge in modality-specific association cortex and heteromodal regions that are important for integrating and organizing this semantic knowledge so that it can be used in a flexible, contextually appropriate manner. We examined this hypothesis in an fMRI study of mild Alzheimer's disease (AD). Participants were presented with pairs of printed words and asked whether the words matched on a given visual-perceptual feature (e.g., guitar, violin: SHAPE). The stimuli probed natural kinds and manufactured objects, and the judgments involved shape or color. We found activation of bilateral ventral temporal cortex and left dorsolateral prefrontal cortex during semantic judgments, with AD patients showing less activation of these regions than healthy seniors. Moreover, AD patients showed less ventral temporal activation than did healthy seniors for manufactured objects, but not for natural kinds. We also used diffusion-weighted MRI of white matter to examine fractional anisotropy (FA). Patients with AD showed significantly reduced FA in the superior longitudinal fasciculus and inferior frontal-occipital fasciculus, which carry projections linking temporal and frontal regions of this semantic network. Our results are consistent with the hypothesis that semantic memory is supported in part by a large-scale neural network involving modality-specific association cortex, heteromodal association cortex, and projections between these regions. The semantic deficit in AD thus arises from gray matter disease that affects the representation of feature knowledge and processing its content, as well as white matter disease that interrupts the integrated functioning of this large-scale network.

Reading skill-fractional anisotropy relationships in visuospatial tracts diverge depending on socioeconomic status.

PubMed

Gullick, Margaret M; Demir-Lira, Özlem Ece; Booth, James R

2016-07-01

Low socioeconomic status (SES) has been repeatedly linked with decreased academic achievement, including lower reading outcomes. Some lower SES children do show skills and scores commensurate with those of their higher SES peers, but whether their abilities stem from the same systems as high SES children or are based on divergent strategies is unknown. We here investigated a potential interactive relationship between SES and real-word reading skill in the white matter in 42 typically developing children. SES was determined based on parental education; reading skill and age were not significantly related to SES. There was a significant neural interaction: Clusters in the bilateral inferior longitudinal fasciculus (ILF), left superior longitudinal fasciculus, and left corticospinal tract demonstrated interactive skill-SES relationships in fractional anisotropy. Follow-up analyses demonstrated that higher SES children showed a positive relationship between fractional anisotropy, reflecting tract coherence, and reading skill in left hemisphere tract clusters, whereas lower SES children showed a positive relationship in the right hemisphere homologues. Broadly, the ILF has been demonstrated to support orthographic skill on the left and more general visuospatial processing on the right, so high reading achievement in lower SES children may rely on supplementary visuospatial processing more than for higher SES readers. This pattern is consistent with previous work reporting low SES children's environments to include less rich verbal experience, which may lead them to disproportionately draw on visuospatial skills for success. Further, these results indicate that group SES differences may be best described by an adaptive, not a deficit, model. © 2016 John Wiley & Sons Ltd.

Joint source based morphometry identifies linked gray and white matter group differences

PubMed Central

Xu, Lai; Pearlson, Godfrey; Calhoun, Vince D.

2009-01-01

We present a multivariate approach called joint source based morphometry (jSBM), to identify linked gray and white matter regions which differ between groups. In jSBM, joint independent component analysis (jICA) is used to decompose preprocessed gray and white matter images into joint sources and statistical analysis is used to determine the significant joint sources showing group differences and their relationship to other variables of interest (e.g. age or sex). The identified joint sources are groupings of linked gray and white matter regions with common covariation among subjects. In this study, we first provide a simulation to validate the jSBM approach. To illustrate our method on real data, jSBM is then applied to structural magnetic resonance imaging (sMRI) data obtained from 120 chronic schizophrenia patients and 120 healthy controls to identify group differences. JSBM identified four joint sources as significantly associated with schizophrenia. Linked gray–white matter regions identified in each of the joint sources included: 1) temporal — corpus callosum, 2) occipital/frontal — inferior fronto-occipital fasciculus, 3) frontal/parietal/occipital/temporal —superior longitudinal fasciculus and 4) parietal/frontal — thalamus. Age effects on all four joint sources were significant, but sex effects were significant only for the third joint source. Our findings demonstrate that jSBM can exploit the natural linkage between gray and white matter by incorporating them into a unified framework. This approach is applicable to a wide variety of problems to study linked gray and white matter group differences. PMID:18992825

Brain activation during a linguistic task in conduction aphasia.

PubMed

Demeurisse, G; Capon, A

1991-06-01

In order to investigate functional cortical reorganization during recovery from conduction aphasia, regional cerebral blood flows (rCBF) were measured by the two-dimensional 133 Xenon inhalation method in ten stroke patients. rCBF measurements were performed at rest and during the performance of a linguistic task, one month and three months after onset. The analysis of flow changes from rest to test condition indicates an increasing contribution of the right hemisphere as time goes on. The absence of flow increase in Broca's region suggests that this region is definitively disconnected from posterior language "centers" by the arcuate fasciculus lesion.

Myelination progression in language-correlated regions in brain of normal children determined by quantitative MRI assessment.

PubMed

Su, Peijen; Kuan, Chen-Chieh; Kaga, Kimitaka; Sano, Masaki; Mima, Kazuo

2008-12-01

To investigate the myelination progression course in language-correlated regions of children with normal brain development by quantitative magnetic resonance imaging (MRI) analysis compared with histological studies. The subjects were 241 neurologically intact neonates, infants and young children (128 boys and 113 girls) who underwent MRI between 2001 and 2007 at the University of Tokyo Hospital, ranging in age from 0 to 429 weeks corrected by postnatal age. To compare their data with adult values, 25 adolescents and adults (14 men and 11 women, aged from 14 to 83 years) were examined as controls. Axial T2-weighted images were obtained using spin-echo sequences at 1.5 T. Subjects with a history of prematurity, birth asphyxia, low Apgar score, seizures, active systemic disease, congenital anomaly, delayed development, infarcts, hemorrhages, brain lesions, or central nervous system malformation were excluded from the analysis. Seven regions of interest in language-correlated areas, namely Broca's area, Wernicke's area, the arcuate fasciculus, and the angular gyrus, as well as their right hemisphere homologous regions, and the auditory cortex, the motor cortex, and the visual cortex were examined. Signal intensity obtained by a region-of-interest methodology progresses from hyper- to hypointensity during myelination. We chose the inferior cerebellar peduncle as the internal standard of maturation. Myelination in all these seven language-correlated regions examined in this study shared the same curve pattern: no myelination was observed at birth, it reached maturation at about 1.5 years of age, and it continued to progress slowly thereafter into adult life. On the basis of scatter plot results, we put these areas into three groups: Group A, which included the motor cortex, the auditory cortex, and the visual cortex, myelinated faster than Group B, which included Broca's area, Wernicke's area, and the angular gyrus before 1.5 years old; Group C, consisting of the arcuate fasciculus, has similar degree of myelination as Group B before 1.5 years but then myelinated more slowly after 3 years of age. No gender or left-right differences between homologous regions were found. In this study, we determined the sequence of myelination of language-correlated regions in infants and children by quantitative MRI assessment. The higher cortical areas matured later than the primary cortical areas, and the arcuate fasciculus matured last. The observation that myelination reaches maturity after 18 months suggests that myelination may be a reason for the acceleration in vocabulary acquisition observed in children from that age. The slow pace of myelination also suggested the possibility of language development's continuation into early adult life. Myelination assessed by MRI was at least 1 month behind that assessed by histological staining. No gender or left-right hemisphere differences in myelination were noted.

The architecture of the chess player's brain.

PubMed

Hänggi, Jürgen; Brütsch, Karin; Siegel, Adrian M; Jäncke, Lutz

2014-09-01

The game of chess can be seen as a typical example for an expertise task requiring domain-specific training and experience. Despite intensive behavioural studies the neural underpinnings of chess performance and expertise are not entirely understood. A few functional neuroimaging studies have shown that expert chess players recruit different psychological functions and activate different brain areas while they are engaged in chess-related activities. Based on this functional literature, we predicted to find morphological differences in a network comprised by parietal and frontal areas and especially the occipito-temporal junction (OTJ), fusiform gyrus, and caudate nucleus. Twenty expert chess players and 20 control subjects were investigated using voxel-based and surface-based morphometry as well as diffusion tensor imaging. Grey matter volume and cortical thickness were reduced in chess players compared with those of control men in the OTJ and precunei. The volumes of both caudate nuclei were not different between groups, but correlated inversely with the years of chess playing experience. Mean diffusivity was increased in chess players compared with that of controls in the left superior longitudinal fasciculus and the Elo score (a chess tournament ranking) was inversely related to mean diffusivity within the right superior longitudinal fasciculus. To the best of our knowledge we showed for the first time that there are specific differences in grey and white matter morphology between chess players and control subjects in brain regions associated with cognitive functions important for playing chess. Whether these anatomical alterations are the cause or consequence of the intensive and long-term chess training and practice remains to be shown in future studies. Copyright © 2014 Elsevier Ltd. All rights reserved.

Relation between aphasia and arcuate fasciculus in chronic stroke patients

PubMed Central

2014-01-01

Background The role of the arcuate fasciculus (AF) in the dominant hemisphere in stroke patients with aphasia has not been clearly elucidated. We investigated the relation between language function and diffusion tensor tractography (DTT) findings for the left AF in chronic stroke patients with aphasia. Method Twenty five consecutive right-handed stroke patients with aphasia following lesions in the left hemisphere were recruited for this study. The aphasia quotient (AQ) of Korean-Western Aphasia Battery was used for assessment of language function. We measured values of fractional anisotropy (FA), apparent diffusion coefficient (ADC), voxel number of the left AF. We classified patients into three groups: type A - the left AF was not reconstructed, type B - the left AF was discontinued between Wernicke’s and Broca’s areas, and type C – the left AF was preserved around the stroke lesion. Results Moderate positive correlation was observed between AQ and voxel number of the left AF (r = 0.471, p < 0.05). However, no correlation was observed between AQ and FA (r = 0.275, p > 0.05) and ADC values (r = -0.286, p > 0.05). Significant differences in AQ scores were observed between the three types (p < 0.05); the AQ score of type C was higher than those of type A and B, and that of type B was also higher than that of type A (p < 0.05). Conclusion According to our findings, the remaining volume of the left AF, irrespective of directionality and diffusivity, showed moderate positive correlation with language function in chronic stroke patients with aphasia. Discontinuation or non-construction of the left AF was also an important factor for language function. PMID:24607148

Voluntary saccade inhibition deficits correlate with extended white-matter cortico-basal atrophy in Huntington's disease.

PubMed

Vaca-Palomares, Israel; Coe, Brian C; Brien, Donald C; Munoz, Douglas P; Fernandez-Ruiz, Juan

2017-01-01

The ability to inhibit automatic versus voluntary saccade commands in demanding situations can be impaired in neurodegenerative diseases such as Huntington's disease (HD). These deficits could result from disruptions in the interaction between basal ganglia and the saccade control system. To investigate voluntary oculomotor control deficits related to the cortico-basal circuitry, we evaluated early HD patients using an interleaved pro- and anti-saccade task that requires flexible executive control to generate either an automatic response (look at a peripheral visual stimulus) or a voluntary response (look away from the stimulus in the opposite direction). The impairments of HD patients in this task are mainly attributed to degeneration in the striatal medium spiny neurons leading to an over-activation of the indirect-pathway thorough the basal ganglia. However, some studies have proposed that damage outside the indirect-pathway also contribute to executive and saccade deficits. We used the interleaved pro- and anti-saccade task to study voluntary saccade inhibition deficits, Voxel-based morphometry and Tract-based spatial statistic to map cortico-basal ganglia circuitry atrophy in HD. HD patients had voluntary saccade inhibition control deficits, including increased regular-latency anti-saccade errors and increased anticipatory saccades. These deficits correlated with white-matter atrophy in the inferior fronto-occipital fasciculus, anterior thalamic radiation, anterior corona radiata and superior longitudinal fasciculus. These findings suggest that cortico-basal ganglia white-matter atrophy in HD, disrupts the normal connectivity in a network controlling voluntary saccade inhibitory behavior beyond the indirect-pathway. This suggests that in vivo measures of white-matter atrophy can be a reliable marker of the progression of cognitive deficits in HD.

Repeating with the right hemisphere: reduced interactions between phonological and lexical-semantic systems in crossed aphasia?

PubMed Central

De-Torres, Irene; Dávila, Guadalupe; Berthier, Marcelo L.; Walsh, Seán Froudist; Moreno-Torres, Ignacio; Ruiz-Cruces, Rafael

2013-01-01

Knowledge on the patterns of repetition amongst individuals who develop language deficits in association with right hemisphere lesions (crossed aphasia) is very limited. Available data indicate that repetition in some crossed aphasics experiencing phonological processing deficits is not heavily influenced by lexical-semantic variables (lexicality, imageability, and frequency) as is regularly reported in phonologically-impaired cases with left hemisphere damage. Moreover, in view of the fact that crossed aphasia is rare, information on the role of right cortical areas and white matter tracts underpinning language repetition deficits is scarce. In this study, repetition performance was assessed in two patients with crossed conduction aphasia and striatal/capsular vascular lesions encompassing the right arcuate fasciculus (AF) and inferior frontal-occipital fasciculus (IFOF), the temporal stem and the white matter underneath the supramarginal gyrus. Both patients showed lexicality effects repeating better words than non-words, but manipulation of other lexical-semantic variables exerted less influence on repetition performance. Imageability and frequency effects, production of meaning-based paraphrases during sentence repetition, or better performance on repeating novel sentences than overlearned clichés were hardly ever observed in these two patients. In one patient, diffusion tensor imaging disclosed damage to the right long direct segment of the AF and IFOF with relative sparing of the anterior indirect and posterior segments of the AF, together with fully developed left perisylvian white matter pathways. These findings suggest that striatal/capsular lesions extending into the right AF and IFOF in some individuals with right hemisphere language dominance are associated with atypical repetition patterns which might reflect reduced interactions between phonological and lexical-semantic processes. PMID:24151460

Reduced integrity of the left arcuate fasciculus is specifically associated with auditory verbal hallucinations in schizophrenia.

PubMed

McCarthy-Jones, Simon; Oestreich, Lena K L; Whitford, Thomas J

2015-03-01

Schizophrenia patients with auditory verbal hallucinations (AVH) have reduced structural integrity in the left arcuate fasciculus (AFL) compared to healthy controls. However, it is neither known whether these changes are specific to AVH, as opposed to hallucinations or schizophrenia per se, nor how radial and/or axial diffusivity are altered. This study aimed to test the hypothesis that reductions to the structural integrity of the AFL are specifically associated with AVH in schizophrenia. Diffusion tensor imaging scans and clinical data were obtained from the Australian Schizophrenia Research Bank for 39 schizophrenia patients with lifetime AVH (18 current, 21 remitted), 74 schizophrenia patients with no lifetime AVH (40 with lifetime hallucinations in other modalities, 34 no lifetime hallucinations) and 40 healthy controls. Fractional anisotropy was significantly reduced in the AFL of patients with lifetime AVH compared to both healthy controls (Cohen's d=1.24) and patients without lifetime AVH (d=.72), including compared to the specific subsets of patients without AVH who either had hallucinations in other modalities (d=.69) or no history of any hallucinations (d=.73). Radial, but not axial, diffusivity was significantly increased in patients with lifetime AVH compared to both healthy controls (d=.89) and patients without lifetime AVH (d=.39). Evidence was found for a non-linear relation between fractional anisotropy in the AFL and state AVH. Reduced integrity of the AFL is specifically associated with AVH, as opposed to schizophrenia in general or hallucinations in other modalities. Increased radial diffusivity suggests dysmyelination or demyelination of the AFL may play a role in AVH. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Sensory-to-motor integration during auditory repetition: a combined fMRI and lesion study

PubMed Central

Parker Jones, ‘Ōiwi; Prejawa, Susan; Hope, Thomas M. H.; Oberhuber, Marion; Seghier, Mohamed L.; Leff, Alex P.; Green, David W.; Price, Cathy J.

2014-01-01

The aim of this paper was to investigate the neurological underpinnings of auditory-to-motor translation during auditory repetition of unfamiliar pseudowords. We tested two different hypotheses. First we used functional magnetic resonance imaging in 25 healthy subjects to determine whether a functionally defined area in the left temporo-parietal junction (TPJ), referred to as Sylvian-parietal-temporal region (Spt), reflected the demands on auditory-to-motor integration during the repetition of pseudowords relative to a semantically mediated nonverbal sound-naming task. The experiment also allowed us to test alternative accounts of Spt function, namely that Spt is involved in subvocal articulation or auditory processing that can be driven either bottom-up or top-down. The results did not provide convincing evidence that activation increased in either Spt or any other cortical area when non-semantic auditory inputs were being translated into motor outputs. Instead, the results were most consistent with Spt responding to bottom up or top down auditory processing, independent of the demands on auditory-to-motor integration. Second, we investigated the lesion sites in eight patients who had selective difficulties repeating heard words but with preserved word comprehension, picture naming and verbal fluency (i.e., conduction aphasia). All eight patients had white-matter tract damage in the vicinity of the arcuate fasciculus and only one of the eight patients had additional damage to the Spt region, defined functionally in our fMRI data. Our results are therefore most consistent with the neurological tradition that emphasizes the importance of the arcuate fasciculus in the non-semantic integration of auditory and motor speech processing. PMID:24550807

Abnormal fronto-parietal white matter organisation in the superior longitudinal fasciculus branches in autism spectrum disorders.

PubMed

Fitzgerald, Jacqueline; Leemans, Alexander; Kehoe, Elizabeth; O'Hanlon, Erik; Gallagher, Louise; McGrath, Jane

2018-03-01

Core features of autism spectrum disorder (ASD) may be underpinned by disrupted functional and structural neural connectivity. Abnormal fronto-parietal functional connectivity has been widely reported in the literature; this may be underpinned by disrupted microstructural organisation of white matter. The superior longitudinal fasciculus (SLF) is a major fronto-parietal white matter tract, the structure of which has been little studied in ASD. The fronto-parietal projections of this tract (SLF I, II and III) are thought to play an important role in a number of cognitive functions including attention and visuospatial processing. To date, the isolation of the fronto-parietal branches of the SLF has been hampered by limitations of traditional tractography approaches. Constrained spherical deconvolution (CSD)-based tractography is an advanced approach that allows valid isolation of the fronto-parietal branches of the SLF. Diffusion MRI data were acquired from 45 participants with ASD and 45 age- and IQ-matched controls. The SLF I, II and III branches were isolated using CSD-based tractography in ExploreDTI. Significantly greater fractional anisotropy (FA) was observed in the right SLF II relative to controls. The ASD group also showed greater linear diffusion coefficient in the left SLF I and the right SLF II. In the SLF II, the ASD group had significantly greater right lateralisation of FA in comparison with the control group. The clinical and functional implications of increased FA in white matter are poorly understood; however, it is possible that this increased white matter organisation in the SLF in ASD may contribute to relative processing advantages in the condition. © 2017 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

White Matter Abnormalities Correlating with Memory and Depression in Heroin Users under Methadone Maintenance Treatment

PubMed Central

Lin, Wei-Che; Chou, Kun-Hsien; Chen, Chien-Chih; Huang, Chu-Chung; Chen, Hsiu-Ling; Lu, Cheng-Hsien; Li, Shau-Hsuan; Wang, Ya-Ling; Cheng, Yu-Fan; Lin, Ching-Po

2012-01-01

Methadone maintenance treatment (MMT) has elevated rates of co-morbid memory deficit and depression that are associated with higher relapse rates for substance abuse. White matter (WM) disruption in MMT patients have been reported but their impact on these co-morbidities is unknown. This study aimed to investigate changes in WM integrity of MMT subjects using diffusion tensor image (DTI), and their relationship with history of heroin and methadone use in treated opiate-dependent individuals. The association between WM integrity changes from direct group comparisons and the severity of memory deficit and depression was also investigated. Differences in WM integrity between 35 MMT patients and 23 healthy controls were evaluated using DTI with tract-based spatial statistical analysis. Differences in DTI indices correlated with diminished memory function, Beck Depression Inventory, duration of heroin use and MMT, and dose of heroin and methadone administration. Changes in WM integrity were found in several WM regions, including the temporal and frontal lobes, pons, cerebellum, and cingulum bundles. The duration of MMT was associated with declining DTI indices in the superior longitudinal fasciculus and para-hippocampus. MMT patients had more memory and emotional deficits than healthy subjects. Worse scores in both depression and memory functions were associated with altered WM integrity in the superior longitudinal fasciculus, para-hippocampus, and middle cerebellar peduncle in MMT. Patients on MMT also had significant WM differences in the reward circuit and in depression- and memory-associated regions. Correlations among decreased DTI indices, disease severity, and accumulation effects of methadone suggest that WM alterations may be involved in the psychopathology and pathophysiology of co-morbidities in MMT. PMID:22496768

Direct evidence for the contributive role of the right inferior fronto-occipital fasciculus in non-verbal semantic cognition.

PubMed

Herbet, Guillaume; Moritz-Gasser, Sylvie; Duffau, Hugues

2017-05-01

The neural foundations underlying semantic processing have been extensively investigated, highlighting a pivotal role of the ventral stream. However, although studies concerning the involvement of the left ventral route in verbal semantics are proficient, the potential implication of the right ventral pathway in non-verbal semantics has been to date unexplored. To gain insights on this matter, we used an intraoperative direct electrostimulation to map the structures mediating the non-verbal semantic system in the right hemisphere. Thirteen patients presenting with a right low-grade glioma located within or close to the ventral stream were included. During the 'awake' procedure, patients performed both a visual non-verbal semantic task and a verbal (control) task. At the cortical level, in the right hemisphere, we found non-verbal semantic-related sites (n = 7 in 6 patients) in structures commonly associated with verbal semantic processes in the left hemisphere, including the superior temporal gyrus, the pars triangularis, and the dorsolateral prefrontal cortex. At the subcortical level, we found non-verbal semantic-related sites in all but one patient (n = 15 sites in 12 patients). Importantly, all these responsive stimulation points were located on the spatial course of the right inferior fronto-occipital fasciculus (IFOF). These findings provide direct support for a critical role of the right IFOF in non-verbal semantic processing. Based upon these original data, and in connection with previous findings showing the involvement of the left IFOF in non-verbal semantic processing, we hypothesize the existence of a bilateral network underpinning the non-verbal semantic system, with a homotopic connectional architecture.

Damage to ventral and dorsal language pathways in acute aphasia

PubMed Central

Hartwigsen, Gesa; Kellmeyer, Philipp; Glauche, Volkmar; Mader, Irina; Klöppel, Stefan; Suchan, Julia; Karnath, Hans-Otto; Weiller, Cornelius; Saur, Dorothee

2013-01-01

Converging evidence from neuroimaging studies and computational modelling suggests an organization of language in a dual dorsal–ventral brain network: a dorsal stream connects temporoparietal with frontal premotor regions through the superior longitudinal and arcuate fasciculus and integrates sensorimotor processing, e.g. in repetition of speech. A ventral stream connects temporal and prefrontal regions via the extreme capsule and mediates meaning, e.g. in auditory comprehension. The aim of our study was to test, in a large sample of 100 aphasic stroke patients, how well acute impairments of repetition and comprehension correlate with lesions of either the dorsal or ventral stream. We combined voxelwise lesion-behaviour mapping with the dorsal and ventral white matter fibre tracts determined by probabilistic fibre tracking in our previous study in healthy subjects. We found that repetition impairments were mainly associated with lesions located in the posterior temporoparietal region with a statistical lesion maximum in the periventricular white matter in projection of the dorsal superior longitudinal and arcuate fasciculus. In contrast, lesions associated with comprehension deficits were found more ventral-anterior in the temporoprefrontal region with a statistical lesion maximum between the insular cortex and the putamen in projection of the ventral extreme capsule. Individual lesion overlap with the dorsal fibre tract showed a significant negative correlation with repetition performance, whereas lesion overlap with the ventral fibre tract revealed a significant negative correlation with comprehension performance. To summarize, our results from patients with acute stroke lesions support the claim that language is organized along two segregated dorsal–ventral streams. Particularly, this is the first lesion study demonstrating that task performance on auditory comprehension measures requires an interaction between temporal and prefrontal brain regions via the ventral extreme capsule pathway. PMID:23378217

Self-face recognition shares brain regions active during proprioceptive illusion in the right inferior fronto-parietal superior longitudinal fasciculus III network.

PubMed

Morita, Tomoyo; Saito, Daisuke N; Ban, Midori; Shimada, Koji; Okamoto, Yuko; Kosaka, Hirotaka; Okazawa, Hidehiko; Asada, Minoru; Naito, Eiichi

2017-04-21

Proprioception is somatic sensation that allows us to sense and recognize position, posture, and their changes in our body parts. It pertains directly to oneself and may contribute to bodily awareness. Likewise, one's face is a symbol of oneself, so that visual self-face recognition directly contributes to the awareness of self as distinct from others. Recently, we showed that right-hemispheric dominant activity in the inferior fronto-parietal cortices, which are connected by the inferior branch of the superior longitudinal fasciculus (SLF III), is associated with proprioceptive illusion (awareness), in concert with sensorimotor activity. Herein, we tested the hypothesis that visual self-face recognition shares brain regions active during proprioceptive illusion in the right inferior fronto-parietal SLF III network. We scanned brain activity using functional magnetic resonance imaging while twenty-two right-handed healthy adults performed two tasks. One was a proprioceptive illusion task, where blindfolded participants experienced a proprioceptive illusion of right hand movement. The other was a visual self-face recognition task, where the participants judged whether an observed face was their own. We examined whether the self-face recognition and the proprioceptive illusion commonly activated the inferior fronto-parietal cortices connected by the SLF III in a right-hemispheric dominant manner. Despite the difference in sensory modality and in the body parts involved in the two tasks, both tasks activated the right inferior fronto-parietal cortices, which are likely connected by the SLF III, in a right-side dominant manner. Here we discuss possible roles for right inferior fronto-parietal activity in bodily awareness and self-awareness. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

White matter developmental trajectories associated with persistence and recovery of childhood stuttering.

PubMed

Chow, Ho Ming; Chang, Soo-Eun

2017-04-08

Stuttering affects the fundamental human ability of fluent speech production, and can have a significant negative impact on an individual's psychosocial development. While the disorder affects about 5% of all preschool children, approximately 80% of them recover naturally within a few years of stuttering onset. The pathophysiology and neuroanatomical development trajectories associated with persistence and recovery of stuttering are still largely unknown. Here, the first mixed longitudinal diffusion tensor imaging (DTI) study of childhood stuttering has been reported. A total of 195 high quality DTI scans from 35 children who stutter (CWS) and 43 controls between 3 and 12 years of age were acquired, with an average of three scans per child, each collected approximately a year apart. Fractional anisotropy (FA), a measure reflecting white matter structural coherence, was analyzed voxel-wise to examine group and age-related differences using a linear mixed-effects (LME) model. Results showed that CWS exhibited decreased FA relative to controls in the left arcuate fasciculus, underlying the inferior parietal and posterior temporal areas, and the mid body of corpus callosum. Further, white matter developmental trajectories reflecting growth rate of these tract regions differentiated children with persistent stuttering from those who recovered from stuttering. Specifically, a reduction in FA growth rate (i.e., slower FA growth with age) in persistent children relative to fluent controls in the left arcuate fasciculus and corpus callosum was found, which was not evident in recovered children. These findings provide first glimpses into the possible neural mechanisms of onset, persistence, and recovery of childhood stuttering. Hum Brain Mapp, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

[Dissociated nystagmus in side gaze. Major symptoms in the diagnosis of an internuclear ophthalmoplegia].

PubMed

Neugebauer, P; Neugebauer, A; Fricke, J; Michel, O

2004-07-01

A prerequisite for a qualified analysis of nystagmus is the recognition of uncommon forms of this condition. In internuclear ophthalmoplegia (INO), a dissociated nystagmus in side gaze is typical. This is accompanied by limited medial excursion of the adducted eye together with a dissociated nystagmus, which is stronger in the abducting fellow eye. This motility disturbance stems from a lesion in the medial longitudinal fasciculus running in the brain stem between the sixth and the third nerve nuclei. The lesion is often due to multiple sclerosis, but can also be ischemic, traumatic, neoplastic or inflammatory (e.g. HIV infection).

White matter microstructural properties correlate with sensorimotor synchronization abilities.

PubMed

Blecher, Tal; Tal, Idan; Ben-Shachar, Michal

2016-09-01

Sensorimotor synchronization (SMS) to an external auditory rhythm is a developed ability in humans, particularly evident in dancing and singing. This ability is typically measured in the lab via a simple task of finger tapping to an auditory beat. While simplistic, there is some evidence that poor performance on this task could be related to impaired phonological and reading abilities in children. Auditory-motor synchronization is hypothesized to rely on a tight coupling between auditory and motor neural systems, but the specific pathways that mediate this coupling have not been identified yet. In this study, we test this hypothesis and examine the contribution of fronto-temporal and callosal connections to specific measures of rhythmic synchronization. Twenty participants went through SMS and diffusion magnetic resonance imaging (dMRI) measurements. We quantified the mean asynchrony between an auditory beat and participants' finger taps, as well as the time to resynchronize (TTR) with an altered meter, and examined the correlations between these behavioral measures and diffusivity in a small set of predefined pathways. We found significant correlations between asynchrony and fractional anisotropy (FA) in the left (but not right) arcuate fasciculus and in the temporal segment of the corpus callosum. On the other hand, TTR correlated with FA in the precentral segment of the callosum. To our knowledge, this is the first demonstration that relates these particular white matter tracts with performance on an auditory-motor rhythmic synchronization task. We propose that left fronto-temporal and temporal-callosal fibers are involved in prediction and constant comparison between auditory inputs and motor commands, while inter-hemispheric connections between the motor/premotor cortices contribute to successful resynchronization of motor responses with a new external rhythm, perhaps via inhibition of tapping to the previous rhythm. Our results indicate that auditory-motor synchronization skills are associated with anatomical pathways that have been previously related to phonological awareness, thus offering a possible anatomical basis for the behavioral covariance between these abilities. Copyright © 2016 Elsevier Inc. All rights reserved.

Neurological problems of jazz legends.

PubMed

Pearl, Phillip L

2009-08-01

A variety of neurological problems have affected the lives of giants in the jazz genre. Cole Porter courageously remained prolific after severe leg injuries secondary to an equestrian accident, until he succumbed to osteomyelitis, amputations, depression, and phantom limb pain. George Gershwin resisted explanations for uncinate seizures and personality change and herniated from a right temporal lobe brain tumor, which was a benign cystic glioma. Thelonious Monk had erratic moods, reflected in his pianism, and was ultimately mute and withdrawn, succumbing to cerebrovascular events. Charlie Parker dealt with mood lability and drug dependence, the latter emanating from analgesics following an accident, and ultimately lived as hard as he played his famous bebop saxophone lines and arpeggios. Charles Mingus hummed his last compositions into a tape recorder as he died with motor neuron disease. Bud Powell had severe posttraumatic headaches after being struck by a police stick defending Thelonious Monk during a Harlem club raid.

Pancreatic Polypeptide Cell Proliferation in the Pancreas and Duodenum Coexisting in a Patient With Pancreatic Adenocarcinoma Treated With a GLP-1 Analog.

PubMed

Talmon, Geoffrey A; Wren, J David; Nguyen, Christophe L; Pour, Parviz M

2017-07-01

A partial pancreaticogastrodudenectomy was performed on a 66-year old man with type 2 diabetes mellitus because of an invasive, moderately differentiated adenocarcinoma in the head of the pancreas. In the adjacent grossly normal tissue of the uncinate process, there was a massive proliferation of pancreatic polypeptide (PP) cells confined to this region and showed invasive pattern. Strikingly, in the heaped area of his duodenum, there was a strikingly large number of PP, glucagon, a few insulin cells in a mini-islet-like patterns composed of glucagon and insulin cells. Among the etiological factors, the possible long-lasting effects of the GLP-1 analog, with which the patient was treated, are discussed. This is the first report in the literature of both the coexistence of a pancreatic adenocarcinoma and invasive PPoma and the occurrence of PP and insulin cells in human duodenal mucosa.

A sex difference in the hypothalamic uncinate nucleus: relationship to gender identity.

PubMed

Garcia-Falgueras, Alicia; Swaab, Dick F

2008-12-01

Transsexuality is an individual's unshakable conviction of belonging to the opposite sex, resulting in a request for sex-reassignment surgery. We have shown previously that the bed nucleus of the stria terminalis (BSTc) is female in size and neuron number in male-to-female transsexual people. In the present study we investigated the hypothalamic uncinate nucleus, which is composed of two subnuclei, namely interstitial nucleus of the anterior hypothalamus (INAH) 3 and 4. Post-mortem brain material was used from 42 subjects: 14 control males, 11 control females, 11 male-to-female transsexual people, 1 female-to-male transsexual subject and 5 non-transsexual subjects who were castrated because of prostate cancer. To identify and delineate the nuclei and determine their volume and shape we used three different stainings throughout the nuclei in every 15th section, i.e. thionin, neuropeptide Y and synaptophysin, using an image analysis system. The most pronounced differences were found in the INAH3 subnucleus. Its volume in thionin sections was 1.9 times larger in control males than in females (P < 0.013) and contained 2.3 times as many cells (P < 0.002). We showed for the first time that INAH3 volume and number of neurons of male-to-female transsexual people is similar to that of control females. The female-to-male transsexual subject had an INAH3 volume and number of neurons within the male control range, even though the treatment with testosterone had been stopped three years before death. The castrated men had an INAH3 volume and neuron number that was intermediate between males (volume and number of neurons P > 0.117) and females (volume P > 0.245 and number of neurons P > 0.341). There was no difference in INAH3 between pre-and post-menopausal women, either in the volume (P > 0.84) or in the number of neurons (P < 0.439), indicating that the feminization of the INAH3 of male-to-female transsexuals was not due to estrogen treatment. We propose that the sex reversal of the INAH3 in transsexual people is at least partly a marker of an early atypical sexual differentiation of the brain and that the changes in INAH3 and the BSTc may belong to a complex network that may structurally and functionally be related to gender identity.

Distinct loci of lexical and semantic access deficits in aphasia: Evidence from voxel-based lesion-symptom mapping and diffusion tensor imaging.

PubMed

Harvey, Denise Y; Schnur, Tatiana T

2015-06-01

Naming pictures and matching words to pictures belonging to the same semantic category negatively affects language production and comprehension. By most accounts, semantic interference arises when accessing lexical representations in naming (e.g., Damian, Vigliocco, & Levelt, 2001) and semantic representations in comprehension (e.g., Forde & Humphreys, 1997). Further, damage to the left inferior frontal gyrus (LIFG), a region implicated in cognitive control, results in increasing semantic interference when items repeat across cycles in both language production and comprehension (Jefferies, Baker, Doran, & Lambon Ralph, 2007). This generates the prediction that the LIFG via white matter connections supports resolution of semantic interference arising from different loci (lexical vs semantic) in the temporal lobe. However, it remains unclear whether the cognitive and neural mechanisms that resolve semantic interference are the same across tasks. Thus, we examined which gray matter structures [using whole brain and region of interest (ROI) approaches] and white matter connections (using deterministic tractography) when damaged impact semantic interference and its increase across cycles when repeatedly producing and understanding words in 15 speakers with varying lexical-semantic deficits from left hemisphere stroke. We found that damage to distinct brain regions, the posterior versus anterior temporal lobe, was associated with semantic interference (collapsed across cycles) in naming and comprehension, respectively. Further, those with LIFG damage compared to those without exhibited marginally larger increases in semantic interference across cycles in naming but not comprehension. Lastly, the inferior fronto-occipital fasciculus, connecting the LIFG with posterior temporal lobe, related to semantic interference in naming, whereas the inferior longitudinal fasciculus (ILF), connecting posterior with anterior temporal regions related to semantic interference in comprehension. These neuroanatomical-behavioral findings have implications for models of the lexical-semantic language network by demonstrating that semantic interference in language production and comprehension involves different representations which differentially recruit a cognitive control mechanism for interference resolution. Copyright © 2015 Elsevier Ltd. All rights reserved.

Asymmetric projections of the arcuate fasciculus to the temporal cortex underlie lateralized language function in the human brain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takaya, Shigetoshi; Kuperberg, Gina R.; Tufts Univ., Medford, MA

The arcuate fasciculus (AF) in the human brain has asymmetric structural properties. However, the topographic organization of the asymmetric AF projections to the cortex and its relevance to cortical function remain unclear. Here we mapped the posterior projections of the human AF in the inferior parietal and lateral temporal cortices using surface-based structural connectivity analysis based on diffusion MRI and investigated their hemispheric differences. We then performed the cross-modal comparison with functional connectivity based on resting-state functional MRI (fMRI) and task-related cortical activation based on fMRI using a semantic classification task of single words. Structural connectivity analysis showed that themore » left AF connecting to Broca's area predominantly projected in the lateral temporal cortex extending from the posterior superior temporal gyrus to the mid part of the superior temporal sulcus and the middle temporal gyrus, whereas the right AF connecting to the right homolog of Broca's area predominantly projected to the inferior parietal cortex extending from the mid part of the supramarginal gyrus to the anterior part of the angular gyrus. The left-lateralized projection regions of the AF in the left temporal cortex had asymmetric functional connectivity with Broca's area, indicating structure-function concordance through the AF. During the language task, left-lateralized cortical activation was observed. Among them, the brain responses in the temporal cortex and Broca's area that were connected through the left-lateralized AF pathway were specifically correlated across subjects. These results suggest that the human left AF, which structurally and functionally connects the mid temporal cortex and Broca's area in asymmetrical fashion, coordinates the cortical activity in these remote cortices during a semantic decision task. As a result, the unique feature of the left AF is discussed in the context of the human capacity for language.« less

Brain stem origins of spinal projections in the lizard Tupinambis nigropunctatus.

PubMed

Cruce, W L; Newman, D B

1981-05-10

In order to study brainstem origins of spinal projections, ten Tegu lizards (Tupinambis nigropunctatus) received complete or partial hemisections of the spinal cord at the first or second cervical segment. Their brains were processed for conventional Nissl staining. The sections were surveyed for the presence or absence of retrograde chromatolysis. Based on analysis and comparison of results from lesions in the various spinal cord funiculi, the following conclusions were reached: The interstitial nucleus projects ipsilaterally to the spinal cord via the medial longitudinal fasciculus, as does the middle reticular field of the metencephalon. The red nucleus and dorsal vagal motor nucleus both project contralaterally to the spinal cord via the dorsal part of the lateral funiculus. The superior reticular field in the rostral metencephalon and the ventrolateral vestibular nucleus project ipsilaterally to the spinal cord via the ventral funiculus. The dorsolateral metencephalic nucleus and the ventral part of the inferior reticular nucleus of the myelencephalon both project ipsilaterally to the spinal cord via the dorsal part of the lateral funiculus. Several brainstem nuclei in Tupinambis project bilaterally to the spinal cord. The ventrolateral metencephalic nucleus, for example, projects ipsilaterally to the cord via the medial longitudinal fasciculus and contralaterally via the dorsal part of the lateral funiculus. The dorsal part of the inferior reticular nucleus projects bilaterally to the spinal cord via the dorsal part of the lateral funiculus. The nucleus solitarius complex projects contralaterally via the dorsal part of the lateral funiculus but ipsilaterally via the middle of the lateral funiculus. The inferior raphe nucleus projects bilaterally to the spinal cord via the middle part of the lateral funiculus. These data suggest that supraspinal projections in reptiles, especially reticulospinal systems, are more highly differentiated than previously thought. On the other hand, recent findings in cat, opossum, and monkey reveal that the organization of supraspinal pathways in the Tegu lizard bears a striking resemblance to that observed in mammals.

White matter pathway supporting phonological encoding in speech production: a multi-modal imaging study of brain damage patients.

PubMed

Han, Zaizhu; Ma, Yujun; Gong, Gaolang; Huang, Ruiwang; Song, Luping; Bi, Yanchao

2016-01-01

In speech production, an important step before motor programming is the retrieval and encoding of the phonological elements of target words. It has been proposed that phonological encoding is supported by multiple regions in the left frontal, temporal and parietal regions and their underlying white matter, especially the left arcuate fasciculus (AF) or superior longitudinal fasciculus (SLF). It is unclear, however, whether the effects of AF/SLF are indeed related to phonological encoding for output and whether there are other white matter tracts that also contribute to this process. We comprehensively investigated the anatomical connectivity supporting phonological encoding in production by studying the relationship between the integrity of all major white matter tracts across the entire brain and phonological encoding deficits in a group of 69 patients with brain damage. The integrity of each white matter tract was measured both by the percentage of damaged voxels (structural imaging) and the mean fractional anisotropy value (diffusion tensor imaging). The phonological encoding deficits were assessed by various measures in two oral production tasks that involve phonological encoding: the percentage of nonword (phonological) errors in oral picture naming and the accuracy of word reading aloud with word comprehension ability regressed out. We found that the integrity of the left SLF in both the structural and diffusion tensor imaging measures consistently predicted the severity of phonological encoding impairment in the two phonological production tasks. Such effects of the left SLF on phonological production remained significant when a range of potential confounding factors were considered through partial correlation, including total lesion volume, demographic factors, lesions on phonological-relevant grey matter regions, or effects originating from the phonological perception or semantic processes. Our results therefore conclusively demonstrate the central role of the left SLF in phonological encoding in speech production.

Disrupted White Matter Microstructure and Mood Disorders after Traumatic Brain Injury.

PubMed

Spitz, Gershon; Alway, Yvette; Gould, Kate Rachel; Ponsford, Jennie L

2017-02-15

Traumatic brain injury (TBI) is associated with an elevated frequency of mood disorders that may, in part, be explained by changes in white-matter microstructure. This study is the first to examine the relationship between mood disorders and white-matter pathology in a sample of patients with mild to severe TBI using a standardized psychiatric interview. This study reports on a sub-sample of 29 individuals recruited from a large prospective study that examined the evolution of psychiatric disorders following complicated, mild to severe TBI. Individuals with TBI were also compared with 23 healthy control participants. Individuals were invited to complete the Structured Clinical Interview for DSM-IV Disorders (SCID) to diagnose psychiatric disorders. Participants who developed a mood disorder within the first 3 years were categorized into a TBI-Mood group. Diffusion tensor tractography assessed white matter microstructure using atlas-based tract-averaged and along-tract approaches. Fractional anisotropy (FA) was used as the measure of white-matter microstructure. TBI participants with and without a mood disorder did not differ in regard to injury severity and other background factors. Nevertheless, TBI participants diagnosed with a mood disorder displayed significantly lower tract-averaged FA values for the right arcuate fasciculus (p = 0.011), right inferior longitudinal fasciculus (p = 0.009), and anterior segments I (p = 0.0004) and II (p = 0.007) of the corpus callosum, as well as the left (p = 0.014) and right (p = 0.015) fronto-occipital longitudinal fasciculi. The pattern of white matter disruption identified in the current study provides further support for a neurobiological basis of post-TBI mood disorders. Greater understanding of individuals' underlying neuropathology may enable better characterization and prediction of mood disorders. Integration of neuropathology may also inform the potential efficacy of pharmacological and psychological interventions.

Asymmetric projections of the arcuate fasciculus to the temporal cortex underlie lateralized language function in the human brain

DOE PAGES

Takaya, Shigetoshi; Kuperberg, Gina R.; Tufts Univ., Medford, MA; ...

2015-09-15

The arcuate fasciculus (AF) in the human brain has asymmetric structural properties. However, the topographic organization of the asymmetric AF projections to the cortex and its relevance to cortical function remain unclear. Here we mapped the posterior projections of the human AF in the inferior parietal and lateral temporal cortices using surface-based structural connectivity analysis based on diffusion MRI and investigated their hemispheric differences. We then performed the cross-modal comparison with functional connectivity based on resting-state functional MRI (fMRI) and task-related cortical activation based on fMRI using a semantic classification task of single words. Structural connectivity analysis showed that themore » left AF connecting to Broca's area predominantly projected in the lateral temporal cortex extending from the posterior superior temporal gyrus to the mid part of the superior temporal sulcus and the middle temporal gyrus, whereas the right AF connecting to the right homolog of Broca's area predominantly projected to the inferior parietal cortex extending from the mid part of the supramarginal gyrus to the anterior part of the angular gyrus. The left-lateralized projection regions of the AF in the left temporal cortex had asymmetric functional connectivity with Broca's area, indicating structure-function concordance through the AF. During the language task, left-lateralized cortical activation was observed. Among them, the brain responses in the temporal cortex and Broca's area that were connected through the left-lateralized AF pathway were specifically correlated across subjects. These results suggest that the human left AF, which structurally and functionally connects the mid temporal cortex and Broca's area in asymmetrical fashion, coordinates the cortical activity in these remote cortices during a semantic decision task. As a result, the unique feature of the left AF is discussed in the context of the human capacity for language.« less

Altered Structural and Functional Connectivity in Late Preterm Preadolescence: An Anatomic Seed-Based Study of Resting State Networks Related to the Posteromedial and Lateral Parietal Cortex.

PubMed

Degnan, Andrew J; Wisnowski, Jessica L; Choi, SoYoung; Ceschin, Rafael; Bhushan, Chitresh; Leahy, Richard M; Corby, Patricia; Schmithorst, Vincent J; Panigrahy, Ashok

2015-01-01

Late preterm birth confers increased risk of developmental delay, academic difficulties and social deficits. The late third trimester may represent a critical period of development of neural networks including the default mode network (DMN), which is essential to normal cognition. Our objective is to identify functional and structural connectivity differences in the posteromedial cortex related to late preterm birth. Thirty-eight preadolescents (ages 9-13; 19 born in the late preterm period (≥32 weeks gestational age) and 19 at term) without access to advanced neonatal care were recruited from a low socioeconomic status community in Brazil. Participants underwent neurocognitive testing, 3-dimensional T1-weighted imaging, diffusion-weighted imaging and resting state functional MRI (RS-fMRI). Seed-based probabilistic diffusion tractography and RS-fMRI analyses were performed using unilateral seeds within the posterior DMN (posterior cingulate cortex, precuneus) and lateral parietal DMN (superior marginal and angular gyri). Late preterm children demonstrated increased functional connectivity within the posterior default mode networks and increased anti-correlation with the central-executive network when seeded from the posteromedial cortex (PMC). Key differences were demonstrated between PMC components with increased anti-correlation with the salience network seen only with posterior cingulate cortex seeding but not with precuneus seeding. Probabilistic tractography showed increased streamlines within the right inferior longitudinal fasciculus and inferior fronto-occipital fasciculus within late preterm children while decreased intrahemispheric streamlines were also observed. No significant differences in neurocognitive testing were demonstrated between groups. Late preterm preadolescence is associated with altered functional connectivity from the PMC and lateral parietal cortex to known distributed functional cortical networks despite no significant executive neurocognitive differences. Selective increased structural connectivity was observed in the setting of decreased posterior interhemispheric connections. Future work is needed to determine if these findings represent a compensatory adaptation employing alternate neural circuitry or could reflect subtle pathology resulting in emotional processing deficits not seen with neurocognitive testing.

Magnetic Resonance Imaging Measures of Brain Structure to Predict Antidepressant Treatment Outcome in Major Depressive Disorder.

PubMed

Korgaonkar, Mayuresh S; Rekshan, William; Gordon, Evian; Rush, A John; Williams, Leanne M; Blasey, Christine; Grieve, Stuart M

2015-01-01

Less than 50% of patients with Major Depressive Disorder (MDD) reach symptomatic remission with their initial antidepressant medication (ADM). There are currently no objective measures with which to reliably predict which individuals will achieve remission to ADMs. 157 participants with MDD from the International Study to Predict Optimized Treatment in Depression (iSPOT-D) underwent baseline MRIs and completed eight weeks of treatment with escitalopram, sertraline or venlafaxine-ER. A score at week 8 of 7 or less on the 17 item Hamilton Rating Scale for Depression defined remission. Receiver Operator Characteristics (ROC) analysis using the first 50% participants was performed to define decision trees of baseline MRI volumetric and connectivity (fractional anisotropy) measures that differentiated non-remitters from remitters with maximal sensitivity and specificity. These decision trees were tested for replication in the remaining participants. Overall, 35% of all participants achieved remission. ROC analyses identified two decision trees that predicted a high probability of non-remission and that were replicated: 1. Left middle frontal volume < 14 · 8 mL & right angular gyrus volume > 6 · 3 mL identified 55% of non-remitters with 85% accuracy; and 2. Fractional anisotropy values in the left cingulum bundle < 0 · 63, right superior fronto-occipital fasciculus < 0 · 54 and right superior longitudinal fasciculus < 0 · 50 identified 15% of the non-remitters with 84% accuracy. All participants who met criteria for both decision trees were correctly identified as non-remitters. Pretreatment MRI measures seem to reliably identify a subset of patients who do not remit with a first step medication that includes one of these commonly used medications. Findings are consistent with a neuroanatomical basis for non-remission in depressed patients. Brain Resource Ltd is the sponsor for the iSPOT-D study (NCT00693849).

Sentence processing and verbal working memory in a white-matter-disconnection patient.

PubMed

Meyer, Lars; Cunitz, Katrin; Obleser, Jonas; Friederici, Angela D

2014-08-01

The Arcuate Fasciculus/Superior Longitudinal Fasciculus (AF/SLF) is the white-matter bundle that connects posterior superior temporal and inferior frontal cortex. Its causal functional role in sentence processing and verbal working memory is currently under debate. While impairments of sentence processing and verbal working memory often co-occur in patients suffering from AF/SLF damage, it is unclear whether these impairments result from shared white-matter damage to the verbal-working-memory network. The present study sought to specify the behavioral consequences of focal AF/SLF damage for sentence processing and verbal working memory, which were assessed in a single patient suffering from a cleft-like lesion spanning the deep left superior temporal gyrus, sparing most surrounding gray matter. While tractography suggests that the ventral fronto-temporal white-matter bundle is intact in this patient, the AF/SLF was not visible to tractography. In line with the hypothesis that the AF/SLF is causally involved in sentence processing, the patient׳s performance was selectively impaired on sentences that jointly involve both complex word orders and long word-storage intervals. However, the patient was unimpaired on sentences that only involved long word-storage intervals without involving complex word orders. On the contrary, the patient performed generally worse than a control group across standard verbal-working-memory tests. We conclude that the AF/SLF not only plays a causal role in sentence processing, linking regions of the left dorsal inferior frontal gyrus to the temporo-parietal region, but moreover plays a crucial role in verbal working memory, linking regions of the left ventral inferior frontal gyrus to the left temporo-parietal region. Together, the specific sentence-processing impairment and the more general verbal-working-memory impairment may imply that the AF/SLF subserves both sentence processing and verbal working memory, possibly pointing to the AF and SLF respectively supporting each. Copyright © 2014 Elsevier Ltd. All rights reserved.

Reduced white matter integrity and facial emotion perception in never-medicated patients with first-episode schizophrenia: A diffusion tensor imaging study.

PubMed

Zhao, Xiaoxin; Sui, Yuxiu; Yao, Jingjing; Lv, Yiding; Zhang, Xinyue; Jin, Zhuma; Chen, Lijun; Zhang, Xiangrong

2017-07-03

Facial emotion perception is impaired in schizophrenia. Although the pathology of schizophrenia is thought to involve abnormality in white matter (WM), few studies have examined the correlation between facial emotion perception and WM abnormalities in never-medicated patients with first-episode schizophrenia. The present study tested associations between facial emotion perception and WM integrity in order to investigate the neural basis of impaired facial emotion perception in schizophrenia. Sixty-three schizophrenic patients and thirty control subjects underwent facial emotion categorization (FEC). The FEC data was inserted into a logistic function model with subsequent analysis by independent-samples T test and the shift point and slope as outcome measurements. Severity of symptoms was measured using a five-factor model of the Positive and Negative Syndrome Scale (PANSS). Voxelwise group comparison of WM fractional anisotropy (FA) was operated using tract-based spatial statistics (TBSS). The correlation between impaired facial emotion perception and FA reduction was examined in patients using simple regression analysis within brain areas that showed a significant FA reduction in patients compared with controls. The same correlation analysis was also performed for control subjects in the whole brain. The patients with schizophrenia reported a higher shift point and a steeper slope than control subjects in FEC. The patients showed a significant FA reduction in left deep WM in the parietal, temporal and occipital lobes, a small portion of the corpus callosum (CC), and the corona radiata. In voxelwise correlation analysis, we found that facial emotion perception significantly correlated with reduced FA in various WM regions, including left forceps major (FM), inferior longitudinal fasciculus (ILF), inferior fronto-occipital fasciculus (IFOF), Left splenium of CC, and left ILF. The correlation analyses in healthy controls revealed no significant correlation of FA with FEC task. These results showed disrupted WM integrity in these regions constitutes a potential neural basis for the facial emotion perception impairments in schizophrenia. Copyright © 2017 Elsevier Inc. All rights reserved.

A multimodal neuroimaging study of a case of crossed nonfluent/agrammatic primary progressive aphasia.

PubMed

Spinelli, Edoardo G; Caso, Francesca; Agosta, Federica; Gambina, Giuseppe; Magnani, Giuseppe; Canu, Elisa; Blasi, Valeria; Perani, Daniela; Comi, Giancarlo; Falini, Andrea; Gorno-Tempini, Maria Luisa; Filippi, Massimo

2015-10-01

Crossed aphasia has been reported mainly as post-stroke aphasia resulting from brain damage ipsilateral to the dominant right hand. Here, we described a case of a crossed nonfluent/agrammatic primary progressive aphasia (nfvPPA), who developed a corticobasal syndrome (CBS). We collected clinical, cognitive, and neuroimaging data for four consecutive years from a 55-year-old right-handed lady (JV) presenting with speech disturbances. 18-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) and DaT-scan with (123)I-Ioflupane were obtained. Functional MRI (fMRI) during a verb naming task was acquired to characterize patterns of language lateralization. Diffusion tensor MRI was used to evaluate white matter damage within the language network. At onset, JV presented with prominent speech output impairment and right frontal atrophy. After 3 years, language deficits worsened, with the occurrence of a mild agrammatism. The patient also developed a left-sided mild extrapyramidal bradykinetic-rigid syndrome. The clinical picture was suggestive of nfvPPA with mild left-sided extrapyramidal syndrome. At this time, voxel-wise SPM analyses of (18)F-FDG PET and structural MRI showed right greater than left frontal hypometabolism and damage, which included the Broca's area. DaT-scan showed a reduced uptake in the right striatum. FMRI during naming task demonstrated bilateral language activations, and tractography showed right superior longitudinal fasciculus (SLF) involvement. Over the following year, JV became mute and developed frank left-sided motor signs and symptoms, evolving into a CBS clinical picture. Brain atrophy worsened in frontal areas bilaterally, and extended to temporo-parietal regions, still with a right-sided asymmetry. Tractography showed an extension of damage to the left SLF and right inferior longitudinal fasciculus. We report a case of crossed nfvPPA followed longitudinally and studied with advanced neuroimaging techniques. The results highlight a complex interaction between individual premorbid developmental differences and the clinical phenotype.

Effects of practice and experience on the arcuate fasciculus: comparing singers, instrumentalists, and non-musicians.

PubMed

Halwani, Gus F; Loui, Psyche; Rüber, Theodor; Schlaug, Gottfried

2011-01-01

Structure and function of the human brain are affected by training in both linguistic and musical domains. Individuals with intensive vocal musical training provide a useful model for investigating neural adaptations of learning in the vocal-motor domain and can be compared with learning in a more general musical domain. Here we confirm general differences in macrostructure (tract volume) and microstructure (fractional anisotropy, FA) of the arcuate fasciculus (AF), a prominent white-matter tract connecting temporal and frontal brain regions, between singers, instrumentalists, and non-musicians. Both groups of musicians differed from non-musicians in having larger tract volume and higher FA values of the right and left AF. The AF was then subdivided in a dorsal (superior) branch connecting the superior temporal gyrus and the inferior frontal gyrus (STG ↔ IFG), and ventral (inferior) branch connecting the middle temporal gyrus and the inferior frontal gyrus (MTG ↔ IFG). Relative to instrumental musicians, singers had a larger tract volume but lower FA values in the left dorsal AF (STG ↔ IFG), and a similar trend in the left ventral AF (MTG ↔ IFG). This between-group comparison controls for the general effects of musical training, although FA was still higher in singers compared to non-musicians. Both musician groups had higher tract volumes in the right dorsal and ventral tracts compared to non-musicians, but did not show a significant difference between each other. Furthermore, in the singers' group, FA in the left dorsal branch of the AF was inversely correlated with the number of years of participants' vocal training. Our findings suggest that long-term vocal-motor training might lead to an increase in volume and microstructural complexity of specific white-matter tracts connecting regions that are fundamental to sound perception, production, and its feedforward and feedback control which can be differentiated from a more general musician effect.

Mixed acinar-neuroendocrine-ductal carcinoma of the pancreas: a tale of three lineages.

PubMed

Anderson, Mark J; Kwong, Christina A; Atieh, Mohammed; Pappas, Sam G

2016-06-02

Most pancreatic cancers arise from a single cell type, although mixed pancreatic carcinomas represent a rare exception. The rarity of these aggressive malignancies and the limitations of fine-needle aspiration (FNA) pose significant barriers to diagnosis and appropriate management. We report a case of a 54-year-old man presenting with abdominal pain, jaundice and a hypodense lesion within the uncinate process on CT. FNA suggested poorly differentiated adenocarcinoma, which was subsequently resected via pancreaticoduodenectomy. Pathological analysis yielded diagnosis of invasive mixed acinar-neuroendocrine-ductal pancreatic carcinoma. Given the rare and deadly nature of these tumours, clinicians must be aware of their pathophysiology and do practice with a high degree of clinical suspicion, when appropriate. Surgical resection and thorough pathological analysis with immunohistochemical staining and electron microscopy remain the standards of care for mixed pancreatic tumours without gross evidence of metastasis. Diligent characterisation of the presentation and histological findings associated with these neoplasms should continue in order to promote optimal diagnostic and therapeutic strategies. 2016 BMJ Publishing Group Ltd.

[Measurement of pancreatic microcirculation using hydrogen gas generated by electrolysis in dogs].

PubMed

Nishiwaki, H; Satake, K; Ko, I; Tanaka, H; Kanazawa, G; Nagai, Y; Umeyama, K

1986-11-01

Measurements of pancreatic microflow were investigated using hydrogen gas generated by electrolysis in dog. After laparatomy under general anesthesia, uncinate process of the pancreas was punctured by a needle electrode for electrolysis and determination of hydrogen gas. The consecutive measurements of pancreatic microflow revealed the good reproducibility at the same point of the pancreas. The simultaneous measurements of pancreatic microflow by electrolysis and pancreatic tissue blood flow by H2 inhalation method were carried out at the same point of the pancreas. Correlation analysis of both measurements revealed coefficient of 0.751 and a significant relationship was observed (p less than 0.05). However, the value was a little higher in pancreatic microflow as compared with pancreatic tissue blood flow. Pancreatic microflow and pancreatic exocrine secretion increased after intravenous administration of Dopamine and Secretin (10 micrograms/kg/min). It is concluded that the measurement of pancreatic microflow by hydrogen gas generated by electrolysis is a useful method on understanding the microcirculation of the pancreas.

Effects of low-level sarin and cyclosarin exposure on white matter integrity in Gulf War Veterans.

PubMed

Chao, Linda L; Zhang, Yu; Buckley, Shannon

2015-05-01

We previously found evidence of reduced gray and white matter volume in Gulf War (GW) veterans with predicted low-level exposure to sarin (GB) and cyclosarin (GF). Because loss of white matter tissue integrity has been linked to both gray and white matter atrophy, the current study sought to test the hypothesis that GW veterans with predicted GB/GF exposure have evidence of disrupted white matter microstructural integrity. Measures of fractional anisotropy and directional (i.e., axial and radial) diffusivity were assessed from the 4T diffusion tensor images (DTI) of 59 GW veterans with predicted GB/GF exposure and 59 "matched" unexposed GW veterans (mean age: 48 ± 7 years). The DTI data were analyzed using regions of interest (ROI) analyses that accounted for age, sex, total brain gray and white matter volume, trauma exposure, posttraumatic stress disorder, current major depression, and chronic multisymptom illness status. There were no significant group differences in fractional anisotropy or radial diffusivity. However, there was increased axial diffusivity in GW veterans with predicted GB/GF exposure compared to matched, unexposed veterans throughout the brain, including the temporal stem, corona radiata, superior and inferior (hippocampal) cingulum, inferior and superior fronto-occipital fasciculus, internal and external capsule, and superficial cortical white matter blades. Post hoc analysis revealed significant correlations between higher fractional anisotropy and lower radial diffusivity with better neurobehavioral performance in unexposed GW veterans. In contrast, only increased axial diffusivity in posterior limb of the internal capsule was associated with better psychomotor function in GW veterans with predicted GB/GF exposure. The finding that increased axial diffusivity in a region of the brain that contains descending corticospinal fibers was associated with better psychomotor function and the lack of significant neurobehavioral deficits in veterans with predicted GB/GF exposure hint at the possibility that the widespread increases in axial diffusivity that we observed in GW veterans with predicted GB/GF exposure relative to unexposed controls may reflect white matter reorganization after brain injury (i.e., exposure to GB/GF). Published by Elsevier B.V.

Delayed Development of Brain Connectivity in Adolescents With Schizophrenia and Their Unaffected Siblings.

PubMed

Zalesky, Andrew; Pantelis, Christos; Cropley, Vanessa; Fornito, Alex; Cocchi, Luca; McAdams, Harrison; Clasen, Liv; Greenstein, Deanna; Rapoport, Judith L; Gogtay, Nitin

2015-09-01

Abnormalities in structural brain connectivity have been observed in patients with schizophrenia. Mapping these abnormalities longitudinally and understanding their genetic risk via sibship studies will provide crucial insight into progressive developmental changes associated with schizophrenia. To identify corticocortical connections exhibiting an altered developmental trajectory in adolescents with childhood-onset schizophrenia (COS) and to determine whether similar alterations are found in patients' unaffected siblings. Using prospective structural brain magnetic resonance imaging, large-scale corticocortical connectivity was mapped from ages 12 to 24 years in 109 patients with COS (272 images), 86 of their unaffected siblings (184 images), and 102 healthy controls (262 images) over a 20-year period beginning January 1, 1991, through April 30, 2011, as part of the ongoing COS study at the National Institute of Mental Health. Structural connectivity between pairs of cortical regions was estimated using a validated technique based on across-subject covariation in magnetic resonance imaging-derived cortical thickness measurements. Compared with normally developing controls, significant left-hemisphere occipitotemporal deficits in cortical thickness correlations were found in patients with COS as well as their healthy siblings (P < .05). Deficits in siblings normalized by mid-adolescence, whereas patients with COS showed significantly longer maturational delays, with cortical thickness correlations between the left temporal lobe and left occipital cortex not showing evidence of development until early adulthood. The normalization of deficits with age in patients with COS correlated with improvement in symptoms. Compared with controls, left-hemisphere occipitotemporal thickness correlations in a subgroup of patients with high positive symptoms were significantly reduced from age 14 to 18 years (P < .05); however, other patients with low positive symptoms showed no significant deficits. Delayed maturation of occipitotemporal connectivity appears to be a trait marker in patients with COS, with a milder endophenotype in unaffected siblings associated with resilience to developing schizophrenia. These findings indicate genetically influenced and connection-specific developmental abnormalities in the schizophrenia connectome, and lead to the hypothesis that visual hallucinations in patients with COS may be because of delayed development of the inferior longitudinal fasciculus, a prominent occipitotemporal fiber.

Cognitive processes and neural basis of language switching: proposal of a new model.

PubMed

Moritz-Gasser, Sylvie; Duffau, Hugues

2009-12-09

Although studies on bilingualism are abundant, cognitive processes and neural foundations of language switching received less attention. The aim of our study is to provide new insights to this still open question: do dedicated region(s) for language switching exist or is this function underlain by a distributed circuit of interconnected brain areas, part of a more general cognitive system? On the basis of recent behavioral, neuroimaging, and brain stimulation studies, we propose an original 'hodological' model of language switching. This process might be subserved by a large-scale cortico-subcortical network, with an executive system (prefrontal cortex, anterior cingulum, caudate nucleus) controlling a more dedicated language subcircuit, which involves postero-temporal areas, supramarginal and angular gyri, Broca's area, and the superior longitudinal fasciculus.

White matter lesional predictors of chronic visual neglect: a longitudinal study

PubMed Central

Lunven, Marine; Thiebaut De Schotten, Michel; Bourlon, Clémence; Duret, Christophe; Migliaccio, Raffaella; Rode, Gilles

2015-01-01

Chronic visual neglect prevents brain-damaged patients from returning to an independent and active life. Detecting predictors of persistent neglect as early as possible after the stroke is therefore crucial to plan the relevant interventions. Neglect signs do not only depend on focal brain lesions, but also on dysfunction of large-scale brain networks connected by white matter bundles. We explored the relationship between markers of axonal degeneration occurring after the stroke and visual neglect chronicity. A group of 45 patients with unilateral strokes in the right hemisphere underwent cognitive testing for neglect twice, first at the subacute phase (<3 months after onset) and then at the chronic phase (>1 year). For each patient, magnetic resonance imaging including diffusion sequences was performed at least 4 months after the stroke. After masking each patient’s lesion, we used tract-based spatial statistics to obtain a voxel-wise statistical analysis of the fractional anisotropy data. Twenty-seven patients had signs of visual neglect at initial testing. Only 10 of these patients had recovered from neglect at follow-up. When compared with patients without neglect, the group including all subacute neglect patients had decreased fractional anisotropy in the second (II) and third (III) branches of the right superior longitudinal fasciculus, as well as in the splenium of the corpus callosum. The subgroup of chronic patients showed reduced fractional anisotropy in a portion the splenium, the forceps major, which provides interhemispheric communication between regions of the occipital lobe and of the superior parietal lobules. The severity of neglect correlated with fractional anisotropy values in superior longitudinal fasciculus II/III for subacute patients and in its caudal portion for chronic patients. Our results confirm a key role of fronto-parietal disconnection in the emergence and chronic persistence of neglect, and demonstrate an implication of caudal interhemispheric disconnection in chronic neglect. Splenial disconnection may prevent fronto-parietal networks in the left hemisphere from resolving the activity imbalance with their right hemisphere counterparts, thus leading to persistent neglect. PMID:25609686

Altered Structural and Functional Connectivity in Late Preterm Preadolescence: An Anatomic Seed-Based Study of Resting State Networks Related to the Posteromedial and Lateral Parietal Cortex

PubMed Central

Degnan, Andrew J.; Wisnowski, Jessica L.; Choi, SoYoung; Ceschin, Rafael; Bhushan, Chitresh; Leahy, Richard M.; Corby, Patricia; Schmithorst, Vincent J.; Panigrahy, Ashok

2015-01-01

Objective Late preterm birth confers increased risk of developmental delay, academic difficulties and social deficits. The late third trimester may represent a critical period of development of neural networks including the default mode network (DMN), which is essential to normal cognition. Our objective is to identify functional and structural connectivity differences in the posteromedial cortex related to late preterm birth. Methods Thirty-eight preadolescents (ages 9–13; 19 born in the late preterm period (≥32 weeks gestational age) and 19 at term) without access to advanced neonatal care were recruited from a low socioeconomic status community in Brazil. Participants underwent neurocognitive testing, 3-dimensional T1-weighted imaging, diffusion-weighted imaging and resting state functional MRI (RS-fMRI). Seed-based probabilistic diffusion tractography and RS-fMRI analyses were performed using unilateral seeds within the posterior DMN (posterior cingulate cortex, precuneus) and lateral parietal DMN (superior marginal and angular gyri). Results Late preterm children demonstrated increased functional connectivity within the posterior default mode networks and increased anti-correlation with the central-executive network when seeded from the posteromedial cortex (PMC). Key differences were demonstrated between PMC components with increased anti-correlation with the salience network seen only with posterior cingulate cortex seeding but not with precuneus seeding. Probabilistic tractography showed increased streamlines within the right inferior longitudinal fasciculus and inferior fronto-occipital fasciculus within late preterm children while decreased intrahemispheric streamlines were also observed. No significant differences in neurocognitive testing were demonstrated between groups. Conclusion Late preterm preadolescence is associated with altered functional connectivity from the PMC and lateral parietal cortex to known distributed functional cortical networks despite no significant executive neurocognitive differences. Selective increased structural connectivity was observed in the setting of decreased posterior interhemispheric connections. Future work is needed to determine if these findings represent a compensatory adaptation employing alternate neural circuitry or could reflect subtle pathology resulting in emotional processing deficits not seen with neurocognitive testing. PMID:26098888

White Matter Tract Integrity in Alzheimer's Disease vs. Late Onset Bipolar Disorder and Its Correlation with Systemic Inflammation and Oxidative Stress Biomarkers.

PubMed

Besga, Ariadna; Chyzhyk, Darya; Gonzalez-Ortega, Itxaso; Echeveste, Jon; Graña-Lecuona, Marina; Graña, Manuel; Gonzalez-Pinto, Ana

2017-01-01

Background: Late Onset Bipolar Disorder (LOBD) is the development of Bipolar Disorder (BD) at an age above 50 years old. It is often difficult to differentiate from other aging dementias, such as Alzheimer's Disease (AD), because they share cognitive and behavioral impairment symptoms. Objectives: We look for WM tract voxel clusters showing significant differences when comparing of AD vs. LOBD, and its correlations with systemic blood plasma biomarkers (inflammatory, neurotrophic factors, and oxidative stress). Materials: A sample of healthy controls (HC) ( n = 19), AD patients ( n = 35), and LOBD patients ( n = 24) was recruited at the Alava University Hospital. Blood plasma samples were obtained at recruitment time and analyzed to extract the inflammatory, oxidative stress, and neurotrophic factors. Several modalities of MRI were acquired for each subject, Methods: Fractional anisotropy (FA) coefficients are obtained from diffusion weighted imaging (DWI). Tract based spatial statistics (TBSS) finds FA skeleton clusters of WM tract voxels showing significant differences for all possible contrasts between HC, AD, and LOBD. An ANOVA F -test over all contrasts is carried out. Results of F -test are used to mask TBSS detected clusters for the AD > LOBD and LOBD > AD contrast to select the image clusters used for correlation analysis. Finally, Pearson's correlation coefficients between FA values at cluster sites and systemic blood plasma biomarker values are computed. Results: The TBSS contrasts with by ANOVA F -test has identified strongly significant clusters in the forceps minor, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, and cingulum gyrus. The correlation analysis of these tract clusters found strong negative correlation of AD with the nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF) blood biomarkers. Negative correlation of AD and positive correlation of LOBD with inflammation biomarker IL6 was also found. Conclusion: TBSS voxel clusters tract atlas localizations are consistent with greater behavioral impairment and mood disorders in LOBD than in AD. Correlation analysis confirms that neurotrophic factors (i.e., NGF, BDNF) play a great role in AD while are absent in LOBD pathophysiology. Also, correlation results of IL1 and IL6 suggest stronger inflammatory effects in LOBD than in AD.

Gray-white matter and cerebrospinal fluid volume differences in children with Specific Language Impairment and/or Reading Disability.

PubMed

Girbau-Massana, Dolors; Garcia-Marti, Gracian; Marti-Bonmati, Luis; Schwartz, Richard G

2014-04-01

We studied gray-white matter and cerebrospinal fluid (CSF) alterations that may be critical for language, through an optimized voxel-based morphometry evaluation in children with Specific Language Impairment (SLI), compared to Typical Language Development (TLD). Ten children with SLI (8;5-10;9) and 14 children with TLD (8;2-11;8) participated. They received a comprehensive language and reading test battery. We also analyzed a subgroup of six children with SLI+RD (Reading Disability). Brain images from 3-Tesla MRIs were analyzed with intelligence, age, gender, and total intracranial volume as covariates. Children with SLI or SLI+RD exhibited a significant lower overall gray matter volume than children with TLD. Particularly, children with SLI showed a significantly lower volume of gray matter compared to children with TLD in the right postcentral parietal gyrus (BA4), and left and right medial occipital gyri (BA19). The group with SLI also exhibited a significantly greater volume of gray matter in the right superior occipital gyrus (BA19), which may reflect a brain reorganization to compensate for their lower volumes at medial occipital gyri. Children with SLI+RD, compared to children with TLD, showed a significantly lower volume of: (a) gray matter in the right postcentral parietal gyrus; and (b) white matter in the right inferior longitudinal fasciculus (RILF), which interconnects the temporal and occipital lobes. Children with TLD exhibited a significantly lower CSF volume than children with SLI and children with SLI+RD respectively, who had somewhat smaller volumes of gray matter allowing for more CSF volume. The significant lower gray matter volume at the right postcentral parietal gyrus and greater cerebrospinal fluid volume may prove to be unique markers for SLI. We discuss the association of poor knowledge/visual representations and language input to brain development. Our comorbid study showed that a significant lower volume of white matter in the right inferior longitudinal fasciculus may be unique to children with SLI and Reading Disability. It was significantly associated to reading comprehension of sentences and receptive language composite z-score, especially receptive vocabulary and oral comprehension of stories. Copyright © 2014 Elsevier Ltd. All rights reserved.

The DCDC2/intron 2 deletion and white matter disorganization: focus on developmental dyslexia.

PubMed

Marino, Cecilia; Scifo, Paola; Della Rosa, Pasquale A; Mascheretti, Sara; Facoetti, Andrea; Lorusso, Maria L; Giorda, Roberto; Consonni, Monica; Falini, Andrea; Molteni, Massimo; Gruen, Jeffrey R; Perani, Daniela

2014-08-01

The DCDC2 gene is involved in neuronal migration. Heterotopias have been found within the white matter of DCDC2-knockdown rats. A deletion in DCDC2/intron 2 (DCDC2d), which encompasses a regulatory region named 'regulatory element associated with dyslexia 1' (READ1), increases the risk for dyslexia. We hypothesized that DCDC2d can be associated to alterations of the white matter structure in general and in dyslexic brains. Based on a full-factorial analysis of covariance (ANCOVA) model, we investigated voxel-based diffusion tensor imaging (VB-DTI) data of four groups of subjects: dyslexia with/without DCDC2d, and normal readers with/without DCDC2d. We also tested DCDC2d effects upon correlation patterns between fractional anisotropy (FA) and reading scores. We found that FA was reduced in the left arcuate fasciculus and splenium of the corpus callosum in subjects with versus without DCDC2d, irrespective of dyslexia. Subjects with dyslexia and DCDC2d showed reduced FA, mainly in the left hemisphere and in the corpus callosum; their counterpart without DCDC2d showed similar FA alterations. Noteworthy, a conjunction analysis in impaired readers revealed common regions with lower FA mainly in the left hemisphere. When we compared subjects with dyslexia with versus without DCDC2d, we found lower FA in the inferior longitudinal fasciculus and genu of the corpus callosum, bilaterally. Normal readers with versus without DCDC2d had FA increases and decreases in both the right and left hemisphere. The major contribution of our study was to provide evidence relating genes, brain and behaviour. Overall, our findings support the hypothesis that DCDC2d is associated with altered FA. In normal readers, DCDC2-related anatomical patterns may mark some developmental cognitive vulnerability to learning disabilities. In subjects with dyslexia, DCDC2d accounted for both common - mainly located in the left hemisphere - and unique - a more severe and extended pattern - alterations of white matter fibre tracts. Copyright © 2014 Elsevier Ltd. All rights reserved.

Altered white matter development in children born very preterm.

PubMed

Young, Julia M; Vandewouw, Marlee M; Morgan, Benjamin R; Smith, Mary Lou; Sled, John G; Taylor, Margot J

2018-06-01

Children born very preterm (VPT) at less than 32 weeks' gestational age (GA) are prone to disrupted white matter maturation and impaired cognitive development. The aims of the present study were to identify differences in white matter microstructure and connectivity of children born VPT compared to term-born children, as well as relations between white matter measures with cognitive outcomes and early brain injury. Diffusion images and T1-weighted anatomical MR images were acquired along with developmental assessments in 31 VPT children (mean GA: 28.76 weeks) and 28 term-born children at 4 years of age. FSL's tract-based spatial statistics was used to create a cohort-specific template and mean fractional anisotropy (FA) skeleton that was applied to each child's DTI data. Whole brain deterministic tractography was performed and graph theoretical measures of connectivity were calculated based on the number of streamlines between cortical and subcortical nodes derived from the Desikan-Killiany atlas. Between-group analyses included FSL Randomise for voxel-wise statistics and permutation testing for connectivity analyses. Within-group analyses between FA values and graph measures with IQ, language and visual-motor scores as well as history of white matter injury (WMI) and germinal matrix/intraventricular haemorrhage (GMH/IVH) were performed. In the children born VPT, FA values within major white matter tracts were reduced compared to term-born children. Reduced measures of local strength, clustering coefficient, local and global efficiency were present in the children born VPT within nodes in the lateral frontal, middle and superior temporal, cingulate, precuneus and lateral occipital regions. Within-group analyses revealed associations in term-born children between FA, Verbal IQ, Performance IQ and Full scale IQ within regions of the superior longitudinal fasciculus, inferior fronto-occipital fasciculus, forceps minor and forceps major. No associations with outcome were found in the VPT group. Global efficiency was reduced in the children born VPT with a history of WMI and GMH/IVH. These findings are evidence for under-developed and less connected white matter in children born VPT, contributing to our understanding of white matter development within this population.

The Dorsal Rather than Ventral Pathway Better Reflects Individual Syntactic Abilities in Second Language

PubMed Central

Yamamoto, Kayako; Sakai, Kuniyoshi L.

2016-01-01

The left inferior frontal gyrus (IFG) has been reported to be critically involved in syntactic processing, not only in first language (L1), but in second language (L2). Indeed, the leftward lateralization of the IFG has been shown to be correlated with the performance of a syntactic task in L2. Given that posterior language-related regions are systematically connected with the left IFG, the next question is which of the dorsal and ventral pathways is more critical to the individual syntactic abilities in L2. Here we used diffusion magnetic resonance imaging (MRI) and tractography with newly developed semi-automatic methods of defining seeds and selecting regions of interest (ROIs). We calculated mean thickness and fractional anisotropy (FA) in each ROI for the arcuate fasciculus (Arcuate) of the dorsal pathway, as well as for the inferior fronto-occipital fasciculus (IFOF) of the ventral pathway. In Experiment I, we performed partial correlation analyses between FA and the accuracy of the syntactic task, removing the effects of the accuracy of a spelling task, gender, and handedness. Among the two pathways in each hemisphere, only FA of the left Arcuate was significantly correlated with individual accuracy of the syntactic task. In Experiment II, we recruited monozygotic twins and examined to what extent their L2 abilities and their structural properties were similar. Within twin pairs, the highest significant correlation was observed for reaction times of the spelling task, while the correlation for the accuracy of the syntactic task was marginal; these two correlation coefficients were significantly different. Moreover, the thickness of the left Arcuate was highly correlated within pairs, while its FA, as well as the thickness/FA in the ventral pathways, was not significantly correlated. The correlation coefficient for the thickness of the left Arcuate was significantly larger than that of the left IFOF. These results suggest that the thickness of the left Arcuate is more associated with the shared genetic/environmental factors, whereas both of mutually correlated FA in the left Arcuate and individual syntactic abilities in L2 may be less prone to these shared factors. PMID:27378889

Brain microstructural development at near-term age in very-low-birth-weight preterm infants: An atlas-based diffusion imaging study

PubMed Central

Rose, Jessica; Vassar, Rachel; Cahill-Rowley, Katelyn; Guzman, Ximena Stecher; Stevenson, David K.; Barnea-Goraly, Naama

2014-01-01

At near-term age the brain undergoes rapid growth and development. Abnormalities identified during this period have been recognized as potential predictors of neurodevelopment in children born preterm. This study used diffusion tensor imaging (DTI) to examine white matter (WM) microstructure in very-low-birth-weight (VLBW) preterm infants to better understand regional WM developmental trajectories at near-term age. DTI scans were analyzed in a cross-sectional sample of 45 VLBW preterm infants (BW ≤ 1500 g, GA ≤ 32 weeks) within a cohort of 102 neonates admitted to the NICU and recruited to participate prior to standard-of-care MRI, from 2010 to 2011, 66/102 also had DTI. For inclusion in this analysis, 45 infants had DTI, no evidence of brain abnormality on MRI, and were scanned at PMA ≤40 weeks (34.7–38.6). White matter microstructure was analyzed in 19 subcortical regions defined by DiffeoMap neonatal brain atlas, using threshold values of trace b0.006 mm2 s−1 and FA >0.15. Regional fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were calculated and temporal–spatial trajectories of development were examined in relation to PMA and brain region location. Posterior regions within the corona radiata (CR), corpus callosum (CC), and internal capsule (IC) demonstrated significantly higher mean FA values compared to anterior regions. Posterior regions of the CR and IC demonstrated significantly lower RD values compared to anterior regions. Centrally located projection fibers demonstrated higher mean FA and lower RD values than peripheral regions including the posterior limb of the internal capsule (PLIC), cerebral peduncle, retrolenticular part of the IC, posterior thalamic radiation, and sagittal stratum. Centrally located association fibers of the external capsule had higher FA and lower RD than the more peripherally-located superior longitudinal fasciculus (SLF). A significant relationship between PMA-at-scan and FA, MD, and RD was demonstrated by a majority of regions, the strongest correlations were observed in the anterior limb of the internal capsule, a region undergoing early stages of myelination at near-term age, in which FA increased (r = .433, p = .003) and MD (r = –.545, p = .000) and RD (r = –.540, p = .000) decreased with PMA-at-scan. No correlation with PMA-at-scan was observed in the CC or SLF, regions that myelinate later in infancy. Regional patterns of higher FA and lower RD were observed at this near-term age, suggestive of more advanced microstructural development in posterior compared to anterior regions within the CR, CC, and IC and in central compared to peripheral WM structures. Evidence of region-specific rates of microstructural development was observed. Temporal–spatial patterns of WM microstructure development at near-term age have important implications for interpretation of near-term DTI and for identification of aberrations in typical developmental trajectories that may signal future impairment. PMID:24091089

Brain microstructural development at near-term age in very-low-birth-weight preterm infants: an atlas-based diffusion imaging study.

PubMed

Rose, Jessica; Vassar, Rachel; Cahill-Rowley, Katelyn; Guzman, Ximena Stecher; Stevenson, David K; Barnea-Goraly, Naama

2014-02-01

At near-term age the brain undergoes rapid growth and development. Abnormalities identified during this period have been recognized as potential predictors of neurodevelopment in children born preterm. This study used diffusion tensor imaging (DTI) to examine white matter (WM) microstructure in very-low-birth-weight (VLBW) preterm infants to better understand regional WM developmental trajectories at near-term age. DTI scans were analyzed in a cross-sectional sample of 45 VLBW preterm infants (BW≤1500g, GA≤32weeks) within a cohort of 102 neonates admitted to the NICU and recruited to participate prior to standard-of-care MRI, from 2010 to 2011, 66/102 also had DTI. For inclusion in this analysis, 45 infants had DTI, no evidence of brain abnormality on MRI, and were scanned at PMA ≤40weeks (34.7-38.6). White matter microstructure was analyzed in 19 subcortical regions defined by DiffeoMap neonatal brain atlas, using threshold values of trace <0.006mm(2)s(-1) and FA >0.15. Regional fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were calculated and temporal-spatial trajectories of development were examined in relation to PMA and brain region location. Posterior regions within the corona radiata (CR), corpus callosum (CC), and internal capsule (IC) demonstrated significantly higher mean FA values compared to anterior regions. Posterior regions of the CR and IC demonstrated significantly lower RD values compared to anterior regions. Centrally located projection fibers demonstrated higher mean FA and lower RD values than peripheral regions including the posterior limb of the internal capsule (PLIC), cerebral peduncle, retrolenticular part of the IC, posterior thalamic radiation, and sagittal stratum. Centrally located association fibers of the external capsule had higher FA and lower RD than the more peripherally-located superior longitudinal fasciculus (SLF). A significant relationship between PMA-at-scan and FA, MD, and RD was demonstrated by a majority of regions, the strongest correlations were observed in the anterior limb of the internal capsule, a region undergoing early stages of myelination at near-term age, in which FA increased (r=.433, p=.003) and MD (r=-.545, p=.000) and RD (r=-.540, p=.000) decreased with PMA-at-scan. No correlation with PMA-at-scan was observed in the CC or SLF, regions that myelinate later in infancy. Regional patterns of higher FA and lower RD were observed at this near-term age, suggestive of more advanced microstructural development in posterior compared to anterior regions within the CR, CC, and IC and in central compared to peripheral WM structures. Evidence of region-specific rates of microstructural development was observed. Temporal-spatial patterns of WM microstructure development at near-term age have important implications for interpretation of near-term DTI and for identification of aberrations in typical developmental trajectories that may signal future impairment. © 2013.

Mesopancreas: myth or reality?

PubMed

Agrawal, Manish K; Thakur, Dilip Singh; Somashekar, Uday; Chandrakar, Shiv Kumar; Sharma, Dhananjaya

2010-05-05

A recently published study hypothesized the concept of 'mesopancreas', defining it as a firm, well-vascularized structure extending from the posterior surface of the pancreatic head to behind the mesenteric vessels. To verify and define mesopancreas from resection specimens obtained from fresh cadavers. Postmortem anatomical-pathological study. Department of Surgery in conjunction with the Departments of Forensic Medicine and Pathology, Government Medical College and Hospital, Jabalpur, MP, India. Twenty fresh adult cadavers without any intra-abdominal injury or gross intra-abdominal pathology. Specimens containing the entire duodenum, pancreatic head and neck, gallbladder, cystic duct, common bile duct, superior mesenteric vessels, inferior vena cava and aorta were removed en-bloc. Gross and histopathological examinations of the specimens were carried out. To look for a fibrous sheath or fascia around the retropancreatic structure purported to be a mesopancreas. Loose areolar tissue, adipose tissue, peripheral nerve, nerve plexus, lymphatic and capillaries were found in the retropancreatic tissue, extending from the head, neck and uncinate process of pancreas to the aorto-caval groove but no fibrous sheath or fascia was found around these structures. The concept of 'mesopancreas' is anatomically unfounded.

Simplified pancreatoduodenectomy for complex blunt pancreaticoduodenal injury.

PubMed

Feng, Xin-Fu; Fan, Wei; Shi, Cheng-Xian; Li, Jun-Hua; Liu, Jun; Liu, Zhen-Hua

2013-01-01

A 34-year-old man admitted to our department with complex blunt pancreaticoduodenal injury after a car accident. The wall of the first, second, and third portions of the duodenum was extensively lacerated, and the pancreas was longitudinally transected along the superior mesenteric vein-portal vein trunk. The pancreatic head and the uncinate process were devitalized and the distal common bile duct and the proximal main pancreatic duct were completely detached from the Vater ampulla. The length of the stump of distal common bile located at the cut surface of remnant pancreas was approximately 0.6 cm. A simplified Kausch-Whipple's procedure was performed after debridement of the devitalized pancreatic head and resection of the damaged duodenum in which the stump of distal common bile duct and the pancreatic remnant were embedded into the jejunal loop. Postoperative wound abscess appeared that eventually recovered by conservative treatment. During 16 months follow-up the patient has been stable and healthy. A simplified pancreaticoduodenectomy is a safe alternative for the Whipple procedure in managing complex pancreaticoduodenal injury in a hemodynamically stable patient.

Concurrent white and gray matter degeneration of disease-specific networks in early-stage Alzheimer's disease and behavioral variant frontotemporal dementia.

PubMed

Steketee, Rebecca M E; Meijboom, Rozanna; de Groot, Marius; Bron, Esther E; Niessen, Wiro J; van der Lugt, Aad; van Swieten, John C; Smits, Marion

2016-07-01

This study investigates regional coherence between white matter (WM) microstructure and gray matter (GM) volume and perfusion measures in Alzheimer's disease (AD) and behavioral variant frontotemporal dementia (bvFTD) using a correlational approach. WM-GM coherence, compared with controls, was stronger between cingulum WM and frontotemporal GM in AD, and temporoparietal GM in bvFTD. In addition, in AD compared with controls, coherence was stronger between inferior fronto-occipital fasciculus WM microstructure and occipital GM perfusion. In this first study assessing regional WM-GM coherence in AD and bvFTD, we show that WM microstructure and GM volume and perfusion measures are coherent, particularly in regions implicated in AD and bvFTD pathology. This indicates concurrent degeneration in disease-specific networks. Our methodology allows for the detection of incipient abnormalities that go undetected in conventional between-group analyses. Copyright © 2016 Elsevier Inc. All rights reserved.

Studies on the pathogenesis of fixed rabies virus in rats*

PubMed Central

Baer, G. M.; Shanthaveerappa, T. R.; Bourne, G. H.

1965-01-01

Investigations were made on the spread of fixed rabies virus after its inoculation into the rear foot-pads of rats. The presence of rabies virus in the central nervous system was first detected in the lumbar segment of the spinal cord. Removal of the sciatic nerve or of its fasciculus, either before or soon after challenge, drastically lowered mortality, thus giving evidence of a rapid neural spread of the infection. Neither the perineural structures nor the axons appeared to be involved. Although the presence of virus in the sciatic nerves was first demonstrated by the development of neutralizing antibodies in the serum of rats ”immunized” by multiple injections of nerve material from rats killed 48 hours after challenge, resection of nerves had to be carried out long before that time to be effective in preventing viral progression. ImagesFIG. 1FIG. 2-5 PMID:5295402

Projections from the rostral mesencephalic reticular formation to the spinal cord - An HRP and autoradiographical tracing study in the cat

NASA Technical Reports Server (NTRS)

Holstege, G.; Cowie, R. J.

1989-01-01

Horseradish peroxidase was injected, or implanted unilaterally, into various levels of the spinal cord of anesthetized cats, to trace the distribution of projections to the spinal cord, of neurons in Field H of Forel, including the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF), and the interstitial nucleus of Cajal with adjacent reticular formation (INC-RF). Results indicate that, unlike the neurons projecting to the extraocular muscle motoneurons, the major portion of the spinally projecting neurons are not located in the riMLF or INC proper, but in adjacent areas, i.e., the ventral and lateral parts of the caudal third of the Field H of Forel and in the INC-RF. Neurons in caudal Field H of Forel, project, via the ventral part of the ventral funicululs, to the lateral part of the upper cervical ventral horn.

Chronic spatial working memory deficit associated with the superior longitudinal fasciculus: a study using voxel-based lesion-symptom mapping and intraoperative direct stimulation in right prefrontal glioma surgery.

PubMed

Kinoshita, Masashi; Nakajima, Riho; Shinohara, Harumichi; Miyashita, Katsuyoshi; Tanaka, Shingo; Okita, Hirokazu; Nakada, Mitsutoshi; Hayashi, Yutaka

2016-10-01

OBJECTIVE Although the right prefrontal region is regarded as a silent area, chronic deficits of the executive function, including working memory (WM), could occur after resection of a right prefrontal glioma. This may be overlooked by postoperative standard examinations, and the disabilities could affect the patient's professional life. The right prefrontal region is a part of the frontoparietal network and is subserved by the superior longitudinal fasciculus (SLF); however, the role of the SLF in spatial WM is unclear. This study investigated a persistent spatial WM deficit in patients who underwent right prefrontal glioma resection, and evaluated the relationship between the spatial WM deficit and the SLF. METHODS Spatial WM was examined in 24 patients who underwent prefrontal glioma resection (right, n = 14; left, n = 10) and in 14 healthy volunteers using a spatial 2-back task during the long-term postoperative period. The neural correlates of spatial WM were evaluated using lesion mapping and voxel-based lesion-symptom mapping. In addition, the spatial 2-back task was performed during surgery under direct subcortical electrical stimulation in 2 patients with right prefrontal gliomas. RESULTS Patients with a right prefrontal lesion had a significant chronic spatial WM deficit. Voxel-based lesion-symptom mapping analysis revealed a significant correlation between spatial WM deficit and the region that overlapped the first and second segments of the SLF (SLF I and SLF II). Two patients underwent awake surgery and had difficulties providing the correct responses in the spatial 2-back task with direct subcortical electrical stimulation on the SLF I, which was preserved and confirmed by postoperative diffusion tensor imaging tractography. These patients exhibited no spatial WM deficits during the postoperative immediate and long-term periods. CONCLUSIONS Spatial WM deficits may persist in patients who undergo resection of the tumor located in the right prefrontal brain parenchyma. Injury to the dorsal frontoparietal subcortical white matter pathway, i.e., the SLF I or SLF I and II, could play a causal role in this chronic deficit. A persistent spatial WM deficit, without motor and language deficits, could affect the professional life of the patient. In such cases, awake surgery would be useful to detect the spatial WM network with appropriate task during tumor exploration.

White Matter Integrity and Treatment-Based Change in Speech Performance in Minimally Verbal Children with Autism Spectrum Disorder.

PubMed

Chenausky, Karen; Kernbach, Julius; Norton, Andrea; Schlaug, Gottfried

2017-01-01

We investigated the relationship between imaging variables for two language/speech-motor tracts and speech fluency variables in 10 minimally verbal (MV) children with autism. Specifically, we tested whether measures of white matter integrity-fractional anisotropy (FA) of the arcuate fasciculus (AF) and frontal aslant tract (FAT)-were related to change in percent syllable-initial consonants correct, percent items responded to, and percent syllable insertion errors (from best baseline to post 25 treatment sessions). Twenty-three MV children with autism spectrum disorder (ASD) received Auditory-Motor Mapping Training (AMMT), an intonation-based treatment to improve fluency in spoken output, and we report on seven who received a matched control treatment. Ten of the AMMT participants were able to undergo a magnetic resonance imaging study at baseline; their performance on baseline speech production measures is compared to that of the other two groups. No baseline differences were found between groups. A canonical correlation analysis (CCA) relating FA values for left- and right-hemisphere AF and FAT to speech production measures showed that FA of the left AF and right FAT were the largest contributors to the synthetic independent imaging-related variable. Change in percent syllable-initial consonants correct and percent syllable-insertion errors were the largest contributors to the synthetic dependent fluency-related variable. Regression analyses showed that FA values in left AF significantly predicted change in percent syllable-initial consonants correct, no FA variables significantly predicted change in percent items responded to, and FA of right FAT significantly predicted change in percent syllable-insertion errors. Results are consistent with previously identified roles for the AF in mediating bidirectional mapping between articulation and acoustics, and the FAT in its relationship to speech initiation and fluency. They further suggest a division of labor between the hemispheres, implicating the left hemisphere in accuracy of speech production and the right hemisphere in fluency in this population. Changes in response rate are interpreted as stemming from factors other than the integrity of these two fiber tracts. This study is the first to document the existence of a subgroup of MV children who experience increases in syllable- insertion errors as their speech develops in response to therapy.

relationship between diffusion tensor imaging findings and cognitive outcomes following adult traumatic brain injury: A meta-analysis.

PubMed

Wallace, E J; Mathias, J L; Ward, L

2018-05-24

Cognitive impairments are common following a traumatic brain injury (TBI) and frequently result from white matter (WM) damage. This damage can be quantified using diffusion tensor imaging (DTI), which measures the directionality (fractional anisotropy: FA) and amount (mean diffusivity/apparent diffusion coefficient: MD/ADC) of water diffusion in WM, with high FA and low MD/ADC thought to indicate greater WM integrity. However, the relationship between DTI and cognitive outcomes is currently unclear. The data from 20 studies that examined the relationship between WM integrity (measured using DTI) and cognition (categorised into seven domains) following mild-severe adult TBI were meta-analysed. Overall, high FA and low MD/ADC in most brain regions was associated with better cognitive performance, with memory and attention most strongly related to DTI findings. Specifically, memory and/or attention were very strongly related to DTI findings in the corpus callosum, fornix, internal capsule, arcuate and uncinate fasciculi. However, most findings were based on single studies and therefore await replication. Larger-scale, longitudinal studies are now needed to determine the predictive utility of DTI. Copyright © 2018. Published by Elsevier Ltd.

[Robot-assisted Pylorus-Preserving Partial Pancreaticoduodenectomy (Kausch-Whipple Procedure)].

PubMed

Aselmann, H; Egberts, J-H; Hinz, S; Jünemann, K-P; Becker, T

2016-04-01

The surgical treatment of pancreatic head tumours is one of the most complex procedures in general surgery. In contrast to colorectal surgery, minimally-invasive techniques are not very commonly applied in pancreatic surgery. Both the delicate dissection along peri- and retropancreatic vessels and the extrahepatic bile ducts and subsequent reconstruction are very demanding with rigid standard laparoscopic instruments. The 4-arm robotic surgery system with angled instruments, unidirectional movement of instruments with adjustable transmission, tremor elimination and a stable, surgeon-controlled 3D-HD view is a promising platform to overcome the limitations of standard laparoscopic surgery regarding precise dissection and reconstruction in pancreatic surgery. Pancreatic head resection for mixed-type IPMN of the pancreatic head. Robot-assisted, minimally-invasive pylorus-preserving pancreaticoduodenectomy (Kausch-Whipple procedure). The robotic approach is particularly suited for complex procedures such as pylorus-preserving pancreatic head resections. The fully robotic Kausch-Whipple procedure is technically feasible and safe. The advantages of the robotic system are apparent in the delicate dissection near vascular structures, in lymph node dissection, the precise dissection of the uncinate process and, especially, bile duct and pancreatic anastomosis. Georg Thieme Verlag KG Stuttgart · New York.

Topography of acute stroke in a sample of 439 right brain damaged patients.

PubMed

Sperber, Christoph; Karnath, Hans-Otto

2016-01-01

Knowledge of the typical lesion topography and volumetry is important for clinical stroke diagnosis as well as for anatomo-behavioral lesion mapping analyses. Here we used modern lesion analysis techniques to examine the naturally occurring lesion patterns caused by ischemic and by hemorrhagic infarcts in a large, representative acute stroke patient sample. Acute MR and CT imaging of 439 consecutively admitted right-hemispheric stroke patients from a well-defined catchment area suffering from ischemia (n = 367) or hemorrhage (n = 72) were normalized and mapped in reference to stereotaxic anatomical atlases. For ischemic infarcts, highest frequencies of stroke were observed in the insula, putamen, operculum and superior temporal cortex, as well as the inferior and superior occipito-frontal fascicles, superior longitudinal fascicle, uncinate fascicle, and the acoustic radiation. The maximum overlay of hemorrhages was located more posteriorly and more medially, involving posterior areas of the insula, Heschl's gyrus, and putamen. Lesion size was largest in frontal and anterior areas and lowest in subcortical and posterior areas. The large and unbiased sample of stroke patients used in the present study accumulated the different sub-patterns to identify the global topographic and volumetric pattern of right hemisphere stroke in humans.

Trauma pancreaticoduodenectomy for complex pancreaticoduodenal injury. Delayed reconstruction.

PubMed

Gupta, Vikas; Wig, Jai Dev; Garg, Harsh

2008-09-02

To assess the feasibility and safety of the delayed reconstruction approach in patients with complex pancreaticoduodenal injuries. Tertiary care center in Northern India. Five patients with complex pancreaticoduodenal injuries, three following blunt and two following penetrating injury. All patients underwent a pancreaticoduodenectomy. T-tube drainage of the common bile duct and external tube drainage of the pancreatic duct were established. A wide bore tube drain was left in the right upper abdomen. The postoperative course was uneventful in four patients. One patient died from coagulopathy on the 4th postoperative day. Delayed reconstruction was carried out in four patients. In one patient, a pancreaticojejunal anastomosis could not be performed. The postoperative period was uneventful and no patient had a biliary or a pancreatic leak. All four patients are well on follow-up. Delayed reconstruction in complex pancreaticoduodenal injuries is a feasible and viable option as was demonstrated by this study. Controlled external tube drainage of the bile and pancreatic ducts facilitates postoperative care and prevents on-going contamination of the peritoneal cavity with bile and pancreatic juice. Leaving behind the uncinate process shortens the operating time with less blood loss. Planned reconstruction is carried out once the inflammatory process has settled.

Hybrid Fiber Layup and Fiber-Reinforced Polymeric Composites Produced Therefrom

NASA Technical Reports Server (NTRS)

Barnell, Thomas J. (Inventor); Garrigan, Sean P. (Inventor); Rauscher, Michael D. (Inventor); Dietsch, Benjamin A. (Inventor); Cupp, Gary N. (Inventor)

2018-01-01

Embodiments of a hybrid fiber layup used to form a fiber-reinforced polymeric composite, and a fiber-reinforced polymeric composite produced therefrom are disclosed. The hybrid fiber layup comprises one or more dry fiber strips and one or more prepreg fiber strips arranged side by side within each layer, wherein the prepreg fiber strips comprise fiber material impregnated with polymer resin and the dry fiber strips comprise fiber material without impregnated polymer resin.

Fiber optic and laser sensors IX; Proceedings of the Meeting, Boston, MA, Sept. 3-5, 1991

NASA Technical Reports Server (NTRS)

Depaula, Ramon P. (Editor); Udd, Eric (Editor)

1991-01-01

The present volume on fiber-optic and laser sensors discusses industrial applications of fiber-optic sensors, fiber-optic temperature sensors, fiber-optic current sensors, fiber-optic pressure/displacement/vibration sensors, and generic fiber-optic systems. Attention is given to a fiber-sensor design for turbine engines, fiber-optic remote Fourier transform IR spectroscopy, near-IR fiber-optic temperature sensors, and an intensity-type fiber-optic electric current sensor. Topics addressed include fiber-optic magnetic field sensors based on the Faraday effect in new materials, diaphragm size and sensitivity for fiber-optic pressure sensors, a microbend pressure sensor for high-temperature environments, and linear position sensing by light exchange between two lossy waveguides. Also discussed are two-mode elliptical-core fiber sensors for measurement of strain and temperature, a fiber-optic interferometric X-ray dosimeter, fiber-optic interferometric sensors using multimode fibers, and optical fiber sensing of corona discharges.

Bonding Properties of Basalt Fiber and Strength Reduction According to Fiber Orientation.

PubMed

Choi, Jeong-Il; Lee, Bang Yeon

2015-09-30

The basalt fiber is a promising reinforcing fiber because it has a relatively higher tensile strength and a density similar to that of a concrete matrix as well as no corrosion possibility. This study investigated experimentally the bonding properties of basalt fiber with cementitious material as well as the effect of fiber orientation on the tensile strength of basalt fiber for evaluating basalt fiber's suitability as a reinforcing fiber. Single fiber pullout tests were performed and then the tensile strength of fiber was measured according to fiber orientation. The test results showed that basalt fiber has a strong chemical bond with the cementitious matrix, 1.88 times higher than that of polyvinyl alcohol fibers with it. However, other properties of basalt fiber such as slip-hardening coefficient and strength reduction coefficient were worse than PVA and polyethylene fibers in terms of fiber bridging capacity. Theoretical fiber-bridging curves showed that the basalt fiber reinforcing system has a higher cracking strength than the PVA fiber reinforcing system, but the reinforcing system showed softening behavior after cracking.

Study on Mechanical Properties of Hybrid Fiber Reinforced Concrete

NASA Astrophysics Data System (ADS)

He, Dongqing; Wu, Min; Jie, Pengyu

2017-12-01

Several common high elastic modulus fibers (steel fibers, basalt fibers, polyvinyl alcohol fibers) and low elastic modulus fibers (polypropylene fiber) are incorporated into the concrete, and its cube compressive strength, splitting tensile strength and flexural strength are studied. The test result and analysis demonstrate that single fiber and hybrid fiber will improve the integrity of the concrete at failure. The mechanical properties of hybrid steel fiber-polypropylene fiber reinforced concrete are excellent, and the cube compressive strength, splitting tensile strength and flexural strength respectively increase than plain concrete by 6.4%, 3.7%, 11.4%. Doped single basalt fiber or polypropylene fiber and basalt fibers hybrid has little effect on the mechanical properties of concrete. Polyvinyl alcohol fiber and polypropylene fiber hybrid exhibit ‘negative confounding effect’ on concrete, its splitting tensile and flexural strength respectively are reduced by 17.8% and 12.9% than the single-doped polyvinyl alcohol fiber concrete.

Longitudinal Changes in White Matter Fractional Anisotropy in Adult-Onset Niemann-Pick Disease Type C Patients Treated with Miglustat.

PubMed

Bowman, Elizabeth A; Velakoulis, Dennis; Desmond, Patricia; Walterfang, Mark

2018-01-01

Niemann-Pick disease type C (NPC) is a rare neurometabolic disorder resulting in impaired intracellular lipid trafficking. The only disease-modifying treatment currently available is miglustat, an iminosugar that inhibits the accumulation of lipid metabolites in neurons and other cells. This longitudinal diffusion tensor imaging (DTI) study examined how the rate of white matter change differed between treated and non-treated adult-onset NPC patient groups. Nine adult-onset NPC patients (seven undergoing treatment with miglustat, two not treated) underwent DTI neuroimaging. Rates of change in white matter structure as indexed by Tract-Based Spatial Statistics (TBSS) of fractional anisotropy were compared between treated and untreated patients. Treated patients were found to have a significantly slower rate of white matter change in the corticospinal tracts, the thalamic radiation and the inferior longitudinal fasciculus. This is further evidence that miglustat treatment may have a protective effect on white matter structure in the adult-onset form of the disease.

No evidence for systematic white matter correlates of dyslexia and dyscalculia.

PubMed

Moreau, David; Wilson, Anna J; McKay, Nicole S; Nihill, Kasey; Waldie, Karen E

2018-01-01

Learning disabilities such as dyslexia, dyscalculia and their comorbid manifestation are prevalent, affecting as much as 15% of the population. Structural neuroimaging studies have indicated that these disorders can be related to differences in white matter integrity, although findings remain disparate. In this study, we used a unique design composed of individuals with dyslexia, dyscalculia, both disorders and controls, to systematically explore differences in fractional anisotropy across groups using diffusion tensor imaging. Specifically, we focused on the corona radiata and the arcuate fasciculus, two tracts associated with reading and mathematics in a number of previous studies. Using Bayesian hypothesis testing, we show that the present data favor the null model of no differences between groups for these particular tracts-a finding that seems to go against the current view but might be representative of the disparities within this field of research. Together, these findings suggest that structural differences associated with dyslexia and dyscalculia might not be as reliable as previously thought, with potential ramifications in terms of remediation.

Using in vivo probabilistic tractography to reveal two segregated dorsal ‘language-cognitive’ pathways in the human brain☆

PubMed Central

Cloutman, Lauren L.; Binney, Richard J.; Morris, David M.; Parker, Geoffrey J.M.; Lambon Ralph, Matthew A.

2013-01-01

Primate studies have recently identified the dorsal stream as constituting multiple dissociable pathways associated with a range of specialized cognitive functions. To elucidate the nature and number of dorsal pathways in the human brain, the current study utilized in vivo probabilistic tractography to map the structural connectivity associated with subdivisions of the left supramarginal gyrus (SMG). The left SMG is a prominent region within the dorsal stream, which has recently been parcellated into five structurally-distinct regions which possess a dorsal–ventral (and rostral-caudal) organisation, postulated to reflect areas of functional specialisation. The connectivity patterns reveal a dissociation of the arcuate fasciculus into at least two segregated pathways connecting frontal-parietal-temporal regions. Specifically, the connectivity of the inferior SMG, implicated as an acoustic-motor speech interface, is carried by an inner/ventro-dorsal arc of fibres, whilst the pathways of the posterior superior SMG, implicated in object use and cognitive control, forms a parallel outer/dorso-dorsal crescent. PMID:23937853

Reconfiguration of brain network architecture to support executive control in aging.

PubMed

Gallen, Courtney L; Turner, Gary R; Adnan, Areeba; D'Esposito, Mark

2016-08-01

Aging is accompanied by declines in executive control abilities and changes in underlying brain network architecture. Here, we examined brain networks in young and older adults during a task-free resting state and an N-back task and investigated age-related changes in the modular network organization of the brain. Compared with young adults, older adults showed larger changes in network organization between resting state and task. Although young adults exhibited increased connectivity between lateral frontal regions and other network modules during the most difficult task condition, older adults also exhibited this pattern of increased connectivity during less-demanding task conditions. Moreover, the increase in between-module connectivity in older adults was related to faster task performance and greater fractional anisotropy of the superior longitudinal fasciculus. These results demonstrate that older adults who exhibit more pronounced network changes between a resting state and task have better executive control performance and greater structural connectivity of a core frontal-posterior white matter pathway. Copyright © 2016 Elsevier Inc. All rights reserved.

Neural control and modulation of swimming speed in the larval zebrafish

PubMed Central

Marques, João C.; O'Malley, Donald M.; Orger, Michael B.; Engert, Florian

2014-01-01

Summary Vertebrate locomotion at different speeds is driven by descending excitatory connections to central pattern generators in the spinal cord. To investigate how these inputs determine locomotor kinematics, we used whole-field visual motion to drive zebrafish to swim at different speeds. Larvae match the stimulus speed by utilizing more locomotor events, or modifying kinematic parameters such as the duration and speed of swimming bouts, the tail-beat frequency, and choice of gait. We used laser ablations, electrical stimulation, and activity recordings in descending neurons of the nucleus of the medial longitudinal fasciculus (nMLF) to dissect their contribution to controlling forward movement. We found that the activity of single identified neurons within the nMLF is correlated with locomotor kinematics, and modulates both the duration and oscillation frequency of tail movements. By identifying the contribution of individual supraspinal circuit elements to locomotion kinematics we build a better understanding of how the brain controls movement. PMID:25066084

Neural control and modulation of swimming speed in the larval zebrafish.

PubMed

Severi, Kristen E; Portugues, Ruben; Marques, João C; O'Malley, Donald M; Orger, Michael B; Engert, Florian

2014-08-06

Vertebrate locomotion at different speeds is driven by descending excitatory connections to central pattern generators in the spinal cord. To investigate how these inputs determine locomotor kinematics, we used whole-field visual motion to drive zebrafish to swim at different speeds. Larvae match the stimulus speed by utilizing more locomotor events, or modifying kinematic parameters such as the duration and speed of swimming bouts, the tail-beat frequency, and the choice of gait. We used laser ablations, electrical stimulation, and activity recordings in descending neurons of the nucleus of the medial longitudinal fasciculus (nMLF) to dissect their contribution to controlling forward movement. We found that the activity of single identified neurons within the nMLF is correlated with locomotor kinematics, and modulates both the duration and oscillation frequency of tail movements. By identifying the contribution of individual supraspinal circuit elements to locomotion kinematics, we build a better understanding of how the brain controls movement. Copyright © 2014 Elsevier Inc. All rights reserved.

Process Versus Product in Social Learning: Comparative Diffusion Tensor Imaging of Neural Systems for Action Execution–Observation Matching in Macaques, Chimpanzees, and Humans

PubMed Central

Hecht, Erin E.; Gutman, David A.; Preuss, Todd M.; Sanchez, Mar M.; Parr, Lisa A.; Rilling, James K.

2013-01-01

Social learning varies among primate species. Macaques only copy the product of observed actions, or emulate, while humans and chimpanzees also copy the process, or imitate. In humans, imitation is linked to the mirror system. Here we compare mirror system connectivity across these species using diffusion tensor imaging. In macaques and chimpanzees, the preponderance of this circuitry consists of frontal–temporal connections via the extreme/external capsules. In contrast, humans have more substantial temporal–parietal and frontal–parietal connections via the middle/inferior longitudinal fasciculi and the third branch of the superior longitudinal fasciculus. In chimpanzees and humans, but not in macaques, this circuitry includes connections with inferior temporal cortex. In humans alone, connections with superior parietal cortex were also detected. We suggest a model linking species differences in mirror system connectivity and responsivity with species differences in behavior, including adaptations for imitation and social learning of tool use. PMID:22539611

[Changes of the phosphatides and their fatty acids in the retina and in the fasciculus opticus after retinal detachment: investigations of human and animal retinae (author's transl)].

PubMed

Weiss, H; Kosmath, B; Graf, A

1976-02-04

In this study the effect of an experimentally provoked retinal detachment on the pattern of the phosphatides and fatty acids of the retina and the optic nerve of adult rabbits was investigated. The analysis was performed one month, and 4 months after the operation, and the values were related to the findings in control animals of the same age, and of the age of one day and 30 days respectively. In this way changes in the total lipide, in the phosphatides and in their fatty acids could be revealed, with a tendency towards the developmental stage of the 20th up to the 30th day of life. Between retina and optic nerve no difference was found neither temporally nor regarding the quantitative reaction. In the detached human retinae the same reactions can be proved as in the animal experiment. The relationship of these findings to the recovery of the operatively reatached human retina is discussed.

Tone-deafness – a new disconnection syndrome?

PubMed Central

Loui, Psyche; Alsop, David; Schlaug, Gottfried

2009-01-01

Communicating with one’s environment requires efficient neural interaction between action and perception. Neural substrates ofsound perception and production are connected by the arcuate fasciculus (AF). While AF is known to be involved in language, its roles in non-linguistic functions are unexplored. Here we show that tone-deaf people, with impaired sound perception and production, have reduced AF connectivity. Diffusion tensor tractography and psychophysics were assessed in tone-deaf individuals and matched controls. Abnormally-reduced AF connectivity was observed in the tone-deaf. Furthermore, we observed relationships between AF and auditory-motor behavior: superior and inferior AF branches predict psychophysically-assessed pitch-discrimination and sound production-perception abilities respectively. This neural abnormality suggests that tone-deafness leads to a reduction in connectivity resulting in pitch-related impairments. Results support a dual-stream anatomy of sound production and perception implicated in vocal communications. By identifying white-matter differences and their psychophysical correlates, results contribute to our understanding of how neural connectivity subserves behavior. PMID:19692596

Multimodal imaging of language reorganization in patients with left temporal lobe epilepsy.

PubMed

Chang, Yu-Hsuan A; Kemmotsu, Nobuko; Leyden, Kelly M; Kucukboyaci, N Erkut; Iragui, Vicente J; Tecoma, Evelyn S; Kansal, Leena; Norman, Marc A; Compton, Rachelle; Ehrlich, Tobin J; Uttarwar, Vedang S; Reyes, Anny; Paul, Brianna M; McDonald, Carrie R

2017-07-01

This study explored the relationships among multimodal imaging, clinical features, and language impairment in patients with left temporal lobe epilepsy (LTLE). Fourteen patients with LTLE and 26 controls underwent structural MRI, functional MRI, diffusion tensor imaging, and neuropsychological language tasks. Laterality indices were calculated for each imaging modality and a principal component (PC) was derived from language measures. Correlations were performed among imaging measures, as well as to the language PC. In controls, better language performance was associated with stronger left-lateralized temporo-parietal and temporo-occipital activations. In LTLE, better language performance was associated with stronger right-lateralized inferior frontal, temporo-parietal, and temporo-occipital activations. These right-lateralized activations in LTLE were associated with right-lateralized arcuate fasciculus fractional anisotropy. These data suggest that interhemispheric language reorganization in LTLE is associated with alterations to perisylvian white matter. These concurrent structural and functional shifts from left to right may help to mitigate language impairment in LTLE. Copyright © 2017 Elsevier Inc. All rights reserved.

Research with Transcranial Magnetic Stimulation in the Treatment of Aphasia

PubMed Central

Martin, Paula I; Naeser, Margaret A.; Ho, Michael; Treglia, Ethan; Kaplan, Elina; Baker, Errol H.; Pascual-Leone, Alvaro

2010-01-01

Repetitive transcranial magnetic stimulation (rTMS) has been used to improve language behavior, including naming, in stroke patients with chronic, nonfluent aphasia. Part 1 of this paper reviews functional imaging studies related to language recovery in aphasia. Part 2 reviews the rationale for using rTMS to treat nonfluent aphasia (based on functional imaging); and presents our current rTMS protocol. We present language results from our rTMS studies, and imaging results from overt naming fMRI scans obtained pre- and post- a series of rTMS treatments. Part 3 presents results from a pilot study where rTMS treatments were followed immediately by constraint-induced language therapy. Part 4 reviews our diffusion tensor imaging study that examined possible connectivity of arcuate fasciculus to different parts of Broca’s area (pars triangularis, PTr; pars opercularis, POp); and to ventral premotor cortex (vPMC). The potential role of mirror neurons in R POp and vPMC in aphasia recovery is discussed. PMID:19818232

[The search of the "intact" structural and functional brain systems as a paradigm shift in schizophrenia research].

PubMed

Lebedeva, I S

2015-01-01

The search of the structural and functional brain characteristics is one of the most studied directions in the modern biological psychiatry. However, in spite of the numerous studies the results are still controversial. As the necessity of the shift of the current paradigm in schizophrenia research evolves it has been suggested to discriminate not only abnormal but stable functioning neuronal circuits as well. Consequently, the aim is formulated as the search of the minimal brain damage sufficient for disease development. Author analyzed the auditory oddball P300 latency (as a marker of information processing speed), N-acetylaspartate level in the dorsolateral prefrontal cortex (as a marker of neuronal integrity in this brain area) and fractional anisotropy of the fasciculus uncindtus which connects the frontal and temporal lobes (as a marker of white matter bundles microstructure) in 30 patients with schizophrenia and 27 healthy people. The findings showed that all the tested characteristics are not "obligatory" for schizophrenia.

Bonding Properties of Basalt Fiber and Strength Reduction According to Fiber Orientation

PubMed Central

Choi, Jeong-Il; Lee, Bang Yeon

2015-01-01

The basalt fiber is a promising reinforcing fiber because it has a relatively higher tensile strength and a density similar to that of a concrete matrix as well as no corrosion possibility. This study investigated experimentally the bonding properties of basalt fiber with cementitious material as well as the effect of fiber orientation on the tensile strength of basalt fiber for evaluating basalt fiber’s suitability as a reinforcing fiber. Single fiber pullout tests were performed and then the tensile strength of fiber was measured according to fiber orientation. The test results showed that basalt fiber has a strong chemical bond with the cementitious matrix, 1.88 times higher than that of polyvinyl alcohol fibers with it. However, other properties of basalt fiber such as slip-hardening coefficient and strength reduction coefficient were worse than PVA and polyethylene fibers in terms of fiber bridging capacity. Theoretical fiber-bridging curves showed that the basalt fiber reinforcing system has a higher cracking strength than the PVA fiber reinforcing system, but the reinforcing system showed softening behavior after cracking. PMID:28793595

A comparison of tensile properties of polyester composites reinforced with pineapple leaf fiber and pineapple peduncle fiber

NASA Astrophysics Data System (ADS)

Juraidi, J. M.; Shuhairul, N.; Syed Azuan, S. A.; Intan Saffinaz Anuar, Noor

2013-12-01

Pineapple fiber which is rich in cellulose, relatively inexpensive, and abundantly available has the potential for polymer reinforcement. This research presents a study of the tensile properties of pineapple leaf fiber and pineapple peduncle fiber reinforced polyester composites. Composites were fabricated using leaf fiber and peduncle fiber with varying fiber length and fiber loading. Both fibers were mixed with polyester composites the various fiber volume fractions of 4, 8 and 12% and with three different fiber lengths of 10, 20 and 30 mm. The composites panels were fabricated using hand lay-out technique. The tensile test was carried out in accordance to ASTM D638. The result showed that pineapple peduncle fiber with 4% fiber volume fraction and fiber length of 30 mm give highest tensile properties. From the overall results, pineapple peduncle fiber shown the higher tensile properties compared to pineapple leaf fiber. It is found that by increasing the fiber volume fraction the tensile properties has significantly decreased but by increasing the fiber length, the tensile properties will be increased proportionally. Minitab software is used to perform the two-way ANOVA analysis to measure the significant. From the analysis done, there is a significant effect of fiber volume fraction and fiber length on the tensile properties.

Method of making a continuous ceramic fiber composite hot gas filter

DOEpatents

Hill, Charles A.; Wagner, Richard A.; Komoroski, Ronald G.; Gunter, Greg A.; Barringer, Eric A.; Goettler, Richard W.

1999-01-01

A ceramic fiber composite structure particularly suitable for use as a hot gas cleanup ceramic fiber composite filter and method of making same from ceramic composite material has a structure which provides for increased strength and toughness in high temperature environments. The ceramic fiber composite structure or filter is made by a process in which a continuous ceramic fiber is intimately surrounded by discontinuous chopped ceramic fibers during manufacture to produce a ceramic fiber composite preform which is then bonded using various ceramic binders. The ceramic fiber composite preform is then fired to create a bond phase at the fiber contact points. Parameters such as fiber tension, spacing, and the relative proportions of the continuous ceramic fiber and chopped ceramic fibers can be varied as the continuous ceramic fiber and chopped ceramic fiber are simultaneously formed on the porous vacuum mandrel to obtain a desired distribution of the continuous ceramic fiber and the chopped ceramic fiber in the ceramic fiber composite structure or filter.

Optical fiber sensor having a sol-gel fiber core and a method of making

DOEpatents

Tao, Shiquan; Jindal, Rajeev; Winstead, Christopher; Singh, Jagdish P.

2006-06-06

A simple, economic wet chemical procedure is described for making sol-gel fibers. The sol-gel fibers made from this process are transparent to ultraviolet, visible and near infrared light. Light can be guided in these fibers by using an organic polymer as a fiber cladding. Alternatively, air can be used as a low refractive index medium. The sol-gel fibers have a micro pore structure which allows molecules to diffuse into the fiber core from the surrounding environment. Chemical and biochemical reagents can be doped into the fiber core. The sol-gel fiber can be used as a transducer for constructing an optical fiber sensor. The optical fiber sensor having an active sol-gel fiber core is more sensitive than conventional evanescent wave absorption based optical fiber sensors.

Apparatus and method for combining light from two or more fibers into a single fiber

DOEpatents

Klingsporn, Paul Edward

2007-02-20

An apparatus and method for combining light signals carried on a plurality of input fibers onto a single receiving fiber with a high degree of efficiency. The apparatus broadly comprises the receiving fiber and a plurality of input fiber-lens assemblies, with each fiber lens assembly including an input fiber; a collimating lens interposed between the input fiber and the receiving fiber and adapted to collimate the light signal; and a focusing lens interposed between the collimating lens and the receiving fiber and adapted to focus the collimated light signal onto the face of the receiving fiber. The components of each fiber-lens assembly are oriented along an optic axis that is inclined relative to the receiving fiber, with the inclination angle depending at least in part on the input fiber's numerical aperture and the focal lengths and diameters of the collimating and focusing lenses.

Apparatus and method for combining light from two or more fibers into a single fiber

DOEpatents

Klingsporn, Paul Edward

2006-03-14

An apparatus and method for combining light signals carried on a plurality of input fibers onto a single receiving fiber with a high degree of efficiency. The apparatus broadly comprises the receiving fiber and a plurality of input fiber-lens assemblies, with each fiber lens assembly including an input fiber; a collimating lens interposed between the input fiber and the receiving fiber and adapted to collimate the light signal; and a focusing lens interposed between the collimating lens and the receiving fiber and adapted to focus the collimated light signal onto the face of the receiving fiber. The components of each fiber-lens assembly are oriented along an optic axis that is inclined relative to the receiving fiber, with the inclination angle depending at least in part on the input fiber's numerical aperture and the focal lengths and diameters of the collimating and focusing lenses.

Effect of different fibers on mechanical properties and ductility of alkali-activated slag cementitious material

NASA Astrophysics Data System (ADS)

Zhu, J.; Zheng, W. Z.; Qin, C. Z.; Xu, Z. Z.; Wu, Y. Q.

2018-01-01

The effect of different fibers on mechanical properties and ductility of alkali-activated slag cementitious material (AASCM) is studied. The research contents include: fiber type (plant fiber, polypropylene fiber), fiber content, mechanical property index, tensile stress-strain relationship curve, treating time. The test results showed that the compressive strength of two fibers reinforced AASCM was about 90 ~ 110MPa, and the tensile strength was about 3 ~ 5MPa. The reinforcement effect of polypropylene fiber is superior to that of plant fiber, and the mechanical properties of polypropylene fiber reinforced AASCM are superior to those of plant fiber, According to the comparison of SEM pictures, the plant fiber and polypropylene fiber are both closely bound with the matrix, and the transition zones are complete and close. Thus, it is proved that plant fiber and polypropylene fiber delay the crack extension and enhance the ductility of AASCM.

Lignin-based active anode materials synthesized from low-cost renewable resources

DOEpatents

Rios, Orlando; Tenhaeff, Wyatt Evan; Daniel, Claus; Dudney, Nancy Johnston; Johs, Alexander; Nunnery, Grady Alexander; Baker, Frederick Stanley

2016-06-07

A method of making an anode includes the steps of providing fibers from a carbonaceous precursor, the carbon fibers having a glass transition temperature T.sub.g. In one aspect the carbonaceous precursor is lignin. The carbonaceous fibers are placed into a layered fiber mat. The fiber mat is fused by heating the fiber mat in the presence of oxygen to above the T.sub.g but no more than 20% above the T.sub.g to fuse fibers together at fiber to fiber contact points and without melting the bulk fiber mat to create a fused fiber mat through oxidative stabilization. The fused fiber mat is carbonized by heating the fused fiber mat to at least 650.degree. C. under an inert atmosphere to create a carbonized fused fiber mat. A battery anode formed from carbonaceous precursor fibers is also disclosed.

Robust fiber clustering of cerebral fiber bundles in white matter

NASA Astrophysics Data System (ADS)

Yao, Xufeng; Wang, Yongxiong; Zhuang, Songlin

2014-11-01

Diffusion tensor imaging fiber tracking (DTI-FT) has been widely accepted in the diagnosis and treatment of brain diseases. During the rendering pipeline of specific fiber tracts, the image noise and low resolution of DTI would lead to false propagations. In this paper, we propose a robust fiber clustering (FC) approach to diminish false fibers from one fiber tract. Our algorithm consists of three steps. Firstly, the optimized fiber assignment continuous tracking (FACT) is implemented to reconstruct one fiber tract; and then each curved fiber in the fiber tract is mapped to a point by kernel principal component analysis (KPCA); finally, the point clouds of fiber tract are clustered by hierarchical clustering which could distinguish false fibers from true fibers in one tract. In our experiment, the corticospinal tract (CST) in one case of human data in vivo was used to validate our method. Our method showed reliable capability in decreasing the false fibers in one tract. In conclusion, our method could effectively optimize the visualization of fiber bundles and would help a lot in the field of fiber evaluation.

Magnetically-induced solid-phase microextraction fiber actuation system for quantitative headspace and liquid sampling

DOEpatents

Harvey, Chris; Carter, Jerry; Chambers, David M.

2017-05-23

A magnetically-induced SPME fiber actuation system includes a SPME fiber holder and a SPME fiber holder actuator, for holding and magnetically actuating a SPME fiber assembly. The SPME fiber holder has a plunger with a magnetic material to which the SPME fiber assembly is connected, and the magnetic SPME fiber holder actuator has an elongated barrel with a loading chamber for receiving the SPME fiber assembly-connected SPME fiber holder, and an external magnet which induces axial motion of the magnetic material of the plunger to extend/retract the SPME fiber from/into the protective needle of the SPME fiber assembly.

The optimal fiber volume fraction and fiber-matrix property compatibility in fiber reinforced composites

NASA Technical Reports Server (NTRS)

Pan, Ning

1992-01-01

Although the question of minimum or critical fiber volume fraction beyond which a composite can then be strengthened due to addition of fibers has been dealt with by several investigators for both continuous and short fiber composites, a study of maximum or optimal fiber volume fraction at which the composite reaches its highest strength has not been reported yet. The present analysis has investigated this issue for short fiber case based on the well-known shear lag (the elastic stress transfer) theory as the first step. Using the relationships obtained, the minimum spacing between fibers is determined upon which the maximum fiber volume fraction can be calculated, depending on the fiber packing forms within the composites. The effects on the value of this maximum fiber volume fraction due to such factors as fiber and matrix properties, fiber aspect ratio and fiber packing forms are discussed. Furthermore, combined with the previous analysis on the minimum fiber volume fraction, this maximum fiber volume fraction can be used to examine the property compatibility of fiber and matrix in forming a composite. This is deemed to be useful for composite design. Finally some examples are provided to illustrate the results.

Evaluating the effect of some mechanical properties for chemically treated various natural fibers reinforced polyester composite

NASA Astrophysics Data System (ADS)

Salih, Wafaa Mahdi; Abdulkader, Niveen Jamal; Salih, Sana Mahdi

2018-05-01

This research were studied the effect of some mechanical properties for composite materials reinforced fiber and prepared from material (polyester with various natural fibers) then studied the effect of chemical treatment on the same fiber immerse in 10% NaOH solution for half an hour and then compared, the results of the same test of composite materials without and with chemical treatment and the results proved that there is a clear effect when treat the fiber compared to non-chemical treatment of the fibers also noted that hemp fibers loaded the stress higher than other fibers for both cases to distinguish them that the hemp fiber has continuous fibers either the other fibers are characterized by the type of cross linking or chopped types in tensile test, and the results of the same test of composite materials without and with chemical treatment and the results proved that the hardness of the fiber composite while the treated fiber composite samples better than the untreated fiber, and from the figures the palm leaf has the highest value than lufa fiber, hemp fiber and the smallest value is in sisal fiber because of the nature of formation fibers materials.

Recent development on high-power tandem-pumped fiber laser

NASA Astrophysics Data System (ADS)

Zhou, Pu; Xiao, Hu; Leng, Jinyong; Zhang, Hanwei; Xu, Jiangmin; Wu, Jian

2016-11-01

High power fiber laser is attracting more and more attention due to its advantage in excellent beam quality, high electricto- optical conversion efficiency and compact system configuration. Power scaling of fiber laser is challenged by the brightness of pump source, nonlinear effect, modal instability and so on. Pumping active fiber by using high-brightness fiber laser instead of common laser diode may be the solution for the brightness limitation. In this paper, we will present the recent development of various kinds of high power fiber laser based on tandem pumping scheme. According to the absorption property of Ytterbium-doped fiber, Thulium-doped fiber and Holmium-doped fiber, we have theoretically studied the fiber lasers that operate at 1018 nm, 1178 nm and 1150 nm, respectively in detail. Consequently, according to the numerical results we have optimized the fiber laser system design, and we have achieved (1) 500 watt level 1018nm Ytterbium-doped fiber laser (2) 100 watt level 1150 nm fiber laser and 100 watt level random fiber laser (3) 30 watt 1178 nm Ytterbium-doped fiber laser, 200 watt-level random fiber laser. All of the above-mentioned are the record power for the corresponded type of fiber laser to the best of our knowledge. By using the high-brightness fiber laser operate at 1018 nm, 1178 nm and 1150 nm that we have developed, we have achieved the following high power fiber laser (1) 3.5 kW 1090 nm Ytterbium-doped fiber amplifier (2) 100 watt level Thulium-doped fiber laser and (3) 50 watt level Holmium -doped fiber laser.

All-fiber Faraday Devices Based on Terbium-doped Fiber

NASA Astrophysics Data System (ADS)

Sun, Lei

Surface damage is one of the most problematic power limits in high-power fiber laser systems. All-fiber Faraday components are demonstrated as a solution to this problem, since they can be completely fusion-spliced into existing systems, eliminating all glass-air interfaces. Beam filamentation due to self-focusing places another limit on the peak power attainable from fiber laser systems. The limits imposed by this phenomenon are analyzed for the first time. The concept of an effective Verdet constant is proposed and experimentally validated. The effective Verdet constant of light propagation in a fiber includes contributions from the materials in both the core and the cladding. It is measured in a 25-wt% terbium-doped-core phosphate fiber to be --6.2 rad/(Tm) at 1053 nm, which is six times larger than silica fiber. The result agrees well with Faraday rotation theory in optical fiber. A compact all-fiber Faraday isolator and a Faraday mirror are demonstrated. At the core of each of these components is an all-fiber Faraday rotator made of a 4cm-long, 65-wt%-terbium-doped silicate fiber. The effective Verdet constant of the terbium-doped fiber is measured to be -32 rad/(Tm), which is 27x larger than that of silica fiber. This effective Verdet constant is the largest value measured to date in any fiber and is 83% of the Verdet constant of commercially available crystals used in bulk-optics-based isolators. Combining the all-fiber Faraday rotator with fiber polarizers results in a fully fusion-spliced all-fiber isolator whose isolation is measured to be 19 dB. Combining the all-fiber Faraday rotator with a fiber Bragg grating results in an all-fiber Faraday mirror that rotates the polarization state of the reflected light by 88 +/- 4°. An all-fiber optical magnetic field sensor is also demonstrated. It consists of a fiber Faraday rotator and a fiber polarizer. The fiber Faraday rotator uses a 2-cm-long section of 56-wt%-terbium-doped silicate fiber with a Verdet constant of -24.5 rad/(Tm) at 1053 nm. The fiber polarizer is Corning SP1060 single-polarization fiber. The sensor has a sensitivity of 0.49 rad/T and can measure magnetic fields from 0.02 to 3.2 T. An all-fiber wavelength-tunable laser based on Faraday rotation is proposed. It consists of an all-fiber wavelength-tunable filter in a conventional fiber laser cavity. The filter includes a fiber polarizer and a fiber Faraday mirror in which a chirped fiber Bragg grating is directly written onto the 65-wt% terbium fiber. The ytterbium-doped fiber in the laser is gain flattened using a. 1030/1090 rim WDM filter, resulting a net gain ripple that is measured to he less than 0.2 dB from 1047 to 1060 nm. The wavelength tuning range of the resulting fiber laser is therefore expected to be in this 1047 to 1060 nm range. Filamentation is one of the nonlinear peak-power-threshold limits in high-power fiber lasers. Starting from the paraxial wave equation, an analytic expression for the filamentation threshold in fiber lasers is derived using a perturbation method. The occurrence of filamentation is determined by the larger of two thresholds, one of perturbative gain and one of spatial confinement. The threshold value is around a few megawatts, depending on the parameters of the fiber.

Fibers comprised of epitaxially grown single-wall carbon nanotubes, and a method for added catalyst and continuous growth at the tip

DOEpatents

Kittrell, W. Carter; Wang, Yuhuang; Kim, Myung Jong; Hauge, Robert H.; Smalley, Richard E.; Marek leg, Irene Morin

2010-06-01

The present invention is directed to fibers of epitaxially grown single-wall carbon nanotubes (SWNTs) and methods of making same. Such methods generally comprise the steps of: (a) providing a spun SWNT fiber; (b) cutting the fiber substantially perpendicular to the fiber axis to yield a cut fiber; (c) etching the cut fiber at its end with a plasma to yield an etched cut fiber; (d) depositing metal catalyst on the etched cut fiber end to form a continuous SWNT fiber precursor; and (e) introducing feedstock gases under SWNT growth conditions to grow the continuous SWNT fiber precursor into a continuous SWNT fiber.

Manufacturing of Nanocomposite Carbon Fibers and Composite Cylinders

NASA Technical Reports Server (NTRS)

Tan, Seng; Zhou, Jian-guo

2013-01-01

Pitch-based nanocomposite carbon fibers were prepared with various percentages of carbon nanofibers (CNFs), and the fibers were used for manufacturing composite structures. Experimental results show that these nanocomposite carbon fibers exhibit improved structural and electrical conductivity properties as compared to unreinforced carbon fibers. Composite panels fabricated from these nanocomposite carbon fibers and an epoxy system also show the same properties transformed from the fibers. Single-fiber testing per ASTM C1557 standard indicates that the nanocomposite carbon fiber has a tensile modulus of 110% higher, and a tensile strength 17.7% times higher, than the conventional carbon fiber manufactured from pitch. Also, the electrical resistance of the carbon fiber carbonized at 900 C was reduced from 4.8 to 2.2 ohm/cm. The manufacturing of the nanocomposite carbon fiber was based on an extrusion, non-solvent process. The precursor fibers were then carbonized and graphitized. The resultant fibers are continuous.

Relationship between Fiber Furnish and the Structural Performance of MDF

Treesearch

Leslie H. Groom; Laurence Mott; Stephen Shaler

1999-01-01

The structural performance of medium density fiberboard (MDF) is attributable to three primary variables which are: physical and mechanical properties of individual wood fibers; fiber-to-fiber stress transfer; and fiber orientation. These origins of fiber properties and stress transfer can be traced to the fiber generation method wherein fiber orientation is associated...

Monitoring Fiber Stress During Curing of Single Fiber Glass- and Graphite-Epoxy Composites

NASA Technical Reports Server (NTRS)

Madhukar, Madhu S.; Kosuri, Ranga P.; Bowles, Kenneth J.

1994-01-01

The difference in thermal expansion characteristics of epoxy matrices and graphite fibers can produce significant residual stresses in the fibers during curing of composite materials. Tests on single fiber glass-epoxy and graphite-epoxy composite specimens were conducted in which the glass and graphite fibers were preloaded in tension, and the epoxy matrix was cast around the fibers. The fiber tension was monitored while the matrix was placed around the fiber and subjected to the temperature-time curing cycle. Two mechanisms responsible for producing stress in embedded fibers were identified as matrix thermal expansion and contraction and matrix cure shrinkage. A simple analysis based on the change in fiber tension during the curing cycle was conducted to estimate the produced stresses. Experimental results on single fiber glass- and graphite-epoxy composites show that the fiber was subjected to significant tensile stresses when the temperature was raised from the first to the second dwell period. When initial fiber pretension is about 60 percent of the fiber failure load, these curing-induced stresses can cause tensile fracture of the embedded fiber.

Common errors in textbook descriptions of muscle fiber size in nontrained humans.

PubMed

Chalmers, Gordon R; Row, Brandi S

2011-09-01

Exercise science and human anatomy and physiology textbooks commonly report that type IIB muscle fibers have the largest cross-sectional area of the three fiber types. These descriptions of muscle fiber sizes do not match with the research literature examining muscle fibers in young adult nontrained humans. For men, most commonly type IIA fibers were significantly larger than other fiber types (six out of 10 cases across six different muscles). For women, either type I, or both I and IIA muscle fibers were usually significantly the largest (five out of six cases across four different muscles). In none of these reports were type IIB fibers significantly larger than both other fiber types. In 27 studies that did not include statistical comparisons of mean fiber sizes across fiber types, in no cases were type IIB or fast glycolytic fibers larger than both type I and IIA, or slow oxidative and fast oxidative glycolytic fibers. The likely reason for mistakes in textbook descriptions of human muscle fiber sizes is that animal data were presented without being labeled as such, and without any warning that there are interspecies differences in muscle fiber properties. Correct knowledge of muscle fiber sizes may facilitate interpreting training and aging adaptations.