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1

Q-Ball of Inferior Fronto-Occipital Fasciculus and Beyond  

PubMed Central

The inferior fronto-occipital fasciculus (IFOF) is historically described as the longest associative bundle in the human brain and it connects various parts of the occipital cortex, temporo-basal area and the superior parietal lobule to the frontal lobe through the external/extreme capsule complex. The exact functional role and the detailed anatomical definition of the IFOF are still under debate within the scientific community. In this study we present a fiber tracking dissection of the right and left IFOF by using a q-ball residual-bootstrap reconstruction of High-Angular Resolution Diffusion Imaging (HARDI) data sets in 20 healthy subjects. By defining a single seed region of interest on the coronal fractional anisotropy (FA) color map of each subject, we investigated all the pathways connecting the parietal, occipital and posterior temporal cortices to the frontal lobe through the external/extreme capsule. In line with recent post-mortem dissection studies we found more extended anterior-posterior association connections than the “classical” fronto-occipital representation of the IFOF. In particular the pathways we evidenced showed: a) diffuse projections in the frontal lobe, b) fronto-parietal lobes connections trough the external capsule in almost all the subjects and c) widespread connections in the posterior regions. Our study represents the first consistent in vivo demonstration across a large group of individuals of these novel anterior and posterior terminations of the IFOF detailed described only by post-mortem anatomical dissection. Furthermore our work establishes the feasibility of consistent in vivo mapping of this architecture with independent in vivo methodologies. In conclusion q-ball tractography dissection supports a more complex definition of IFOF, which includes several subcomponents likely underlying specific function.

Amirbekian, Bagrat; Berger, Mitchel S.; Henry, Roland G.

2014-01-01

2

The anatomy of fronto-occipital connections from early blunt dissections to contemporary tractography.  

PubMed

The occipital and frontal lobes are anatomically distant yet functionally highly integrated to generate some of the most complex behaviour. A series of long associative fibres, such as the fronto-occipital networks, mediate this integration via rapid feed-forward propagation of visual input to anterior frontal regions and direct top-down modulation of early visual processing. Despite the vast number of anatomical investigations a general consensus on the anatomy of fronto-occipital connections is not forthcoming. For example, in the monkey the existence of a human equivalent of the 'inferior fronto-occipital fasciculus' (iFOF) has not been demonstrated. Conversely, a 'superior fronto-occipital fasciculus' (sFOF), also referred to as 'subcallosal bundle' by some authors, is reported in monkey axonal tracing studies but not in human dissections. In this study our aim is twofold. First, we use diffusion tractography to delineate the in vivo anatomy of the sFOF and the iFOF in 30 healthy subjects and three acallosal brains. Second, we provide a comprehensive review of the post-mortem and neuroimaging studies of the fronto-occipital connections published over the last two centuries, together with the first integral translation of Onufrowicz's original description of a human fronto-occipital fasciculus (1887) and Muratoff's report of the 'subcallosal bundle' in animals (1893). Our tractography dissections suggest that in the human brain (i) the iFOF is a bilateral association pathway connecting ventro-medial occipital cortex to orbital and polar frontal cortex, (ii) the sFOF overlaps with branches of the superior longitudinal fasciculus (SLF) and probably represents an 'occipital extension' of the SLF, (iii) the subcallosal bundle of Muratoff is probably a complex tract encompassing ascending thalamo-frontal and descending fronto-caudate connections and is therefore a projection rather than an associative tract. In conclusion, our experimental findings and review of the literature suggest that a ventral pathway in humans, namely the iFOF, mediates a direct communication between occipital and frontal lobes. Whether the iFOF represents a unique human pathway awaits further ad hoc investigations in animals. PMID:23137651

Forkel, Stephanie J; Thiebaut de Schotten, Michel; Kawadler, Jamie M; Dell'Acqua, Flavio; Danek, Adrian; Catani, Marco

2014-07-01

3

Effects of fronto-occipital cranial reshaping on mandibular form.  

PubMed

Cultural reshaping (artificial deformation or modification) of the neurocranial vault provides an artificially increased range of morphological variability within which the relationship between the growing neurocranium and face can be investigated. We analyze crania which have been fronto-occipitally compressed to ascertain possible morphological effects on the mandible. We collected measures of mandibular breadth, length, and height from 82 modified (N = 48) and unmodified (N = 34) crania from a Peruvian Ancon series. Angle classification was also scored in order to investigate whether or not occlusal relationships were affected by neurocranial reshaping. Only intercondylar distance (posterior mandibular breadth) exhibited significant differences between unmodified and modified groups, though this difference was relatively small compared with vault deformation. The modified crania had a higher frequency of normal occlusion (Class I) than the unmodified crania. Increased intercondylar breadth in modified skulls is due to a cascade of effects which begin with a direct effect of the fronto-occipital deforming device on neurocranial shape (increased neurocranial width). The increase in mandibular breadth may be a compensatory response to increased cranial base breadth and maintains articulation between the cranial base and mandible. The increased posterior breadth, coupled with a slight decrease in mandibular depth, may contribute to the change in occlusal relationships suggested for this sample. PMID:1543243

Cheverud, J M; Midkiff, J E

1992-02-01

4

Structural connectivity in a single case of progressive prosopagnosia: The role of the right inferior longitudinal fasciculus.  

PubMed

Progressive prosopagnosia (PP) is a clinical syndrome characterized by a progressive and selective inability to recognize and identify faces of familiar people. Here we report a patient (G.S.) with PP, mainly related to a prominent deficit in recognition of familiar faces, without a semantic (cross-modal) impairment. An in-depth evaluation showed that his deficit extended to other classes of objects, both living and non-living. A follow-up neuropsychological assessment did not reveal substantial changes after about 1 year. Structural MRI showed predominant right temporal lobe atrophy. Diffusion tensor imaging was performed to elucidate structural connectivity of the inferior longitudinal fasciculus (ILF) and the inferior fronto-occipital fasciculus (IFOF), the two major tracts that project through the core fusiform region to the anterior temporal and frontal cortices, respectively. Right ILF was markedly reduced in G.S., while left ILF and IFOFs were apparently preserved. These data are in favour of a crucial role of the neural circuit subserved by right ILF in the pathogenesis of PP. PMID:23099263

Grossi, Dario; Soricelli, Andrea; Ponari, Marta; Salvatore, Elena; Quarantelli, Mario; Prinster, Anna; Trojano, Luigi

2014-07-01

5

Neuropsychological evidence for the functional role of the uncinate fasciculus in semantic control.  

PubMed

Understanding a word requires mapping sounds to a word-form and then identifying its correct meaning, which in some cases necessitates the recruitment of cognitive control processes to direct the activation of semantic knowledge in a task appropriate manner (i.e., semantic control). Neuroimaging and neuropsychological studies identify a fronto-temporal network important for word comprehension. However, little is known about the connectional architecture subserving controlled retrieval and selection of semantic knowledge during word comprehension. We used diffusion tensor imaging (DTI) and resting-state functional magnetic resonance imaging (rs-fMRI) in aphasic individuals with varying degrees of word comprehension deficits to examine the role of three white matter pathways within this network: the uncinate fasciculus (UF), inferior longitudinal fasciculus (ILF), and inferior fronto-occipital fasciculus (IFOF). Neuroimaging data from a group of age-matched controls were also collected in order to establish that the patient group had decreased structural and functional connectivity profiles. We obtained behavioral data from aphasic participants on two measures of single word comprehension that involve semantic control, and assessed pathway functional significance by correlating patients' performance with indices of pathway structural integrity and the functional connectivity profiles of regions they connect. Both the structural integrity of the UF and the functional connectivity strength of regions it connects predicted patients' performance. This result suggests the semantic control impairment in word comprehension resulted from poor neural communication between regions the UF connects. Inspections of other subcortical and cortical structures revealed no relationship with patients' performance. We conclude that the UF mediates semantic control during word comprehension by connecting regions specialized for cognitive control with those storing word meanings. These findings also support a relationship between structural and functional connectivity measures, as the rs-fMRI results provide converging evidence with those obtained using DTI. PMID:23395830

Harvey, Denise Y; Wei, Tao; Ellmore, Timothy M; Hamilton, A Cris; Schnur, Tatiana T

2013-04-01

6

Maxillary changes and occlusal traits in crania with artificial fronto-occipital deformation.  

PubMed

Artificial fronto-occipital deformation of the cranial vault was typical of pre-Columbian cultures in the central Andean coastal regions. We have studied the influence of this deformation on maxillary and mandibular morphology. Measurements were performed on 86 adult Ancon skulls with anteroposterior deformation. Undeformed skulls from the area of Makatampu (n = 52) were used as the control group. To explore the influence of the deformity on occlusion, the skulls were categorized using the Angle classification and the alignment of the interincisor midline. In the group of deformed skulls, there was an increase in lateral growth of the vault and of the base of the skull (P < 0.001), giving rise to a greater interpterygoid width of the maxilla (P < 0.001), and an increase in the transverse diameter of the palatal vault. The mandible presented an increase in the length of the rami (P < 0.001) and in the intercondylar width, with no alteration of mandibular length. The deformed skulls had normal (class I) occlusion, with no displacement of the midline. The difference in the asymmetry index between the two groups was not statistically significant. Artificial fronto-occipital deformation of the cranial vault provoked compensatory lateral expansion of the base that was correlated with the transverse development of the maxilla and mandible. Occlusion and sagittal intermaxillary position were not affected by the cranial deformity. These results provide evidence of the integration between the neurocranium and the viscerocranium in craniofacial development, and support the hypothesis of a compensatory effect of function. PMID:21990029

Jimenez, Publio; Martinez-Insua, Arturo; Franco-Vazquez, Jaime; Otero-Cepeda, Xose Luis; Santana, Urbano

2012-01-01

7

Quantitative Diffusion Tensor Tractography of Association and Projection Fibers in Normally Developing Children and Adolescents  

Microsoft Academic Search

Whole-brain diffusion tensor tractography (DTT) at high signal-to- noise ratio and angular and spatial resolutions were utilized to study the effects of age, sex differences, and lateral asymmetries of 6 white matter pathways (arcuate fasciculus (AF), inferior longitudinal fasciculus, inferior fronto-occipital fasciculus (IFOF), uncinate fasciculus (UF), corticospinal tract (CST), and somato- sensory pathway (SS)) in 31 right-handed children (6--17 years).

Thomas J. Eluvathingal; Khader M. Hasan; Larry Kramer; Jack M. Fletcher; Linda Ewing-Cobbs

2007-01-01

8

Damage to the left ventral, arcuate fasciculus and superior longitudinal fasciculus-related pathways induces deficits in object naming, phonological language function and writing, respectively.  

PubMed

The anatomic localization of brain functions can be characterized via diffusion tensor imaging in patients with brain tumors and neurological symptoms. The goal of the present study was to evaluate the function of the ventral, arcuate fasciculus (AF) and the superior longitudinal fasciculus (SLF)-related language pathways using these techniques by analyzing 9 patients treated in our hospital between 2007 and 2011. In cases 1-3, the left ventral pathways, namely, the inferior longitudinal fasciculus, uncinate fasciculus or inferior fronto-occipital fasciculus, were mainly damaged, and the common dysfunction experienced by these patients was a deficit in object naming. In cases 4-6, the left SLF was mainly damaged, and the common deficit was dysgraphia. In cases 7-9, the left AF was mainly damaged, and almost all language functions related to phonology were abnormal. These results suggest that the left ventral, AF and SLF-related pathways are closely related to visual, auditory and hand-related language function, respectively. PMID:23311714

Shinoura, Nobusada; Midorikawa, Akira; Onodera, Toshiyuki; Tsukada, Masanobu; Yamada, Ryozi; Tabei, Yusuke; Itoi, Chisato; Saito, Seiko; Yagi, Kazuo

2013-07-01

9

Association of dorsal inferior frontooccipital fasciculus fibers in the deep parietal lobe with both reading and writing processes: a brain mapping study.  

PubMed

Alexia and agraphia are disorders common to the left inferior parietal lobule, including the angular and supramarginal gyri. However, it is still unclear how these cortical regions interact with other cortical sites and what the most important white matter tracts are in relation to reading and writing processes. Here, the authors present the case of a patient who underwent an awake craniotomy for a left inferior parietal lobule glioma using direct cortical and subcortical electrostimulation. The use of subcortical stimulation allowed identification of the specific white matter tracts associated with reading and writing. These tracts were found as portions of the dorsal inferior frontooccipital fasciculus (IFOF) fibers in the deep parietal lobe that are responsible for connecting the frontal lobe to the superior parietal lobule. These findings are consistent with previous diffusion tensor imaging tractography and functional MRI studies, which suggest that the IFOF may play a role in the reading and writing processes. This is the first report of transient alexia and agraphia elicited through intraoperative direct subcortical electrostimulation, and the findings support the crucial role of the IFOF in reading and writing. PMID:24655122

Motomura, Kazuya; Fujii, Masazumi; Maesawa, Satoshi; Kuramitsu, Shunichiro; Natsume, Atsushi; Wakabayashi, Toshihiko

2014-07-01

10

Damage to Association Fiber Tracts Impairs Recognition of the Facial Expression of Emotion  

PubMed Central

An array of cortical and subcortical structures have been implicated in the recognition of emotion from facial expressions. It remains unknown how these regions communicate as parts of a system to achieve recognition, but white matter tracts are likely critical to this process. We hypothesized that (1) damage to white matter tracts would be associated with recognition impairment and (2) the degree of disconnection of association fiber tracts [inferior longitudinal fasciculus (ILF) and/or inferior fronto-occipital fasciculus (IFOF)] connecting the visual cortex with emotion-related regions would negatively correlate with recognition performance. One hundred three patients with focal, stable brain lesions mapped onto a reference brain were tested on their recognition of six basic emotional facial expressions. Association fiber tracts from a probabilistic atlas were coregistered to the reference brain. Parameters estimating disconnection were entered in a general linear model to predict emotion recognition impairments, accounting for lesion size and cortical damage. Damage associated with the right IFOF significantly predicted an overall facial emotion recognition impairment and specific impairments for sadness, anger, and fear. One subject had a pure white matter lesion in the location of the right IFOF and ILF. He presented specific, unequivocal emotion recognition impairments. Additional analysis suggested that impairment in fear recognition can result from damage to the IFOF and not the amygdala. Our findings demonstrate the key role of white matter association tracts in the recognition of the facial expression of emotion and identify specific tracts that may be most critical.

Philippi, Carissa L.; Mehta, Sonya; Grabowski, Thomas; Adolphs, Ralph; Rudrauf, David

2010-01-01

11

Alterations in white matter pathways in Angelman syndrome  

PubMed Central

Aim Angelman syndrome is a neurogenetic disorder characterized by severe intellectual disability, absent speech, seizures, and outbursts of laughter. The aim of this study was to utilize diffusion tensor imaging (DTI) to examine alterations in white matter pathways in Angelman syndrome, with an emphasis on correlations with clinical severity. Methods DTI was used to examine the arcuate fasciculus (AF), uncinate fasciculus (UF), inferior longitudinal fasciculus (ILF), inferior fronto-occipital fasciculus (IFOF), and the corpus callosum (CC). We enrolled 14 children aged 8 to 17 years (mean age 10y 8mo; SD 2y 7mo) with Angelman syndrome (seven male; seven female) and 13 typically developing children, aged 8 to 17 years, for comparison (five male; eight female; mean age 12y; SD 2y 9mo). Individuals with Angelman syndrome were assessed using standardized measures of development, language, and behaviour. Results The children with Angelman syndrome exhibited lower fractional anisotropy and increased radial diffusivity values than the comparison group for the AF, UF, ILF, and CC (p<0.006 corrected for multiple comparisons). They also had lower fractional anisotropy values for the IFOF and higher radial diffusivity values for the left IFOF (p<0.006). Additionally, children with Angelman syndrome had significantly higher apparent diffusion coefficient values in the AF, CC, ILF, and the left IFOF (p<0.006). Significant correlations were noted between DTI parameters and some of the clinical assessment outcomes (e.g. language, socialization, cognition) for three of the temporal pathways (AF, UF, ILF; p<0.05). Interpretation Changes in DTI parameters in individuals with Angelman syndrome suggest decreased/delayed myelination, decreased axonal density or diameter, or aberrant axonal organization. Our findings suggest a generalized white matter alteration throughout the brain in those with Angelman syndrome; however, only the alterations in temporal white matter pathways were associated with language and cognitive and social functioning.

PETERS, SARIKA U; KAUFMANN, WALTER E; BACINO, CARLOS A; ANDERSON, ADAM W; ADAPA, PAVANI; CHU, ZILI; YALLAMPALLI, RAGINI; TRAIPE, ELFRIDES; HUNTER, JILL V; WILDE, ELISABETH A

2010-01-01

12

AN AFFERENT SYSTEM IN THE CENTRAL TEGMENTAL FASCICULUS  

Microsoft Academic Search

The brainstem course of the limb afferent component of the central tegmental fasciculus has been determined in both the cat and the phalanger, Trichosurus vulpecula, using evoked potentials. Unit records obtained from the reticular formation indicate that the ascending central tegmental fasciculus arises in large part from the level of the superior olives. The termination of the system is found

Barbara J Dennis; DIB Kerr

1961-01-01

13

Reading skill in adult survivors of childhood brain tumor: A theory-based neurocognitive model.  

PubMed

Objective: This study investigated the relationship between word reading and white matter (WM) integrity within a neuroanatomical-based reading system comparing adult survivors of childhood brain tumors and controls. It was predicted that the association between WM integrity and word reading would be mediated by processing speed, and this indirect effect would be moderated by group. Method: Thirty-seven adult survivors of childhood brain tumor and typically developing adults participated (age M = 24.19 ± 4.51 years, 62% female). DTI Tractography identified the WM tract for 3 of the reading system connections: inferior fronto-occipital fasciculus (IFOF), arcuate fasciculus (AF), and parietotemporal-occipitotemporal connection (PT-OT). Results: Fractional anisotropy values (FA) of the PT-OT tract were significantly correlated with word reading in survivors and controls (r = .45, .58, respectively; p < .05) and IFOF values were associated with reading in survivors only (r = .59, p < .01). Further, the moderated mediated model was significant for PT-OT and IFOF, such that the indirect effect of processing speed was only present for survivors (CI: PT-OT: 2.90, 28.41, IFOF: 2.92, 40.17). Conclusion: Results suggest the tracts emerging from the occipitotemporal area are a critical component of the reading system in adults. The finding that processing speed was the mechanism by which WM was associated with reading in survivors is in alignment with the developmental cascade model. Current findings bolster the existing theory-based models of reading using innovative diffusion tensor imaging and moderated mediation statistical neurodevelopmental model, establishing the role of processing speed and specific WM pathway integrity in word reading skill. (PsycINFO Database Record (c) 2014 APA, all rights reserved). PMID:24548126

Smith, Kristen M; King, Tricia Z; Jayakar, Reema; Morris, Robin D

2014-05-01

14

Cortex-sparing fiber dissection: an improved method for the study of white matter anatomy in the human brain  

PubMed Central

Classical fiber dissection of post mortem human brains enables us to isolate a fiber tract by removing the cortex and overlying white matter. In the current work, a modification of the dissection methodology is presented that preserves the cortex and the relationships within the brain during all stages of dissection, i.e. ‘cortex-sparing fiber dissection’. Thirty post mortem human hemispheres (15 right side and 15 left side) were dissected using cortex-sparing fiber dissection. Magnetic resonance imaging study of a healthy brain was analyzed using diffusion tensor imaging (DTI)-based tractography software. DTI fiber tract reconstructions were compared with cortex-sparing fiber dissection results. The fibers of the superior longitudinal fasciculus (SLF), inferior fronto-occipital fasciculus (IFOF), inferior longitudinal fasciculus (ILF) and uncinate fasciculus (UF) were isolated so as to enable identification of their cortical terminations. Two segments of the SLF were identified: first, an indirect and superficial component composed of a horizontal and vertical segment; and second, a direct and deep component or arcuate fasciculus. The IFOF runs within the insula, temporal stem and sagittal stratum, and connects the frontal operculum with the occipital, parietal and temporo-basal cortex. The UF crosses the limen insulae and connects the orbito-frontal gyri with the anterior temporal lobe. Finally, a portion of the ILF was isolated connecting the fusiform gyrus with the occipital gyri. These results indicate that cortex-sparing fiber dissection facilitates study of the 3D anatomy of human brain tracts, enabling the tracing of fibers to their terminations in the cortex. Consequently, it is an important tool for neurosurgical training and neuroanatomical research.

Martino, Juan; De Witt Hamer, Philip C; Vergani, Francesco; Brogna, Christian; de Lucas, Enrique Marco; Vazquez-Barquero, Alfonso; Garcia-Porrero, Juan A; Duffau, Hugues

2011-01-01

15

Evaluation of Diffusion-Tensor Imaging-Based Global Search and Tractography for Tumor Surgery Close to the Language System  

PubMed Central

Pre-operative planning and intra-operative guidance in neurosurgery require detailed information about the location of functional areas and their anatomo-functional connectivity. In particular, regarding the language system, post-operative deficits such as aphasia can be avoided. By combining functional magnetic resonance imaging and diffusion tensor imaging, the connectivity between functional areas can be reconstructed by tractography techniques that need to cope with limitations such as limited resolution and low anisotropic diffusion close to functional areas. Tumors pose particular challenges because of edema, displacement effects on brain tissue and infiltration of white matter. Under these conditions, standard fiber tracking methods reconstruct pathways of insufficient quality. Therefore, robust global or probabilistic approaches are required. In this study, two commonly used standard fiber tracking algorithms, streamline propagation and tensor deflection, were compared with a previously published global search, Gibbs tracking and a connection-oriented probabilistic tractography approach. All methods were applied to reconstruct neuronal pathways of the language system of patients undergoing brain tumor surgery, and control subjects. Connections between Broca and Wernicke areas via the arcuate fasciculus (AF) and the inferior fronto-occipital fasciculus (IFOF) were validated by a clinical expert to ensure anatomical feasibility, and compared using distance- and diffusion-based similarity metrics to evaluate their agreement on pathway locations. For both patients and controls, a strong agreement between all methods was observed regarding the location of the AF. In case of the IFOF however, standard fiber tracking and Gibbs tracking predominantly identified the inferior longitudinal fasciculus that plays a secondary role in semantic language processing. In contrast, global search resolved connections in almost every case via the IFOF which could be confirmed by probabilistic fiber tracking. The results show that regarding the language system, our global search is superior to clinically applied conventional fiber tracking strategies with results similar to time-consuming global or probabilistic approaches.

Richter, Mirco; Zolal, Amir; Ganslandt, Oliver; Buchfelder, Michael; Nimsky, Christopher; Merhof, Dorit

2013-01-01

16

Is the left uncinate fasciculus essential for language?  

Microsoft Academic Search

Despite a better understanding of the anatomy of the uncinate fasciculus (UF), its function remains poorly known. Our aim\\u000a was to study the exact role of UF in language, and the possible existence of parallel distributed language networks within\\u000a the “ventral stream”, underlaid by distinct subcortical tracts – namely the inferior occipito-temporal fasciculus (IOF) and\\u000a UF.\\u000a \\u000a We report a series

Hugues Duffau; Peggy Gatignol; Sylvie Moritz-Gasser; Emmanuel Mandonnet

2009-01-01

17

Dissecting the uncinate fasciculus: disorders, controversies and a hypothesis.  

PubMed

The uncinate fasciculus is a bidirectional, long-range white matter tract that connects lateral orbitofrontal cortex and Brodmann area 10 with the anterior temporal lobes. Although abnormalities in the uncinate fasciculus have been associated with several psychiatric disorders and previous studies suggest it plays a putative role in episodic memory, language and social emotional processing, its exact function is not well understood. In this review we summarize what is currently known about the anatomy of the uncinate, we review its role in psychiatric and neurological illnesses, and we evaluate evidence related to its putative functions. We propose that an overarching role of the uncinate fasciculus is to allow temporal lobe-based mnemonic associations (e.g. an individual's name + face + voice) to modify behaviour through interactions with the lateral orbitofrontal cortex, which provides valence-based biasing of decisions. The bidirectionality of the uncinate fasciculus information flow allows orbital frontal cortex-based reward and punishment history to rapidly modulate temporal lobe-based mnemonic representations. According to this view, disruption of the uncinate may cause problems in the expression of memory to guide decisions and in the acquisition of certain types of learning and memory. Moreover, uncinate perturbation should cause problems that extend beyond memory to include social-emotional problems owing to people and objects being stripped of personal value and emotional history and lacking in higher-level motivational value. PMID:23649697

Von Der Heide, Rebecca J; Skipper, Laura M; Klobusicky, Elizabeth; Olson, Ingrid R

2013-06-01

18

The Role of the Arcuate Fasciculus in Conduction Aphasia  

ERIC Educational Resources Information Center

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…

Bernal, Byron; Ardila, Alfredo

2009-01-01

19

MR Imaging of the Temporal Stem: Anatomic Dissection Tractography of the Uncinate Fasciculus, Inferior Occipitofrontal Fasciculus, and Meyer's Loop of the Optic Radiation  

Microsoft Academic Search

BACKGROUND AND PURPOSE: The MR anatomy of the uncinate fasciculus, inferior occipitofrontal fasciculus, and Meyer's loop of the optic radiation, which traverse the temporal stem, is not well known. The purpose of this investigation was to study these structures in the anterior temporal lobe and the external and extreme capsules and to correlate the dissected anatomy with the cross-sectional MR

E. Leon Kier; Lawrence H. Staib; Lawrence M. Davis; Richard A. Bronen

20

Brain white matter microstructure is associated with susceptibility to motion-induced nausea.  

PubMed

Nausea is associated with significant morbidity, and there is a wide range in the propensity of individuals to experience nausea. The neural basis of the heterogeneity in nausea susceptibility is poorly understood. Our previous functional magnetic resonance imaging (fMRI) study in healthy adults showed that a visual motion stimulus caused activation in the right MT+/V5 area, and that increased sensation of nausea due to this stimulus was associated with increased activation in the right anterior insula. For the current study, we hypothesized that individual differences in visual motion-induced nausea are due to microstructural differences in the inferior fronto-occipital fasciculus (IFOF), the white matter tract connecting the right visual motion processing area (MT+/V5) and right anterior insula. To test this hypothesis, we acquired diffusion tensor imaging data from 30 healthy adults who were subsequently dichotomized into high and low nausea susceptibility groups based on the Motion Sickness Susceptibility Scale. We quantified diffusion along the IFOF for each subject based on axial diffusivity (AD); radial diffusivity (RD), mean diffusivity (MD) and fractional anisotropy (FA), and evaluated between-group differences in these diffusion metrics. Subjects with high susceptibility to nausea rated significantly (P < 0.001) higher nausea intensity to visual motion stimuli and had significantly (P < 0.05) lower AD and MD along the right IFOF compared to subjects with low susceptibility to nausea. This result suggests that differences in white matter microstructure within tracts connecting visual motion and nausea-processing brain areas may contribute to nausea susceptibility or may have resulted from an increased history of nausea episodes. PMID:23360260

Napadow, V; Sheehan, J; Kim, J; Dassatti, A; Thurler, A H; Surjanhata, B; Vangel, M; Makris, N; Schaechter, J D; Kuo, B

2013-05-01

21

A combined DTI and structural MRI study in medicated-naïve chronic schizophrenia.  

PubMed

Disconnection in white matter (WM) pathway and alterations in gray matter (GM) structure have been hypothesized as pathogenesis in schizophrenia. However, the relationship between the abnormal WM integrity and the alteration of GM in anatomically connected areas remains uncertain. Moreover, the potential influence of antipsychotic medication on WM anisotropy and cortical morphology was not excluded in previous studies. In this study, a total number of 34 subjects were enrolled, including 17 medicated-naïve chronic schizophrenia patients and 17 healthy controls. Tract-based spatial statistics (TBSS) were applied to investigate the level of WM integrity. The FreeSurfer surface-based analysis was used to determine GM volume, cortical thickness and the surface area of GM regions which corresponded to abnormal WM fiber tracts. We observed that patients possessed lower fractional anisotropy (FA) values in the left inferior fronto-occipital fasciculus (IFOF) and left inferior longitudinal fasciculus (ILF), along with smaller GM volume and cortical thinning in temporal lobe than the healthy controls, which reflected the underlying WM and GM disruption that contributed to the disease. In the patient population, the lower connectivity of ILF and IFOF was positively associated with cortical thickness in left lateral orbitofrontal cortex, superior temporal gyrus and lingual gyrus in males, and positively correlated with GM volume in left lateral orbitofrontal cortex in females. On the other hand, it was negatively correlated with cortical area of middle temporal gyrus in males and temporal pole in females respectively, but not when genders were combined. These findings suggested that abnormal WM integrity and anatomical correspondence of GM alterations in schizophrenia were interdependent on gender-separated analysis in patients with schizophrenia. Moreover, combining TBSS and FreeSurfer might be a useful method to provide significant insight into interacting processes related to WM fiber tracts and GM changes in schizophrenia. PMID:24161847

Liu, Xiaoyi; Lai, Yunyao; Wang, Xijin; Hao, Chuanxi; Chen, Lei; Zhou, Zhenyu; Yu, Xin; Hong, Nan

2014-01-01

22

Diffusion Tensor Anisotropy in Adolescents and Adults  

Microsoft Academic Search

We acquired diffusion tensor images on 33 normal adults aged 22–64 and 15 adolescents aged 14–21. We assessed relative anisotropy in stereotaxically located regions of interest in the internal capsule, corpus callosum, anterior thalamic radiations, frontal anterior fasciculus, fronto-occipital fasciculus, temporal lobe white matter, cingulum bundle, frontal inferior longitudinal fasciculus, frontal superior longitudinal fasciculus, and optic radiations. All of these

Jason S. Schneiderman; Monte S. Buchsbaum; M. Mehmet. Haznedar; Erin A. Hazlett; Adam M. Brickman; Lina Shihabuddin; Jesse G. Brand; Yuliya Torosjan; Randall E. Newmark; Cheuk Tang; Jonathan Aronowitz; Reshmi Paul-Odouard; William Byne; Patrick R. Hof

2007-01-01

23

Naming and the role of the uncinate fasciculus in language function.  

PubMed

In this paper, an overview of the studies relating naming to the uncinate fasciculus is reported. With the introduction of contemporary neuroimaging techniques, namely of diffusion tensor imaging, white matter tracts have been investigated more thoroughly and possible changes in the uncinate fasciculus integrity have been correlated to different neuropsychological deficits. Although previous research has proposed a role of the left uncinate fasciculus on action and object naming or in semantic processing, a more recent study has suggested that naming famous people could be the most relevant task in which this bundle is involved, the semantic component being intact. The uncinate fasciculus connects the orbitofrontal cortex, involved in face encoding and in processing famous names, to the temporal pole, which is crucial in naming people. This conclusion is supported by the fact that tip-of-the-tongue states in older adults with reduced integrity of the uncinate fasciculus mainly concern proper names. PMID:21853238

Papagno, Costanza

2011-12-01

24

Superior longitudinal fasciculus and language functioning in healthy aging.  

PubMed

Structural deterioration of brain tissue in older adults is thought to be responsible for the majority of age-related cognitive decline. Disruption of widespread cortical networks due to a loss of axonal integrity may also play an important role. Research examining correlations between structural change and functional decline has focused heavily on working memory, processing speed, and executive processes while other aspects of cognition, such as language functioning, have received less attention. The current study aimed to determine whether age-related changes in the superior longitudinal fasciculus (SLF), are responsible for the deterioration in language functioning associated with age. Subjects included 112 right-handed volunteers (ages 19-76). For each subject, the SLF of the left hemisphere was reconstructed from diffusion tensor images (DTI). Mean fractional anisotropy (FA) values were extracted from parietal (SLFp) and temporal (SLFt) bundles. Language functioning was measured using the Peabody Picture Vocabulary Test (PPVT), Boston Naming Test (BNT), Controlled Oral Word Association Test (COWAT), and Semantic Fluency Test (SFT). Regression analyses revealed that males and females showed a different pattern of decline in FA across adulthood. For males, greater SLFt FA was significantly associated with increased COWAT performance, and there was a positive relationship between both age and SLFp FA with BNT scores. In females, greater SLFp FA was related to lower COWAT performance. Taken together, the results suggest that white matter integrity of the SLF follows a different pattern of decline in adulthood for males and females, and this decline differentially affects language functioning. PMID:24680744

Madhavan, Kiely M; McQueeny, Tim; Howe, Steven R; Shear, Paula; Szaflarski, Jerzy

2014-05-01

25

Microstructural connectivity of the arcuate fasciculus in adolescents with high-functioning autism  

PubMed Central

The arcuate fasciculus is a white matter fiber bundle of great importance in language. In this study, diffusion tensor imaging (DTI) was used to infer white matter integrity in the arcuate fasciculi of a group of subjects with high-functioning autism and a control group matched for age, handedness, IQ, and head size. The arcuate fasciculus for each subject was automatically extracted from the imaging data using a new volumetric DTI segmentation algorithm. The results showed a significant increase in mean diffusivity (MD) in the autism group, due mostly to an increase in the radial diffusivity (RD). A test of the lateralization of DTI measurements showed that both MD and fractional anisotropy (FA) were less lateralized in the autism group. These results suggest that white matter microstructure in the arcuate fasciculus is affected in autism and that the language specialization apparent in the left arcuate of healthy subjects is not as evident in autism, which may be related to poorer language functioning.

Fletcher, P. Thomas; Whitaker, Ross T.; Tao, Ran; DuBray, Molly B.; Froehlich, Alyson; Ravichandran, Caitlin; Alexander, Andrew L.; Bigler, Erin D.; Lange, Nicholas; Lainhart, Janet E.

2010-01-01

26

Pre-cue Fronto-Occipital Alpha Phase and Distributed Cortical Oscillations Predict Failures of Cognitive Control  

PubMed Central

Cognitive control is required for correct performance on antisaccade tasks, including the ability to inhibit an externally driven ocular motor repsonse (a saccade to a peripheral stimulus) in favor of an internally driven ocular motor goal (a saccade directed away from a peripheral stimulus). Healthy humans occasionally produce errors during antisaccade tasks, but the mechanisms associated with such failures of cognitive control are uncertain. Most research on cognitive control failures focuses on post-stimulus processing, although a growing body of literature highlights a role of intrinsic brain activity in perceptual and cognitive performance. The current investigation used dense array electroencephalography and distributed source analyses to examine brain oscillations across a wide frequency bandwidth in the period prior to antisaccade cue onset. Results highlight four important aspects of ongoing and preparatory brain activations that differentiate error from correct antisaccade trials: (i) ongoing oscillatory beta (20–30Hz) power in anterior cingulate prior to trial initiation (lower for error trials), (ii) instantaneous phase of ongoing alpha-theta (7Hz) in frontal and occipital cortices immediately before trial initiation (opposite between trial types), (iii) gamma power (35–60Hz) in posterior parietal cortex 100 ms prior to cue onset (greater for error trials), and (iv) phase locking of alpha (5–12Hz) in parietal and occipital cortices immediately prior to cue onset (lower for error trials). These findings extend recently reported effects of pre-trial alpha phase on perception to cognitive control processes, and help identify the cortical generators of such phase effects.

Hamm, Jordan P.; Dyckman, Kara A.; McDowell, Jennifer E.; Clementz, Brett A.

2012-01-01

27

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

Microsoft Academic Search

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

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

2008-01-01

28

The relationship between uncinate fasciculus white matter integrity and verbal memory proficiency in children.  

PubMed

During childhood, verbal learning and memory are important for academic performance. Recent functional MRI studies have reported on the functional correlates of verbal memory proficiency, but few have reported the underlying structural correlates. The present study sought to test the relationship between fronto-temporal white matter integrity and verbal memory proficiency in children. Diffusion weighted images were collected from 17 Black children (age 8-11 years) who also completed the California Verbal Learning Test. To index white matter integrity, fractional anisotropy values were calculated for bilateral uncinate fasciculus. The results revealed that low anisotropy values corresponded to poor verbal memory, whereas high anisotropy values corresponded to significantly better verbal memory scores. These findings suggest that a greater degree of myelination and cohesiveness of axonal fibers in uncinate fasciculus underlie better verbal memory proficiency in children. PMID:24949818

Schaeffer, David J; Krafft, Cynthia E; Schwarz, Nicolette F; Chi, Lingxi; Rodrigue, Amanda L; Pierce, Jordan E; Allison, Jerry D; Yanasak, Nathan E; Liu, Tianming; Davis, Catherine L; McDowell, Jennifer E

2014-08-20

29

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

PubMed Central

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 variation in the microstructural properties of arcuate fibers and behavioral measures of language and reading skills. A second objective was to use novel fiber-tracking methods to reassess estimates of arcuate lateralization. In a sample of 55 children, we found that measurements of diffusivity in the left arcuate correlate with phonological awareness skills and arcuate volume lateralization correlates with phonological memory and reading skills. Contrary to previous investigations that report the absence of the right arcuate in some subjects, we demonstrate that new techniques can identify the pathway in every individual. Our results provide empirical support for the role of the arcuate fasciculus in the development of reading skills.

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

2011-01-01

30

Evaluating the Arcuate Fasciculus With Combined Diffusion-Weighted MRI Tractography and Electrocorticography  

PubMed Central

The conventional model of language-related brain structure describing the arcuate fasciculus as a key white matter tract providing a direct connection between Wernicke’s region and Broca’s area has been called into question. Specifically, the inferior precentral gyrus, possessing both primary motor (Brodmann Area [BA] 4) and premotor cortex (BA 6), has been identified as a potential alternative termination. The authors initially localized cortical sites involved in language using measurement of event-related gamma-activity on electrocorticography (ECoG). The authors then determined whether language-related sites of the temporal lobe were connected, via white matter structures, to the inferior frontal gyrus more tightly than to the precentral gyrus. The authors found that language-related sites of the temporal lobe were far more likely to be directly connected to the inferior precentral gyrus through the arcuate fasciculus. Furthermore, tractography was a significant predictor of frontal language-related ECoG findings. Analysis of an interaction between anatomy and tractography in this model revealed tractrography to have the highest predictive value for language-related ECoG findings of the precentral gyrus. This study failed to support the conventional model of language-related brain structure. More feasible models should include the inferior precentral gyrus as a termination of the arcuate fasciculus. The exact functional significance of direct connectivity between temporal language-related sites and the precentral gyrus requires further study.

Brown, Erik C.; Jeong, Jeong-Won; Muzik, Otto; Rothermel, Robert; Matsuzaki, Naoyuki; Juhasz, Csaba; Sood, Sandeep; Asano, Eishi

2014-01-01

31

What is the role of the uncinate fasciculus? Surgical removal and proper name retrieval.  

PubMed

The functional role of the uncinate fasciculus is still a matter of debate. We examined 44 patients submitted to awake surgery for removal of a left frontal or temporal glioma. In 18 patients, the removal included the uncinate fasciculus. We compared patients with or without removal on a series of neuropsychological tasks, performed at different time intervals: pre-surgery, in the first week after surgery and 3 months after surgery. Functional magnetic resonance and diffusion tensor imaging, fibre-tracking techniques were performed before surgery. At the last examination, patients with uncinate removal were significantly impaired in naming of famous faces and objects as compared with patients without removal. We further divided patients according to the site of the tumour (either frontal or temporal). At the follow-up, patients with a temporal glioma who underwent uncinate removal had the worst loss of performance in famous face naming. In addition, on the same task, the group with a frontal glioma that underwent resection of the frontal part of the uncinate performed significantly worse than the group with a frontal glioma but without uncinate removal. In conclusion, the resection of the uncinate fasciculus, in its frontal or temporal part, has long-lasting consequences for famous face naming. We suggest that this fibre tract is part of a circuitry involved in the retrieval of word form for proper names. Retrieval of conceptual knowledge was intact. PMID:20959310

Papagno, Costanza; Miracapillo, Christiano; Casarotti, Alessandra; Romero Lauro, Leonor J; Castellano, Antonella; Falini, Andrea; Casaceli, Giuseppe; Fava, Enrica; Bello, Lorenzo

2011-02-01

32

Quantification of the spatiotemporal microstructural organization of the human brain association, projection and commissural pathways across the lifespan using diffusion tensor tractography  

PubMed Central

Using diffusion tensor tractography, we quantified the microstructural changes in the association, projection, and commissural compact white matter pathways of the human brain over the lifespan in a cohort of healthy right-handed children and adults aged 6–68 years. In both males and females, the diffusion tensor radial diffusivity of the bilateral arcuate fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, uncinate fasciculus, corticospinal, somatosensory tracts, and the corpus callosum followed a U-curve with advancing age; fractional anisotropy in the same pathways followed an inverted U-curve. Our study provides useful baseline data for the interpretation of data collected from patients.

Kamali, Arash; Abid, Humaira; Kramer, Larry A.; Fletcher, Jack M.; Ewing-Cobbs, Linda

2010-01-01

33

Diffusion tensor imaging in autism spectrum disorders: Preliminary evidence of abnormal neural connectivity  

PubMed Central

Objective This study indirectly tested the hypothesis that individuals with autism spectrum disorders (ASDs) have impaired neural connections between the amygdala, fusiform face area, and superior temporal sulcus, key processing nodes of the “social brain.” This would be evidenced by abnormalities in the major fibre tracts known to connect these structures, including the inferior longitudinal fasciculus and inferior fronto-occipital fasciculus. Method Magnetic resonance diffusion tensor imaging was performed on 20 right-handed males (ASD = 10, controls = 10) with a mean age 13.5 ± 4.0 years. Subjects were group-matched according to age, full-scale IQ, handedness, and ethnicity. Fractional anisotropy was used to assess structural integrity of major fibre tracts. Voxel-wise comparison of white matter fractional anisotropy was conducted between groups using ANCOVA adjusting for age, full-scale IQ, and brain volume. Volumes of interest were identified using predetermined probability and cluster thresholds. Follow-up tractography was performed to confirm the anatomic location of all volumes of interest. Results All volumes of interest were regions of lower FA and were observed primarily in pericallosal regions and temporal lobes. As confirmed by tractography, affected white matter structures included the inferior longitudinal fasciculus/inferior fronto-occipital fasciculus, superior longitudinal fasciculus, and corpus callosum/cingulum. Notably, some volumes of interest were adjacent to the fusiform face area, bilaterally, corresponding to involvement of the inferior longitudinal fasciculus. The largest effect sizes were noted for volumes of interest in the right anterior radiation of the corpus callosum/cingulum and right fusiform face area (inferior longitudinal fasciculus). Conclusions This study provides preliminary evidence of impaired neural connectivity in the corpus callosum/cingulum and temporal lobes involving the inferior longitudinal fasciculus/inferior fronto-occipital fasciculus and superior longitudinal fasciculus in ASDs. These findings provide preliminary support for aberrant neural connectivity between the amygdala, fusiform face area, and superior temporal sulcus – temporal lobe structures critical for normal social perception and cognition.

Jou, Roger J.; Jackowski, Andrea P.; Papademetris, Xenophon; Rajeevan, Nallakkandi; Staib, Lawrence H.; Volkmar, Fred R.

2011-01-01

34

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

PubMed

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. PMID:19642255

Coppens, Christian

2009-01-01

35

Diffusion Tensor Anisotropy in Adolescents and Adults  

PubMed Central

We acquired diffusion tensor images on 33 normal adults aged 22–64 and 15 adolescents aged 14–21. We assessed relative anisotropy in stereotaxically located regions of interest in the internal capsule, corpus callosum, anterior thalamic radiations, frontal anterior fasciculus, fronto-occipital fasciculus, temporal lobe white matter, cingulum bundle, frontal inferior longitudinal fasciculus, frontal superior longitudinal fasciculus, and optic radiations. All of these structures except the optic radiations, corpus callosum, and frontal inferior longitudinal fasciculus exhibited differences in anisotropy between adolescents and adults. Areas with anisotropy increasing with age included the anterior limb of the internal capsule, superior levels of the frontal superior longitudinal fasciculus and the inferior portion of the temporal white matter. Areas with anisotropy decreasing with age included the posterior limb of the internal capsule, anterior thalamic radiations, fronto-occipital fasciculus, anterior portion of the frontal anterior fasciculus, inferior portion of the frontal superior longitudinal fasciculus, cingulum bundle and superior portion of the temporal axis. Sex differences were found in the majority of areas but were most marked in the cingulum bundle and internal capsule. These results suggest continuing white matter development between adolescence and adulthood.

Schneiderman, Jason S.; Buchsbaum, Monte S.; Haznedar, M. Mehmet; Hazlett, Erin A.; Brickman, Adam M.; Shihabuddin, Lina; Brand, Jesse G.; Torosjan, Yuliya; Newmark, Randall E.; Tang, Cheuk; Aronowitz, Jonathan; Paul-Odouard, Reshmi; Byne, William; Hof, Patrick R.

2009-01-01

36

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

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,…

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

37

Predicting Behavioral Deficits in Pediatric Traumatic Brain Injury Through Uncinate Fasciculus Integrity  

PubMed Central

Behavioral dysregulation is a common and detrimental consequence of traumatic brain injury (TBI) in children that contributes to poor academic achievement and deficits in social development. Unfortunately, behavioral dysregulation is difficult to predict from either injury severity or early neuropsychological evaluation. The uncinate fasciculus (UF) connects orbitofrontal and anterior temporal lobes, which are commonly implicated in emotional and behavioral regulation. Using probabilistic diffusion tensor tractography (DTT), we examined the relationship between the integrity of the UF 3 months post-injury and ratings of executive functions 12 months post-injury in children with moderate to severe TBI and a comparison group with orthopedic injuries. As expected, fractional anisotropy of the UF was lower in the TBI group relative to the orthopedic injury group. DTT metrics from the UF served as a biomarker and predicted ratings of emotional and behavior regulation, but not metacognition. In contrast, the Glasgow Coma Scale score was not related to either UF integrity or to executive function outcomes. Neuroanatomical biomarkers like the uncinate fasciculus may allow for early identification of behavioral problems and allow for investigation into the relationship of frontotemporal networks to brain-behavior relationships.

Johnson, Chad P.; Juranek, Jenifer; Kramer, Larry A.; Prasad, Mary R.; Swank, Paul R.; Ewing-Cobbs, Linda

2013-01-01

38

Evidence of Slow Maturation of the Superior Longitudinal Fasciculus in Early Childhood by Diffusion Tensor Imaging  

PubMed Central

While the majority of axonal organization is established by birth in mammalian brains, axonal wiring and pruning processes, as well as myelination, are known to extend to the postnatal periods, where environmental stimuli often play a major role. Normal axonal and myelin development of individual white matter tracts of human in this period is poorly understood and may have a major role in cognitive development of human. In this study, we applied diffusion tensor imaging and normalization-based population analyses to 44 preteen children and 30 adult images. We observed highly significant changes of fiber orientations at regions that correspond to the superior longitudinal fasciculus during the first five years. The result is attributed to slow axonal and/or myelin maturation of this tract, which is believed to be involved in language functions.

Zhang, Jiangyang; Evans, Alan; Hermoye, Laurent; Lee, Seung-Koo; Wakana, Setsu; Zhang, Weihong; Donohue, Pamela; Miller, Michael I.; Huang, Hao; Wang, Xiaoqing; van Zijl, Peter C.M.; Mori, Susumu

2009-01-01

39

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

PubMed Central

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, regardless of the direction of hand preference, demonstrated the most asymmetric arcuate fasciculus, with larger left versus right arcuate, as measured by DTI. Functional language lateralization in Wernicke's area, measured via fMRI, was related to arcuate fasciculus volume in consistent-left-handers only, and only in people who were not right hemisphere lateralized for language; given the small sample size for this finding, future investigation is warranted. Results suggest handedness degree may be an important variable to investigate in the context of neuroanatomical asymmetries.

Propper, Ruth 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

40

Mild Traumatic Brain Injury and Conduction Aphasia from a Close Proximity Blast Resulting in Arcuate Fasciculus Damage Diagnosed on DTI Tractography.  

National Technical Information Service (NTIS)

The authors present a case demonstrating that a blast injury was associated with both conduction aphasia and an abnormality in the left Arcuate Fasciculus (AF) on MR DTI (Diffusion Tensor Imaging). In addition, this study showed the presence of conduction...

A. Kasprisin A. Rosen J. W. Ashford W. Han Y. Zhang

2009-01-01

41

Increased Brain White Matter Axial Diffusivity Associated with Fatigue, Pain and Hyperalgesia in Gulf War Illness  

PubMed Central

Background 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. Methods 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. Results 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. Conclusion 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.

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

2013-01-01

42

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

Microsoft Academic Search

Recent evidence points to white-matter abnormalities as a key factor in autism physiopathology. Using Diffusion Tensor Imaging,\\u000a we studied white-matter structural properties in a convenience sample of twenty-two subjects with low-functioning autism exposed\\u000a to long-term augmentative and alternative communication, combined with sessions of cognitive and behavioral therapy. Uncinate\\u000a fasciculus structural properties correlated significantly with therapy length and early onset, as

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

43

Sex differences of uncinate fasciculus structural connectivity in individuals with conduct disorder.  

PubMed

Conduct disorder (CD) is one of the most common behavior disorders in adolescents, such as impulsivity, aggression, and running from school. Males are more likely to develop CD than females, and two previous diffusion tensor imaging (DTI) studies have demonstrated abnormal microstructural integrity in the uncinate fasciculus (UF) in boys with CD compared to a healthy control group. However, little is known about changes in the UF in females with CD. In this study, the UF was illustrated by tractography; then, the fractional anisotropy (FA), axial diffusivity, mean diffusion, radial diffusivity (RD), and the length and number of the UF fiber bundles were compared between male and female patients with CD and between female patients with CD and female healthy controls, as well as between males with CD and healthy males. We found that males with CD showed significantly higher FA of the bilateral UF and significantly lower RD of the left UF when comparing with females with CD. Meanwhile, significantly higher FA and lower RD of the bilateral UF were also found in boys with CD relative to the male healthy controls. Our results replicated previous reports that the microstructural integrity of the UF was abnormal in boys with CD. Additionally, our results demonstrated significant gender effects on the UF of patients with CD, which may indicate why boys have higher rates of conduct problems than girls. PMID:24829912

Zhang, Jibiao; Gao, Junling; Shi, Huqing; Huang, Bingsheng; Wang, Xiang; Situ, Weijun; Cai, Weixiong; Yi, Jinyao; Zhu, Xiongzhao; Yao, Shuqiao

2014-01-01

44

Individual differences in crossmodal brain activity predict arcuate fasciculus connectivity in developing readers.  

PubMed

Crossmodal integration of auditory and visual information, such as phonemes and graphemes, is a critical skill for fluent reading. Previous work has demonstrated that white matter connectivity along the arcuate fasciculus (AF) is predicted by reading skill and that crossmodal processing particularly activates the posterior STS (pSTS). However, the relationship between this crossmodal activation and white matter integrity has not been previously reported. We investigated the interrelationship of crossmodal integration, both in terms of behavioral performance and pSTS activity, with AF tract coherence using a rhyme judgment task in a group of 47 children with a range of reading abilities. We demonstrate that both response accuracy and pSTS activity for crossmodal (auditory-visual) rhyme judgments was predictive of fractional anisotropy along the left AF. Unimodal (auditory-only or visual-only) pSTS activity was not significantly related to AF connectivity. Furthermore, activity in other reading-related ROIs did not show the same AV-only AF coherence relationship, and AV pSTS activity was not related to connectivity along other language-related tracts. This study is the first to directly show that crossmodal brain activity is specifically related to connectivity in the AF, supporting its role in phoneme-grapheme integration ability. More generally, this study helps to define an interdependent neural network for reading-related integration. PMID:24456399

Gullick, Margaret M; Booth, James R

2014-07-01

45

Sex Differences of Uncinate Fasciculus Structural Connectivity in Individuals with Conduct Disorder  

PubMed Central

Conduct disorder (CD) is one of the most common behavior disorders in adolescents, such as impulsivity, aggression, and running from school. Males are more likely to develop CD than females, and two previous diffusion tensor imaging (DTI) studies have demonstrated abnormal microstructural integrity in the uncinate fasciculus (UF) in boys with CD compared to a healthy control group. However, little is known about changes in the UF in females with CD. In this study, the UF was illustrated by tractography; then, the fractional anisotropy (FA), axial diffusivity, mean diffusion, radial diffusivity (RD), and the length and number of the UF fiber bundles were compared between male and female patients with CD and between female patients with CD and female healthy controls, as well as between males with CD and healthy males. We found that males with CD showed significantly higher FA of the bilateral UF and significantly lower RD of the left UF when comparing with females with CD. Meanwhile, significantly higher FA and lower RD of the bilateral UF were also found in boys with CD relative to the male healthy controls. Our results replicated previous reports that the microstructural integrity of the UF was abnormal in boys with CD. Additionally, our results demonstrated significant gender effects on the UF of patients with CD, which may indicate why boys have higher rates of conduct problems than girls.

Zhang, Jibiao; Gao, Junling; Shi, Huqing; Huang, Bingsheng; Wang, Xiang; Situ, Weijun; Cai, Weixiong; Yi, Jinyao; Zhu, Xiongzhao; Yao, Shuqiao

2014-01-01

46

Superior longitudinal fasciculus and cognitive dysfunction in adolescents born preterm and at term  

PubMed Central

Aim To understanding the relation between cognition and white matter structure in adolescents born preterm without obvious brain injury. Methods Thirty-two adolescents were selected based on birth risk (Full-term: M:F=8:5, Median (Interquartile Range) Age=16.1(.8); Low-risk preterm: M:F=4:5, Age=16.0(.3); High-risk preterm: M:F=3:7, Age=16.2(1.2)) and reading ability (Good-readers: M:F=3:8, Age=16.0(.6); Average-readers, M:F=6:3, Age=16.8(1.0); Poor-readers M:F=6:6, Age=16.0(.5)) from a longitudinal study on child development. Preterm birth was defined as a gestational age ?36 weeks and a birth weight <=1600g. All participants demonstrated normal clinical neuroimaging. We examined fractional anisotropy (FA), radial diffusivity and volume of three major white matter fasciculi. The relations between structural measures and birth risk, hemisphere and cognitive ability (attention, lexical and sublexical decoding, auditory phonological awareness and processing speed) were analyzed using mixed-model regression. Results Left superior longitudinal fasciculus (SLF) FA and radial diffusivity was related to reading-related skills while right SLF FA was related to attention skills. SLF volume decreased as these skills declined for adolescents born preterm, but not those born at term. Interpretation The relation between cognitive skills and SLF volume suggests that cryptic white matter injury may exist, possibly related to oligodendrocyte or axonal loss, despite normal clinical neuroimaging in adolescents born preterm.

Frye, Richard E.; Hasan, Khader; Malmberg, Benjamin; deSouza, Laura; Swank, Paul; Smith, Karen; Landry, Susan

2010-01-01

47

White matter alterations in temporal lobe epilepsy  

NASA Astrophysics Data System (ADS)

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.

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

2011-03-01

48

Analysis of the subcomponents and cortical terminations of the perisylvian superior longitudinal fasciculus: a fiber dissection and DTI tractography study.  

PubMed

The anatomy of the perisylvian component of the superior longitudinal fasciculus (SLF) has recently been reviewed by numerous diffusion tensor imaging tractography (DTI) studies. However, little is known about the exact cortical terminations of this tract. The aim of the present work is to isolate the different subcomponents of this tract with fiber dissection and DTI tractography, and to identify the exact cortical connections. Twelve postmortem human hemispheres (6 right and 6 left) were dissected using the cortex-sparing fiber dissection. In addition, three healthy brains were analyzed using DTI-based tractography software. The different components of the perisylvian SLF were isolated and the fibers were followed until the cortical terminations. Three segments of the perisylvian SLF were identified: (1) anterior segment, connecting the supramarginal gyrus and superior temporal gyrus with the precentral gyrus, (2) posterior segment, connecting the posterior portion of the middle temporal gyrus with the angular gyrus, and (3) long segment of the arcuate fasciculus that connects the middle and inferior temporal gyri with the precentral gyrus and posterior portion of the inferior and middle frontal gyri. In the present study, three different components of the perisylvian SLF were identified. For the first time, our dissections revealed that each component was connected to a specific cortical area within the frontal, parietal and temporal lobes. By accurately depicting not only the trajectory but also cortical connections of this bundle, it is possible to develop new insights into the putative functional role of this tract. PMID:22422148

Martino, Juan; De Witt Hamer, Philip C; Berger, Mitchel S; Lawton, Michael T; Arnold, Christine M; de Lucas, Enrique Marco; Duffau, Hugues

2013-01-01

49

Abnormal Language Pathway in Children with Angelman Syndrome  

PubMed Central

Angelman Syndrome is a genetic disorder characterized by pervasive developmental disability with failure to develop speech. We examined the basis for severe language delay in Angelman Syndrome patients using diffusion tensor imaging. Magnetic Resonance Imaging/diffusion tensor imaging was performed in seven genetically confirmed Angelman Syndrome children (age:70±26 months, five males) and four age-matched controls to investigate the microstructural integrity of arcuate fasciculus and other major association tracts. Six of seven Angelman Syndrome children had unidentifiable left arcuate fasciculus while all controls had identifiable arcuate fasciculus. The right arcuate fasciculus was absent in six of seven Angelman Syndrome children and one of four controls. Diffusion tensor imaging color map suggested aberrant morphology of the arcuate fasciculus region. Other association tracts, including uncinate fasciculus, inferior-fronto-occipital fasciculus, inferior-longitudinal fasciculus, and corticospinal tract, were identifiable but showed decreased fractional anisotropy in Angelman Syndrome children. Increased apparent diffusion coefficient was seen in all tracts except uncinate fasciculus when compared to controls. Angelman Syndrome patients have global impairment of white matter integrity in association tracts, particularly, the arcuate fasciculus which shows severe morphological changes. This could be due to a potential problem with axon guidance during brain development possibly due to loss of UBE3A gene expression.

Wilson, Benjamin J.; Sundaram, Senthil K.; Huq, AHM; Jeong, Jeong-Won; Halverson, Stacey R.; Behen, Michael E.; Bui, Duy Q.; Chugani, Harry T.

2011-01-01

50

Changes in maps of language function and the integrity of the arcuate fasciculus after therapy for chronic aphasia  

PubMed Central

A patient with chronic aphasia secondary to unilateral stroke in the left hemisphere underwent language testing, diffusion tensor imaging (DTI), and functional imaging using magnetoencephalography (MEG) at four time points: 3 weeks prior to, immediately prior to, immediately after, and 3 months after Constraint Induced Language Therapy (CILT). Performance on language tests involving visual naming and repetition of spoken sentences improved between the immediately prior to and immediately after CILT testing sessions, but not between the pre-CILT sessions. MEG activation in putative pre-morbid language areas of the left hemisphere and homotopic areas of the right hemisphere increased immediately after therapy, as did integrity within the arcuate fasciculus bilaterally. These changes were not evident between the two pre-CILT sessions. While some of these functional, neurophysiological and structural changes had regressed 3 months after therapy, all remained at or above baseline levels. Results provide evidence for an association between improvement in functional status and the increased integrity within a white matter tract known to be involved in language function and its contralateral homologue, as well as increased neurophysiological activity in areas that have the potential to subserve language function bilaterally.

Breier, Joshua I.; Juranek, Jenifer; Papanicolaou, Andrew C.

2012-01-01

51

Relations between white matter maturation and reaction time in childhood.  

PubMed

White matter matures with age and is important for the efficient transmission of neuronal signals. Consequently, white matter growth may underlie the development of cognitive processes important for learning, including the speed of information processing. To dissect the relationship between white matter structure and information processing speed, we administered a reaction time task (finger abduction in response to visual cue) to 27 typically developing, right-handed children aged 4 to 13. Magnetoencephalography and Diffusion Tensor Imaging were used to delineate white matter connections implicated in visual-motor information processing. Fractional anisotropy (FA) and radial diffusivity (RD) of the optic radiation in the left hemisphere, and FA and mean diffusivity (MD) of the optic radiation in the right hemisphere changed significantly with age. MD and RD decreased with age in the right inferior fronto-occipital fasciculus, and bilaterally in the cortico-spinal tracts. No age-related changes were evident in the inferior longitudinal fasciculus. FA of the cortico-spinal tract in the left hemisphere and MD of the inferior fronto-occipital fasciculus of the right hemisphere contributed uniquely beyond the effect of age in accounting for reaction time performance of the right hand. Our findings support the role of white matter maturation in the development of information processing speed. PMID:24168858

Scantlebury, Nadia; Cunningham, Todd; Dockstader, Colleen; Laughlin, Suzanne; Gaetz, William; Rockel, Conrad; Dickson, Jolynn; Mabbott, Donald

2014-01-01

52

Differences in white matter reflect atypical developmental trajectory in autism: A Tract-based Spatial Statistics study.  

PubMed

Autism is a neurodevelopmental disorder in which white matter (WM) maturation is affected. We assessed WM integrity in 16 adolescents and 14 adults with high-functioning autism spectrum disorder (ASD) and in matched neurotypical controls (NT) using diffusion weighted imaging and Tract-based Spatial Statistics. Decreased fractional anisotropy (FA) was observed in adolescents with ASD in tracts involved in emotional face processing, language, and executive functioning, including the inferior fronto-occipital fasciculus and the inferior and superior longitudinal fasciculi. Remarkably, no differences in FA were observed between ASD and NT adults. We evaluated the effect of age on WM development across the entire age range. Positive correlations between FA values and age were observed in the right inferior fronto-occipital fasciculus, the left superior longitudinal fasciculus, the corpus callosum, and the cortical spinal tract of ASD participants, but not in NT participants. Our data underscore the dynamic nature of brain development in ASD, showing the presence of an atypical process of WM maturation, that appears to normalize over time and could be at the basis of behavioral improvements often observed in high-functioning autism. PMID:24179736

Bakhtiari, Reyhaneh; Zürcher, Nicole R; Rogier, Ophélie; Russo, Britt; Hippolyte, Loyse; Granziera, Cristina; Araabi, Babak Nadjar; Nili Ahmadabadi, Majid; Hadjikhani, Nouchine

2012-01-01

53

Differences in white matter reflect atypical developmental trajectory in autism: A Tract-based Spatial Statistics study?  

PubMed Central

Autism is a neurodevelopmental disorder in which white matter (WM) maturation is affected. We assessed WM integrity in 16 adolescents and 14 adults with high-functioning autism spectrum disorder (ASD) and in matched neurotypical controls (NT) using diffusion weighted imaging and Tract-based Spatial Statistics. Decreased fractional anisotropy (FA) was observed in adolescents with ASD in tracts involved in emotional face processing, language, and executive functioning, including the inferior fronto-occipital fasciculus and the inferior and superior longitudinal fasciculi. Remarkably, no differences in FA were observed between ASD and NT adults. We evaluated the effect of age on WM development across the entire age range. Positive correlations between FA values and age were observed in the right inferior fronto-occipital fasciculus, the left superior longitudinal fasciculus, the corpus callosum, and the cortical spinal tract of ASD participants, but not in NT participants. Our data underscore the dynamic nature of brain development in ASD, showing the presence of an atypical process of WM maturation, that appears to normalize over time and could be at the basis of behavioral improvements often observed in high-functioning autism.

Bakhtiari, Reyhaneh; Zurcher, Nicole R.; Rogier, Ophelie; Russo, Britt; Hippolyte, Loyse; Granziera, Cristina; Araabi, Babak Nadjar; Nili Ahmadabadi, Majid; Hadjikhani, Nouchine

2012-01-01

54

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

PubMed

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. PMID:22088488

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

2012-01-01

55

White matter abnormalities in adolescents with generalized anxiety disorder: a diffusion tensor imaging study  

PubMed Central

Background Previous neuroimaging studies have suggested an abnormal neural circuitry of emotion regulation including the amygdala and prefrontal cortex in both adult and adolescent generalized anxiety disorder (GAD) patients. Aberrant integrity of white matter in this neural circuitry has been verified in adult GAD patients. White matter abnormalities in adolescent GAD patients have not been detected. Methods Twenty-five adolescents with GAD and 24 healthy controls underwent a diffusion tensor imaging scan. Fractional anisotropy (FA) was compared between groups with a voxel-wise Tract-Based Spatial Statistics (TBSS) analysis method. Results Compared with healthy controls, adolescents with GAD showed significantly reduced FA in bilateral uncinate fasciculus, inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, and corona radiata. Conclusions The findings in the present study suggest a neural basis of emotion dysregulation in adolescent GAD patients.

2014-01-01

56

Cerebral white matter deficiencies in pedophilic men.  

PubMed

The present investigation sought to identify which brain regions distinguish pedophilic from nonpedophilic men, using unbiased, automated analyses of the whole brain. T1-weighted magnetic resonance images (MRIs) were acquired from men who demonstrated illegal or clinically significant sexual behaviors or interests (n = 65) and from men who had histories of nonsexual offenses but no sexual offenses (n = 62). Sexual interest in children was assessed by participants' admissions of pedophilic interest, histories of committing sexual offenses against children, and psychophysiological responses in the laboratory to erotic stimuli depicting children or adults. Automated parcellation of the MRIs revealed significant negative associations between pedophilia and white matter volumes of the temporal and parietal lobes bilaterally. Voxel-based morphometry corroborated the associations and indicated that the regions of lower white matter volumes followed, and were limited to, two major fiber bundles: the superior fronto-occipital fasciculus and the right arcuate fasciculus. No significant differences were found in grey matter or in cerebrospinal fluid (CSF). Because the superior fronto-occipital and arcuate fasciculi connect the cortical regions that respond to sexual cues, these results suggest (1) that those cortical regions operate as a network for recognizing sexually relevant stimuli and (2) that pedophilia results from a partial disconnection within that network. PMID:18039544

Cantor, James M; Kabani, Noor; Christensen, Bruce K; Zipursky, Robert B; Barbaree, Howard E; Dickey, Robert; Klassen, Philip E; Mikulis, David J; Kuban, Michael E; Blak, Thomas; Richards, Blake A; Hanratty, M Katherine; Blanchard, Ray

2008-02-01

57

The left superior longitudinal fasciculus within the primary sensory area of inferior parietal lobe plays a role in dysgraphia of kana omission within sentences.  

PubMed

Functional neurological changes after surgery combined with diffusion tensor imaging (DTI) tractography can directly provide evidence of anatomical localization of brain function. Using these techniques, a patient with dysgraphia before surgery was analyzed at our hospital in 2011. The patient showed omission of kana within sentences before surgery, which improved after surgery. The brain tumor was relatively small and was located within the primary sensory area (S1) of the inferior parietal lobe (IPL). DTI tractography before surgery revealed compression of the branch of the superior longitudinal fasciculus (SLF) by the brain tumor. These results suggest that the left SLF within the S1 of IPL plays a role in the development of dysgraphia of kana omission within sentences. PMID:22713399

Shinoura, Nobusada; Midorikawa, Akira; Onodera, Toshiyuki; Yamada, Ryozi; Tabei, Yusuke; Onda, Yasumitsu; Itoi, Chihiro; Saito, Seiko; Yagi, Kazuo

2012-01-01

58

Horizontal portion of arcuate fasciculus fibers track to pars opercularis, not pars triangularis, in right and left hemispheres: a DTI study.  

PubMed

The arcuate fasciculus (AF) is a white matter pathway traditionally considered to connect left Broca's area with posterior language zones. We utilized diffusion tensor imaging (DTI) in eight healthy subjects (5 M) to track pathways in the horizontal mid-portion of the AF (hAF) to subregions of Broca's area - pars triangularis (PTr) and pars opercularis (POp); and to ventral premotor cortex (vPMC) in the right and left hemispheres (RH, LH). These pathways have previously been studied in the LH, but not in the RH. Only 1/8 subjects showed fiber tracts between PTr and hAF in the RH (also, only 1/8 in the LH). In contrast to PTr, 5/8 subjects showed fiber tracts between POp and hAF in the RH (8/8 in the LH). Fiber tracts for vPMC were similar to those of POp, where 7/8 subjects showed fiber tracts between vPMC and hAF in the RH (8/8 in the LH). Our designated hAF could have included some of the superior longitudinal fasciculus (SLF) III, because it is difficult to separate the two fiber bundles. The SLF III has been previously reported to connect supramarginal gyrus with POp and vPMC in the LH. Thus, although the present DTI study showed almost no pathways between PTr and hAF in the RH (and in the LH), robust pathways were observed between POp and/or vPMC with hAF in the RH (and in LH). These results replicate previous studies for the LH, but are new, for the RH. They could contribute to better understanding of recovery in aphasia. PMID:20438853

Kaplan, Elina; Naeser, Margaret A; Martin, Paula I; Ho, Michael; Wang, Yunyan; Baker, Errol; Pascual-Leone, Alvaro

2010-08-15

59

Patterns of dysgraphia in primary progressive aphasia compared to post-stroke aphasia.  

PubMed

We report patterns of dysgraphia in participants with primary progressive aphasia that can be explained by assuming disruption of one or more cognitive processes or representations in the complex process of spelling. These patterns are compared to those described in participants with focal lesions (stroke). Using structural imaging techniques, we found that damage to the left extrasylvian regions, including the uncinate, inferior fronto-occipital fasciculus, and sagittal stratum (including geniculostriate pathway and inferior longitudinal fasciculus), as well as other deep white and grey matter structures, was significantly associated with impairments in access to orthographic word forms and semantics (with reliance on phonology-to-orthography to produce a plausible spelling in the spelling to dictation task). These results contribute not only to our understanding of the patterns of dysgraphia following acquired brain damage but also the neural substrates underlying spelling. PMID:22713396

Faria, Andreia V; Crinion, Jenny; Tsapkini, Kyrana; Newhart, Melissa; Davis, Cameron; Cooley, Shannon; Mori, Susumu; Hillis, Argye E

2013-01-01

60

Patterns of Dysgraphia in Primary Progressive Aphasia Compared to Post-Stroke Aphasia  

PubMed Central

We report patterns of dysgraphia in participants with primary progressive aphasia that can be explained by assuming disruption of one or more cognitive processes or representations in the complex process of spelling. These patterns are compared to those described in participants with focal lesions (stroke). Using structural imaging techniques, we found that damage to the left extrasylvian regions, including the uncinate, inferior fronto-occipital fasciculus, and sagittal stratum (including geniculostriate pathway and inferior longitudinal fasciculus), as well as other deep white and grey matter structures, was significantly associated with impairments in access to orthographic word forms and semantics (with reliance on phonology-to-orthography to produce a plausible spelling in the spelling to dictation task). These results contribute not only to our understanding of the patterns of dysgraphia following acquired brain damage but also the neural substrates underlying spelling.

Faria, Andreia V.; Crinion, Jenny; Tsapkini, Kyrana; Newhart, Melissa; Davis, Cameron; Cooley, Shannon; Mori, Susumu; Hillis, Argye E.

2013-01-01

61

White matter structural connectivity underlying semantic processing: evidence from brain damaged patients.  

PubMed

Widely distributed brain regions in temporal, parietal and frontal cortex have been found to be involved in semantic processing, but the anatomical connections supporting the semantic system are not well understood. In a group of 76 right-handed brain-damaged patients, we tested the relationship between the integrity of major white matter tracts and the presence of semantic deficits. The integrity of white matter tracts was measured by percentage of lesion voxels obtained in structural imaging and mean fractional anisotropy values obtained in diffusion tensor imaging. Semantic deficits were assessed by jointly considering the performance on three semantic tasks that vary in the modalities of input (visual and auditory stimuli) and output (oral naming and associative judgement). We found that the lesion volume and fractional anisotropy value of the left inferior fronto-occipital fasciculus, left anterior thalamic radiation, and left uncinate fasciculus significantly correlated with severity of impairment in all three semantic tasks. These associations remained significant even when we controlled for a wide range of potential confounding variables, including overall cognitive state, whole lesion volume, or type of brain damage. The effects of these three white matter tracts could not be explained by potential involvement of relevant grey matter, and were (relatively) specific to object semantic processing, as no correlation with performance on non-object semantic control tasks (oral repetition and number processing tasks) was observed. These results underscore the causal role of left inferior fronto-occipital fasciculus, left anterior thalamic radiation, and left uncinate fasciculus in semantic processing, providing direct evidence for (part of) the anatomical skeleton of the semantic network. PMID:23975453

Han, Zaizhu; Ma, Yujun; Gong, Gaolang; He, Yong; Caramazza, Alfonso; Bi, Yanchao

2013-10-01

62

Downbeat nystagmus associated with damage to the medial longitudinal fasciculus of the pons: a vestibular balance control mechanism via the lower brainstem paramedian tract neurons.  

PubMed

The paramedian tract (PMT) neurons, a group of neurons associated with eye movement that project into the cerebellar flocculus, are present in or near the medial longitudinal fasciculus (MLF) in the paramedian region of the lower brainstem. A 66-year-old man with multiple sclerosis in whom downbeat nystagmus appeared along with right MLF syndrome due to a unilateral pontomedullary lesion is described. In light of these findings, a possible schema for the vestibular balance control mechanism circuit of the PMT neurons via the flocculus is presented. Damage to the PMT neurons impaired the elective inhibitory control mechanism of the anterior semicircular canal neural pathway by the flocculus. This resulted in the appearance of anterior semicircular canal-dominant vestibular imbalance and the formation of downbeat nystagmus. From the pathogenesis of this vertical vestibular nystagmus, the action of the PMT neurons in the vestibular eye movement neuronal pathway to maintain vestibular balance was conjectured to be as follows. PMT neurons transmit vestibular information from the anterior semicircular canals to the cerebellum, forming a cerebellum/brainstem feedback loop. Vestibular information from that loop is integrated in the cerebellum, inhibiting only the anterior semicircular canal neuronal pathway via the flocculus and controlling vestibular balance. PMID:23510567

Nakamagoe, Kiyotaka; Fujizuka, Natsu; Koganezawa, Tadachika; Yamaguchi, Tetsuto; Tamaoka, Akira

2013-05-15

63

White Matter Microstructure in Attention-Deficit/Hyperactivity Disorder Subjects and Their Siblings  

PubMed Central

Objective Previous voxel-based and regions-of-interest (ROI)-based diffusion tensor imaging (DTI) studies have found above-normal mean diffusivity (MD) and below-normal fractional anisotropy (FA) in subjects with attention-deficit/hyperactivity disorder (ADHD). However, findings remain mixed and few studies have examined the contribution of ADHD familial liability to white matter microstructure. Method We used refined DTI tractography methods to examine MD, FA, axial diffusivity (AD) and radial diffusivity (RD) of the anterior thalamic radiation, cingulum, corticospinal tract, inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, forceps major, forceps minor, superior longitudinal fasciculus and uncinate fasciculus in children and adolescents with ADHD (n = 56), unaffected siblings of ADHD probands (n = 31) and healthy controls (n = 17). Results Subjects with ADHD showed significantly higher MD than controls in the anterior thalamic radiation, forceps minor, and superior longitudinal fasciculus. Unaffected siblings of subjects with ADHD displayed similar differences in MD as subjects with ADHD. While none of the tested tracts showed a significant effect of FA, the tracts with elevated MD likewise displayed elevated AD in both subjects with ADHD and unaffected siblings. Differences in RD between subjects with ADHD, unaffected siblings and controls were not as widespread as differences in MD and AD. Conclusion Our findings suggest that disruptions in white matter microstructure occur in several large white matter pathways in association with ADHD and indicate a familial liability for the disorder. Furthermore, MD may reflect these abnormalities more sensitively than FA.

Lawrence, Katherine E.; Levitt, Jennifer G.; Loo, Sandra K.; Ly, Ronald; Yee, Victor; O'Neill, Joseph; Alger, Jeffry; Narr, Katherine L.

2013-01-01

64

Origin and neurochemical properties of bulbospinal neurons projecting to the rat lumbar spinal cord via the medial longitudinal fasciculus and caudal ventrolateral medulla  

PubMed Central

Bulbospinal systems (BS) originate from various regions of the brainstem and influence spinal neurons by classical synaptic and modulatory mechanisms. Our aim was to determine the brainstem locations of cells of origin of BS pathways passing through the medial longitudinal fasciculus (MLF) and the caudal ventrolateral medulla (CVLM). We also examined the transmitter content of spinal terminations of the CVLM pathway. Six adult rats received Fluorogold (FG) injections to the right intermediate gray matter of the lumbar cord (L1–L2) and the b-subunit of cholera toxin (CTb) was injected either into the MLF or the right CVLM (3 animals each). Double-labeled cells were identified within brainstem structures with confocal microscopy and mapped onto brainstem diagrams. An additional 3 rats were injected with CTb in the CVLM to label axon terminals in the lumbar spinal cord. Double-labeled cells projecting via the MLF or CVLM were found principally in reticular regions of the medulla and pons but small numbers of cells were also located within the midbrain. CVLM projections to the lumbar cord were almost exclusively ipsilateral and concentrated within the intermediate gray matter. Most (62%) of terminals were immunoreactive for the vesicular glutamate transporter 2 while 23% contained the vesicular GABA transporter. The inhibitory subpopulation was glycinergic, GABAergic or contained both transmitters. The proportions of excitatory and inhibitory axons projecting via the CVLM to the lumbar cord are similar to those projecting via the MLF. Unlike the MLF pathway, CVLM projections are predominantly ipsilateral and concentrated within intermediate gray but do not extend into motor nuclei or laminia VIII. Terminations of the CVLM pathway are located in a region of the gray matter that is rich in premotor interneurons; thus its primary function may be to coordinate activity of premotor networks.

Huma, Zilli; Du Beau, Amy; Brown, Christina; Maxwell, David J.

2014-01-01

65

Reduced fractional anisotropy in the uncinate fasciculus in patients with major depression carrying the met-allele of the Val66Met brain-derived neurotrophic factor genotype.  

PubMed

Experimental studies support a neurotrophic hypothesis of major depressive disorder (MDD). The aim of this study was to determine the effect of Val66Met brain-derived neurotrophic factor (BDNF) polymorphism on the white matter fiber tracts connecting hippocampus and amygdala with the prefrontal lobe in a sample of patients with MDD and healthy controls. Thirty-seven patients with MDD and 42 healthy volunteers were recruited. Diffusion tensor imaging (DTI) data with 61 diffusion directions were obtained with MRI 3 Tesla scanner. Deterministic tractography was applied with ExploreDTI and Val66Met BDNF SNP (rs6265) was genotyped. Fiber tracts connecting the hippocampus and amygdala with the prefrontal lobe, namely uncinate fasciculus (UF), fornix, and cingulum were analyzed. A significant interaction was found in the UF between BDNF alleles and diagnosis. Patients carrying the BDNF met-allele had smaller fractional anisotropy (FA) in the UF compared to those patients homozygous for val-allele and compared to healthy subjects carrying the met-allele. A significant three-way interaction was detected between region of the cingulum (dorsal, rostral, and parahippocampal regions), brain hemisphere and BDNF genotype. Larger FA was detectable in the left rostral cingulum for met-allele carriers when compared to val/val alelle carriers. We provide evidence for the importance of the neurotrophic involvement in limbic and prefrontal connections. The met-allele of the BDNF polymorphism seems to render subjects more vulnerable for dysfunctions associated with the UF, a tract known to be related to negative emotional-cognitive processing bias, declarative memory problems, and autonoetic self awareness. PMID:22585743

Carballedo, A; Amico, F; Ugwu, I; Fagan, A J; Fahey, C; Morris, D; Meaney, J F; Leemans, A; Frodl, T

2012-07-01

66

Language-general and -specific white matter microstructural bases for reading.  

PubMed

In the past decade, several studies have investigated language-general and -specific brain regions for reading. However, very limited research has examined the white matter that connects these cortical regions. By using diffusion tensor imaging (DTI), the current study investigated the common and divergent relationship between white matter integrity indexed by fractional anisotropy (FA) and native language reading abilities in 89 Chinese and 93 English speakers. Conjunction analysis revealed that for both groups, reading ability was associated with the FA of seven white matter fiber bundles in two main anatomical locations in the left hemisphere: the dorsal corona radiate/corpus callosum/superior longitudinal fasciculus which might be for phonological access, and the ventral uncinate fasciculus/external capsule/inferior fronto-occipital fasciculus which might be for semantic processing. Contrast analysis showed that the FA of the left temporal part of superior longitudinal fasciculus contributed more to reading in English than in Chinese, which is consistent with the notion that this tract is involved in grapheme-to-phoneme conversion for alphabetic language reading. These results are the first evidence of language-general and -specific white matter microstructural bases for reading. PMID:24814214

Zhang, Mingxia; Chen, Chuansheng; Xue, Gui; Lu, Zhong-Lin; Mei, Leilei; Xue, Hongli; Wei, Miao; He, Qinghua; Li, Jin; Dong, Qi

2014-09-01

67

Case series: fractional anisotropy along the trajectory of selected white matter tracts in adolescents born preterm with ventricular dilation.  

PubMed

This case series assesses white matter microstructure in 3 adolescents born preterm with nonshunted ventricular dilation secondary to intraventricular hemorrhage. Subjects (ages 12-17 years, gestational age 26-29 weeks, birth weight 825-1624 g) were compared to 3 full-term controls (13-17 years, 39-40 weeks, 3147-3345 g) and 3 adolescents born preterm without ventricular dilation (10-13 years, 26-29 weeks, 630-1673 g). Tractography using a 2 region of interest method reconstructed the following white matter tracts: superior longitudinal/arcuate fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, uncinate fasciculus, and corticospinal tract. Subjects showed increased fractional anisotropy and changes in the pattern of fractional anisotropy along the trajectory of tracts adjacent to the lateral ventricles. Tensor shape at areas of increased fractional anisotropy demonstrated increased linear anisotropy at the expense of planar and spherical anisotropy. These findings suggest increased axonal packing density and straightening of fibers secondary to ventricular enlargement. PMID:22859695

Myall, Nathaniel J; Yeom, Kristen W; Yeatman, Jason D; Gaman-Bean, Shayna; Feldman, Heidi M

2013-06-01

68

Interpersonal competence in young adulthood and right laterality in white matter.  

PubMed

The right hemisphere of the human brain is known to be involved in processes underlying emotion and social cognition. Clinical neuropsychology investigations and brain lesion studies have linked a number of personality and social disorders to abnormal white matter (WM) integrity in the right hemisphere. Here, we tested the hypothesis that interpersonal competencies are associated with integrity of WM tracts in the right hemisphere of healthy young adults. Thirty-one participants underwent diffusion tensor imaging scanning. Fractional anisotropy was used to quantify water diffusion. After the scanning session, participants completed the Adolescent Interpersonal Competence Questionnaire. Fractional anisotropy was subsequently correlated with Adolescent Interpersonal Competence Questionnaire scores using tract-based spatial statistics. Higher interpersonal competencies are related to higher WM integrity in several major tracts of the right hemisphere, in specific the uncinate fasciculus, the cingulum, the forceps minor, the infero-fronto occipital fasciculus, the inferior longitudinal fasciculus, and the superior longitudinal fasciculus. These results provide the first direct analysis of the neuroanatomical basis of interpersonal competencies and young adult self-reported skills in social contexts. PMID:24345175

De Pisapia, Nicola; Serra, Mauro; Rigo, Paola; Jager, Justin; Papinutto, Nico; Esposito, Gianluca; Venuti, Paola; Bornstein, Marc H

2014-06-01

69

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

PubMed Central

Lithium is the mainstay for the treatment of bipolar disorder (BD) and inhibits glycogen synthase kinase 3-? (GSK3-?). The less active GSK3-? promoter gene variants have been associated with less detrimental clinical features of BD. GSK3-? 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-? 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-? rs334558*C gene-promoter variants, and the long-term administration of the GSK3-? 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-? 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.

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

70

Effects of aging and calorie restriction on white matter in rhesus macaques  

PubMed Central

Rhesus macaques on a calorie restricted diet (CR) develop less age-related disease, have virtually no indication of diabetes, are protected against sarcopenia, and potentially live longer. Beneficial effects of CR likely include reductions in age-related inflammation and oxidative damage. Oligodendrocytes are particularly susceptible to inflammation and oxidative stress, therefore, we hypothesized that CR would have a beneficial effect on brain white matter and would attenuate age-related decline in this tissue. CR monkeys and controls underwent diffusion tensor imaging (DTI). A beneficial effect of CR indexed by DTI was observed in superior longitudinal fasciculus, fronto-occipital fasciculus, external capsule, and brainstem. Aging effects were observed in several regions, although CR appeared to attenuate age-related alterations in superior longitudinal fasciculus, frontal white matter, external capsule, right parahippocampal white matter and dorsal occipital bundle. The results, however, were regionally specific and also suggested that CR is not salutary across all white matter. Further evaluation of this unique cohort of elderly primates to mortality will shed light on the ultimate benefits of an adult-onset, moderate CR diet for deferring brain aging.

Bendlin, B.B.; Canu, E.; Willette, A.A.; Kastman, E.K.; McLaren, D.G.; Kosmatka, K.J.; Xu, G.; Field, A.S.; Colman, R.J.; Coe, C.L.; Weindruch, R.H.; Alexander, A.L.; Johnson, S.C.

2010-01-01

71

Alterations in frontal lobe tracts and corpus callosum in young children with autism spectrum disorder.  

PubMed

Major frontal lobe tracts and corpus callosum (CC) were investigated in 32 children with autism spectrum disorder (ASD, mean age: 5 years), 12 nonautistic developmentally impaired children (DI, mean age: 4.6 years), and 16 typically developing children (TD, mean age: 5.5 years) using diffusion tensor imaging tractography and tract-based spatial statistics. Various diffusion and geometric properties were calculated for uncinate fasciculus (UF), inferior fronto-occipital fasciculus (IFO), arcuate fasciculus (AF), cingulum (Cg), CC, and corticospinal tract. Fractional anisotropy was lower in the right UF, right Cg and CC in ASD and DI children; in right AF in ASD children; and in bilateral IFO in DI children, compared with TD children. Apparent diffusion coefficient was increased in right AF in both ASD and DI children. The ASD group showed shorter length of left UF and increased length, volume, and density of right UF; increased length and density of CC; and higher density of left Cg, compared with the TD group. Compared with DI group, ASD group had increased length, volume, and density of right UF; higher volume of left UF; and increased length of right AF and CC. Volume of bilateral UF and right AF and fiber density of left UF were positively associated with autistic features. PMID:20019145

Kumar, Ajay; Sundaram, Senthil K; Sivaswamy, Lalitha; Behen, Michael E; Makki, Malek I; Ager, Joel; Janisse, James; Chugani, Harry T; Chugani, Diane C

2010-09-01

72

White matter integrity is associated with cerebrospinal fluid markers of Alzheimer's disease in normal adults.  

PubMed

We explored whether white matter (WM) integrity in cognitively normal (CN) older adults is associated with cerebrospinal fluid (CSF) markers of Alzheimer's disease pathology. Twenty CN older adults underwent lumbar puncture and magnetic resonance imaging within a few days of each other. Analysis of diffusion tensor imaging data involved a priori region of interest and voxelwise approaches. The region of interest results revealed a positive correlation between CSF measures of amyloid-beta (A?42 and A?42/p-Tau181) and WM integrity in the fornix, a relationship which persisted after controlling for hippocampal volume and fornix volume. Lower WM integrity in the same portion of the fornix was also associated with reduced performance on the Digit Symbol test. Subsequent exploratory voxelwise analyses indicated a positive correlation between CSF A?42/p-Tau181 and WM integrity in bilateral portions of the fornix, superior longitudinal fasciculus, inferior fronto-occipital fasciculus, and in the corpus callosum and left inferior longitudinal fasciculus. Our results link lower WM microstructural integrity in CN older adults with CSF biomarkers of Alzheimer's disease and suggest that this association in the fornix may be independent of volumetric measures. PMID:24866404

Gold, Brian T; Zhu, Zude; Brown, Christopher A; Andersen, Anders H; LaDu, Mary Jo; Tai, Leon; Jicha, Greg A; Kryscio, Richard J; Estus, Steven; Nelson, Peter T; Scheff, Steve W; Abner, Erin; Schmitt, Frederick A; Van Eldik, Linda J; Smith, Charles D

2014-10-01

73

Clinical correlations of microstructural changes in progressive supranuclear palsy.  

PubMed

In patients with progressive supranuclear palsy (PSP), previous reports have shown a severe white matter (WM) damage involving supra and infratentorial regions including cerebellum. In the present study, we investigated potential correlations between WM integrity loss and clinical-cognitive features of patients with PSP. By using magnetic resonance imaging and diffusion tensor imaging with tract based spatial statistic analysis, we analyzed WM volume in 18 patients with PSP and 18 healthy controls (HCs). All patients and HCs underwent a detailed clinical and neuropsychological evaluation. Relative to HCs, patients with PSP showed WM changes encompassing supra and infratentorial areas such as corpus callosum, fornix, midbrain, inferior fronto-occipital fasciculus, anterior thalamic radiation, superior cerebellar peduncle, superior longitudinal fasciculus, uncinate fasciculus, cingulate gyrus, and cortico-spinal tract bilaterally. Among different correlations between motor-cognitive features and WM structural abnormalities, we detected a significant association between fronto-cerebellar WM loss and executive cognitive impairment in patients with PSP. Our findings, therefore, corroborate the hypothesis that cognitive impairment in PSP may result from both "intrinsic" and "extrinsic" frontal lobe dysfunction, likely related to cerebellar disconnection. PMID:24786632

Tessitore, Alessandro; Giordano, Alfonso; Caiazzo, Giuseppina; Corbo, Daniele; De Micco, Rosa; Russo, Antonio; Liguori, Sara; Cirillo, Mario; Esposito, Fabrizio; Tedeschi, Gioacchino

2014-10-01

74

Principal eigenvector field segmentation for reproducible diffusion tensor tractography of white matter structures.  

PubMed

The study was aimed to test the feasibility of utilizing an algorithmically determinable stable fiber mass (SFM) map obtained by an unsupervised principal eigenvector field segmentation (PEVFS) for automatic delineation of 18 white matter (WM) tracts: (1) corpus callosum (CC), (2) tapetum (TP), (3) inferior longitudinal fasciculus (ILF), (4) uncinate fasciculus (UNC), (5) inferior fronto-occipital fasciculus (IFO), (6) optic pathways (OP), (7) superior longitudinal fasciculus (SLF), (8) arcuate fasciculus (AF), (9) fornix (FX), (10) cingulum (CG), (11) anterior thalamic radiation (ATR), (12) superior thalamic radiation (STR), (13) posterior thalamic radiation (PTR), (14) corticospinal/corticopontine tract (CST/CPT), (15) medial lemniscus (ML), (16) superior cerebellar peduncle (SCP), (17) middle cerebellar peduncle (MCP) and (18) inferior cerebellar peduncle (ICP). Diffusion tensor imaging (DTI)-derived fractional anisotropy (FA) and the principal eigenvector field have been used to create the SFM consisting of a collection of linear voxel structures which are grouped together by color-coding them into seven natural classes to provide PEVFS signature segments which greatly facilitate the selection of regions of interest (ROIs) for fiber tractography using just a single mouse click, as compared with a manual drawing of ROIs in the classical approach. All the 18 fiber bundles have been successfully reconstructed, in all the subjects, using the single ROIs provided by the SFM approach, with their reproducibility characterized by the fact that the ROI selection is user independent. The essentially automatic PEVFS method is robust, efficient and compares favorably with the classical ROI methods for diffusion tensor tractography (DTT). PMID:21664783

Rathore, Ram K S; Gupta, Rakesh K; Agarwal, Shruti; Trivedi, Richa; Tripathi, Rajendra P; Awasthi, Rishi

2011-10-01

75

Individual differences in white matter anatomy predict dissociable components of reading skill in adults.  

PubMed

We used diffusion tensor imaging (DTI) to investigate relationships between white matter anatomy and different reading subskills in typical-reading adults. A series of analytic approaches revealed that phonological decoding ability is associated with anatomical markers that do not relate to other reading-related cognitive abilities. Thus, individual differences in phonological decoding might relate to connectivity between a network of cortical regions, while skills like sight word reading might rely less strongly on integration across regions. Specifically, manually-drawn ROIs and probabilistic tractography revealed an association between the volume and integrity of white matter underlying primary auditory cortex and nonword reading ability. In a related finding, more extensive cross-hemispheric connections through the isthmus of the corpus callosum predicted better phonological decoding. Atlas-based white matter ROIs demonstrated that relationships with nonword reading were strongest in the inferior fronto-occipital fasciculus and uncinate fasciculus that connect occipital and anterior temporal cortex with inferior frontal cortex. In contrast, tract volume underlying the left angular gyrus was related to nonverbal IQ. Finally, connectivity underlying functional ROIs that are differentially active during phonological and semantic processing predicted nonword reading and reading comprehension, respectively. Together, these results provide important insights into how white matter anatomy may relate to both typical reading subskills, and perhaps a roadmap for understanding neural connectivity in individuals with reading impairments. PMID:24704456

Welcome, Suzanne E; Joanisse, Marc F

2014-08-01

76

Diffusion Tensor Imaging of Aicardi Syndrome  

PubMed Central

Aicardi syndrome is a congenital neurodevelopmental disorder associated with significant cognitive and motor impairment. Diffusion Tensor Imaging was performed on two subjects with Aicardi syndrome, as well as on two matched subjects with callosal agenesis and cortical malformations, but not a clinical diagnosis of Aicardi syndrome. Whole brain three-dimensional fiber tractography was performed, and major white matter tracts were isolated using standard tracking protocols. One Aicardi subject demonstrated an almost complete lack of normal cortico-cortical connectivity, with only the left inferior fronto-occipital fasciculus recovered by diffusion tensor tractography. A second Aicardi subject showed evidence of bilateral cingulum bundles and right uncinate fasciculus, but other cortico-cortical tracts were not recovered. Major subcortical white matter tracts, including corticospinal, pontocerebellar, and anterior thalamic radiation tracts, were recovered in both Aicardi subjects. In contrast, diffusion tensor tractography analysis on the two matched control subjects with callosal agenesis and cortical malformations recovered all major intrahemispheric cortical and subcortical white matter tracts. These results reveal a widespread disruption in the corticocortical white matter organization of individuals with Aicardi syndrome. Furthermore, such disruption in white matter organization appears to be a feature specific to Aicardi syndrome, and not shared by other neurodevelopmental disorders with similar anatomic manifestations.

Wahl, Michael; Strominger, Zoe A.; Wakahiro, Mari; Jeremy, Rita J.; Mukherjee, Pratik; Sherr, Elliott H.

2010-01-01

77

White matter microstructure in body dysmorphic disorder and its clinical correlates.  

PubMed

Body dysmorphic disorder (BDD) is characterized by an often-delusional preoccupation with misperceived defects of appearance, causing significant distress and disability. Although previous studies have found functional abnormalities in visual processing, frontostriatal, and limbic systems, no study to date has investigated the microstructure of white matter connecting these systems in BDD. Participants comprised 14 medication-free individuals with BDD and 16 healthy controls who were scanned using diffusion-weighted magnetic resonance imaging (MRI). We utilized probabilistic tractography to reconstruct tracts of interest, and tract-based spatial statistics to investigate whole brain white matter. To estimate white matter microstructure, we used fractional anisotropy (FA), mean diffusivity (MD), and linear and planar anisotropy (c(l) and c(p)). We correlated diffusion measures with clinical measures of symptom severity and poor insight/delusionality. Poor insight negatively correlated with FA and c(l) and positively correlated with MD in the inferior longitudinal fasciculus (ILF) and the forceps major (FM). FA and c(l) were lower in the ILF and the inferior fronto-occipital fasciculus and higher in the FM in the BDD group, but differences were nonsignificant. This is the first diffusion-weighted MR investigation of white matter in BDD. Results suggest a relationship between impairments in insight, a clinically important phenotype, and fiber disorganization in tracts connecting visual with emotion/memory processing systems. PMID:23375265

Feusner, Jamie D; Arienzo, Donatello; Li, Wei; Zhan, Liang; Gadelkarim, Johnson; Thompson, Paul M; Leow, Alex D

2013-02-28

78

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

PubMed Central

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 (?R2 =10–12%, ps < .01), and baseline fornix integrity predicted follow-up delinquent behaviors (?R2 = 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.

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

2012-01-01

79

Multivariate pattern analysis of DTI reveals differential white matter in individuals with obsessive-compulsive disorder.  

PubMed

Diffusion tensor imaging (DTI) studies have revealed group differences in white matter between patients with obsessive-compulsive disorder (OCD) and healthy controls. However, the results of these studies were based on average differences between the two groups, and therefore had limited clinical applicability. The objective of this study was to investigate whether fractional anisotropy (FA) of white matter can be used to discriminate between patients with OCD and healthy controls at the level of the individual. DTI data were acquired from 28 OCD patients and 28 demographically matched healthy controls, scanned using a 3T MRI system. Differences in FA values of white matter between OCD and healthy controls were examined using a multivariate pattern classification technique known as support vector machine (SVM). SVM applied to FA images correctly identified OCD patients with a sensitivity of 86% and a specificity of 82% resulting in a statistically significant accuracy of 84% (P ? 0.001). This discrimination was based on a distributed network including bilateral prefrontal and temporal regions, inferior fronto-occipital fasciculus, superior fronto-parietal fasciculus, splenium of corpus callosum and left middle cingulum bundle. The present study demonstrates subtle and spatially distributed white matter abnormalities in individuals with OCD, and provides preliminary support for the suggestion that that these could be used to aid the identification of individuals with OCD in clinical practice. PMID:24048702

Li, Fei; Huang, Xiaoqi; Tang, Wanjie; Yang, Yanchun; Li, Bin; Kemp, Graham J; Mechelli, Andrea; Gong, Qiyong

2014-06-01

80

Left hemisphere fractional anisotropy increase in noise-induced tinnitus: a diffusion tensor imaging (DTI) study of white matter tracts in the brain.  

PubMed

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. PMID:24212050

Benson, Randall R; Gattu, Ramtilak; Cacace, Anthony T

2014-03-01

81

White Matter Hyperintensities, Exercise and Improvement in Gait Speed: Does the Type of Gait Rehabilitation Matter?  

PubMed Central

Background and Objectives White matter hyperintensities (WMH) on brain MRI are associated with cognitive and mobility impairment in older adults. We examined whether WMH in tracts in older adults with mobility impairment are linked to outcomes of gait rehabilitation interventions. Design A 12-week randomized controlled single-blind trial. Setting University-based mobility research laboratory. Participants Ambulatory adults aged 65 and older with mobility impairment. Intervention A conventional gait intervention focusing on walking, endurance, balance, and strength (WEBS, n=21) compared to a task-oriented intervention focused on timing and coordination of gait (TC, n=23). Measurements We measured self-paced gait speed over an instrumented walkway, pre and post intervention, and quantified WMH and brain volumes on pre-intervention brain MRI using an automated segmentation process. We overlaid a white matter tract atlas on the segmented images to measure tract WMH volumes and normalized WMH volumes to total brain volume. Aggregate WMH volumes in all white matter tracts and individual WMH volumes in specific longitudinal tracts (the superior longitudinal fasciculus, inferior longitudinal fasciculus and the fronto-occipital fasciculus) and cingulum were obtained. Results Gait speed gains in the TC group were of the same magnitude, independent of the WMH volume measures in all except the cingulum. However, in the WEBS group, gain in gait speed was smaller with greater overall tract WMH volumes (P<0.001) and with greater WMH volume in the three longitudinal tracts (P< 0.001 to 0.025). Conclusion Gains in gait speed with two types of gait rehabilitation are associated with individual differences in WMH. Task-oriented therapy that targets timing and coordination of gait may particularly benefit older adults with WMH in brain tracts that influence gait and cognition.

Nadkarni, Neelesh K.; Studenski, Stephanie A.; Perera, Subashan; Rosano, Caterina; Aizenstein, Howard J.; Brach, Jennifer S.; VanSwearingen, Jessie M.

2013-01-01

82

White Matter Abnormalities in Patients with Focal Cortical Dysplasia Revealed by Diffusion Tensor Imaging Analysis in a Voxelwise Approach  

PubMed Central

Background: Diffusion tensor imaging (DTI) allows the analysis of changes in microstructure, through the quantification of the spread and direction of water molecules in tissues. We used fractional anisotropy (FA) maps to compare the integrity of WM between patients and controls. The objective of the present study was to investigate WM abnormalities in patients with frontal lobe epilepsy secondary to focal cortical dysplasia (FCD). Materials and Methods: We included 31 controls (12 women, 33.1?±?9.6?years, mean?±?SD) and 22 patients (11 women, 30.4?±?10.0?years), recruited from our outpatient clinic. They had clinical and EEG diagnosis of frontal lobe epilepsy, secondary to FCD detected on MRI. Patients and controls underwent 3T MRI, including the DTI sequence, obtained in 32 directions and b value of 1000?s/mm2. To process the DTI we used the following softwares: MRIcroN and FSL/TBSS (tract-based spatial statistics). We used a threshold-free cluster enhancement with significance at p?fasciculus (p?=?0.044), uncinate fasciculus, and inferior fronto-occipital fasciculus (p?=?0.042). Conclusion: Our results showed a widespread pattern of WM microstructural abnormalities extending beyond the main lesion seen on MRI (frontal lobe), which may be related to frequent seizures or to the extent of MRI-invisible portion of FCD.

Fonseca, Viviane de Carvalho; Yasuda, Clarissa Lin; Tedeschi, Guilherme Garlipp; Betting, Luiz Eduardo; Cendes, Fernando

2012-01-01

83

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 Central

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.

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

84

White matter structure and symptom dimensions in obsessive-compulsive disorder.  

PubMed

There is evidence that the different symptom dimensions in obsessive-compulsive disorder (OCD) may be mediated by partially distinct neural systems. This DTI study investigated the relationship between symptom dimensions and white matter microstructure. Fractional anisotropy (FA), axial and radial diffusivity was analyzed in relation to the main OCD symptom dimensions. Symptom severity on the obsessing dimension was negatively correlated with FA in the corpus callosum and the cingulate bundle. Severity on the ordering dimension was negatively correlated with FA in, amongst others, the right inferior fronto-occipital fasciculus and the right optic radiation. All correlations were ascribable to alterations in radial diffusivity while there was no association between symptoms and axial diffusivity. Present results illustrate an association between alterations in visual processing tracts and ordering symptoms which are characterized by altered visual processing and increased attention towards irrelevant detail. They also indicate an association between obsessive thoughts and alterations in structures known to be relevant for cognitive control and inhibition. Hence, different symptom dimensions must be taken into account in order to disentangle the neurobiological underpinnings of OCD. PMID:22099866

Koch, Kathrin; Wagner, Gerd; Schachtzabel, Claudia; Schultz, C Christoph; Straube, Thomas; Güllmar, Daniel; Reichenbach, Jürgen R; Peikert, Gregor; Sauer, Heinrich; Schlösser, Ralf G M

2012-02-01

85

White Matter Integrity is Reduced in Bulimia Nervosa  

PubMed Central

Objective To investigate brain white matter (WM) functionality in bulimia nervosa (BN) in relation to anxiety. Method Twenty-one control (CW, mean age 27±7 years) and 20 BN women (mean age 25±5 years) underwent brain diffusion tensor imaging (DTI) to measure fractional anisotropy (FA; an indication of WM axon integrity) and the apparent diffusion coefficient (ADC; reflecting WM cell damage). Results FA was decreased in BN in the bilateral corona radiata extending into the posterior limb of the internal capsule, the corpus callosum, the right sub-insular white matter and right fornix. In CW but not BN trait anxiety correlated negatively with fornix, corpus callosum and left corona radiata FA. ADC was increased in BN compared to CW in the bilateral corona radiata, corpus callosum, inferior fronto-occipital and uncinate fasciculus. Alterations in BN WM functionality were not due to structural brain alterations. Discussion WM integrity is disturbed in BN, especially in the corona radiate, which has been associated with taste and brain reward processing. Whether this is a premorbid condition or an effect from the illness is yet uncertain. The relationships between WM FA and trait anxiety in CW but not BN may suggest that altered WM functionality contributes to high anxious traits in BN.

Mettler, Lisa N.; Shott, Megan E.; Pryor, Tamara; Yang, Tony T.; Frank, Guido K.W.

2013-01-01

86

Altered fimbria-fornix white matter integrity in anorexia nervosa predicts harm avoidance  

PubMed Central

The eating disorder anorexia nervosa (AN) is associated with high anxiety. The brain mechanisms that drive those behaviors are unknown. In this study we wanted to test whether brain WM integrity is altered in AN, and related to heightened anxiety. Sixteen adult women with AN (mean age 24±7 years) and 17 healthy control women (CW, mean age 25±4 years) underwent diffusion tensor imaging (DTI) of the brain. The DTI brain images were used to calculate the fractional anisotropy (FA) of WM tracts, which is a measure for WM integrity. AN individuals compared to CW showed clusters of significantly reduced FA (p<0.05, corrected) in the bilateral fimbria-fornix, fronto-occipital fasciculus, as well as posterior cingulum WM. In the AN group, Harm Avoidance was predicted by left (F=5.8, Beta=?0.54, p<0.03) and right (F=6.0, Beta=?0.55, p<0.03) fimbria-fornix FA. Those findings were not due to WM volume deficits in AN. This study indicates that WM integrity is abnormal in AN in limbic and association pathways, which could contribute to disturbed feeding, emotion processing and body perception in AN. The prediction of Harm Avoidance in AN by fimbria-fornix WM integrity suggests that this pathway may be mechanistically involved in high anxiety in AN.

Kazlouski, Demitry; Rollin, Michael D.H.; Tregellas, Jason; Shott, Megan E.; Jappe, Leah M.; Hagman, Jennifer O.; Pryor, Tamara; Yang, Tony T.; Frank, Guido K.W.

2011-01-01

87

Altered fimbria-fornix white matter integrity in anorexia nervosa predicts harm avoidance.  

PubMed

The eating disorder anorexia nervosa (AN) is associated with high anxiety. The brain mechanisms that drive those behaviors are unknown. In this study we wanted to test whether brain white matter (WM) integrity is altered in AN, and related to heightened anxiety. Sixteen adult women with AN (mean age 24 ± 7 years) and 17 healthy control women (CW, mean age 25 ± 4 years) underwent diffusion tensor imaging (DTI) of the brain. The DTI brain images were used to calculate the fractional anisotropy (FA) of WM tracts, which is a measure for WM integrity. AN individuals compared to CW showed clusters of significantly reduced FA (p<0.05, corrected) in the bilateral fimbria-fornix and the fronto-occipital fasciculus, as well as the posterior cingulum WM. In the AN group, Harm Avoidance was predicted by FA in the left and right fimbria-fornix. Those findings were not due to WM volume deficits in AN. This study indicates that WM integrity is abnormal in AN in limbic and association pathways, which could contribute to disturbed feeding, emotion processing and body perception in AN. The prediction of Harm Avoidance in AN by fimbria-fornix WM integrity suggests that this pathway may be mechanistically involved in high anxiety in AN. PMID:21498054

Kazlouski, Demitry; Rollin, Michael D H; Tregellas, Jason; Shott, Megan E; Jappe, Leah M; Hagman, Jennifer O; Pryor, Tamara; Yang, Tony T; Frank, Guido K W

2011-05-31

88

Anatomo-functional study of the temporo-parieto-occipital region: dissection, tractographic and brain mapping evidence from a neurosurgical perspective.  

PubMed

The temporo-parieto-occipital (TPO) junction is a complex brain territory heavily involved in several high-level neurological functions, such as language, visuo-spatial recognition, writing, reading, symbol processing, calculation, self-processing, working memory, musical memory, and face and object recognition. Recent studies indicate that this area is covered by a thick network of white matter (WM) connections, which provide efficient and multimodal integration of information between both local and distant cortical nodes. It is important for neurosurgeons to have good knowledge of the three-dimensional subcortical organisation of this highly connected region to minimise post-operative permanent deficits. The aim of this dissection study was to highlight the subcortical functional anatomy from a topographical surgical perspective. Eight human hemispheres (four left, four right) obtained from four human cadavers were dissected according to Klingler's technique. Proceeding latero-medially, the authors describe the anatomical courses of and the relationships between the main pathways crossing the TPO. The results obtained from dissection were first integrated with diffusion tensor imaging reconstructions and subsequently with functional data obtained from three surgical cases, all resection of infiltrating glial tumours using direct electrical mapping in awake patients. The subcortical limits for performing safe lesionectomies within the TPO region are as follows: within the parietal region, the anterior horizontal part of the superior longitudinal fasciculus and, more deeply, the arcuate fasciculus; dorsally, the vertical projective thalamo-cortical fibres. For lesions located within the temporal and occipital lobes, the resection should be tailored according to the orientation of the horizontal associative pathways (the inferior fronto-occipital fascicle, inferior longitudinal fascicle and optic radiation). The relationships between the WM tracts and the ventricle system were also examined. These results indicate that a detailed anatomo-functional awareness of the WM architecture within the TPO area is mandatory when approaching intrinsic brain lesions to optimise surgical results and to minimise post-operative morbidity. PMID:24975421

De Benedictis, Alessandro; Duffau, Hugues; Paradiso, Beatrice; Grandi, Enrico; Balbi, Sergio; Granieri, Enrico; Colarusso, Enzo; Chioffi, Franco; Marras, Carlo Efisio; Sarubbo, Silvio

2014-08-01

89

Neuroanatomical Correlates of Developmental Dyscalculia: Combined Evidence from Morphometry and Tractography  

PubMed Central

Poor mathematical abilities adversely affect academic and career opportunities. The neuroanatomical basis of developmental dyscalculia (DD), a specific learning deficit with prevalence rates exceeding 5%, is poorly understood. We used structural MRI and diffusion tensor imaging (DTI) to examine macro- and micro-structural impairments in 7- to 9-year-old children with DD, compared to a group of typically developing (TD) children matched on age, gender, intelligence, reading abilities and working memory capacity. Voxel-based morphometry (VBM) revealed reduced grey matter (GM) bilaterally in superior parietal lobule, intra-parietal sulcus, fusiform gyrus, parahippocampal gyrus and right anterior temporal cortex in children with DD. VBM analysis also showed reduced white matter (WM) volume in right temporal-parietal cortex. DTI revealed reduced fractional anisotropy (FA) in this WM region, pointing to significant right hemisphere micro-structural impairments. Furthermore, FA in this region was correlated with numerical operations but not verbal mathematical reasoning or word reading. Atlas-based tract mapping identified the inferior longitudinal fasciculus, inferior fronto-occipital fasciculus and caudal forceps major as key pathways impaired in DD. DTI tractography suggests that long-range WM projection fibers linking the right fusiform gyrus with temporal-parietal WM are a specific source of vulnerability in DD. Network and classification analysis suggest that DD in children may be characterized by multiple dysfunctional circuits arising from a core WM deficit. Our findings link GM and WM abnormalities in children with DD and they point to macro- and micro-structural abnormalities in right hemisphere temporal-parietal WM, and pathways associated with it, as key neuroanatomical correlates of DD.

Rykhlevskaia, Elena; Uddin, Lucina Q.; Kondos, Leeza; Menon, Vinod

2009-01-01

90

Relationship of a variant in the NTRK1 gene to white matter microstructure in young adults  

PubMed Central

The NTRK1 gene (also known as TRKA) encodes a high affinity receptor for NGF, a neurotrophin involved in nervous system development and myelination. NTRK1 has been implicated in neurological function via links between the T allele at rs6336 (NTRK1-T) and schizophrenia risk. A variant in the neurotrophin gene, BDNF, was previously associated with white matter integrity in young adults, highlighting the importance of neurotrophins to white matter development. We hypothesized that NTRK1-T would relate to lower FA in healthy adults. We scanned 391 healthy adult human twins and their siblings (mean age: 23.6 ± 2.2 years; 31 NTRK1-T carriers, 360 non-carriers) using 105-gradient diffusion tensor imaging at 4 Tesla. We evaluated in brain white matter how NTRK1-T and NTRK1 rs4661063 allele A (rs4661063-A, which is in moderate linkage disequilibrium with rs6336) related to voxelwise fractional anisotropy – a common diffusion tensor imaging measure of white matter microstructure. We used mixed-model regression to control for family relatedness, age, and sex. The sample was split in half to test results reproducibility. The false discovery rate method corrected for voxelwise multiple comparisons. NTRK1-T and rs4661063-A correlated with lower white matter fractional anisotropy, independent of age and sex (multiple comparisons corrected: false discovery rate critical p = 0.038 for NTRK1-T and 0.013 for rs4661063-A). In each half-sample, the NTRK1-T effect was replicated in the cingulum, corpus callosum, superior and inferior longitudinal fasciculi, inferior fronto-occipital fasciculus, superior corona radiata, and uncinate fasciculus. Our results suggest that NTRK1-T is important for developing white matter microstructure.

Braskie, Meredith N; Jahanshad, Neda; Stein, Jason L; Barysheva, Marina; Johnson, Kori; McMahon, Katie L; de Zubicaray, Greig I; Martin, Nicholas G; Wright, Margaret J; Ringman, John M; Toga, Arthur W; Thompson, Paul M

2012-01-01

91

Novel DTI Methodology to Detect and Quantify Injured Regions and Affected Brain Pathways in Traumatic Brain Injury  

PubMed Central

Purpose To develop and apply DTI based normalization methodology for the detection and quantification of traumatic brain injury (TBI) and the impact of injury along specific brain pathways in: a) individual TBI subjects, and b) a TBI group. Materials and Methods Normalized DTI tractography was conducted in the native space of 12 TBI and 10 age-matched control subjects using the same number of seeds in each subject, distributed at anatomically equivalent locations. Whole-brain tracts from the control group were mapped onto the head of each TBI subject. Differences in the Fractional Anisotropy (FA) maps between each TBI subject and the control group were computed in a common space using a t-test, transformed back to the individual TBI subject's head-space, and thresholded to form Regions of Interest (ROIs) that were used to sort tracts from the control group and the individual TBI subject. Tract-counts for a given ROI in each TBI subject were compared to group mean for the same ROI to quantify impact of injury along affected pathways. Same procedure was used to compare TBI group to control group in a common space. Results Sites of injury within individual TBI subjects and affected pathways included hippocampal/fornix, inferior fronto-occipital, inferior longitudinal fasciculus, corpus callosum (genu and splenium), cortico-spinal tracts and the uncinate fasciculus. Most of these regions were also detected in the group study. Conclusions The DTI normalization methodology presented here enables automatic delineation of ROIs within the heads of individual subjects (or in a group). These ROIs not only localize and quantify the extent of injury, but also quantify the impact of injury on affected pathways in an individual or a group of TBI subjects.

Singh, Manbir; Jeong, Jeongwon; Hwang, Darryl; Sungkarat, Witaya; Gruen, Peter

2009-01-01

92

Repeating with the right hemisphere: reduced interactions between phonological and lexical-semantic systems in crossed aphasia?  

PubMed Central

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.

De-Torres, Irene; Davila, Guadalupe; Berthier, Marcelo L.; Walsh, Sean Froudist; Moreno-Torres, Ignacio; Ruiz-Cruces, Rafael

2013-01-01

93

Repeating with the right hemisphere: reduced interactions between phonological and lexical-semantic systems in crossed aphasia?  

PubMed

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

De-Torres, Irene; Dávila, Guadalupe; Berthier, Marcelo L; Walsh, Seán Froudist; Moreno-Torres, Ignacio; Ruiz-Cruces, Rafael

2013-01-01

94

Word learning is mediated by the left arcuate fasciculus  

PubMed Central

Human language requires constant learning of new words, leading to the acquisition of an average vocabulary of more than 30,000 words in adult life. The ability to learn new words is highly variable and may rely on the integration between auditory and motor information. Here, we combined diffusion imaging tractography and functional MRI to study whether the strength of anatomical and functional connectivity between auditory and motor language networks is associated with word learning ability. Our results showed that performance in word learning correlates with microstructural properties and strength of functional connectivity of the direct connections between Broca’s and Wernicke’s territories in the left hemisphere. This study suggests that our ability to learn new words relies on an efficient and fast communication between temporal and frontal areas. The absence of these connections in other animals may explain the unique ability of learning words in humans.

Lopez-Barroso, Diana; Catani, Marco; Ripolles, Pablo; Dell'Acqua, Flavio; Rodriguez-Fornells, Antoni; de Diego-Balaguer, Ruth

2013-01-01

95

Atlas-based white matter analysis in individuals with velo-cardio-facial syndrome (22q11.2 deletion syndrome) and unaffected siblings  

PubMed Central

Background Velo-cardio-facial syndrome (VCFS, MIM#192430, 22q11.2 Deletion Syndrome) is a genetic disorder caused by a deletion of about 40 genes at the q11.2 band of one copy of chromosome 22. Individuals with VCFS present with deficits in cognition and social functioning, high risk of psychiatric disorders, volumetric reductions in gray and white matter (WM) and some alterations of the WM microstructure. The goal of the current study was to characterize the WM microstructural differences in individuals with VCFS and unaffected siblings, and the correlation of WM microstructure with neuropsychological performance. We hypothesized that individuals with VCFS would have decreased indices of WM microstructure (fractional anisotropy (FA), axial diffusivity (AD) and radial diffusivity (RD)), particularly in WM tracts to the frontal lobe, and that these measures would be correlated with cognitive functioning. Methods Thirty-three individuals with VCFS (21 female) and 16 unaffected siblings (8 female) participated in DTI scanning and neuropsychological testing. We performed an atlas-based analysis, extracted FA, AD, and RD measures for 54 WM tracts (27 in each hemisphere) for each participant, and used MANOVAs to compare individuals with VCFS to siblings. For WM tracts that were statistically significantly different between VCFS and siblings (pFDR?fasciculus, and decreased AD in multiple WM tracts (bilateral superior and posterior corona radiata, dorsal cingulum, inferior fronto-occipital fasciculus, superior longitudinal fasciculus, superior cerebellar peduncle, posterior thalamic radiation, and left anterior corona radiata, retrolenticular part of the internal capsule, external capsule, sagittal stratum). We also found significant correlations of AD with measures of executive function, IQ, working memory, and/or social cognition. Conclusions Our results suggest that individuals with VCFS display abnormal WM connectivity in a widespread cerebro-anatomical network, involving tracts from/to all cerebral lobes and the cerebellum. Future studies could focus on the WM developmental trajectory in VCFS, the association of WM alterations with psychiatric disorders, and the effects of candidate 22q11.2 genes on WM anomalies.

2012-01-01

96

Prediction of post-surgical seizure outcome in left mesial temporal lobe epilepsy?  

PubMed Central

Mesial temporal lobe epilepsy is the most common type of focal epilepsy and in its course often becomes refractory to anticonvulsant pharmacotherapy. A resection of the mesial temporal lobe structures is a promising option in these cases. However, approximately 30% of all patients remain with persistent seizures after surgery. In other words, reliable criteria for patients' outcome prediction are absent. To address this limitation, we investigated pre-surgical brain morphology of patients with unilateral left mesial temporal lobe epilepsy who underwent a selective amygdalohippocampectomy. Using support vector classification, we aimed to predict the post-surgical seizure outcome of each patient based on the pre-surgical T1-weighted structural brain images. Due to morphological gender differences and the evidence that men and women differ in onset, prevalence and symptomology in most neurological diseases, we investigated male and female patients separately. Thus, we benefitted from the capability to validate the reliability of our method in two independent samples. Notably, we were able to accurately predict the individual patients' outcome in the male (94% balanced accuracy) as well as in the female (96% balanced accuracy) group. In the male cohort relatively larger white matter volumes in the favorable as compared to the non-favorable outcome group were identified bilaterally in the cingulum bundle, fronto-occipital fasciculus and both caudate nuclei, whereas the left inferior longitudinal fasciculus showed relatively larger white matter volume in the non-favorable group. While relatively larger white matter volumes in the female cohort in the left inferior and right middle longitudinal fasciculus were associated with the favorable outcome, relatively larger white matter volumes in the non-favorable outcome group were identified bilaterally in the superior longitudinal fasciculi I and II. Here, we observed a clear lateralization and distinction of structures involved in the classification in men as compared to women with men exhibiting more alterations in the hemisphere contralateral to the seizure focus. In conclusion, individual post-surgical outcome predictions based on a single T1-weighted magnetic resonance image seem plausible and may thus support the routine pre-surgical workup of epilepsy patients.

Feis, Delia-Lisa; Schoene-Bake, Jan-Christoph; Elger, Christian; Wagner, Jan; Tittgemeyer, Marc; Weber, Bernd

2013-01-01

97

Neuroanatomical Changes due to Hearing Loss and Chronic Tinnitus: A Combined VBM and DTI Study  

PubMed Central

Subjective tinnitus is the perception of sound in the absence of an external source. Tinnitus is often accompanied by hearing loss but not everyone with hearing loss experiences tinnitus. We examined neuroanatomical alterations associated with hearing loss and tinnitus in three groups of subjects: those with hearing loss with tinnitus, those with hearing loss without tinnitus and normal hearing controls without tinnitus. To examine changes in gray matter we used structural MRI scans and voxel-based morphometry (VBM) and to identify changes in white matter tract orientation we used diffusion tensor imaging (DTI). A major finding of our study was that there were both gray and white matter changes in the vicinity of the auditory cortex for subjects with hearing loss alone relative to those with tinnitus and those with normal hearing. We did not find significant changes in gray or white matter in subjects with tinnitus and hearing loss compared to normal hearing controls. VBM analysis revealed that individuals with hearing loss without tinnitus had gray matter decreases in anterior cingulate and superior and medial frontal gyri relative to those with hearing loss and tinnitus. Region-of-interest analysis revealed additional decreases in superior temporal gyrus for the hearing loss group compared to the tinnitus group. Investigating effects of hearing loss alone, we found gray matter decreases in superior and medial frontal gyri in participants with hearing loss compared to normal hearing controls. DTI analysis showed decreases in fractional anisotropy values in the right superior and inferior longitudinal fasciculi, corticospnial tract, inferior fronto-occipital tract, superior occipital fasciculus, and anterior thalamic radiation for the hearing loss group relative to normal hearing controls. In attempting to dissociate the effect of tinnitus from hearing loss, we observed that hearing loss rather than tinnitus had the greatest influence on gray and white matter alterations.

Husain, Fatima T.; Medina, Roberto E.; Davis, Caroline W.; Szymko-Bennett, Yvonne; Simonyan, Kristina; Pajor, Nathan M.; Horwitz, Barry

2010-01-01

98

The "frontal syndrome" revisited: lessons from electrostimulation mapping studies.  

PubMed

For a long time, in a localizationist view of brain functioning, a combination of symptoms called "frontal syndrome" has been interpreted as the direct result of damages involving the frontal lobe(s). The goal of this review is to challenge this view, that is, to move to a hodotopical approach to lesion mapping, on the basis of new insights provided by intraoperative electrostimulation mapping investigations in patients who underwent awake surgery for cerebral tumors. These original data reported in the last decade break with the traditional dogma of a modular and fixed organization of the central nervous system, by switching to the concepts of cerebral connectivity and plasticity - i.e., a brain organization based on dynamic interrelationships between parallel distributed networks. According to this revisited model, "frontal symptoms" can be generated by tumor or electrostimulation not only of the frontal lobes, but also of cortical and subcortical (white matter pathways/deep gray nuclei) structures outside the frontal lobes: especially, stimulation of the superior longitudinal fascicle may elicit speech production disorders, syntactic disturbances, involuntary language switching or phonemic paraphasia (arcuate fascicle), stimulation of the inferior fronto-occipital fascicle can generate semantic paraphasia or deficit of cross-modal judgment, stimulation of the subcallosal fasciculus may elicit transcortical motor aphasia, while stimulation of the striatum induces preservations. On the other hand, it is also possible to perform extensive right or left frontal lobectomy in patients who continue to have a normal familial, social and professional life, without "frontal syndrome". Therefore, this provocative approach may open the door to a renewal in the modeling of brain processing as well as in its clinical applications, especially in the fields of cerebral surgery and functional rehabilitation. These findings illustrate well the need to reinforce links between cognitive neuroscience and clinical neurology/neurosurgery. PMID:21621762

Duffau, Hugues

2012-01-01

99

White matter abnormalities in pediatric obsessive-compulsive disorder.  

PubMed

Obsessive-compulsive disorder (OCD) is a prevalent and often severely disabling illness with onset generally in childhood or adolescence. Although white matter deficits have been implicated in the neurobiology of OCD, few studies have been conducted in pediatric patients when the brain is still developing and have examined their functional correlates. In this study, 23 pediatric OCD patients and 23 healthy volunteers, between the ages of 9 and 17 years, matched for sex, age, handedness, and IQ, received a diffusion tensor imaging exam on a 3T GE system and a brief neuropsychological battery tapping executive functions. Patient symptom severity was assessed using the Children's Yale-Brown Obsessive-Compulsive Scale (CY-BOCS). Patients with OCD exhibited significantly greater fractional anisotropy compared to matched controls in the left dorsal cingulum bundle, splenium of the corpus callosum, right corticospinal tract, and left inferior fronto-occipital fasciculus. There were no regions of significantly lower fractional anisotropy in patients compared to controls. Higher fractional anisotropy in the splenium was significantly correlated with greater obsession severity on the CY-BOCS in the subgroup of psychotropic drug-naïve patients. Among patients, there was a significant association between greater fractional anisotropy in the dorsal cingulum bundle and better performance on measures of response inhibition and cognitive control. The overall findings suggest a pattern of greater directional coherence of white matter tracts in OCD very early in the course of illness, which may serve a compensatory mechanism, at least for response inhibition functions typically subserved by the cingulum bundle. PMID:22871914

Gruner, Patricia; Vo, An; Ikuta, Toshikazu; Mahon, Katie; Peters, Bart D; Malhotra, Anil K; Ulu?, Aziz M; Szeszko, Philip R

2012-11-01

100

Abnormal White Matter Integrity in Adolescents with Internet Addiction Disorder: A Tract-Based Spatial Statistics Study  

PubMed Central

Background Internet addiction disorder (IAD) is currently becoming a serious mental health issue around the globe. Previous studies regarding IAD were mainly focused on associated psychological examinations. However, there are few studies on brain structure and function about IAD. In this study, we used diffusion tensor imaging (DTI) to investigate white matter integrity in adolescents with IAD. Methodology/Principal Findings Seventeen IAD subjects and sixteen healthy controls without IAD participated in this study. Whole brain voxel-wise analysis of fractional anisotropy (FA) was performed by tract-based spatial statistics (TBSS) to localize abnormal white matter regions between groups. TBSS demonstrated that IAD had significantly lower FA than controls throughout the brain, including the orbito-frontal white matter, corpus callosum, cingulum, inferior fronto-occipital fasciculus, and corona radiation, internal and external capsules, while exhibiting no areas of higher FA. Volume-of-interest (VOI) analysis was used to detect changes of diffusivity indices in the regions showing FA abnormalities. In most VOIs, FA reductions were caused by an increase in radial diffusivity while no changes in axial diffusivity. Correlation analysis was performed to assess the relationship between FA and behavioral measures within the IAD group. Significantly negative correlations were found between FA values in the left genu of the corpus callosum and the Screen for Child Anxiety Related Emotional Disorders, and between FA values in the left external capsule and the Young's Internet addiction scale. Conclusions Our findings suggest that IAD demonstrated widespread reductions of FA in major white matter pathways and such abnormal white matter structure may be linked to some behavioral impairments. In addition, white matter integrity may serve as a potential new treatment target and FA may be as a qualified biomarker to understand the underlying neural mechanisms of injury or to assess the effectiveness of specific early interventions in IAD.

Qin, Lindi; Zhao, Zhimin; Xu, Jianrong; Lei, Hao

2012-01-01

101

Fiber tract-specific white matter lesion severity Findings in late-life depression and by AGTR1 A1166C genotype.  

PubMed

Past work demonstrated that late-life depression is associated with greater severity of ischemic cerebral hyperintense white matter lesions, particularly frontal lesions. However, these lesions are also associated with other neuropsychiatric deficits, so these clinical relationships may depend on which fiber tracts are damaged. We examined the ratio of lesion to nonlesioned white matter tissue within multiple fiber tracts between depressed and nondepressed elders. We also sought to determine if the AGTR1 A1166C and BDNF Val66Met polymorphisms contributed to vulnerability to lesion development in discrete tracts. The 3T structural MR images and blood samples for genetic analyses were acquired on 54 depressed and 37 nondepressed elders. Lesion maps were created through an automated tissue segmentation process and applied to a probabilistic white matter fiber tract atlas allowing for identification of the fraction of the tract occupied by lesion. The depressed cohort exhibited a significantly greater lesion ratio only in the left upper cingulum near the cingulate gyrus (F((1,86)) = 4.62, P = 0.0344), supporting past work implicating cingulate dysfunction in the pathogenesis of depression. In the 62 Caucasian subjects with genetic data, AGTR1 C1166 carriers exhibited greater lesion ratios across multiple tracts including the anterior thalamic radiation and inferior fronto-occipital fasciculus. In contrast, BDNF Met allele carriers exhibited greater lesion ratios only in the frontal corpus callosum. Although these findings did not survive correction for multiple comparisons, this study supports our hypothesis and provides preliminary evidence that genetic differences related to vascular disease may increase lesion vulnerability differentially across fiber tracts. PMID:22021115

Taylor, Warren D; Zhao, Zheen; Ashley-Koch, Allison; Payne, Martha E; Steffens, David C; Krishnan, Ranga R; Hauser, Elizabeth; MacFall, James R

2013-02-01

102

Neuroanatomical pattern classification in a population-based sample of first-episode schizophrenia.  

PubMed

Recent neuroanatomical pattern classification studies have attempted to individually classify cases with psychotic disorders using morphometric MRI data in an automated fashion. However, this approach has not been tested in population-based samples, in which variable patterns of comorbidity and disease course are typically found. We aimed to evaluate the diagnostic accuracy (DA) of the above technique to discriminate between incident cases of first-episode schizophrenia identified in a circumscribed geographical region over a limited period of time, in comparison with next-door healthy controls. Sixty-two cases of first-episode schizophrenia or schizophreniform disorder and 62 age, gender and educationally-matched controls underwent 1.5 T MRI scanning at baseline, and were naturalistically followed-up over 1 year. T1-weighted images were used to train a high-dimensional multivariate classifier, and to generate both spatial maps of the discriminative morphological patterns between groups and ROC curves. The spatial map discriminating first-episode schizophrenia patients from healthy controls revealed a complex pattern of regional volumetric abnormalities in the former group, affecting fronto-temporal-occipital gray and white matter regions bilaterally, including the inferior fronto-occipital fasciculus, as well as the third and lateral ventricles. However, an overall modest DA (73.4%) was observed for the individual discrimination between first-episode schizophrenia patients and controls, and the classifier failed to predict 1-year prognosis (remitting versus non-remitting course) of first-episode schizophrenia (DA=58.3%). In conclusion, using a "real world" sample recruited with epidemiological methods, the application of a neuroanatomical pattern classifier afforded only modest DA to classify first-episode schizophrenia subjects and next-door healthy controls, and poor discriminative power to predict the 1-year prognosis of first-episode schizophrenia. PMID:23261522

Zanetti, Marcus V; Schaufelberger, Maristela S; Doshi, Jimit; Ou, Yangming; Ferreira, Luiz K; Menezes, Paulo R; Scazufca, Marcia; Davatzikos, Christos; Busatto, Geraldo F

2013-06-01

103

White Matter Abnormalities in Pediatric Obsessive-Compulsive Disorder  

PubMed Central

Obsessive-compulsive disorder (OCD) is a prevalent and often severely disabling illness with onset generally in childhood or adolescence. Although white matter deficits have been implicated in the neurobiology of OCD, few studies have been conducted in pediatric patients when the brain is still developing and have examined their functional correlates. In this study, 23 pediatric OCD patients and 23 healthy volunteers, between the ages of 9 and 17 years, matched for sex, age, handedness, and IQ, received a diffusion tensor imaging exam on a 3T GE system and a brief neuropsychological battery tapping executive functions. Patient symptom severity was assessed using the Children's Yale-Brown Obsessive-Compulsive Scale (CY-BOCS). Patients with OCD exhibited significantly greater fractional anisotropy compared to matched controls in the left dorsal cingulum bundle, splenium of the corpus callosum, right corticospinal tract, and left inferior fronto-occipital fasciculus. There were no regions of significantly lower fractional anisotropy in patients compared to controls. Higher fractional anisotropy in the splenium was significantly correlated with greater obsession severity on the CY-BOCS in the subgroup of psychotropic drug-naïve patients. Among patients, there was a significant association between greater fractional anisotropy in the dorsal cingulum bundle and better performance on measures of response inhibition and cognitive control. The overall findings suggest a pattern of greater directional coherence of white matter tracts in OCD very early in the course of illness, which may serve a compensatory mechanism, at least for response inhibition functions typically subserved by the cingulum bundle.

Gruner, Patricia; Vo, An; Ikuta, Toshikazu; Mahon, Katie; Peters, Bart D; Malhotra, Anil K; Ulug, Aziz M; Szeszko, Philip R

2012-01-01

104

The anatomy of the callosal and visual association pathways in high-functioning autism: a DTI tractography study  

PubMed Central

There is increasing recognition that many of the core behavioral impairments that characterize autism potentially emerge from poor neural synchronization across nodes comprising dispersed cortical networks. A likely candidate for the source of this atypical functional connectivity in autism is an alteration in the structural integrity of intra- and inter-hemispheric white matter tracts that form large-scale cortical networks. To test this hypothesis, in a group of adults with high functioning autism (HFA) and matched control participants, we used diffusion tensor tractography to compare the structural integrity of three intra-hemispheric visual-association white matter tracts, the inferior longitudinal fasciculus (ILF), the inferior fronto-occipito fasciculus (IFOF) and the uncinate fasciculus (UF), with the integrity of three sub-portions of the major inter-hemispheric fiber tract, the corpus callosum. Compared with the control group, the HFA group evinced an increase in the volume of the intra-hemispheric fibers, particularly in the left hemisphere, and a reduction in the volume of the forceps minor and body of the corpus callosum. The reduction in the volume of the forceps minor also correlated with an increase in repetitive and stereotypical behavior as measured by the Autism Diagnostic Interview. These findings suggest that the abnormalities in the integrity of key inter-and intra-hemispheric white matter tracts may underlie the atypical information processing observed in these individuals.

Thomas, Cibu; Humphreys, Kate; Jung, Kwan-jin; Minshew, Nancy; Behrmann, Marlene

2010-01-01

105

Beyond the Arcuate Fasciculus: Consensus and Controversy in the Connectional Anatomy of Language  

ERIC Educational Resources Information Center

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…

Dick, Anthony Steven; Tremblay, Pascale

2012-01-01

106

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

ERIC Educational Resources Information Center

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…

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

2012-01-01

107

Assessment of arcuate fasciculus with diffusion-tensor tractography may predict the prognosis of aphasia in patients with left middle cerebral artery infarcts  

Microsoft Academic Search

Introduction  It is often clinically difficult to assess the severity of aphasia in the earliest stage of cerebral infarction. A method\\u000a enabling objective assessment of verbal function is needed for this purpose. We examined whether diffusion tensor (DT) tractography\\u000a is of clinical value in assessing aphasia.\\u000a \\u000a \\u000a \\u000a Methods  Thirteen right-handed patients with left middle cerebral artery infarcts who were scanned within 2 days

Akiko Hosomi; Yoshinari Nagakane; Kei Yamada; Nagato Kuriyama; Toshiki Mizuno; Tsunehiko Nishimura; Masanori Nakagawa

2009-01-01

108

Multiple dermoid sinuses of type Vb and IIIb on the head of a Saint Bernard dog  

PubMed Central

Dermoid sinus, a congenital malformation of neural tube development, has been reported in humans and several animal species including dogs. It is typically found in the dorsal midline and commonly occurs in the Rhodesian Ridgeback breed. A case of multiple dermoid sinuses in the fronto-occipital region is described. An 11-month-old, intact female Saint Bernard dog was presented with a 2 day history of discharge from a large irregular subcutaneous mass in the fronto-occipital region. The dog was otherwise healthy. The dog had two circular skin lesions (approximately 4?×?4 and 4?×?2 cm diameter) surrounded by multiple irregular elevated masses. The masses had multiple small openings on the skin surface with tufts of hair protruding from the apertures. The masses were surgically removed, and the diagnosis of multiple dermoid sinuses was confirmed by histological examination. Histopathological examination showed multiple, variably sized, spherical to tubular cysts expanding the dermis and subcutis. Cysts were filled with hair shafts and lamellar keratin and were lined by a stratified squamous epithelium. Sebaceous and apocrine gland adnexal structures were also observed. To the best of our knowledge, this is the first reported case of multiple dermoid sinuses of two different types in the head of a Saint Bernard dog.

2013-01-01

109

Imaging cortical association tracts in the human brain using diffusion-tensor-based axonal tracking.  

PubMed

Diffusion-tensor fiber tracking was used to identify the cores of several long-association fibers, including the anterior (ATR) and posterior (PTR) thalamic radiations, and the uncinate (UNC), superior longitudinal (SLF), inferior longitudinal (ILF), and inferior fronto-occipital (IFO) fasciculi. Tracking results were compared to existing anatomical knowledge, and showed good qualitative agreement. Guidelines were developed to reproducibly track these fibers in vivo. The interindividual variability of these reconstructions was assessed in a common spatial reference frame (Talairach space) using probabilistic mapping. As a first illustration of this technical capability, a reduction in brain connectivity in a patient with a childhood neurodegenerative disease (X-linked adrenoleukodystrophy) was demonstrated. PMID:11810663

Mori, Susumu; Kaufmann, Walter E; Davatzikos, Christos; Stieltjes, Bram; Amodei, Laura; Fredericksen, Kim; Pearlson, Godfrey D; Melhem, Elias R; Solaiyappan, Meiyappan; Raymond, Gerald V; Moser, Hugo W; van Zijl, Peter C M

2002-02-01

110

The language network.  

PubMed

Language processing is supported by different regions located in separate parts of the brain. A crucial condition for these regions to function as a network is the information transfer between them. This is guaranteed by dorsal and ventral pathways connecting prefrontal and temporal language-relevant regions. Based on functional brain imaging studies, these pathways' language functions can be assigned indirectly. Dorsally, one pathway connecting the temporal cortex (TC) and premotor cortex supports speech repetition, another one connecting the TC and posterior Broca's area supports complex syntactic processes. Ventrally, the uncinate fascile and the inferior fronto-occipital fascile subserve semantic and basic syntactic processes. Thus, the available evidence points towards a neural language network with at least two dorsal and two ventral pathways. PMID:23146876

Friederici, Angela D; Gierhan, Sarah M E

2013-04-01

111

Heterozygosity and craniofacial dimensions of Zapotec school children from a subsistence community in the valley of Oaxaca, southern Mexico.  

PubMed

Gene flow is associated with differences in craniofacial and postcranial dimensions among indigenous populations of southern Mexico. This study compares four craniofacial dimensions in 322 children from families which have an average inbreeding coefficient of 0.01 and 36 children from families which have an inbreeding coefficient of zero (more heterozygous) in a Zapotec speaking community. In addition, two indices were computed. With sex and chronological age constant, there is a statistically significant difference between more and less heterozygous children in bizygomatic diameter. Differences in biparietal diameter and fronto-occipital length reflect the same tendency. The differences probably reflect more an effect of heterozygosity on these dimensions than facial dissimilarity of the populations from which the new genetic materials were drawn because gene flow was from related groups of Indians (e.g., Mixtec) in southern Mexico. Hence, midface growth and overall normal size appear to be affected by fluctuation in level of heterozygosity. PMID:2061401

Little, B B; Buschang, P H; Malina, R M

1991-01-01

112

Fiber density asymmetry of the arcuate fasciculus in relation to functional hemispheric language lateralization in both right- and left-handed healthy subjects: A combined fMRI and DTI study  

Microsoft Academic Search

Previously reported leftward asymmetry in language-related gray and white matter areas of the brain has been proposed as a structural correlate of left-sided functional hemispheric language lateralization. However, structural asymmetry in non-left-sided functional language lateralization has as yet not been studied. Furthermore, the neuroanatomical basis of the reported volumetric white matter asymmetry is not fully understood. In 20 healthy volunteers,

M. W. Vernooij; M. Smits; P. A. Wielopolski; G. C. Houston; G. P. Krestin; A. van der Lugt

2007-01-01

113

40 CFR 63.4741 - How do I demonstrate initial compliance with the emission limitations?  

Code of Federal Regulations, 2013 CFR

...not need to redetermine the mass of organic HAP in coatings...compliant material option. If the mass fraction of organic HAP of...providing density or specific gravity data for pure materials. If...of this section. Wc = Mass fraction of organic HAP in...

2013-07-01

114

47 CFR 73.1217 - Broadcast hoaxes.  

Code of Federal Regulations, 2013 CFR

...information concerning a crime or a catastrophe if...of the information will cause substantial public harm...does in fact directly cause substantial public harm...begin immediately, and cause direct and actual...harm would occur. A âcrimeâ is any act or...

2013-10-01

115

26 CFR 1.692-1 - Abatement of income taxes of certain members of the Armed Forces of the United States upon death.  

Code of Federal Regulations, 2013 CFR

...the Armed Forces of the United States upon death. 1.692-1 Section 1.692-1...the Armed Forces of the United States upon death. (a)(1) This section applies if...of the United States, and (ii) His death occurs while he is serving in a...

2013-04-01

116

Prediction of brain-computer interface aptitude from individual brain structure  

PubMed Central

Objective: Brain-computer interface (BCI) provide a non-muscular communication channel for patients with impairments of the motor system. A significant number of BCI users is unable to obtain voluntary control of a BCI-system in proper time. This makes methods that can be used to determine the aptitude of a user necessary. Methods: We hypothesized that integrity and connectivity of involved white matter connections may serve as a predictor of individual BCI-performance. Therefore, we analyzed structural data from anatomical scans and DTI of motor imagery BCI-users differentiated into high and low BCI-aptitude groups based on their overall performance. Results: Using a machine learning classification method we identified discriminating structural brain trait features and correlated the best features with a continuous measure of individual BCI-performance. Prediction of the aptitude group of each participant was possible with near perfect accuracy (one error). Conclusions: Tissue volumetric analysis yielded only poor classification results. In contrast, the structural integrity and myelination quality of deep white matter structures such as the Corpus Callosum, Cingulum, and Superior Fronto-Occipital Fascicle were positively correlated with individual BCI-performance. Significance: This confirms that structural brain traits contribute to individual performance in BCI use.

Halder, S.; Varkuti, B.; Bogdan, M.; Kubler, A.; Rosenstiel, W.; Sitaram, R.; Birbaumer, N.

2013-01-01

117

State-dependent microstructural white matter changes in bipolar I depression  

PubMed Central

Abnormalities in fronto-limbic-striatal white matter (WM) have been reported in bipolar disorder (BD), but results have been inconsistent across studies. Furthermore, there have been no detailed investigations as to whether acute mood states contribute to microstructural changes in WM tracts. In order to compare fiber density and structural integrity within WM tracts between BD depression and remission, whole-brain fractional anisotropy (FA) and mean diffusivity (MD) were assessed in 37 bipolar I disorder (BD-I) patients (16 depressed and 21 remitted), and 26 healthy individuals with diffusion tensor imaging. Significantly decreased FA and increased MD in bilateral prefronto-limbic-striatal white matter and right inferior fronto-occipital, superior and inferior longitudinal fasciculi were shown in all BD-I patients versus controls, as well as in depressed BD-I patients compared to both controls and remitted BD-I patients. Depressed BD-I patients also exhibited increased FA in the ventromedial prefrontal cortex. Remitted BD-I patients did not differ from controls in FA or MD. These findings suggest that BD-I depression may be associated with acute microstructural WM changes.

Zanetti, Marcus V.; Jackowski, Marcel P.; Versace, Amelia; Almeida, Jorge R. C.; Hassel, Stefanie; Duran, Fabio L. S.; Kupfer, David J.; Phillips, Mary L.

2009-01-01

118

Changes in whole-brain functional networks and memory performance in aging.  

PubMed

We used resting-functional magnetic resonance imaging data from 98 healthy older adults to analyze how local and global measures of functional brain connectivity are affected by age, and whether they are related to differences in memory performance. Whole-brain networks were created individually by parcellating the brain into 90 cerebral regions and obtaining pairwise connectivity. First, we studied age-associations in interregional connectivity and their relationship with the length of the connections. Aging was associated with less connectivity in the long-range connections of fronto-parietal and fronto-occipital systems and with higher connectivity of the short-range connections within frontal, parietal, and occipital lobes. We also used the graph theory to measure functional integration and segregation. The pattern of the overall age-related correlations presented positive correlations of average minimum path length (r = 0.380, p = 0.008) and of global clustering coefficients (r = 0.454, p < 0.001), leading to less integrated and more segregated global networks. Main correlations in clustering coefficients were located in the frontal and parietal lobes. Higher clustering coefficients of some areas were related to lower performance in verbal and visual memory functions. In conclusion, we found that older participants showed lower connectivity of long-range connections together with higher functional segregation of these same connections, which appeared to indicate a more local clustering of information processing. Higher local clustering in older participants was negatively related to memory performance. PMID:24814675

Sala-Llonch, Roser; Junqué, Carme; Arenaza-Urquijo, Eider M; Vidal-Piñeiro, Dídac; Valls-Pedret, Cinta; Palacios, Eva M; Domènech, Sara; Salvà, Antoni; Bargalló, Nuria; Bartrés-Faz, David

2014-10-01

119

Automatic Tractography Segmentation Using a High-Dimensional White Matter Atlas  

Microsoft Academic Search

We propose a new white matter atlas creation method that learns a model of the common white matter structures present in a group of subjects. We demonstrate that our atlas creation method, which is based on group spectral clustering of tractography, discovers structures corresponding to expected white matter anatomy such as the corpus callosum, uncinate fasciculus, cingulum bundles, arcuate fasciculus,

Lauren J. O'Donnell; Carl-fredrik Westin

2007-01-01

120

DTI Tractography of the Human Brain's Language Pathways  

Microsoft Academic Search

Diffusion Tensor Imaging (DTI) tractography has been used to detect leftward asymmetries in the arcuate fasciculus, a pathway that links temporal and inferior frontal language cortices. In this study, we more specifically define this asymmetry with respect to both anatomy and function. Twenty right-handed male subjects were scanned with DTI, and the arcuate fasciculus was reconstructed using deterministic tractography. The

Matthew F. Glasser; James K. Rilling

2008-01-01

121

An exploratory study on the spatial relationship between regional cortical volume changes and white matter integrity in multiple sclerosis.  

PubMed

Multiple sclerosis (MS) is a chronic inflammatory central nervous system disorder with a neurodegenerative component. While in the past, MS has been predominantly viewed as a white matter (WM) disease, gray matter (GM) pathology receives increasing attention in MS research. In this study, we tested hypothesis-free for a possible spatial relationship between cortical volume changes and disturbed integrity of projecting WM tracts. We used voxel-based morphometry (VBM), lesion probability maps (LPM), and probabilistic tractography to compare brain magnetic resonance imaging (MRI) scans obtained at 3 Tesla of 15 low disabled MS patients with 15 matched healthy controls (HCs). Areas of decreased cortical volume in the patients identified by VBM were used as seeds for tractography. Volume in two cortical areas in the left inferior frontal gyrus (IFG) and the left lateral occipital cortex (LOC) was reduced in patients compared to HCs. Starting from the IFG-region, tractography suggested impaired connections between left and right portions of the frontal lobe in the patients. Using the LOC as a seed, in patients, the left inferior longitudinal and fronto-occipital pathways appeared disintegrated compared to HCs. Swapping the seeds to homologous contralateral areas showed similar results for frontal, but different results for occipital brain areas. This at least partly could be explained by differential interference with WM lesions. These findings suggest a regional dependence between cortical GM and WM tract alterations in MS patients. While confirmation in larger and more heterogenic samples is needed, this study indicates that combining several MRI methods (VBM, LPM, and Probabilistic Tractography) may provide important insights into interacting processes related to the fiber tract and GM changes in MS. PMID:23573900

Jehna, Margit; Langkammer, Christian; Khalil, Michael; Fuchs, Siegrid; Reishofer, Gernot; Fazekas, Franz; Ebner, Franz; Enzinger, Christian

2013-01-01

122

White Matter Fractional Anisotropy Correlates With Speed of Processing and Motor Speed in Young Childhood Cancer Survivors  

SciTech Connect

Purpose: To determine whether childhood medulloblastoma and acute lymphoblastic leukemia (ALL) survivors have decreased white matter fractional anisotropy (WMFA) and whether WMFA is related to the speed of processing and motor speed. Methods and Materials: For this study, 17 patients (6 medulloblastoma, 5 ALL treated with high-dose methotrexate (MTX) (4 x 5 g/m{sup 2}) and 6 with low-dose MTX (3 x 2 g/m{sup 2})) and 17 age-matched controls participated. On a 3.0-T magnetic resonance imaging (MRI) scanner, diffusion tensor imaging (DTI) was performed, and WMFA values were calculated, including specific regions of interest (ROIs), and correlated with the speed of processing and motor speed. Results: Mean WMFA in the patient group, mean age 14 years (range 8.9 - 16.9), was decreased compared with the control group (p = 0.01), as well as WMFA in the right inferior fronto-occipital fasciliculus (IFO) (p = 0.03) and in the genu of the corpus callosum (gCC) (p = 0.01). Based on neurocognitive results, significant positive correlations were present between processing speed and WMFA in the splenium (sCC) (r = 0.53, p = 0.03) and the body of the corpus callosum (bCC) (r = 0.52, p = 0.03), whereas the right IFO WMFA was related to motor speed (r = 0.49, p < 0.05). Conclusions: White matter tracts, using a 3.0-T MRI scanner, show impairment in childhood cancer survivors, medulloblastoma survivors, and also those treated with high doses of MTX. In particular, white matter tracts in the sCC, bCC and right IFO are positively correlated with speed of processing and motor speed.

Aukema, Eline J. [Pediatric Psychosocial Department, Emma Children's Hospital/Academic Medical Center, Amsterdam (Netherlands)], E-mail: e.j.aukema@amc.uva.nl; Caan, Matthan W.A. [Department of Radiology, Academic Medical Center, University of Amsterdam, Amsterdam (Netherlands); Delft University of Technology, Delft (Netherlands); Oudhuis, Nienke [Pediatric Psychosocial Department, Emma Children's Hospital/Academic Medical Center, Amsterdam (Netherlands); Majoie, Charles [Department of Radiology, Academic Medical Center, University of Amsterdam, Amsterdam (Netherlands); Vos, Frans M. [Department of Radiology, Academic Medical Center, University of Amsterdam, Amsterdam (Netherlands); Delft University of Technology, Delft (Netherlands); Reneman, Liesbeth [Department of Radiology, Academic Medical Center, University of Amsterdam, Amsterdam (Netherlands); Last, Bob F. [Pediatric Psychosocial Department, Emma Children's Hospital/Academic Medical Center, Amsterdam (Netherlands); Department of Developmental Psychology, Free University of Amsterdam, Amsterdam (Netherlands); Grootenhuis, Martha A. [Pediatric Psychosocial Department, Emma Children's Hospital/Academic Medical Center, Amsterdam (Netherlands); Schouten-van Meeteren, Antoinette Y.N. [Department of Pediatric Oncology, Emma Children's Hospital/Academic Medical Center, Amsterdam (Netherlands)

2009-07-01

123

Gravity Influences Top-Down Signals in Visual Processing  

PubMed Central

Visual perception is not only based on incoming visual signals but also on information about a multimodal reference frame that incorporates vestibulo-proprioceptive input and motor signals. In addition, top-down modulation of visual processing has previously been demonstrated during cognitive operations including selective attention and working memory tasks. In the absence of a stable gravitational reference, the updating of salient stimuli becomes crucial for successful visuo-spatial behavior by humans in weightlessness. Here we found that visually-evoked potentials triggered by the image of a tunnel just prior to an impending 3D movement in a virtual navigation task were altered in weightlessness aboard the International Space Station, while those evoked by a classical 2D-checkerboard were not. Specifically, the analysis of event-related spectral perturbations and inter-trial phase coherency of these EEG signals recorded in the frontal and occipital areas showed that phase-locking of theta-alpha oscillations was suppressed in weightlessness, but only for the 3D tunnel image. Moreover, analysis of the phase of the coherency demonstrated the existence on Earth of a directional flux in the EEG signals from the frontal to the occipital areas mediating a top-down modulation during the presentation of the image of the 3D tunnel. In weightlessness, this fronto-occipital, top-down control was transformed into a diverging flux from the central areas toward the frontal and occipital areas. These results demonstrate that gravity-related sensory inputs modulate primary visual areas depending on the affordances of the visual scene.

Cheron, Guy; Leroy, Axelle; Palmero-Soler, Ernesto; De Saedeleer, Caty; Bengoetxea, Ana; Cebolla, Ana-Maria; Vidal, Manuel; Dan, Bernard; Berthoz, Alain; McIntyre, Joseph

2014-01-01

124

A big-world network in ASD: dynamical connectivity analysis reflects a deficit in long-range connections and an excess of short-range connections.  

PubMed

Over the last years, increasing evidence has fuelled the hypothesis that Autism Spectrum Disorder (ASD) is a condition of altered brain functional connectivity. The great majority of these empirical studies relies on functional magnetic resonance imaging (fMRI) which has a relatively poor temporal resolution. Only a handful of studies has examined networks emerging from dynamic coherence at the millisecond resolution and there are no investigations of coherence at the lowest frequencies in the power spectrum-which has recently been shown to reflect long-range cortico-cortical connections. Here we used electroencephalography (EEG) to assess dynamic brain connectivity in ASD focusing in the low-frequency (delta) range. We found that connectivity patterns were distinct in ASD and control populations and reflected a double dissociation: ASD subjects lacked long-range connections, with a most prominent deficit in fronto-occipital connections. Conversely, individuals with ASD showed increased short-range connections in lateral-frontal electrodes. This effect between categories showed a consistent parametric dependency: as ASD severity increased, short-range coherence was more pronounced and long-range coherence decreased. Theoretical arguments have been proposed arguing that distinct patterns of connectivity may result in networks with different efficiency in transmission of information. We show that the networks in ASD subjects have less Clustering coefficient, greater Characteristic Path Length than controls - indicating that the topology of the network departs from small-world behaviour - and greater modularity. Together these results show that delta-band coherence reveal qualitative and quantitative aspects associated with ASD pathology. PMID:21110988

Barttfeld, Pablo; Wicker, Bruno; Cukier, Sebastián; Navarta, Silvana; Lew, Sergio; Sigman, Mariano

2011-01-01

125

Gravity influences top-down signals in visual processing.  

PubMed

Visual perception is not only based on incoming visual signals but also on information about a multimodal reference frame that incorporates vestibulo-proprioceptive input and motor signals. In addition, top-down modulation of visual processing has previously been demonstrated during cognitive operations including selective attention and working memory tasks. In the absence of a stable gravitational reference, the updating of salient stimuli becomes crucial for successful visuo-spatial behavior by humans in weightlessness. Here we found that visually-evoked potentials triggered by the image of a tunnel just prior to an impending 3D movement in a virtual navigation task were altered in weightlessness aboard the International Space Station, while those evoked by a classical 2D-checkerboard were not. Specifically, the analysis of event-related spectral perturbations and inter-trial phase coherency of these EEG signals recorded in the frontal and occipital areas showed that phase-locking of theta-alpha oscillations was suppressed in weightlessness, but only for the 3D tunnel image. Moreover, analysis of the phase of the coherency demonstrated the existence on Earth of a directional flux in the EEG signals from the frontal to the occipital areas mediating a top-down modulation during the presentation of the image of the 3D tunnel. In weightlessness, this fronto-occipital, top-down control was transformed into a diverging flux from the central areas toward the frontal and occipital areas. These results demonstrate that gravity-related sensory inputs modulate primary visual areas depending on the affordances of the visual scene. PMID:24400069

Cheron, Guy; Leroy, Axelle; Palmero-Soler, Ernesto; De Saedeleer, Caty; Bengoetxea, Ana; Cebolla, Ana-Maria; Vidal, Manuel; Dan, Bernard; Berthoz, Alain; McIntyre, Joseph

2014-01-01

126

Impaired empathic abilities and reduced white matter integrity in schizophrenia.  

PubMed

Empathic abilities are impaired in schizophrenia. Although the pathology of schizophrenia is thought to involve disrupted white matter integrity, the relationship between empathic disabilities and altered white matter in the disorder remains unclear. The present study tested associations between empathic disabilities and white matter integrity in order to investigate the neural basis of impaired empathy in schizophrenia. Sixty-nine patients with schizophrenia and 69 age-, gender-, handedness-, education- and IQ level-matched healthy controls underwent diffusion-weighted imaging. Empathic abilities were assessed using the Interpersonal Reactivity Index (IRI). Using tract-based spatial statistics (TBSS), the associations between empathic abilities and white matter fractional anisotropy (FA), a measure of white matter integrity, were examined in the patient group within brain areas that showed a significant FA reduction compared with the controls. The patients with schizophrenia reported lower perspective taking and higher personal distress according to the IRI. The patients showed a significant FA reduction in bilateral deep white matter in the frontal, temporal, parietal and occipital lobes, a large portion of the corpus callosum, and the corona radiata. In schizophrenia patients, fantasy subscales positively correlated with FA in the left inferior fronto-occipital fasciculi and anterior thalamic radiation, and personal distress subscales negatively correlated with FA in the splenium of the corpus callosum. These results suggest that disrupted white matter integrity in these regions constitutes a pathology underpinning specific components of empathic disabilities in schizophrenia, highlighting that different aspects of empathic impairments in the disorder would have, at least partially, distinct neuropathological bases. PMID:24099786

Fujino, Junya; Takahashi, Hidehiko; Miyata, Jun; Sugihara, Genichi; Kubota, Manabu; Sasamoto, Akihiko; Fujiwara, Hironobu; Aso, Toshihiko; Fukuyama, Hidenao; Murai, Toshiya

2014-01-01

127

Differential vulnerability of gray matter and white matter to intrauterine growth restriction in preterm infants at 12 months corrected age.  

PubMed

Intrauterine growth restriction (IUGR) is associated with a high risk of abnormal neurodevelopment. Underlying neuroanatomical substrates are partially documented. We hypothesized that at 12 months preterm infants would evidence specific white-matter microstructure alterations and gray-matter differences induced by severe IUGR. Twenty preterm infants with IUGR (26-34 weeks of gestation) were compared with 20 term-born infants and 20 appropriate for gestational age preterm infants of similar gestational age. Preterm groups showed no evidence of brain abnormalities. At 12 months, infants were scanned sleeping naturally. Gray-matter volumes were studied with voxel-based morphometry. White-matter microstructure was examined using tract-based spatial statistics. The relationship between diffusivity indices in white matter, gray matter volumes, and perinatal data was also investigated. Gray-matter decrements attributable to IUGR comprised amygdala, basal ganglia, thalamus and insula bilaterally, left occipital and parietal lobes, and right perirolandic area. Gray-matter volumes positively correlated with birth weight exclusively. Preterm infants had reduced FA in the corpus callosum, and increased FA in the anterior corona radiata. Additionally, IUGR infants had increased FA in the forceps minor, internal and external capsules, uncinate and fronto-occipital white matter tracts. Increased axial diffusivity was observed in several white matter tracts. Fractional anisotropy positively correlated with birth weight and gestational age at birth. These data suggest that IUGR differentially affects gray and white matter development preferentially affecting gray matter. At 12 months IUGR is associated with a specific set of structural gray-matter decrements. White matter follows an unusual developmental pattern, and is apparently affected by IUGR and prematurity combined. PMID:24361462

Padilla, Nelly; Junqué, Carme; Figueras, Francesc; Sanz-Cortes, Magdalena; Bargalló, Núria; Arranz, Angela; Donaire, Antonio; Figueras, Josep; Gratacos, Eduard

2014-01-30

128

Tracking the Roots of Reading Ability: White Matter Volume and Integrity Correlate with Phonological Awareness in Prereading and Early-Reading Kindergarten Children  

PubMed Central

Developmental dyslexia, an unexplained difficulty in learning to read, has been associated with alterations in white matter organization as measured by diffusion-weighted imaging. It is unknown, however, whether these differences in structural connectivity are related to the cause of dyslexia or if they are consequences of reading difficulty (e.g., less reading experience or compensatory brain organization). Here, in 40 kindergartners who had received little or no reading instruction, we examined the relation between behavioral predictors of dyslexia and white matter organization in left arcuate fasciculus, inferior longitudinal fasciculus, and the parietal portion of the superior longitudinal fasciculus using probabilistic tractography. Higher composite phonological awareness scores were significantly and positively correlated with the volume of the arcuate fasciculus, but not with other tracts. Two other behavioral predictors of dyslexia, rapid naming and letter knowledge, did not correlate with volumes or diffusion values in these tracts. The volume and fractional anisotropy of the left arcuate showed a particularly strong positive correlation with a phoneme blending test. Whole-brain regressions of behavioral scores with diffusion measures confirmed the unique relation between phonological awareness and the left arcuate. These findings indicate that the left arcuate fasciculus, which connects anterior and posterior language regions of the human brain and which has been previously associated with reading ability in older individuals, is already smaller and has less integrity in kindergartners who are at risk for dyslexia because of poor phonological awareness. These findings suggest a structural basis of behavioral risk for dyslexia that predates reading instruction.

Osher, David E.; Beach, Sara D.; Cyr, Abigail B.; Ozernov-Palchik, Ola; Yendiki, Anastasia; Fischl, Bruce; Gaab, Nadine; Gabrieli, John D.E.

2013-01-01

129

Microstructural Abnormalities in Language and Limbic Pathways in Orphanage-reared Children: A Diffusion Tensor Imaging Study  

PubMed Central

This study utilized diffusion tensor imaging fiber tractography to examine the miscrostructural integrity of limbic and paralimbic white matter tracts in thirty-six children (Mean age=124 months) with histories of early deprivation, raised from birth in orphanages and subsequently adopted into the United States, compared to 16 age-matched typically developing children. We found increased mean diffusivity bilaterally in the arcuate fasciculus, and increased mean diffusivity and reduced fractional anisotropy bilaterally in the uncinate fasciculus and cingulum in children with early deprivation. Microstructural integrity of the left arcuate fasciculus and right cingulum was related to language and behavioral functioning, respectively. White matter abnormalities were also associated with length of deprivation and time in the adoptive home. Our findings suggest that white matter pathways, connecting limbic and paralimbic brain regions is abnormal in children with histories of early deprivation; with some pathways appearing more susceptible to early deprivation than others.

Kumar, Ajay; Behen, Michael E.; Singsoonsud, Piti; Veenstra, Amy L.; Wolfe-Christensen, Cortney; Helder, Emily; Chugani, Harry T.

2013-01-01

130

Fronto-temporal Anatomical Connectivity and Working-Relational Memory Performance Predict Everyday Functioning in Schizophrenia  

PubMed Central

Hippocampal (relational memory) and prefrontal cortex (PFC; working memory) impairments have been found in patients with schizophrenia (SP), possibly due to a dysfunctional connection between structures. Neuroanatomical studies that describe reduced fractional anisotropy (FA) in the uncinate fasciculus support this idea. The dysconnection hypothesis in SP was investigated by examining fronto-temporal anatomical connectivity (uncinate fasciculus FA) and PFC-hippocampal memory and their relationship with each other and everyday functioning. PFC-hippocampal memory was examined with two working-relational memory tasks: transverse patterning and virtual Morris water task. SP exhibited a performance deficit on both tasks and had lower FA in bilateral uncinate fasciculus than healthy volunteers. Lower fronto-temporal anatomical connectivity was related to lower working-relational memory performance, and both predicted worse everyday functioning.

Hanlon, Faith M.; Houck, Jon M.; Klimaj, Stefan D.; Caprihan, Arvind; Mayer, Andrew R.; Weisend, Michael P.; Bustillo, Juan R.; Hamilton, Derek A.; Tesche, Claudia D.

2014-01-01

131

Frontotemporal anatomical connectivity and working-relational memory performance predict everyday functioning in schizophrenia.  

PubMed

Hippocampal (relational memory) and prefrontal cortex (PFC; working memory) impairments have been found in patients with schizophrenia (SP), possibly due to a dysfunctional connection between structures. Neuroanatomical studies that describe reduced fractional anisotropy (FA) in the uncinate fasciculus support this idea. The dysconnection hypothesis in SP was investigated by examining frontotemporal anatomical connectivity (uncinate fasciculus FA) and PFC-hippocampal memory and their relationship with each other and everyday functioning. PFC-hippocampal memory was examined with two working-relational memory tasks: transverse patterning and a virtual Morris water task. SP exhibited a performance deficit on both tasks and had lower FA in bilateral uncinate fasciculus than healthy volunteers. Lower frontotemporal anatomical connectivity was related to lower working-relational memory performance, and both predicted worse everyday functioning. PMID:22882287

Hanlon, Faith M; Houck, Jon M; Klimaj, Stefan D; Caprihan, Arvind; Mayer, Andrew R; Weisend, Michael P; Bustillo, Juan R; Hamilton, Derek A; Tesche, Claudia D

2012-10-01

132

Effects of NG-nitro-L-arginine and L-arginine on regional cerebral blood flow in the cat.  

PubMed

1. We studied the effects of NG-nitro-L-arginine (NOLA), a potent inhibitor of the L-arginine-nitric oxide pathway, and L-arginine, the precursor of nitric oxide, on regional cerebral blood flow, electrocortical activity and ex vivo cerebrovascular reactivity in the cat. Flow was measured via radiolabelled microspheres, and vascular responses were studied by measuring isometric tension of isolated middle cerebral arterial rings. 2. NOLA (30 mg kg-1 bolus followed by 1 mg kg-1 min-1 infusion) caused an approximately 40 mmHg elevation in the mean arterial blood pressure, a regionally heterogenous increase of the regional cerebrovascular resistance and a decrease in the regional cerebral blood flow 15 and 40 min after the start of its administration. In contrast L-arginine (30 mg kg-1 bolus followed by 10 mg kg-1 min-1 infusion) did not alter blood pressure, cerebrovascular resistance nor regional cerebral blood flow 15 min after the start of its administration. The NOLA-induced changes in tissue flow were the most pronounced in the cerebellum, pituitary and medulla oblongata, whereas there was no decrease in the flow of the cortex and white matter. 3. NOLA caused characteristic changes in total fronto-occipital EEG power and in power spectra which were unlikely to have been due to cerebral ischaemia. In addition, the ex vivo reactivity of the middle cerebral arteries showed signs of impaired endothelial nitric oxide synthesis: there were enhanced noradrenaline-induced contractions and N-ethoxycarbonyl-3-morpholino-sydnonimine (SIN-1)-induced relaxations and markedly attenuated acetylcholine- and ATP-induced relaxations after NOLA treatment. 4. The present data indicate that resting cerebral blood flow and cerebrovascular resistance are regulated by nitric oxide derived from L-arginine in a regionally heterogenous way and that exogenous L-arginine availability is not a limiting factor in this nitric oxide generation. Possibly, both the vascular endothelium and the neurons contribute to this basal nitric oxide release. PMID:1522509

Kovách, A G; Szabó, C; Benyó, Z; Csáki, C; Greenberg, J H; Reivich, M

1992-04-01

133

Traumatic injuries: imaging of head injuries.  

PubMed

Due to the forces of acceleration, linear translation, as well as rotational and angular acceleration, the brain undergoes deformation and distortion depending on the site of impact of traumatizing force direction, severity of the traumatizing force, and tissue resistance of the brain. Linear translation of accereration in a closed-head injury can run along the shorter diameter of the skull in latero-lateral direction causing mostly extra-axial lesions (subdural hematoma,epidural hematoma, subarachnoidal hemorrhage) or quite pronounced coup and countercoup contusions. Contusions are considerably less frequently present in medial or paramedial centroaxial blows (fronto-occipital or occipito-frontal). The centroaxial blows produce a different pattern of lesions mostly in the deep structures, causing in some cases a special category of the brain injury, the diffuse axonal injury (DAI). The brain stem can also be damaged, but it is damaged more often in patients who have suffered centroaxial traumatic force direction. Computed tomography and MRI are the most common techniques in patients who have suffered brain injury. Computed tomography is currently the first imaging technique to be used after head injury, in those settings where CT is available. Using CT, scalp, bone, extra-axial hematomas, and parenchymal injury can be demonstrated. Computed tomography is rapid and easily performed also in monitored patients. It is the most relevant imaging procedure for surgical lesions. Computed tomography is a suitable method to follow the dynamics of lesion development giving an insight into the corresponding pathological development of the brain injury. Magnetic resonance imaging is more sensitive for all posttraumatic lesions except skull fractures and subarachnoidal hemorrhage, but scanning time is longer, and the problem with the monitoring of patients outside the MRI field is present. If CT does not demonstrate pathology as can adequately be explained to account for clinical state, MRI is warranted. Follow-up is best done with MRI as it is more sensitive to parenchymal changes. In routine MR protocol gradient-recalled-echo sequences should be included at any other time after a traumatic event since they are very sensitive in detection of hemosiderin as well as former hematoma without hemosiderin. The MR signal intensity varies depending on sequences and time scanning after trauma. PMID:12042929

Besenski, N

2002-06-01

134

Paraphasias in Multilingual Conduction Aphasia: A Single Case Study  

ERIC Educational Resources Information Center

Conduction aphasia is a type of fluent aphasia, which is caused due to the damage to the supramarginal gyrus and arcuate fasciculus resulting in repetition disturbance. It has been speculated that linguistic system in bilingual aphasics can breakdown in different ways across languages. There is a lack of detailed linguistic studies in specific…

Hegde, Medha; Bhat, Sapna

2007-01-01

135

Prenatal cocaine produces signs of neurodegeneration in the lateral habenula  

Microsoft Academic Search

The lateral habenula is a nucleus in the dorsal thalamus that innervates midbrain dopaminergic and serotonergic nuclei via projections through its major efferent pathway, the fasciculus retroflexus (FR). It was previously demonstrated that cocaine administered continuously to adult rats over several days produces neurodegeneration in the lateral habenula and FR. Because exposure to cocaine during pregnancy reportedly can cause neurobehavioral

Carol A. Murphy; Leyla Ghazi; Azideh Kokabi; Gaylord Ellison

1999-01-01

136

White matter in aphasia: a historical review of the Dejerines' studies.  

PubMed

The Objective was to describe the contributions of Joseph Jules Dejerine and his wife Augusta Dejerine-Klumpke to our understanding of cerebral association fiber tracts and language processing. The Dejerines (and not Constantin von Monakow) were the first to describe the superior longitudinal fasciculus/arcuate fasciculus (SLF/AF) as an association fiber tract uniting Broca's area, Wernicke's area, and a visual image center in the angular gyrus of a left hemispheric language zone. They were also the first to attribute language-related functions to the fasciculi occipito-frontalis (FOF) and the inferior longitudinal fasciculus (ILF) after describing aphasia patients with degeneration of the SLF/AF, ILF, uncinate fasciculus (UF), and FOF. These fasciculi belong to a functional network known as the Dejerines' language zone, which exceeds the borders of the classically defined cortical language centers. The Dejerines provided the first descriptions of the anatomical pillars of present-day language models (such as the SLF/AF). Their anatomical descriptions of fasciculi in aphasia patients provided a foundation for our modern concept of the dorsal and ventral streams in language processing. PMID:23895939

Krestel, Heinz; Annoni, Jean-Marie; Jagella, Caroline

2013-12-01

137

Investigating the contribution of ventral-lexical and dorsal-sublexical pathways during reading in bilinguals  

PubMed Central

Several studies suggest the existence of ventral-lexical and dorsal-sublexical systems for reading. The relative contribution of these pathways can be manipulated by stimulus type and task demands. However, little is known about how bilinguals use these systems to read in their second language. In this study diffusion tensor imaging (DTI) was used to investigate the relationship between white matter (WM) integrity and reaction time in a group of 12 Chinese–English bilingual and 11 age-matched English monolingual adults. Considering a dual-route model of reading, the following four tracts were isolated in both the left and right hemispheres using a tractography measurement approach. Ventral tracts included the uncinate fasciculus (UF) and the inferior longitudinal fasciculus (ILF). The dorsal tracts of interest were the arcuate fasciculus (AF) and the superior longitudinal fasciculus (SLF). A significant correlation between the reaction time in a reading task and the mean diffusivity (MD) value was observed in the right UF in both bilingual and monolingual groups. Moreover, in the bilingual group we observed significantly more positive relationships between reaction time and MD in the right AF, and bilaterally in the SLF. We concluded that the relative contribution of the dorsal system for reading is greater in bilinguals than monolinguals. Further, these findings implicate a role of the right hemisphere in reading.

Bakhtiari, Reyhaneh; Boliek, Carol; Cummine, Jacqueline

2014-01-01

138

[Arteries of the human thalamus. I. Artery and polar thalamic territory of the posterior communicating artery].  

PubMed

The posterior communicating artery participates to the thalamic vascularization in 60 to 70 p. 100 of the brains. It does by one unic, well characterized artery, the polar artery. Its territory comprises the rostral pole of the lateral region up to the mamillo thalamic fasciculus. PMID:959701

Percheron, G

1976-05-01

139

Roll tilt reflexes after vestibulospinal tract lesions  

Microsoft Academic Search

The effects of lesions of the vestibulospinal tracts on vestibular reflexes evoked by roll tilt in forelimb and neck extensors were examined in decerebrate cats. Sectioning the medial longitudinal fasciculus, which contains the medial vestibulospinal tract, had no major effect on the phase of the reflex, although some gain was usually lost at high stimulus frequencies. Spinal lesions at C2–C3,

A. D. Miller; P. S. Roossin; R. H. Schor

1982-01-01

140

A Tractography Study in Dyslexia: Neuroanatomic Correlates of Orthographic, Phonological and Speech Processing  

ERIC Educational Resources Information Center

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…

Vandermosten, Maaike; Boets, Bart; Poelmans, Hanne; Sunaert, Stefan; Wouters, Jan; Ghesquiere, Pol

2012-01-01

141

Diffusion tensor analysis of temporal and extra-temporal lobe tracts in temporal lobe epilepsy  

PubMed Central

Objective To determine whether the major temporal lobe white matter tracts in patients with temporal lobe epilepsy manifest abnormal water diffusion properties. Methods Diffusion tensor MRI measurements were obtained from tractography for uncinate, arcuate, inferior longitudinal fasciculi and corticospinal tract in 13 children with left temporal lobe epilepsy and normal conventional MRI, and the data were compared to measurements in 12 age-matched normal volunteers. The relationship between tensor parameters and duration of epilepsy was also determined. Results All four tracts in the affected left hemisphere showed lower mean anisotropy, planar and linear indices, but higher spherical index in patients versus controls. Diffusion changes in the left uncinate and arcuate fasciculus correlated significantly with duration of epilepsy. Arcuate fasciculus showed a reversal of the normal left-right asymmetry. Various diffusion abnormalities were also seen in the four tracts studied in the right hemisphere. Conclusion Our findings indicate abnormal water diffusion in temporal lobe and extra-temporal lobe tracts with robust changes in the direction perpendicular to the axons. Diffusion abnormalities associated with duration of epilepsy suggest progressive changes in ipsilateral uncinate and arcuate fasciculus due to chronic seizure activity. Finally, our results in arcuate fasciculus are consistent with language reorganization to the contralateral right hemisphere.

Govindan, Rajkumar Munian; Makki, Malek I.; Sundaram, Senthil K; Juhasz, Csaba; Chugani, Harry T.

2008-01-01

142

Progressive White Matter Microstructure Damage in Male Chronic Heroin Dependent Individuals: A DTI and TBSS Study  

PubMed Central

Background To investigate the WM microstructure deficits in heroin dependent individuals (HDIs) with different length of heroin dependence, and to investigate whether these WM deficits can be related to the duration of heroin use and to decision-making deficits in HDIs. Methodology/Principal Findings Thirty-six HDIs [including eighteen sHDIs (duration of heroin dependent is less than 10 years) and eighteen lHDIs (duration of dependent is between 10?20 years)] and sixteen healthy controls participated in this study. Whole brain voxel-wise analysis of fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (Da) and radial diffusivity (Dr) were performed by tract-based spatial statistics (TBSS) to localize abnormal WM regions among groups. TBSS demonstrated that sHDIs had significantly lower FA than controls in right orbito-frontal WM, bilateral temporal WM and right parietal WM. The lHDIs had significantly lower FA throughout the brain compared with the controls and sHDIs. The lHDIs had significantly lower Da than controls in bilateral inferior frontaloccipital fasciculus, bilateral splenium of corpus callosum, left inferior longitudinal fasciculus, and had significantly higher Dr than controls in bilateral uncinatus fasciculus, bilateral inferior frontaloccipital fasciculus and bilateral cortical spinal fasciculus. Volume-of-interest (VOI) analyses detect the changes of diffusivity indices in the regions with FA abnormalities revealed by control vs sHDIs. In most VOIs, FA reductions were caused by the increase in Dr as well as the decrease in Da. Correlation analysis was used to assess the relationship between FA and behavioral measures in HDIs and controls available. Significantly positively correlations were found between the FA values in the right orbital-frontal WM, right parietal WM and IGT performance. Conclusions The extent and severity of WM integrity deficits in HDIs was associated with the length of heroin dependent. Furthermore, abnormal WM microstructure may correlate with decision-making impairments in HDIs.

Su, Huanhuan; Lv, Xiaofei; Zhang, Xuelin; Tian, Junzhang; Zhuo, Fuzhen

2013-01-01

143

Comparison of white matter integrity between autism spectrum disorder subjects and typically developing individuals: a meta-analysis of diffusion tensor imaging tractography studies  

PubMed Central

Background Aberrant brain connectivity, especially with long-distance underconnectivity, has been recognized as a candidate pathophysiology of autism spectrum disorders. However, a number of diffusion tensor imaging studies investigating people with autism spectrum disorders have yielded inconsistent results. Methods To test the long-distance underconnectivity hypothesis, we performed a systematic review and meta-analysis of diffusion tensor imaging studies in subjects with autism spectrum disorder. Diffusion tensor imaging studies comparing individuals with autism spectrum disorders with typically developing individuals were searched using MEDLINE, Web of Science and EMBASE from 1980 through 1 August 2012. Standardized mean differences were calculated as an effect size of the tracts. Results A comprehensive literature search identified 25 relevant diffusion tensor imaging studies comparing autism spectrum disorders and typical development with regions-of-interest methods. Among these, 14 studies examining regions of interest with suprathreshold sample sizes were included in the meta-analysis. A random-effects model demonstrated significant fractional anisotropy reductions in the corpus callosum (P = 0.023, n = 387 (autism spectrum disorders/typically developing individuals: 208/179)), left uncinate fasciculus (P = 0.011, n = 242 (117/125)), and left superior longitudinal fasciculus (P = 0.016, n = 182 (96/86)), and significant increases of mean diffusivity in the corpus callosum (P = 0.006, n = 254 (129/125)) and superior longitudinal fasciculus bilaterally (P = 0.031 and 0.011, left and right, respectively, n = 109 (51/58)), in subjects with autism spectrum disorders compared with typically developing individuals with no significant publication bias. Conclusion The current meta-analysis of diffusion tensor imaging studies in subjects with autism spectrum disorders emphasizes important roles of the superior longitudinal fasciculus, uncinate fasciculus, and corpus callosum in the pathophysiology of autism spectrum disorders and supports the long-distance underconnectivity hypothesis.

2013-01-01

144

Anatomy is strategy: skilled reading differences associated with structural connectivity differences in the reading network.  

PubMed

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

Graves, William W; Binder, Jeffrey R; Desai, Rutvik H; Humphries, Colin; Stengel, Benjamin C; Seidenberg, Mark S

2014-06-01

145

An 8-month exercise intervention alters frontotemporal white matter integrity in overweight children.  

PubMed

In childhood, excess adiposity and low fitness are linked to poor academic performance, lower cognitive function, and differences in brain structure. Identifying ways to mitigate obesity-related alterations is of current clinical importance. This study examined the effects of an 8-month exercise intervention on the uncinate fasciculus, a white matter fiber tract connecting frontal and temporal lobes. Participants consisted of 18 unfit, overweight 8- to 11-year-old children (94% Black) who were randomly assigned to either an aerobic exercise (n?=?10) or a sedentary control group (n?=?8). Before and after the intervention, all subjects participated in a diffusion tensor MRI scan. Tractography was conducted to isolate the uncinate fasciculus. The exercise group showed improved white matter integrity as compared to the control group. These findings are consistent with an emerging literature suggesting beneficial effects of exercise on white matter integrity. PMID:24797659

Schaeffer, David J; Krafft, Cynthia E; Schwarz, Nicolette F; Chi, Lingxi; Rodrigue, Amanda L; Pierce, Jordan E; Allison, Jerry D; Yanasak, Nathan E; Liu, Tianming; Davis, Catherine L; McDowell, Jennifer E

2014-08-01

146

Neural pathways for language in autism: the potential for music-based treatments  

PubMed Central

Language deficits represent the core diagnostic characteristics of autism, and some of these individuals never develop functional speech. The language deficits in autism may be due to structural and functional abnormalities in certain language regions (e.g., frontal and temporal), or due to altered connectivity between these brain regions. In particular, a number of anatomical pathways that connect auditory and motor brain regions (e.g., the arcuate fasciculus, the uncinate fasciculus and the extreme capsule) may be altered in individuals with autism. These pathways may also provide targets for experimental treatments to facilitate communication skills in autism. We propose that music-based interventions (e.g., auditory–motor mapping training) would take advantage of the musical strengths of these children, and are likely to engage, and possibly strengthen, the connections between frontal and temporal regions bilaterally. Such treatments have important clinical potential in facilitating expressive language in nonverbal children with autism.

Wan, Catherine Y; Schlaug, Gottfried

2010-01-01

147

Microsurgical and tractographic anatomical study of insular and transsylvian transinsular approach  

Microsoft Academic Search

This study is to define the operative anatomy of the insula with emphasis on the transsylvian transinsular approach. The anatomy\\u000a was studied in 15 brain specimens, among five were dissected by use of fiber dissection technique; diffusion tensor imaging\\u000a of 10 healthy volunteers was obtained with a 1.5-T MR system. The temporal stem consists mainly of the uncinate fasciculus,\\u000a inferior

Feng WangTao; Tao Sun; XinGang Li; HeChun Xia; ZongZheng Li

148

Modern Tennis Physiology  

Microsoft Academic Search

\\u000a Human skeletal and face muscles, accounting for more than 40% of the body weight in man, consist of bundles of elongated, cylindric cells called muscle fibers, 50 to 200 ? in diameter and often many centimeters long. Bundles of muscle fibers, each called fasciculus, are surrounded by a connective tissue covering, the endomysium (see, e.g., [Mou80, Mar98]).\\u000a \\u000a \\u000a A muscle consists

Tijana T. Ivancevic; Bojan Jovanovic; Sasa Jovanovic; Milka Djukic; Natalia Djukic; Alexandar Lukman

149

Microstructural White Matter Changes, Not Hippocampal Atrophy, Detect Early Amnestic Mild Cognitive Impairment  

PubMed Central

Background Alzheimer’s disease (AD) is generally considered to be characterized by pathology in gray matter of the brain, but convergent evidence suggests that white matter degradation also plays a vital role in its pathogenesis. The evolution of white matter deterioration and its relationship with gray matter atrophy remains elusive in amnestic mild cognitive impairment (aMCI), a prodromal stage of AD. Methods We studied 155 cognitively normal (CN) and 27 ‘late’ aMCI individuals with stable diagnosis over 2 years, and 39 ‘early’ aMCI individuals who had converted from CN to aMCI at 2-year follow up. Diffusion tensor imaging (DTI) tractography was used to reconstruct six white matter tracts three limbic tracts critical for episodic memory function - the fornix, the parahippocampal cingulum, and the uncinate fasciculus; two cortico-cortical association fiber tracts - superior longitudinal fasciculus and inferior longitudinal fasciculus; and one projection fiber tract - corticospinal tract. Microstructural integrity as measured by fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD) and axial diffusivity (AxD) was assessed for these tracts. Results Compared with CN, late aMCI had lower white matter integrity in the fornix, the parahippocampal cingulum, and the uncinate fasciculus, while early aMCI showed white matter damage in the fornix. In addition, fornical measures were correlated with hippocampal atrophy in late aMCI, whereas abnormality of the fornix in early aMCI occurred in the absence of hippocampal atrophy and did not correlate with hippocampal volumes. Conclusions Limbic white matter tracts are preferentially affected in the early stages of cognitive dysfunction. Microstructural degradation of the fornix preceding hippocampal atrophy may serve as a novel imaging marker for aMCI at an early stage.

Zhuang, Lin; Sachdev, Perminder S.; Trollor, Julian N.; Reppermund, Simone; Kochan, Nicole A.; Brodaty, Henry; Wen, Wei

2013-01-01

150

Neuronal pathways for the lingual reflex in the Japanese toad  

Microsoft Academic Search

1.Anuran tongue is controlled by visual stimuli for releasing the prey-catching behavior (‘snapping’) and also by the intra-oral stimuli for eliciting the lingual reflex. To elucidate the neural mechanisms controlling tongue movements, we analyzed the neuronal pathways from the glossopharyngeal (IX) afferents to the hypoglossal (XII) tongue-muscle motoneurons.2.Field potentials were recorded from the bulbar dorsal surface over the fasciculus solitarius

Toshiya Matsushima; Masahiko Satou; Kazuo Ueda

1988-01-01

151

The Projection of Cervical Primary Fibers to the DCN of the Squirrel, Sciurus niger: Fiber Sorting in the Dorsal Columns  

Microsoft Academic Search

The course and terminal distribution of cervical primary afferents in the dorsal column nuclei were studied in the fox squirrel, Sciurus niger. Unilateral rhizotomies were performed at cervical levels C3, C4, C5, C6 and C8. For all spinal levels studied except C8, degeneration in the medullary cuneate fasciculus was present within two distinct groups. They included a large oblique lateral

B. C. Albright; J. I. Johnson; E. M. Ostapoff

1983-01-01

152

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

PubMed

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. PMID:19446642

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

153

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

PubMed Central

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.

Chakravarty, Ambar

2012-01-01

154

Developmental dyscalculia: a dysconnection syndrome?  

PubMed

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. PMID:23783231

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

2013-06-20

155

White matter damage is associated with memory decline in chronic alcoholics: a quantitative diffusion tensor tractography study.  

PubMed

Neuroimaging studies have reported an association between white matter integrity and cognitive performance in normal aging and various neuropathological conditions. We compared alcoholics with controls and hypothesized that the degree of disconnection of white matter fibers would be negatively correlated with memory dysfunction scores. Diffusion tensor imaging (DTI) based tractography and PGI-memory scale (PGIMS) test was performed in 10 abstinent chronic alcoholic and 10 demographically equivalent control men. DTI measures [fractional anisotropy (FA), and mean diffusivity (MD)] from all of the major cerebral tracts were calculated and a comparison was done between patient group and controls. Spearman's rank correlation coefficient was computed between memory dysfunction score and DTI measures. Compared to controls alcoholic participants had significantly reduced FA in corpus callosum (CC), fornix (FX), and right hemispheric arcuate fasciculus (AF), anterior thalamic radiation (ATR) and inferior longitudinal fasciculus (ILF). A significant inverse correlation with memory dysfunction score was observed with right cingulum, right uncinate fasciculus, right ILF and left ILF. The inverse correlation of memory dysfunction score with FA of white matter tracts suggest that white matter deficit in these white matter fibers may contribute to underlying dysfunction in memory in alcoholism. PMID:23669136

Trivedi, Richa; Bagga, Deepika; Bhattacharya, Debajyoti; Kaur, Prabhjot; Kumar, Pawan; Khushu, Subash; Tripathi, Rajendra Prashad; Singh, Namita

2013-08-01

156

Eye movements evoked by electrical stimualtion of the brain in anesthetized fishes.  

PubMed

Several eye movements were evoked by electrical stimulation of the brain in anesthetized sunfish and goldfish. Conjugate lateral rolling movements, similar to eye movements observed when an unoperated fish is rotated about its long axis, were evoked from the acoustico-lateral area of the medulla and the eminentia granularis and an adjacent medial portion of the cerebellum. Bilateral and unilateral backward rotations, similar to the eye movements observed when unoperated fish are rotated forward about the interpupillary axis, were evoked from the medial longitudinal fasciculus and areas related to the oculomotor nerve. Bilateral forward rotations, comparable to the eye movements resulting when unoperated fish are rotated backward about the interpupillary axis, were elicited by stimulation near the trochlear nerve roots in the valvula of the cerebellum; unilateral responses resulted from stimulation near the exiting trochlear nerves. Convergence was elicited by stimulation in the midline near the oculomotor complex and the medial longitudinal fasciculus while unilateral vergence responses were triggered by stimulation in the medial longitudinal fasciculus and areas lateral to the oculomotor nucleus. Conjugate eye movements in the horizontal plane were frequently evoked but were not studied in detail. PMID:1174932

Demski, L S; Bauer, D H

1975-01-01

157

Changes to memory structures in children treated for posterior fossa tumors.  

PubMed

Children treated for medulloblastoma (MB) exhibit long-term impairments in declarative memory, but the pathophysiology underlying this is unclear. Previous studies report declines in global white matter volume, but have failed to link this to declines in memory performance. We examined the effects of treatment on measures of global brain structure (i.e., total white and gray matter volume) and specific memory structures (i.e., hippocampus and uncinate fasciculus). We used volumetric MRI and diffusion tensor imaging in pediatric survivors of MB and one survivor of astrocytoma treated with cranial-spinal radiation (n = 20), and healthy controls (n = 13). Compared to controls, the survivor group exhibited reduced white matter volume, damage to the uncinate fasciculus, and a smaller right hippocampus. Critically, reduced hippocampal volume was not related to differences in brain volume, suggesting that the hippocampus may be especially vulnerable to treatment effects. A subset of the survivors (n = 10) also underwent memory testing using the Children's Memory Scale (CMS). Performance on the general index of the CMS was significantly correlated with measures of hippocampal volume and uncinate fasciculus. The examination of treatment effects on specific brain regions provides a better understanding of long-term cognitive outcome in children with brain tumors, particularly medulloblastoma. PMID:24460980

Riggs, Lily; Bouffet, Eric; Laughlin, Suzanne; Laperriere, Normand; Liu, Fang; Skocic, Jovanka; Scantlebury, Nadia; Wang, Frank; Schoenhoff, Nicholas J; Strother, Douglas; Hukin, Juliette; Fryer, Christopher; McConnell, Dina; Mabbott, Donald J

2014-02-01

158

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

PubMed

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. PMID:24599641

Agosta, Federica; Galantucci, Sebastiano; Svetel, Marina; Luki?, Milica Je?menica; Copetti, Massimiliano; Davidovic, Kristina; Tomi?, Aleksandra; Spinelli, Edoardo G; Kosti?, Vladimir S; Filippi, Massimo

2014-05-01

159

White matter microstructure in late middle-age: Effects of apolipoprotein E4 and parental family history of Alzheimer's disease  

PubMed Central

Introduction Little is still known about the effects of risk factors for Alzheimer's disease (AD) on white matter microstructure in cognitively healthy adults. The purpose of this cross-sectional study was to assess the effect of two well-known risk factors for AD, parental family history and APOE4 genotype. Methods This study included 343 participants from the Wisconsin Registry for Alzheimer's Prevention, who underwent diffusion tensor imaging (DTI). A region of interest analysis was performed on fractional anisotropy maps, in addition to mean, radial, and axial diffusivity maps, aligned to a common template space using a diffeomorphic, tensor-based registration method. The analysis focused on brain regions known to be affected in AD including the corpus callosum, superior longitudinal fasciculus, fornix, cingulum, and uncinate fasciculus. Analyses assessed the impact of APOE4, parental family history of AD, age, and sex on white matter microstructure in late middle-aged participants (aged 47–76 years). Results Both APOE4 and parental family history were associated with microstructural white matter differences. Participants with parental family history of AD had higher FA in the genu of the corpus callosum and the superior longitudinal fasciculus. We observed an interaction between family history and APOE4, where participants who were family history positive but APOE4 negative had lower axial diffusivity in the uncinate fasciculus, and participants who were both family history positive and APOE4 positive had higher axial diffusivity in this region. We also observed an interaction between APOE4 and age, whereby older participants (=65 years of age) who were APOE4 carriers, had higher MD in the superior longitudinal fasciculus and in the portion of the cingulum bundle running adjacent to the cingulate cortex, compared to non-carriers. Older participants who were APOE4 carriers also showed higher radial diffusivity in the genu compared to non-carriers. Across all participants, age had an effect on FA, MD, and axial and radial diffusivities. Sex differences were observed in FA and radial diffusivity. Conclusion APOE4 genotype, parental family history of AD, age, and sex are all associated with microstructural white matter differences in late middle-aged adults. In participants at risk for AD, alterations in diffusion characteristics—both expected and unexpected—may represent cellular changes occurring at the earliest disease stages, but further work is needed. Higher mean, radial, and axial diffusivities were observed in participants who are more likely to be experiencing later stage preclinical pathology, including participants who were both older and carried APOE4, or who were positive for both APOE4 and parental family history of AD.

Adluru, Nagesh; Destiche, Daniel J.; Lu, Sharon Yuan-Fu; Doran, Samuel T.; Birdsill, Alex C.; Melah, Kelsey E.; Okonkwo, Ozioma C.; Alexander, Andrew L.; Dowling, N. Maritza; Johnson, Sterling C.; Sager, Mark A.; Bendlin, Barbara B.

2014-01-01

160

Interhemispheric temporal lobe connectivity predicts language impairment in adolescents born preterm  

PubMed Central

Although language difficulties are common in children born prematurely, robust neuroanatomical correlates of these impairments remain to be established. This study investigated whether the greater prevalence of language problems in preterm (versus term-born) children might reflect injury to major intra- or interhemispheric white matter pathways connecting frontal and temporal language regions. To investigate this, we performed a comprehensive assessment of language and academic abilities in a group of adolescents born prematurely, some of whom had evidence of brain injury at birth (n = 50, mean age: 16 years, mean gestational age: 27 weeks) and compared them to a term-born control group (n = 30). Detailed structural magnetic resonance imaging and diffusion-tractography analyses of intrahemispheric and interhemispheric white matter bundles were performed. Analysis of intrahemispheric pathways included the arcuate fasciculus (dorsal language pathway) and uncinate fasciculus/extreme capsule (ventral language pathway). Analysis of interhemispheric pathways (in particular, connections between the temporal lobes) included the two major commissural bundles: the corpus callosum and anterior commissure. We found language impairment in 38% of adolescents born preterm. Language impairment was not related to abnormalities of the arcuate fasciculus (or its subsegments), but was associated with bilateral volume reductions in the ventral language pathway. However, the most significant volume reduction was detected in the posterior corpus callosum (splenium), which contains interhemispheric connections between the occipital, parietal and temporal lobes. Diffusion tractography showed that of the three groups of interhemispheric fibres within the splenium, only those connecting the temporal lobes were reduced. Crucially, we found that language impairment was only detectable if the anterior commissure (a second temporal lobe commissural pathway) was also small. Regression analyses showed that a combination of anatomical measures of temporal interhemispheric connectivity (through the splenium of the corpus callosum and anterior commissure) explained 57% of the variance in language abilities. This supports recent theories emphasizing the importance of interhemispheric connections for language, particularly in the developing brain.

Northam, Gemma B.; Liegeois, Frederique; Tournier, Jacques-Donald; Croft, Louise J.; Johns, Paul N.; Chong, Wui K.; Wyatt, John S.

2012-01-01

161

The projections from the parafascicular thalamic nucleus to the subthalamic nucleus and the striatum arise from separate neuronal populations: a comparison with the corticostriatal and corticosubthalamic efferents in a retrograde fluorescent double-labelling study.  

PubMed

The parafascicular thalamic nucleus projects to the subthalamic nucleus and the striatum. Double-retrograde fluorescent tracing was used to determine whether these projections arise from the same neurons via axon collaterals. True Blue was injected into the subthalamic nucleus and Nuclear Yellow was injected into the striatum of each rat and the parafascicular thalamic nucleus was examined under the fluorescence light-microscope. Individual parafascicular neurons were not double-labelled with the tracers. The True Blue- and Nuclear Yellow-labelled neurons wee located in different parts of the parafascicular nucleus ipsilateral to the injections. In the rostral part of the parafascicular nucleus, True Blue-labelled neurons were located ventral to the fasciculus retroflexus, and in the caudal part of the nucleus. True Blue-labelled neurons were located close to the medial and lateral borders of fasciculus retroflexus. Nuclear Yellow-labelled neurons were found mainly to encircle the fasciculus retroflexus in the rostral part of the parafascicular nucleus and in the dorsolateral sector of the caudal part of the parafascicular nucleus. Double-labelled neurons were, however, found in the cortex. The proportion of neurons projecting to both the subthalamic nucleus and the striatum accounted for 38% of the total number of cortiscosubthalamic neurons in the prefrontal cortex, 15.5% in the cingulate cortex and 9% in the sensorimotor cortex. The present finding of an individualization between the parafascicular efferents to the subthalamic nucleus and the striatum emphasize the importance of this projection and provides further evidence of the associative functions attributable to the subthalamic nucleus. PMID:8052406

Féger, J; Bevan, M; Crossman, A R

1994-05-01

162

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

PubMed Central

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.

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

163

White Matter Hyperintensity Burden and Disability in Older Adults: Is Chronic Pain a Contributor?  

PubMed Central

Objective To primarily explore differences in global and regional white matter hyper-intensities (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. Design A cross-sectional, case-control study. Setting University of Pittsburgh. Participants 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. Methods All participants underwent structural brain magnetic resonance imaging, and all participants with CLBP underwent the 4-m walk test. Main Outcome Measurements 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. Results 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. Conclusions 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.

Buckalew, Neilly; Haut, Marc W.; Aizenstein, Howard; Rosano, Caterina; Dunfee Edelman, Kathryn; Perera, Subashan; Marrow, Lisa; Tadic, Stasa; Venkatraman, Vijay; Weiner, Debra

2014-01-01

164

Anatomical predictors of aphasia recovery: a tractography study of bilateral perisylvian language networks.  

PubMed

Stroke-induced aphasia is associated with adverse effects on quality of life and the ability to return to work. For patients and clinicians the possibility of relying on valid predictors of recovery is an important asset in the clinical management of stroke-related impairment. Age, level of education, type and severity of initial symptoms are established predictors of recovery. However, anatomical predictors are still poorly understood. In this prospective longitudinal study, we intended to assess anatomical predictors of recovery derived from diffusion tractography of the perisylvian language networks. Our study focused on the arcuate fasciculus, a language pathway composed of three segments connecting Wernicke's to Broca's region (i.e. long segment), Wernicke's to Geschwind's region (i.e. posterior segment) and Broca's to Geschwind's region (i.e. anterior segment). In our study we were particularly interested in understanding how lateralization of the arcuate fasciculus impacts on severity of symptoms and their recovery. Sixteen patients (10 males; mean age 60 ± 17 years, range 28-87 years) underwent post stroke language assessment with the Revised Western Aphasia Battery and neuroimaging scanning within a fortnight from symptoms onset. Language assessment was repeated at 6 months. Backward elimination analysis identified a subset of predictor variables (age, sex, lesion size) to be introduced to further regression analyses. A hierarchical regression was conducted with the longitudinal aphasia severity as the dependent variable. The first model included the subset of variables as previously defined. The second model additionally introduced the left and right arcuate fasciculus (separate analysis for each segment). Lesion size was identified as the only independent predictor of longitudinal aphasia severity in the left hemisphere [beta = -0.630, t(-3.129), P = 0.011]. For the right hemisphere, age [beta = -0.678, t(-3.087), P = 0.010] and volume of the long segment of the arcuate fasciculus [beta = 0.730, t(2.732), P = 0.020] were predictors of longitudinal aphasia severity. Adding the volume of the right long segment to the first-level model increased the overall predictive power of the model from 28% to 57% [F(1,11) = 7.46, P = 0.02]. These findings suggest that different predictors of recovery are at play in the left and right hemisphere. The right hemisphere language network seems to be important in aphasia recovery after left hemispheric stroke. PMID:24951631

Forkel, Stephanie J; Thiebaut de Schotten, Michel; Dell'Acqua, Flavio; Kalra, Lalit; Murphy, Declan G M; Williams, Steven C R; Catani, Marco

2014-07-01

165

Acute onset of upbeat nystagmus, exotropia, and internuclear ophthalmoplegia--a tell-tale of ponto-mesencephalic infarct.  

PubMed

Two patients were assessed for acute onset of diplopia. Clinical examination revealed upbeat nystagmus, exotropia, and internuclear ophthalmoplegia (INO). Both patients had vascular risk factors; acute ischemic stroke affecting ponto-mesencephalic junction was suspected. Magnetic resonance imaging confirmed strategic location of the acute infarct affecting the medial longitudinal fasciculus, adjacent occulomotor nuclei, and paramedian tract. We propose that constellation of acute onset of upbeat nystagmus, INO, and exotropia in patients with vascular risk factors might be unequivocal manifestation of the ponto-mesencephalic stroke. PMID:23830476

Shaikh, Aasef G; Ghasia, Fatema F; Rasouli, Golta; DeGeorgia, Michael; Sundararajan, Sophia

2013-09-15

166

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

PubMed

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. PMID:24033571

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

2013-09-01

167

Long-term effects of postearthquake distress on brain microstructural changes.  

PubMed

Stressful events can have both short- and long-term effects on the brain. Our recent investigation identified short-term white matter integrity (WMI) changes in 30 subjects soon after the Japanese earthquake. Our findings suggested that lower WMI in the right anterior cingulum (Cg) was a pre-existing vulnerability factor and increased WMI in the left anterior Cg and uncinate fasciculus (Uf) after the earthquake was an acquired sign of postearthquake distress. However, the long-term effects on WMI remained unclear. Here, we examined the 1-year WMI changes in 25 subjects to clarify long-term effects on the WMI. We found differential FAs in the right anterior Cg, bilateral Uf, left superior longitudinal fasciculus (SLF), and left thalamus, suggesting that synaptic enhancement and shrinkage were long-term effects. Additionally, the correlation between psychological measures related to postearthquake distress and the degree of WMI alternation in the right anterior Cg and the left Uf led us to speculate that temporal WMI changes in some subjects with emotional distress occurred soon after the disaster. We hypothesized that dynamic WMI changes predict a better prognosis, whereas persistently lower WMI is a marker of cognitive dysfunction, implying the development of anxiety disorders. PMID:24551840

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

2014-01-01

168

White matter microstructure, alcohol exposure, and familial risk for alcohol dependence  

PubMed Central

Offspring from families with alcohol dependence (AD) have been shown to exhibit brain morphological alterations that appear to be related to their familial/genetic risk for AD. Greater susceptibility for developing AD may be related to structural underpinnings of behavioral traits that predispose to AD. We examined white matter (WM) integrity in 81 individuals with either a high density of AD in their families (N=44) or without a family history for either alcohol or drug dependence (N=37). Magnetic resonance images were acquired on a Siemens 3 T scanner with fractional anistropy (FA) and the apparent diffusion coefficient (ADC), along with radial diffusivity (RD) and longitudinal (axial) diffusivity calculated for major white matter tracts in both hemispheres. Extensive personal histories of alcohol and drug use were available from longitudinal collection of data allowing for reliable estimates of alcohol and drug exposure. We found that the interaction of personal exposure to alcohol and familial risk for AD predicts reduction in WM integrity for the inferior longitudinal fasciculus (ILF) and the superior longitudinal fasciculus (SLF) in the left hemisphere and the forceps major tract. Only one tract showed a significant difference for exposure alone, the anterior thalamic radiation.

Hill, Shirley Y.; Terwilliger, Robert; McDermott, Michael

2013-01-01

169

DTI tractography and white matter fiber tract characteristics in euthymic bipolar I patients and healthy control subjects.  

PubMed

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

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

2013-06-01

170

White matter damage in frontotemporal lobar degeneration spectrum.  

PubMed

White matter (WM) tract damage was assessed in patients with the behavioral variant frontotemporal dementia (bvFTD) and the 3 primary progressive aphasia (PPA) variants and compared with the corresponding brain atrophy patterns. Thirteen bvFTD and 20 PPA patients were studied. Tract-based spatial statistics and voxel-based morphometry were used. Patients with bvFTD showed widespread diffusion tensor magnetic resonance imaging (DT MRI) abnormalities affecting most of the WM bilaterally. In PPA patients, WM damage was more focal and varied across the 3 syndromes: left frontotemporoparietal in nonfluent, left frontotemporal in semantic, and left frontoparietal in logopenic patients. In each syndrome, DT MRI changes extended beyond the topography of gray matter loss. Left uncinate damage was the best predictor of frontotemporal lobar degeneration diagnosis versus controls. DT MRI measures of the anterior corpus callosum and left superior longitudinal fasciculus differentiated bvFTD from nonfluent cases. The best predictors of semantic PPA compared with both bvFTD and nonfluent cases were diffusivity abnormalities of the left uncinate and inferior longitudinal fasciculus. This study provides insights into the similarities and differences of WM damage in bvFTD and PPA variants. DT MRI metrics hold promise to serve as early markers of WM integrity loss that only at a later stage may be detectable by volumetric measures. PMID:21988828

Agosta, F; Scola, E; Canu, E; Marcone, A; Magnani, G; Sarro, L; Copetti, M; Caso, F; Cerami, C; Comi, G; Cappa, S F; Falini, A; Filippi, M

2012-12-01

171

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

PubMed Central

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.

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

172

Neural systems predicting long-term outcome in dyslexia  

PubMed Central

Individuals with developmental dyslexia vary in their ability to improve reading skills, but the brain basis for improvement remains largely unknown. We performed a prospective, longitudinal study over 2.5 y in children with dyslexia (n = 25) or without dyslexia (n = 20) to discover whether initial behavioral or brain measures, including functional MRI (fMRI) and diffusion tensor imaging (DTI), can predict future long-term reading gains in dyslexia. No behavioral measure, including widely used and standardized reading and language tests, reliably predicted future reading gains in dyslexia. Greater right prefrontal activation during a reading task that demanded phonological awareness and right superior longitudinal fasciculus (including arcuate fasciculus) white-matter organization significantly predicted future reading gains in dyslexia. Multivariate pattern analysis (MVPA) of these two brain measures, using linear support vector machine (SVM) and cross-validation, predicted significantly above chance (72% accuracy) which particular child would or would not improve reading skills (behavioral measures were at chance). MVPA of whole-brain activation pattern during phonological processing predicted which children with dyslexia would improve reading skills 2.5 y later with >90% accuracy. These findings identify right prefrontal brain mechanisms that may be critical for reading improvement in dyslexia and that may differ from typical reading development. Brain measures that predict future behavioral outcomes (neuroprognosis) may be more accurate, in some cases, than available behavioral measures.

Hoeft, Fumiko; McCandliss, Bruce D.; Black, Jessica M.; Gantman, Alexander; Zakerani, Nahal; Hulme, Charles; Lyytinen, Heikki; Whitfield-Gabrieli, Susan; Glover, Gary H.; Reiss, Allan L.; Gabrieli, John D. E.

2010-01-01

173

Voxel-based assessment of gray and white matter volumes in Alzheimer's disease.  

PubMed

Using the study-specific templates and optimized voxel-based morphometry (VBM), this study investigated abnormalities in gray and white matter to provide depiction of the concurrent structural changes in 13 patients with Alzheimer's disease (AD) compared with 14 age- and sex-matched normal controls. Consistent with previous studies, patients with AD exhibited significant gray matter volume reductions mainly in the hippocampus, parahippocampal gyrus, insula, superior/middle temporal gyrus, thalamus, cingulate gyrus, and superior/inferior parietal lobule. In addition, white matter volume reductions were found predominately in the temporal lobe, corpus callosum, and inferior longitudinal fasciculus. Furthermore, a number of additional white matter regions such as precentral gyrus, cingulate fasciculus, superior and inferior frontal gyrus, and sub-gyral in parietal lobe were also affected. The pattern of gray and white matter volume reductions helps us understand the underlying pathologic mechanisms in AD and potentially can be used as an imaging marker for the studies of AD in the future. PMID:19879920

Guo, Xiaojuan; Wang, Zhiqun; Li, Kuncheng; Li, Ziyi; Qi, Zhigang; Jin, Zhen; Yao, Li; Chen, Kewei

2010-01-01

174

Voxel-based assessment of gray and white matter volumes in Alzheimer's disease  

PubMed Central

Using the study-specific templates and optimized voxel-based morphometry (VBM), this study investigated abnormalities in gray and white matter to provide depiction of the concurrent structural changes in 13 patients with Alzheimer’s disease (AD) compared with 14 age- and sex-matched normal controls. Consistent with previous studies, patients with AD exhibited significant gray matter volume reductions mainly in the hippocampus, parahippocampal gyrus, insula, superior/middle temporal gyrus, thalamus, cingulate gyrus, and superior/inferior parietal lobule. In addition, white matter volume reductions were found predominately in the temporal lobe, corpus callosum, and inferior longitudinal fasciculus. Furthermore, a number of additional white matter regions such as precentral gyrus, cingulate fasciculus, superior and inferior frontal gyrus, and sub-gyral in parietal lobe were also affected. The pattern of gray and white matter volume reductions helps us understand the underlying pathologic mechanisms in AD and potentially can be used as an imaging marker for the studies of AD in the future.

Guo, Xiaojuan; Wang, Zhiqun; Li, Kuncheng; Li, Ziyi; Qi, Zhigang; Jin, Zhen; Yao, Li; Chen, Kewei

2010-01-01

175

Frequency Mapping of Rat Spinal Cord at 7T  

NASA Astrophysics Data System (ADS)

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.

Chen, Evan; Rauscher, Alexander; Kozlowski, Piotr; Yung, Andrew

2012-10-01

176

Gender differences in the relationship between white matter organization and adolescent substance use disorders  

PubMed Central

Few studies have focused on the neurobiological correlates of adolescent-onset substance use disorders (SUDs), particularly with respect to white matter development and organization. This study investigated microstructural white matter characteristics associated with SUDs during the adolescent developmental period. Twenty-four case adolescents (ages 14-18) entering treatment for SUDs and 12 sex- and age-matched control adolescents with no psychopathology were compared. Diffusion tensor imaging data were collected and analyzed using the whole brain, tract-based spatial statistics (TBSS) method. In order to comprehensively characterize diffusivity characteristics, we first studied fractional anisotropy (FA), and within regions that differed in FA, other indicators of microstructure, including the axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (MD). A large cluster of significantly lower FA values was found in cases compared to controls in the superior longitudinal fasciculus (SLF). Within this cluster, AD and RD were also significantly different between the groups, while MD was not significantly different. For FA, a significant group by sex interaction was found; females with SUD exhibited lower FA than males with SUD, while control females exhibited higher FA than control males. These results indicated significantly lower white matter integrity in the superior longitudinal fasciculus region of association cortex, and assessed using multiple indicators of diffusion. These findings suggest that the disruption of normal white matter development due to substance exposure may be more severe in females than in males.

Thatcher, Dawn L.; Pajtek, Stefan; Chung, Tammy; Terwilliger, Robert A.; Clark, Duncan B.

2011-01-01

177

Structural Modifications of the Brain in Acclimatization to High-Altitude  

PubMed Central

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.

Zhang, Jiaxing; Yan, Xiaodan; Shi, Jinfu; Gong, Qiyong; Weng, Xuchu; Liu, Yijun

2010-01-01

178

Long-Term Effects of Postearthquake Distress on Brain Microstructural Changes  

PubMed Central

Stressful events can have both short- and long-term effects on the brain. Our recent investigation identified short-term white matter integrity (WMI) changes in 30 subjects soon after the Japanese earthquake. Our findings suggested that lower WMI in the right anterior cingulum (Cg) was a pre-existing vulnerability factor and increased WMI in the left anterior Cg and uncinate fasciculus (Uf) after the earthquake was an acquired sign of postearthquake distress. However, the long-term effects on WMI remained unclear. Here, we examined the 1-year WMI changes in 25 subjects to clarify long-term effects on the WMI. We found differential FAs in the right anterior Cg, bilateral Uf, left superior longitudinal fasciculus (SLF), and left thalamus, suggesting that synaptic enhancement and shrinkage were long-term effects. Additionally, the correlation between psychological measures related to postearthquake distress and the degree of WMI alternation in the right anterior Cg and the left Uf led us to speculate that temporal WMI changes in some subjects with emotional distress occurred soon after the disaster. We hypothesized that dynamic WMI changes predict a better prognosis, whereas persistently lower WMI is a marker of cognitive dysfunction, implying the development of anxiety disorders.

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

2014-01-01

179

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

PubMed Central

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.

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

2013-01-01

180

Age-related decline in white matter tract integrity and cognitive performance: A DTI tractography and structural equation modeling study  

PubMed Central

Age-related decline in microstructural integrity of certain white matter tracts may explain cognitive decline associated with normal aging. Whole brain tractography and a clustering segmentation in 48 healthy individuals across the adult lifespan were used to examine: interhemispheric (corpus callosum), intrahemispheric association (cingulum, uncinate, arcuate, inferior longitudinal, inferior occipitofrontal), and projection (corticospinal) fibers. Principal components analysis reduced cognitive tests into 6 meaningful factors: (1) memory and executive function; (2) visuomotor dexterity; (3) motor speed; (4) attention and working memory; (5) set-shifting/flexibility; and (6) visuospatial construction. Using theory-based structural equation modeling, relationships among age, white matter tract integrity, and cognitive performance were investigated. Parsimonious model fit demonstrated relationships where decline in white matter integrity may explain age-related decline in cognitive performance: inferior longitudinal fasciculus (ILF) with visuomotor dexterity; the inferior occipitofrontal fasciculus with visuospatial construction; and posterior fibers (i.e., splenium) of the corpus callosum with memory and executive function. Our findings suggest that decline in the microstructural integrity of white matter fibers can account for cognitive decline in normal aging.

Voineskos, Aristotle N.; Rajji, Tarek K.; Lobaugh, Nancy J.; Miranda, Dielle; Shenton, Martha E.; Kennedy, James L.; Pollock, Bruce G.; Mulsant, Benoit H.

2010-01-01

181

Origins of the descending spinal projections in petromyzontid and myxinoid agnathans.  

PubMed

The origins of the descending spinal pathways in sea lampreys (Petromyzon marinus), silver lampreys (Ichthyomyzon unicuspis), and Pacific hagfish (Eptatretus stouti) were identified by the retrograde transport of horseradish peroxidase (HRP) placed in the rostral spinal cord. In lampreys, the majority of HRP-labeled cells were located along the length of the brainstem reticular formation in the inferior, middle, and superior reticular nuclei of the medulla, mesencephalic tegmentum, and nucleus of the medial longitudinal fasciculus. Labeled reticular cells included the Mauthner and Müller cells. Horseradish-peroxidase-filled cells were also present in the descending trigeminal tract, intermediate and posterior octavomotor nuclei, and a diencephalic cell group, the nucleus of the posterior tubercle. As in lampreys, the reticular formation of the Pacific hagfish was the largest source of descending afferents to the spinal cord. Labeled cells were found in the dorsolateral and ventromedial reticular nuclei, the dorsal tegmentum at the juncture of the medulla and midbrain, and the nucleus of the medial longitudinal fasciculus. Additional medullary cells projecting to the cord were located in the perivagal nucleus, the central gray, and the anterior and posterior magnocellular octavolateralis nuclei. The existence of reticulospinal and possible vestibulo-, trigemino-, and solitary spinal projections in lampreys and hagfishes and the wide distribution of these pathways in jawed vertebrates suggest that they evolved in the common ancestor of gnathostomes and both groups of jawless fishes. However, descending spinal pathways from the cerebellum, red nucleus, and telencephalon appear to be gnathostome characters. PMID:2925902

Ronan, M

1989-03-01

182

Eel calcitonin binding site distribution and antinociceptive activity in rats  

SciTech Connect

The distribution of binding site for (/sup 125/I)-eel-calcitonin (ECT) to rat central nervous system, studied by an autoradiographic technique, showed concentrations of binding in the diencephalon, the brain stem and the spinal cord. Large accumulations of grains were seen in the hypothalamus, the amygdala, in the fasciculus medialis prosencephali, in the fasciculus longitudinalis medialis, in the ventrolateral part of the periventricular gray matter, in the lemniscus medialis and in the raphe nuclei. The density of grains in the reticular formation and in the nucleus tractus spinalis nervi trigemini was more moderate. In the spinal cord, grains were scattered throughout the dorsal horns. Binding of the ligand was displaced equally by cold ECT and by salmon CT(sCT), indicating that both peptides bind to the same receptors. Human CT was much weaker than sCT in displacing (/sup 125/I)-ECT binding. The administration of ECT into the brain ventricles of rats dose-dependently induced a significant and long-lasting enhancement of hot-plate latencies comparable with that obtained with sCT. The antinociceptive activity induced by ECT is compatible with the topographical distribution of binding sites for the peptide and is a further indication that fish CTs are active in the mammalian brain.

Guidobono, F.; Netti, C.; Sibilia, V.; Villa, I.; Zamboni, A.; Pecile, A.

1986-03-01

183

[The oculoauricular phenomenon: a new reflex, a new muscle -- m. retroauricularis (polygraphic EMG study) (author's transl)].  

PubMed

On forced lateral gaze the outer and upper part of both ears is turned backward (oculoauricular phenomenon). A new, as far as we know, skin muscle of the external ear is described and called "m. retroauricularis". The oculoauricular phenomenon is a reflex mechanism between the abducens (m. rectus externus) and facial (m. retroauricularis) nerves. The verification of the automatic and tonic coinnervation is made polygraphically (EMG, stimulodetection) and clinically (unilateral abolition in case of homolateral facial paralysis). The oculoauricular reflex is a physiological and bilateral phenomenon, often rudimentary in man. It serves in looking, hearing and miming. The bilateral mechanism of innervation in the brainstem via the medial longitudinal fasciculus corresponds to Bell's phenomenon as to the "anti Bell". PMID:57221

Heuser, M

1976-03-23

184

Fiber Pathways of Attention Subnetworks Revealed with Tract-Based Spatial Statistics (TBSS) and Probabilistic Tractography  

PubMed Central

It has been widely accepted that attention can be divided into three subnetworks - alerting, orienting and executive control (EC), and the subnetworks of attention are linked to distinct brain regions. However, the association between specific white matter fibers and the subnetworks of attention is not clear enough. Using diffusion tensor imaging (DTI), the white matter connectivity related to the performance of attention was assessed by attention network test (ANT) in 85 healthy adolescents. Tract-based spatial statistics (TBSS) and probabilistic diffusion tractography analysis demonstrated that cerebellothalamic tract was involved in alerting, while orienting depended upon the superior longitudinal fasciculus (SLF). In addition, EC was under the control of anterior corona radiata (ACR). Our findings suggest that different fiber pathways are involved in the three distinct subnetworks of attention. The current study will yield more precise information about the structural substrates of attention function and may aid the efforts to understand the neurophysiology of several attention disorders.

Ge, Haitao; Yin, Xuntao; Xu, Junhai; Tang, Yuchun; Han, Yan; Xu, Wenjian; Pang, Zengchang; Meng, Haiwei; Liu, Shuwei

2013-01-01

185

Cross-linguistic sound symbolism and crossmodal correspondence: Evidence from fMRI and DTI.  

PubMed

Non-arbitrary correspondences between spoken words and categories of meanings exist in natural language, with mounting evidence that listeners are sensitive to this sound symbolic information. Native English speakers were asked to choose the meaning of spoken foreign words from one of four corresponding antonym pairs selected from a previously developed multi-language stimulus set containing both sound symbolic and non-symbolic stimuli. In behavioral (n=9) and fMRI (n=15) experiments, participants showed reliable sensitivity to the sound symbolic properties of the stimulus set, selecting the consistent meaning for the sound symbolic words at above chances rates. There was increased activation for sound symbolic relative to non-symbolic words in left superior parietal cortex, and a cluster in left superior longitudinal fasciculus showed a positive correlation between fractional anisotropy (FA) and an individual's sensitivity to sound symbolism. These findings support the idea that crossmodal correspondences underlie sound symbolism in spoken language. PMID:24316238

Revill, Kate Pirog; Namy, Laura L; DeFife, Lauren Clepper; Nygaard, Lynne C

2014-01-01

186

ADAPTIVE CUTS FOR EXTRACTING SPECIFIC WHITE MATTER TRACTS  

PubMed Central

Extracting specific white matter tracts (e.g., uncinate fasciculus) from whole brain tractography has numerous applications in studying individual differences in white matter. Typically specific tracts are extracted manually, following replicable protocols which can be prohibitively expensive for large scale studies. A tract clustering framework is a suitable computational framework but from a neuroanatomical point of view, one of the key challenges is that it is very hard to design a universal similarity function for different types of white matter tracts (e.g., projection, association, commissural tracts). In this paper, we propose an adaptive cuts framework in which, using normalized cuts motivated objective function, we adaptively learn tract-tract similarity for each specific tract class using atlas based training data. Using the learnt similarity function we train an ensemble of binary support vector machines to extract specific tracts from unlabeled whole-brain tractography sets.

Adluru, Nagesh; Singh, Vikas; Alexander, Andrew L.

2013-01-01

187

Visual neglect as a disconnection syndrome? A confirmatory case report.  

PubMed

Visual neglect has classically been associated with right hemisphere injury in parietal, frontal, or temporal cortex, in the basal ganglia or in the thalamus. More recently, visual neglect has been associated with injury extended into fronto-parietal white matter tracts. However, in most published cases white and gray matter injuries were associated. We present the anatomo-clinical study of a patient presenting with severe acute left visual neglect due to ischemic infarct limited to the right cerebral hemisphere white matter. Magnetic resonance diffusion tensor imaging tractography was instrumental to accurately localize the injury to the right arcuate fasciculus that is a component of the large-scale networks controlling visuo-spatial attention. These results add to a growing appreciation that neglect may result from disruption of a distributed attentional network. PMID:22551209

Ciaraffa, Francesca; Castelli, Gianmarco; Parati, Eugenio Agostino; Bartolomeo, Paolo; Bizzi, Alberto

2013-08-01

188

An Anatomical Variation of the Lesser Occipital Nerve in the "Carefree part" of the Posterior Triangle  

PubMed Central

The occurrence of the lesser occipital nerve (LON) at an anomalous location in the “carefree part” within the posterior triangle has been seldom reported in the literature. We are reporting a rare case of location of the LON in the “carefree part” of the posterior triangle, in a 55-year-old formalin embalmed male cadaver. LON, after emerging from the posterior margin of the sternomastoid muscle (SM), ran obliquely towards the trapezius muscle. Here, it hooked around the unusual separated muscle fasciculus of the trapezius, 7.5 cm below the superior nuchal line. Further, LON gave contributions to spinal accessory nerve (SAN); one deep into the SM and another one in the posterior triangle. The knowledge on the unusual location and course of the LON and its contribution to the SAN is significantly important while an anaesthetic blockade is being performed for the management of a cervicogenic headache and a super selective radical neck dissection.

Sirasanagandla, Srinivasa Rao; Nayak, Satheesha B; Rao KG, Mohandas; Patil, Jyothsna

2014-01-01

189

Frontolimbic Neural Circuitry at 6 Months Predicts Individual Differences in Joint Attention at 9 Months  

PubMed Central

Elucidating the neural basis of joint attention in infancy promises to yield important insights into the development of language and social cognition, and directly informs developmental models of autism. We describe a new method for evaluating responding to joint attention performance in infancy that highlights the 9 to 10 month period as a time interval of maximal individual differences. We then demonstrate that fractional anisotropy in the right uncinate fasciculus, a white matter fiber bundle connecting the amygdala to the ventral-medial prefrontal cortex and anterior temporal pole, measured in 6 month-olds predicts individual differences in responding to joint attention at 9 months of age. The white matter microstructure of the right uncinate was not related to receptive language ability at 9 months. These findings suggest that the development of core nonverbal social communication skills in infancy is largely supported by preceding developments within right lateralized frontotemporal brain systems.

Elison, Jed T.; Wolff, Jason J.; Heimer, Debra C.; Paterson, Sarah J.; Gu, Hongbin; Hazlett, Heather C.; Styner, Martin; Gerig, Guido; Piven, Joseph

2012-01-01

190

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)

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.

Holstege, G.; Cowie, R. J.

1989-01-01

191

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

PubMed Central

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.

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

2013-01-01

192

Neuropsychological Disturbance in Schizophrenia: A Diffusion Tensor Imaging Study  

PubMed Central

Patients with schizophrenia and healthy control subjects underwent both neuropsychological evaluation and magnetic resonance diffusion tensor imaging, during which the cingulum bundle (CB) and the uncinate fasciculus (UF) were defined with fiber tractography and their integrity was quantified. On the basis of prior findings, it was hypothesized that neuropsychological disturbance in schizophrenia may be characterized, in part, by 2 dissociable functional neuroanatomical relationships: (a) executive functioning–CB integrity and (b) episodic memory–UF integrity. In support of the hypothesis, hierarchical regression results indicated that reduced white matter of the CB and the UF differentially and specifically predicted deficits in executive functioning and memory, respectively. Neuropsychological correlates of the CB also extended to lower generalized intelligence, as well as to reduced visual memory that may be related to failures of contextual monitoring of to-be-remembered scenes. Reduced white matter of the CB and the UF may each make distinct contributions to neuropsychological disturbance in schizophrenia.

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

2009-01-01

193

Atypical conduction aphasia and the right hemisphere: Cross-hemispheric plasticity of phonology in a developmentally dyslexic and dysgraphic patient with early left frontal damage.  

PubMed

We report the rare case of a patient, JNR, with history of mixed handedness, developmental dyslexia, dysgraphia, and attentional deficits associated with a Klippel-Trenaunay syndrome and a small subcortical frontal lesion involving the left arcuate fasciculus. In adulthood, he suffered a large right perisylvian stroke and developed atypical conduction aphasia with deficits in input and output phonological processing and poor auditory-verbal short-term memory. Lexical-semantic processing for single words was intact, but he was unable to access meaning in sentence comprehension and repetition. Reading and writing deficits worsened after the stroke and he presented a combination of developmental and acquired dysgraphia and dyslexia with mixed lexical and phonological processing deficits. This case suggest that a small lesion sustained prenatally or early in life could induce a selective rightward shift of phonology sparing the standard left hemisphere lateralisation of lexical-semantic functions. PMID:20818576

Berthier, Marcelo L; Dávila, Guadalupe; García-Casares, Natalia; Green, Cristina; Juárez, Rocío; Ruiz-Cruces, Rafael; Pablo Lara, J; Barbancho, M A

2011-01-01

194

Dissociated nystagmus as a common sign of ocular motor disorders in HIV-infected patients.  

PubMed

In order to determine if ocular motor disturbances due to brainstem and cerebellar dysfunction provide a frequent and early marker for HIV infection of the brain, neurological examination was performed in 133 HIV-infected persons who were consecutively admitted to our hospital. In 22 patients (17%) we found no other reason for cerebellar or pontomesencephalic signs than HIV encephalopathy. Ocular motor disorders accounted for the most frequent signs of cerebellar and pontomesencephalic dysfunction. Ocular motor disorders mainly consisted of dissociated nystagmus (n = 12), gaze-evoked nystagmus (n = 10) and impaired smooth pursuit (n = 6). Cerebellar ataxic gait and dysmetria were present in 3 patients. Since dissociated nystagmus was the primary ocular motor disorder, we assume that the medial longitudinal fasciculus may be a predilected circumscribed area for HIV infection of the brain. We suppose that cerebellar and pontomesencephalic disorders may be an early marker for HIV encephalopathy because they were the only neurological signs found in 12 patients. PMID:2792147

Pfister, H W; Einhäupl, K M; Büttner, U; Goebel, F; Matuschke, A; Shielke, E; Fröschl, M

1989-01-01

195

White-Matter damage in Clade C HIV-positive subjects: a diffusion tensor imaging study.  

PubMed

The relationship between cognitive impairment and white-matter integrity in human immunodeficiency virus (HIV) remains poorly understood, particularly in clade C. The authors utilized diffusion tensor imaging (DTI) and a comprehensive neuropsychological evaluation to investigate the relationship between cognitive impairment and white-matter integrity in HIV-positive subjects with clade C HIV. Forty-four HIV-infected individuals and 10 seronegative subjects were compared, using a whole-brain, voxel-based approach to define fractional anisotropy (FA) and mean diffusion (MD). Compared with healthy-control subjects, the HIV-infected group exhibited decreased FA in the corpus callosum, superior longitudinal fasciculus, and cingulum and sagittal stratum. This study provides evidence that white-matter integrity is compromised in individuals infected with clade C HIV. PMID:21948892

Hoare, Jacqueline; Fouche, Jean-Paul; Spottiswoode, Bruce; Sorsdahl, Katherine; Combrinck, Marc; Stein, Dan J; Paul, Robert H; Joska, John A

2011-01-01

196

White matter abnormalities correlating with memory and depression in heroin users under methadone maintenance treatment.  

PubMed

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

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

197

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

PubMed Central

Objective: 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. Method: 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. Results: 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. Conclusion: 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.

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

2013-01-01

198

The relation between structural and functional connectivity depends on age and on task goals  

PubMed Central

The last decade has seen an increase in neuroimaging studies examining structural (i.e., structural integrity of white matter tracts) and functional connectivity (e.g., correlations in neural activity throughout the brain). Although structural and functional connectivity changes have often been measured independently, examining the relation between these two measures is critical to understanding the specific function of neural networks and the ways they may differ across tasks and individuals. The current study addressed this question by examining the effect of age (treated as a continuous variable) and emotional valence on the relation between functional and structural connectivity. As prior studies have suggested that prefrontal regions may guide and regulate emotional memory search via functional connections with the amygdala, the current analysis focused on functional connectivity between the left amygdala and the left prefrontal cortex, and structural integrity of the uncinate fasciculus, a white matter tract connecting prefrontal and temporal regions. Participants took part in a scanned retrieval task in which they recalled positive, negative, and neutral images associated with neutral titles. Aging was associated with a significant increase in the relation between measures of structural integrity (specifically, fractional anisotropy, or FA) along the uncinate fasciculus and functional connectivity between the left ventral prefrontal cortex and amygdala during positive event retrieval, but not negative or neutral retrieval. Notably, during negative event retrieval, age was linked to stronger structure-function relations between the amygdala and the dorsal anterior cingulate cortex, such that increased structural integrity predicted stronger negative functional connectivity in older adults only. These findings suggest that young and older adults may utilize a structural pathway to engage different retrieval and regulatory strategies, even when structural integrity along that pathway does not differ.

Ford, Jaclyn H.; Kensinger, Elizabeth A.

2014-01-01

199

Relating brain anatomy and cognitive ability using a multivariate multimodal framework.  

PubMed

Linking structural neuroimaging data from multiple modalities to cognitive performance is an important challenge for cognitive neuroscience. In this study we examined the relationship between verbal fluency performance and neuroanatomy in 54 patients with frontotemporal degeneration (FTD) and 15 age-matched controls, all of whom had T1- and diffusion-weighted imaging. Our goal was to incorporate measures of both gray matter (voxel-based cortical thickness) and white matter (fractional anisotropy) into a single statistical model that relates to behavioral performance. We first used eigenanatomy to define data-driven regions of interest (DD-ROIs) for both gray matter and white matter. Eigenanatomy is a multivariate dimensionality reduction approach that identifies spatially smooth, unsigned principal components that explain the maximal amount of variance across subjects. We then used a statistical model selection procedure to see which of these DD-ROIs best modeled performance on verbal fluency tasks hypothesized to rely on distinct components of a large-scale neural network that support language: category fluency requires a semantic-guided search and is hypothesized to rely primarily on temporal cortices that support lexical-semantic representations; letter-guided fluency requires a strategic mental search and is hypothesized to require executive resources to support a more demanding search process, which depends on prefrontal cortex in addition to temporal network components that support lexical representations. We observed that both types of verbal fluency performance are best described by a network that includes a combination of gray matter and white matter. For category fluency, the identified regions included bilateral temporal cortex and a white matter region including left inferior longitudinal fasciculus and frontal-occipital fasciculus. For letter fluency, a left temporal lobe region was also selected, and also regions of frontal cortex. These results are consistent with our hypothesized neuroanatomical models of language processing and its breakdown in FTD. We conclude that clustering the data with eigenanatomy before performing linear regression is a promising tool for multimodal data analysis. PMID:24830834

Cook, Philip A; McMillan, Corey T; Avants, Brian B; Peelle, Jonathan E; Gee, James C; Grossman, Murray

2014-10-01

200

Brain Regions Underlying Repetition and Auditory-Verbal Short-term Memory Deficits in Aphasia: Evidence from Voxel-based Lesion Symptom Mapping  

PubMed Central

Background A deficit in the ability to repeat auditory-verbal information is common among individuals with aphasia. The neural basis of this deficit has traditionally been attributed to the disconnection of left posterior and anterior language regions via damage to a white matter pathway, the arcuate fasciculus. However, a number of lesion and imaging studies have called this notion into question. Aims The goal of this study was to identify the neural correlates of repetition and a related process, auditory-verbal short-term memory (AVSTM). Both repetition and AVSTM involve common elements such as auditory and phonological analysis and translation to speech output processes. Based on previous studies, we predicted that both repetition and AVSTM would be most dependent on posterior language regions in left temporo-parietal cortex. Methods & Procedures We tested 84 individuals with left hemisphere lesions due to stroke on an experimental battery of repetition and AVSTM tasks. Participants were tested on word, pseudoword, and number-word repetition, as well as digit and word span tasks. Brain correlates of these processes were identified using a statistical, lesion analysis approach known as voxel-based lesion symptom mapping (VLSM). VLSM allows for a voxel-by-voxel analysis of brain areas most critical to performance on a given task, including both grey and white matter regions. Outcomes & Results The VLSM analyses showed that left posterior temporo-parietal cortex, not the arcuate fasciculus, was most critical for repetition as well as for AVSTM. The location of maximal foci, defined as the voxels with the highest t values, varied somewhat among measures: Word and pseudoword repetition had maximal foci in the left posterior superior temporal gyrus, on the border with inferior parietal cortex, while word and digit span, as well as number-word repetition, were centered on the border between the middle temporal and superior temporal gyri and the underlying white matter. Conclusions Findings from the current study show that 1) repetition is most critically mediated by cortical regions in left posterior temporo-parietal cortex; 2) repetition and AVSTM are mediated by partially overlapping networks; and 3) repetition and AVSTM deficits can be observed in different types of aphasia, depending on the site and extent of the brain injury. These data have implications for the prognosis of chronic repetition and AVSTM deficits in individuals with aphasia when lesions involve critical regions in left temporo-parietal cortex.

Baldo, Juliana V.; Katseff, Shira; Dronkers, Nina F.

2014-01-01

201

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

PubMed Central

Apolipoprotein E (APOE) ? 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 ?4 “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 ?3/?4 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.

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

2014-01-01

202

Gray-white matter and cerebrospinal fluid volume differences in children with Specific Language Impairment and/or Reading Disability.  

PubMed

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. PMID:24418156

Girbau-Massana, Dolors; Garcia-Marti, Gracian; Marti-Bonmati, Luis; Schwartz, Richard G

2014-04-01

203

Altered white matter microstructure in adolescent substance users.  

PubMed

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. PMID:19699064

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

2009-09-30

204

Vasoactive intestinal peptide binding sites and fibers in the brain of the pigeon Columba livia: An autoradiographic and immunohistochemical study  

SciTech Connect

The distribution of vasoactive intestinal peptide (VIP) binding sites in the pigeon brain was examined by in vitro autoradiography on slide-mounted sections. A fully characterized monoiodinated form of VIP, which maintains the biological activity of the native peptide, was used throughout this study. The highest densities of binding sites were observed in the hyperstriatum dorsale, archistriatum, auditory field L of neostriatum, area corticoidea dorsolateralis and temporo-parieto-occipitalis, area parahippocampalis, tectum opticum, nucleus dorsomedialis anterior thalami, and in the periventricular area of the hypothalamus. Lower densities of specific binding occurred in the neostriatum, hyperstriatum ventrale and nucleus septi lateralis, dorsolateral area of the thalamus, and lateral and posteromedial hypothalamus. Very low to background levels of VIP binding were detected in the ectostriatum, paleostriatum primitivum, paleostriatum augmentatum, lobus parolfactorius, nucleus accumbens, most of the brainstem, and the cerebellum. The distribution of VIP-containing fibers and terminals was examined by indirect immunofluorescence using a polyclonal antibody against porcine VIP. Fibers and terminals were observed in the area corticoidea dorsolateralis, area parahippocampalis, hippocampus, hyperstriatum accessorium, hyperstriatum dorsale, archistriatum, tuberculum olfactorium, nuclei dorsolateralis and dorsomedialis of the thalamus, and throughout the hypothalamus and the median eminence. Long projecting fibers were visualized in the tractus septohippocampalis. In the brainstem VIP immunoreactive fibers and terminals were observed mainly in the substantia grisea centralis, fasciculus longitudinalis medialis, lemniscus lateralis, and in the area surrounding the nuclei of the 7th, 9th, and 10th cranial nerves.

Hof, P.R.; Dietl, M.M.; Charnay, Y.; Martin, J.L.; Bouras, C.; Palacios, J.M.; Magistretti, P.J. (Fishberg Research Center for Neurobiology, Mount Sinai School of Medicine, New York, NY (USA))

1991-03-15

205

Patterns of gene expression associated with pten deficiency in the developing inner ear.  

PubMed

In inner ear development, phosphatase and tensin homolog (PTEN) is necessary for neuronal maintenance, such as neuronal survival and accurate nerve innervations of hair cells. We previously reported that Pten conditional knockout (cKO) mice exhibited disorganized fasciculus with neuronal apoptosis in spiral ganglion neurons (SGNs). To better understand the genes and signaling networks related to auditory neuron maintenance, we compared the profiles of differentially expressed genes (DEGs) using microarray analysis of the inner ear in E14.5 Pten cKO and wild-type mice. We identified 46 statistically significant transcripts using significance analysis of microarrays, with the false-discovery rate set at 0%. Among the DEGs, expression levels of candidate genes and expression domains were validated by quantitative real-time RT-PCR and in situ hybridization, respectively. Ingenuity pathway analysis using DEGs identified significant signaling networks associated with apoptosis, cellular movement, and axon guidance (i.e., secreted phosphoprotein 1 (Spp1)-mediated cellular movement and regulator of G-protein signaling 4 (Rgs4)-mediated axon guidance). This result was consistent with the phenotypic defects of SGNs in Pten cKO mice (e.g., neuronal apoptosis, abnormal migration, and irregular nerve fiber patterns of SGNs). From this study, we suggest two key regulatory signaling networks mediated by Spp1 and Rgs4, which may play potential roles in neuronal differentiation of developing auditory neurons. PMID:24893171

Kim, Hyung Jin; Ryu, Jihee; Woo, Hae-Mi; Cho, Samuel Sunghwan; Sung, Min Kyung; Kim, Sang Cheol; Park, Mi-Hyun; Park, Taesung; Koo, Soo Kyung

2014-01-01

206

Evaluation of voxel-based group-level analysis of diffusion tensor images using simulated brain lesions.  

PubMed

We simulated brain lesions in mean diffusivity (MD) and fractional anisotropy (FA) images of healthy subjects to evaluate the performance of voxel-based analysis (VBA) with SPM2. We increased MD and decreased FA, simulating the most typical abnormalities in brain pathologies, in the superior longitudinal fasciculus (SLF), corticospinal tract (CST), and corpus callosum (CC). Lesion sizes varied from 10 to 400 voxels (10.5 mm³ each) and intensity changes from 10 to 100%. The VBA contained eddy current correction, spatial normalization, smoothing, and statistical analysis. The preprocessing steps changed the intensities of MD and FA lesions from the original values, and many lesions remained undetected. The detection thresholds varied between the three brain areas, and between MD and FA images. Although spatial smoothing often improved the sensitivity, it also markedly enlarged the estimated lesion sizes. Since conventional VBA preprocessing significantly affected the outcome and sensitivity of the method itself, the impact of analysis steps should be verified and considered before interpreting the findings. Our results provide insight into the sizes and intensity changes of lesions that can be detected with VBA applied to diffusion tensor imaging (DTI) data. PMID:21978550

Hiltunen, Jaana; Seppä, Mika; Hari, Riitta

2011-12-01

207

[Neural representation of human body schema and corporeal self-consciousness].  

PubMed

The human brain processes every sensation evoked by altered posture and builds up a constantly changing postural model of the body. This is called a body schema, and somatic signals originating from skeletal muscles and joints, i.e. proprioceptive signals, largely contribute its formation. Recent neuroimaging techniques have revealed neuronal substrates for human body schema. A dynamic limb position model seems to be computed in the central motor network (represented by the primary motor cortex). Here, proprioceptive (kinesthetic) signals from muscle spindles are transformed into motor commands, which may underlie somatic perception of limb movement and facilitate its efficient motor control. Somatic signals originating from different body parts are integrated in the course of hierarchical somatosensory processing, and activity in higher-order somatosensory parietal cortices is capable of representing a postural model of the entire body. The left fronto-parietal network associates internal motor representation with external object representation, allowing the embodiment of external objects. In contrast, the right fronto-parietal regions connected by the most inferior branch of superior longitudinal fasciculus fibers seem to have the functions of monitoring bodily states and updating body schema. We hypothesize that activity in these right-sided fronto-parietal regions is deeply involved in corporeal self-consciousness. PMID:24748084

Naito, Eiichi; Morita, Tomoyo

2014-04-01

208

Disrupted white matter in language and motor tracts in developmental stuttering.  

PubMed

White matter tracts connecting areas involved in speech and motor control were examined using diffusion-tensor imaging in a sample of people who stutter (n=29) who were heterogeneous with respect to age, sex, handedness and stuttering severity. The goals were to replicate previous findings in developmental stuttering and to extend our knowledge by evaluating the relationship between white matter differences in people who stutter and factors such as age, sex, handedness and stuttering severity. We replicated previous findings that showed reduced integrity in white matter underlying ventral premotor cortex, cerebral peduncles and posterior corpus callosum in people who stutter relative to controls. Tractography analysis additionally revealed significantly reduced white matter integrity in the arcuate fasciculus bilaterally and the left corticospinal tract and significantly reduced connectivity within the left corticobulbar tract in people who stutter. Region-of-interest analyses revealed reduced white matter integrity in people who stutter in the three pairs of cerebellar peduncles that carry the afferent and efferent fibers of the cerebellum. Within the group of people who stutter, the higher the stuttering severity index, the lower the white matter integrity in the left angular gyrus, but the greater the white matter connectivity in the left corticobulbar tract. Also, in people who stutter, handedness and age predicted the integrity of the corticospinal tract and peduncles, respectively. Further studies are needed to determine which of these white matter differences relate to the neural basis of stuttering and which reflect experience-dependent plasticity. PMID:23819900

Connally, Emily L; Ward, David; Howell, Peter; Watkins, Kate E

2014-04-01

209

Differences in integrity of white matter and changes with training in spelling impaired children: a diffusion tensor imaging study  

PubMed Central

While the functional correlates of spelling impairment have been rarely investigated, to our knowledge no study exists regarding the structural characteristics of spelling impairment and potential changes with interventions. Using diffusion tensor imaging at 3.0 T, we here therefore sought to investigate (a) differences between children with poor spelling abilities (training group and waiting group) and controls, and (b) the effects of a morpheme- based spelling intervention in children with poor spelling abilities on DTI parameters. A baseline comparison of white matter indices revealed significant differences between controls and spelling-impaired children, mainly located in the right hemisphere (superior corona radiata (SCR), posterior limb of internal capsule, superior longitudinal fasciculus). After 5 weeks of training, spelling ability improved in the training group, along with increases in fractional anisotropy and decreases of radial diffusivity in the right hemisphere compared to controls. In addition, significantly higher decreases of mean diffusivity in the right SCR for the spelling-impaired training group compared to the waiting group were observed. Our results suggest that spelling impairment is associated with differences in white-matter integrity in the right hemisphere. We also provide first indications that white matter changes occur during successful training, but this needs to be more specifically addressed in future research.

Gebauer, D.; Fink, A.; Filippini, N.; Johansen-Berg, H.; Reishofer, G.; Koschutnig, K.; Kargl, R.; Purgstaller, C.; Fazekas, F.; Enzinger, C.

2013-01-01

210

Tracking cerebral white matter changes across the lifespan: insights from diffusion tensor imaging studies.  

PubMed

Delineating the normal development of brain white matter (WM) over the human lifespan is crucial to improved understanding of underlying WM pathology in neuropsychiatric and neurological conditions. We review the extant literature concerning diffusion tensor imaging studies of brain WM development in healthy individuals available until October 2012, summarise trends of normal development of human brain WM and suggest possible future research directions. Temporally, brain WM maturation follows a curvilinear pattern with an increase in fractional anisotropy (FA) from newborn to adolescence, decelerating in adulthood till a plateau around mid-adulthood, and a more rapid decrease of FA from old age onwards. Spatially, brain WM tracts develop from central to peripheral regions, with evidence of anterior-to-posterior maturation in commissural and projection fibres. The corpus callosum and fornix develop first and decline earlier, whilst fronto-temporal WM tracts like cingulum and uncinate fasciculus have protracted maturation and decline later. Prefrontal WM is most vulnerable with greater age-related FA reduction compared with posterior WM. Future large scale studies adopting longitudinal design will better clarify human brain WM changes over time. PMID:23328950

Yap, Qian Jun; Teh, Irvin; Fusar-Poli, Paolo; Sum, Min Yi; Kuswanto, Carissa; Sim, Kang

2013-09-01

211

Associations Between White Matter Microstructure and Infants' Working Memory  

PubMed Central

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.

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

212

A Brain Centred View of Psychiatric Comorbidity in Tinnitus: From Otology to Hodology  

PubMed Central

Introduction. Comorbid psychiatric disorders are frequent among patients affected by tinnitus. There are mutual clinical influences between tinnitus and psychiatric disorders, as well as neurobiological relations based on partially overlapping hodological and neuroplastic phenomena. The aim of the present paper is to review the evidence of alterations in brain networks underlying tinnitus physiopathology and to discuss them in light of the current knowledge of the neurobiology of psychiatric disorders. Methods. Relevant literature was identified through a search on Medline and PubMed; search terms included tinnitus, brain, plasticity, cortex, network, and pathways. Results. Tinnitus phenomenon results from systemic-neurootological triggers followed by neuronal remapping within several auditory and nonauditory pathways. Plastic reorganization and white matter alterations within limbic system, arcuate fasciculus, insula, salience network, dorsolateral prefrontal cortex, auditory pathways, ffrontocortical, and thalamocortical networks are discussed. Discussion. Several overlapping brain network alterations do exist between tinnitus and psychiatric disorders. Tinnitus, initially related to a clinicoanatomical approach based on a cortical localizationism, could be better explained by an holistic or associationist approach considering psychic functions and tinnitus as emergent properties of partially overlapping large-scale neural networks.

Minichino, Amedeo; Panico, Roberta; Testugini, Valeria; Altissimi, Giancarlo; Cianfrone, Giancarlo

2014-01-01

213

Genetic & Neuronanatomic Associations in Sporadic Frontotemporal Lobar Degeneration  

PubMed Central

Genome-wide association studies have identified SNPs that are sensitive for tau or TDP-43 pathology in frontotemporal lobar degeneration (FTLD). Neuroimaging analyses have revealed distinct distributions of disease in FTLD patients with genetic mutations. However, genetic influences on neuroanatomical structure in sporadic FTLD have not been assessed. In this report we use novel multivariate tools, eigenanatomy and sparse canonical correlation analysis (SCCAN), to identify associations between SNPs and neuroanatomical structure in sporadic FTLD. MRI analyses revealed that rs8070723 (MAPT) was associated with grey matter variance in the temporal cortex. DTI analyses revealed that rs1768208 (MOBP), rs646776 (near SORT1) and rs5848 (PGRN) were associated with white matter variance in the midbrain and superior longitudinal fasciculus. In an independent autopsy series we observed that rs8070723 and rs1768208 conferred significant risk of tau pathology relative to TDP-43, and rs646776 conferred increased risk of TDP-43 pathology relative to tau. Identified brain regions and SNPs may help provide an in vivo screen for underlying pathology in FTLD and contribute to our understanding of sporadic FTLD.

McMillan, Corey T.; Toledo, Jon B.; Avants, Brian B.; Cook, Philip A.; Wood, Elisabeth M.; Suh, Eunran; Irwin, David J.; Powers, John; Olm, Christopher; Elman, Lauren; McCluskey, Leo; Schellenberg, Gerard D.; Lee, Virginia M.-Y.; Trojanowski, John Q.; Van Deerlin, Vivianna M.; Grossman, Murray

2014-01-01

214

A crucial role for the cortico-striato-cortical loop in the pathogenesis of stroke-related neurogenic stuttering.  

PubMed

Neurogenic stuttering is an acquired speech disorder characterized by the occurrence of stuttering-like dysfluencies following brain damage. Because the onset of stuttering in these patients is associated with brain lesions, this condition provides a unique opportunity to study the neural processes underlying speech dysfluencies. Lesion localizations of 20 stroke subjects with neurogenic stuttering and 17 control subjects were compared using voxel-based lesion symptom mapping. The results showed nine left-hemisphere areas associated with the presence of neurogenic stuttering. These areas were largely overlapping with the cortico-basal ganglia-cortical network comprising the inferior frontal cortex, superior temporal cortex, intraparietal cortex, basal ganglia, and their white matter interconnections through the superior longitudinal fasciculus and internal capsule. These results indicated that stroke-induced neurogenic stuttering is not associated with neural dysfunction in one specific brain area but can occur following one or more lesion throughout the cortico-basal ganglia-cortical network. It is suggested that the onset of neurogenic stuttering in stroke subjects results from a disintegration of neural functions necessary for fluent speech. PMID:22451328

Theys, Catherine; De Nil, Luc; Thijs, Vincent; van Wieringen, Astrid; Sunaert, Stefan

2013-09-01

215

Reduced Prefrontal Connectivity in Psychopathy  

PubMed Central

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.

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

2012-01-01

216

Reduced prefrontal connectivity in psychopathy.  

PubMed

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

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

2011-11-30

217

Localisation of motoneurons supplying the extra-ocular muscles of the rat using horseradish peroxidase and fluorescent double labelling.  

PubMed Central

This paper describes a qualitative and quantitative investigation into the location of the motoneurons innervating the extra-ocular muscles of the rat. Injections of horseradish peroxidase, bisbenzimide, propidium iodide and DAPI-primuline were made either in one or simultaneously in two muscles. Unlike those of the cat, rabbit and monkey, the motoneurons which make up the oculomotor nucleus of the rat are not arranged in spatially separate subgroups belonging each to its corresponding extra-ocular muscle, but instead allow a high degree of superposition among the motor pools which they compose. The motoneurons innervating the lateral rectus and inferior oblique muscles are all homolateral; those of the medial and inferior rectus muscles are mainly homolateral with a few contralateral exceptions; and those of the superior rectus, levator palpebrae and superior oblique muscles are mainly contralateral with a small minority of homolateral exceptions. As well as from the main motor pools with which they are associated, the medial rectus, inferior rectus, superior rectus, levator palpebrae, superior oblique and lateral rectus muscles all receive innervation from motoneurons lying among the fibres of the fasciculus longitudinalis medialis. All these observations are supported by quantitative data. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4

Labandeira Garcia, J L; Gomez Segade, L A; Suarez Nunez, J M

1983-01-01

218

Initial evaluation of vertigo.  

PubMed

Dizziness is one of the most common reasons patients visit their physicians. Balance control depends on receiving afferent sensory information from several sensory systems: vestibular, optical and proprioceptive. Bioelectric signals, generated by body movements in the semicircular canals and in the otolithic apparatus, are transported via the vestibular nerve to the vestibular nucleus. All four vestibular nuclei, located bilaterally in medial longitudinal fasciculus, are linked with central nervous system structures. These central nervous system structures are involved in maintaining visual stability, spatial orientation and balance control. Nystagmus is a result of afferent signals balance disorders. Nystagmus due to peripheral lesions is conjugate nystagmus, because there is a bilateral central connection. Lesions above the vestibular nuclei induce deficits in synchronization and conjugation of eye movements, thus the nystagmus is dissociated. This paper shows that in peripheral vestibular disorders spontaneous nystagmus is rhythmic, associated, horizontal-rotatory or horizontal, with subjective sensation of dizziness which decreases with time and harmonic signs whose direction coincides with the slow phase of nystagmus and it is associated with mild disorders during pendular stimulation with statistically significant vestibular hypofunction. Spontaneous nystagmus in central vestibular lesions is severe, dissociated, horizontal, rotatory or vertical, without changes related to optical suppression; if vestibular symptoms are present, they are non-harmonic. In central disorders, findings after thermal stimulation are either normal or pathological, with dysrhythmias and inhibition in pendular stimulation. This paper deals with differential diagnosis of vertigo based on anamnesis and clinical examination, as well as objective diagnostic tests. PMID:17633903

Lemaji?-Komazec, Slobodanka; Komazec, Zoran

2006-01-01

219

Functional responses and structural connections of cortical areas for processing faces and voices in the superior temporal sulcus.  

PubMed

It was the aim of this study to delineate the areas along the right superior temporal sulcus (STS) for processing of faces, voices, and face-voice integration using established functional magnetic resonance imaging (fMRI) localizers and to assess their structural connectivity profile with diffusion tensor imaging (DTI). We combined this approach with an fMRI adaptation design during which the participants judged emotions in facial expressions and prosody and demonstrated response habituation in the orbitofrontal cortex (OFC) which occurred irrespective of the sensory modality. These functional data were in line with DTI findings showing separable fiber projections of the three different STS modules converging in the OFC which run through the external capsule for the voice area, through the dorsal superior longitudinal fasciculus (SLF) for the face area and through the ventral SLF for the audiovisual integration area. The OFC was structurally connected with the supplementary motor area (SMA) and activation in these two areas was correlated with faster stimulus evaluation during repetition priming. Based on these structural and functional properties, we propose that the OFC is part of the extended system for perception of emotional information in faces and voices and constitutes a neural interface linking sensory areas with brain regions implicated in generation of behavioral responses. PMID:23507387

Ethofer, Thomas; Bretscher, Johannes; Wiethoff, Sarah; Bisch, Jeanne; Schlipf, Sarah; Wildgruber, Dirk; Kreifelts, Benjamin

2013-08-01

220

Linear high intensity area along the medial margin of the internal segment of the globus pallidus in Machado-Joseph disease patients.  

PubMed

Our new finding on magnetic resonance imaging (MRI) of Machado-Joseph disease (MJD) patients indicates degeneration of the lenticular fasciculus (LF), a major outflow of the internal segment of the globus pallidus (GPi). We examined the clinical, radiological, and autopsy findings of one MJD patient and then retrospectively reviewed the MRI images of another 15 patients looking for a similar abnormal signal intensity. The significance of the clinicoradiological correlation of the MRI finding was confirmed by examining the MRI images of 130 control subjects. In the autopsy case, abnormal linear high intensity areas were observed along the bilateral medial margins of the internal segments of the GPi on T2 weighted, FLAIR, and proton density images, but not on T1 weighted images. Pathologically, this abnormal signal intensity was consistent with degeneration of the LF. The same finding was also observed in the other 15 patients. In two patients the finding was only unilaterally observed. No control subject showed this MRI finding. In MJD patients, abnormal linear high intensity areas indicating LF degeneration are usually observed along the medial margin of the GPi on T2 weighted, FLAIR, and proton density sequences. To our knowledge, this MRI finding has not previously been described. PMID:15774449

Yamada, S; Nishimiya, J; Nakajima, T; Taketazu, F

2005-04-01

221

Bilateral Fronto-Parietal Integrity in Young Chronic Cigarette Smokers: A Diffusion Tensor Imaging Study  

PubMed Central

Background Cigarette smoking continues to be the leading cause of preventable morbidity and mortality in China and other countries. Previous studies have demonstrated gray matter loss in chronic smokers. However, only a few studies assessed the changes of white matter integrity in this group. Based on those previous reports of alterations in white matter integrity in smokers, the aim of this study was to examine the alteration of white matter integrity in a large, well-matched sample of chronic smokers and non-smokers. Methodology/Principal Findings Using in vivo diffusion tensor imaging (DTI) to measure the differences of whole-brain white matter integrity between 44 chronic smoking subjects (mean age, 28.0±5.6 years) and 44 healthy age- and sex-matched comparison non-smoking volunteers (mean age, 26.3±5.8 years). DTI was performed on a 3-Tesla Siemens scanner (Allegra; Siemens Medical System). The data revealed that smokers had higher fractional anisotropy (FA) than healthy non-smokers in almost symmetrically bilateral fronto-parietal tracts consisting of a major white matter pathway, the superior longitudinal fasciculus (SLF). Conclusion/Significance We found the almost symmetrically bilateral fronto-parietal whiter matter changes in a relatively large sample of chronic smokers. These findings support the hypothesis that chronic cigarette smoking involves alterations of bilateral fronto-parietal connectivity.

Liao, Yanhui; Tang, Jinsong; Deng, Qijian; Deng, Yongwen; Luo, Tao; Wang, Xuyi; Chen, Hongxian; Liu, Tieqiao; Chen, Xiaogang; Brody, Arthur L.; Hao, Wei

2011-01-01

222

Music Making as a Tool for Promoting Brain Plasticity across the Life Span  

PubMed Central

Playing a musical instrument is an intense, multisensory, and motor experience that usually commences at an early age and requires the acquisition and maintenance of a range of skills over the course of a musician's lifetime. Thus, musicians offer an excellent human model for studying the brain effects of acquiring specialized sensorimotor skills. For example, musicians learn and repeatedly practice the association of motor actions with specific sound and visual patterns (musical notation) while receiving continuous multisensory feedback. This association learning can strengthen connections between auditory and motor regions (e.g., arcuate fasciculus) while activating multimodal integration regions (e.g., around the intraparietal sulcus). We argue that training of this neural network may produce cross-modal effects on other behavioral or cognitive operations that draw on this network. Plasticity in this network may explain some of the sensorimotor and cognitive enhancements that have been associated with music training. These enhancements suggest the potential for music making as an interactive treatment or intervention for neurological and developmental disorders, as well as those associated with normal aging.

Wan, Catherine Y.; Schlaug, Gottfried

2010-01-01

223

Research with rTMS in the treatment of aphasia.  

PubMed

This review of our research with rTMS to treat aphasia contains four parts: Part 1 reviews functional brain imaging studies related to recovery of language in aphasia with emphasis on nonfluent aphasia. Part 2 presents the rationale for using rTMS to treat nonfluent aphasia patients (based on results from functional imaging studies). Part 2 also reviews our current rTMS treatment protocol used with nonfluent aphasia patients, and our functional 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 (CILT). Part 4 reviews our diffusion tensor imaging (DTI) study that examined white matter connections between the horizontal, midportion of the arcuate fasciculus (hAF) to different parts within Broca's area (pars triangularis, PTr; pars opercularis, POp), and the ventral premotor cortex (vPMC) in the RH and in the LH. Part 4 also addresses some of the possible mechanisms involved with improved naming and speech, following rTMS with nonfluent aphasia patients. PMID:20714075

Naeser, Margaret A; Martin, Paula I; Treglia, Ethan; Ho, Michael; Kaplan, Elina; Bashir, Shahid; Hamilton, Roy; Coslett, H Branch; Pascual-Leone, Alvaro

2010-01-01

224

Research with transcranial magnetic stimulation in the treatment of aphasia.  

PubMed

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 article 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 as well as imaging results from overt naming functional MRI scans obtained before and after a series of rTMS treatments. Part 3 presents results from a pilot study in which rTMS treatments were followed immediately by constraint-induced language therapy. Part 4 reviews our diffusion tensor imaging study examining the possible connectivity of the arcuate fasciculus to different parts of Broca's area (pars triangularis, pars opercularis) and to the ventral premotor cortex. The potential role of mirror neurons in the right pars opercularis and ventral premotor cortex in aphasia recovery is discussed. PMID:19818232

Martin, Paula I; Naeser, Margaret A; Ho, Michael; Treglia, Ethan; Kaplan, Elina; Baker, Errol H; Pascual-Leone, Alvaro

2009-11-01

225

Music making as a tool for promoting brain plasticity across the life span.  

PubMed

Playing a musical instrument is an intense, multisensory, and motor experience that usually commences at an early age and requires the acquisition and maintenance of a range of skills over the course of a musician's lifetime. Thus, musicians offer an excellent human model for studying the brain effects of acquiring specialized sensorimotor skills. For example, musicians learn and repeatedly practice the association of motor actions with specific sound and visual patterns (musical notation) while receiving continuous multisensory feedback. This association learning can strengthen connections between auditory and motor regions (e.g., arcuate fasciculus) while activating multimodal integration regions (e.g., around the intraparietal sulcus). We argue that training of this neural network may produce cross-modal effects on other behavioral or cognitive operations that draw on this network. Plasticity in this network may explain some of the sensorimotor and cognitive enhancements that have been associated with music training. These enhancements suggest the potential for music making as an interactive treatment or intervention for neurological and developmental disorders, as well as those associated with normal aging. PMID:20889966

Wan, Catherine Y; Schlaug, Gottfried

2010-10-01

226

Patterns of Gene Expression Associated with Pten Deficiency in the Developing Inner Ear  

PubMed Central

In inner ear development, phosphatase and tensin homolog (PTEN) is necessary for neuronal maintenance, such as neuronal survival and accurate nerve innervations of hair cells. We previously reported that Pten conditional knockout (cKO) mice exhibited disorganized fasciculus with neuronal apoptosis in spiral ganglion neurons (SGNs). To better understand the genes and signaling networks related to auditory neuron maintenance, we compared the profiles of differentially expressed genes (DEGs) using microarray analysis of the inner ear in E14.5 Pten cKO and wild-type mice. We identified 46 statistically significant transcripts using significance analysis of microarrays, with the false-discovery rate set at 0%. Among the DEGs, expression levels of candidate genes and expression domains were validated by quantitative real-time RT-PCR and in situ hybridization, respectively. Ingenuity pathway analysis using DEGs identified significant signaling networks associated with apoptosis, cellular movement, and axon guidance (i.e., secreted phosphoprotein 1 (Spp1)-mediated cellular movement and regulator of G-protein signaling 4 (Rgs4)-mediated axon guidance). This result was consistent with the phenotypic defects of SGNs in Pten cKO mice (e.g., neuronal apoptosis, abnormal migration, and irregular nerve fiber patterns of SGNs). From this study, we suggest two key regulatory signaling networks mediated by Spp1 and Rgs4, which may play potential roles in neuronal differentiation of developing auditory neurons.

Kim, Hyung Jin; Ryu, Jihee; Woo, Hae-Mi; Cho, Samuel Sunghwan; Sung, Min Kyung; Kim, Sang Cheol; Park, Mi-Hyun; Park, Taesung; Koo, Soo Kyung

2014-01-01

227

Identification and distribution of three gonadotropin-releasing hormone (GnRH) isoforms in the brain of a clupeiform fish, Engraulis japonicus.  

PubMed

To gain a better understanding of the reproductive endocrinology of a primitive order clupeiform fish (Japanese anchovy, Engraulis japonicus), cDNAs encoding three gonadotropin-releasing hormone (GnRH) isoforms were isolated from the brain, and their distribution was analyzed using insitu hybridization (ISH). The three GnRH isoforms include GnRH1 (herring GnRH), GnRH2 (chicken GnRH-ll) and GnRH3 (salmon GnRH), and their full-length cDNAs encode 88, 86, and 89 deduced amino acids (aa), respectively. Alignment analysis of Japanese anchovy GnRH isoforms showed lower identities with other teleost fish. The major population of GnRH1 neurons was localized in the ventral telencephalon (VT) and nucleus preopticus (NPO) of the preoptic area (POA) with minor population in the anterior olfactory bulb (OB). GnRH2 neurons were restricted to the midbrain tegmentum (MT), specific to the nucleus of the medial longitudinal fasciculus (nMLF). GnRH3 neurons were localized in the olfactory nerve (ON), ventral OB, and transitional area between OB and ON. Interestingly, GnRH1 neurons were also localized in the olfactory bulb, in addition to its major population in the preoptic area. These results indicate the differential distribution of three GnRH isoforms expressed in the brain of the Japanese anchovy. PMID:24320187

Sukhan, Zahid Parvez; Kitano, Hajime; Selvaraj, Sethu; Yoneda, Michio; Yamaguchi, Akihiko; Matsuyama, Michiya

2013-12-01

228

Immunoreactive gonadotropin-releasing hormone (GnRHir) is associated with vestibular structures in the green anole (Anolis carolinensis).  

PubMed

The distribution of immunoreactive gonadotropin-releasing hormone (GnRHir) in relation to endocrine and behavioral pathways is not well established for lizards. To more completely understand the GnRHir distribution and its possible function in a lizard, we investigated the brain of Anolis carolinensis, a species whose visual courtship displays, mating postures and gonadal cycles are well known. Using antisera that recognize multiple GnRH forms, we observed no GnRHir cells or fibers in the forebrain. In the midbrain, however, GnRHir cells occurred along the medial border of the medial longitudinal fasciculus. These cells appeared to project GnRHir fibers to nuclei of cranial nerve III and IV. In the hindbrain, positive fibers were observed in the area of the vestibular nuclei and dorsal funiculus. These hindbrain fibers were followed to their terminals in the cerebellum. The GnRHir midbrain distribution suggests an association of GnRH with eye movements, whereas the hindbrain distribution suggests a GnRH-vestibular association. The lack of GnRHir in the forebrain of Anolis could reflect the minimal role of the vomeronasal system in mediating reproduction in this species. Thus, our study cannot verify hypothalamic GnRH control of the pituitary in A. carolinensis, but it does indicate GnRH control of oculomotor and vestibular nuclei, which might play a role in Anolis reproductive behaviors. PMID:9288413

Rosen, G; Sherwood, N; King, J A

1997-01-01

229

In vivo definition of parieto-motor connections involved in planning of grasping movements.  

PubMed

We combined bifocal transcranial magnetic stimulation (TMS) and diffusion tensor imaging (DTI) tractography to investigate in humans the contribution of connections originating from different parietal areas in planning of different reaching to grasp movements. TMS experiments revealed that in the left hemisphere functional connectivity between the primary motor cortex (M1) and a portion of the angular gyrus (AG) close to the caudal intraparietal sulcus was activated during early preparation of reaching and grasping movements only when the movement was made with a whole hand grasp (WHG) towards objects in contralateral space. In contrast, a different pathway, linking M1 with a part of the supramarginal gyrus (SMG) close to the anterior intraparietal sulcus, was sensitive only to the type of grasp required (precision grasping) but not to the position of the object in space. A triple coil experiment revealed that inactivation of the ventral premotor area (PMv) by continuous theta burst stimulation interfered with some of these interactions. Anatomical DTI tractography revealed that AG and SMG are strongly connected with PMv and with M1 by different bundles of the superior longitudinal fasciculus (SLF). These results demonstrate the existence of segregated parieto-premotor-motor pathways crucial for preparation of different grasping actions and indicate that these may process information relevant to both the position of the object and the hand shape required to use it. PMID:20156564

Koch, Giacomo; Cercignani, Mara; Pecchioli, Cristiano; Versace, Viviana; Oliveri, Massimiliano; Caltagirone, Carlo; Rothwell, John; Bozzali, Marco

2010-05-15

230

Individual differences in left parietal white matter predict math scores on the Preliminary Scholastic Aptitude Test.  

PubMed

Mathematical skills are of critical importance, both academically and in everyday life. Neuroimaging research has primarily focused on the relationship between mathematical skills and functional brain activity. Comparatively few studies have examined which white matter regions support mathematical abilities. The current study uses diffusion tensor imaging (DTI) to test whether individual differences in white matter predict performance on the math subtest of the Preliminary Scholastic Aptitude Test (PSAT). Grades 10 and 11 PSAT scores were obtained from 30 young adults (ages 17-18) with wide-ranging math achievement levels. Tract based spatial statistics was used to examine the correlation between PSAT math scores, fractional anisotropy (FA), radial diffusivity (RD) and axial diffusivity (AD). FA in left parietal white matter was positively correlated with math PSAT scores (specifically in the left superior longitudinal fasciculus, left superior corona radiata, and left corticospinal tract) after controlling for chronological age and same grade PSAT critical reading scores. Furthermore, RD, but not AD, was correlated with PSAT math scores in these white matter microstructures. The negative correlation with RD further suggests that participants with higher PSAT math scores have greater white matter integrity in this region. Individual differences in FA and RD may reflect variability in experience dependent plasticity over the course of learning and development. These results are the first to demonstrate that individual differences in white matter are associated with mathematical abilities on a nationally administered scholastic aptitude measure. PMID:23108272

Matejko, Anna A; Price, Gavin R; Mazzocco, Michèle M M; Ansari, Daniel

2012-10-27

231

White matter integrity and its relationship to PTSD and childhood trauma--a systematic review and meta-analysis.  

PubMed

Recent reviews and meta-analyses reported structural gray matter changes in patients suffering from adult-onset posttraumatic stress disorder (PTSD) and in subjects with and without PTSD who experienced childhood trauma. However, it remains unclear if such structural changes are also affecting the white matter. The aim of this systematic review is to provide a comprehensive overview of all empirical investigations measuring white matter integrity in populations affected by PTSD and/or childhood trauma. To this end, results from different methodological approaches were included. Twenty-five articles are reviewed of which 10 pertained to pediatric PTSD and the effects of childhood trauma measured during childhood, seven to the effects of childhood trauma measured during adulthood, and eight to adult-onset PTSD. Overall, reductions in white matter volume were reported more often than increases in these populations. However, the heterogeneity of the exact locations indicates only a weak overlap across published studies. In addition, a meta-analysis was carried out on seven whole-brain diffusion tensor imaging (DTI) studies in adults. Significant clusters of both increases and decreases were identified in various structures, most notably the cingulum and the superior longitudinal fasciculus. Future research directions are discussed. PMID:23319445

Daniels, Judith K; Lamke, Jan-Peter; Gaebler, Michael; Walter, Henrik; Scheel, Michael

2013-03-01

232

Projections From Gudden's Tegmental Nuclei to the Mammillary Body Region in the Cynomolgus Monkey (Macaca fascicularis)  

PubMed Central

Gudden's tegmental nuclei provide major inputs to the rodent mammillary bodies, where they are thought to be important for learning and navigation. Comparable projections have yet to be described in the primate brain, where part of the problem has been in effectively delineating these nuclei. Immunohistochemical staining of tissue from a series of macaque monkeys (Macaca mulatta) showed that cells in the region of both the ventral and dorsal tegmental nuclei selectively stain for parvalbumin, thus helping to reveal these nuclei. These same tegmental nuclei were not selectively revealed when tissue was stained for SMI32, acetylcholinesterase, calbindin, or calretinin. In a parallel study, horseradish peroxidase was injected into the mammillary bodies of five cynomolgus monkeys (Macaca fascicularis). Retrogradely labeled neurons were consistently found in the three subdivisions of the ventral tegmental nucleus of Gudden, which are located immediately below, within, and above the medial longitudinal fasciculus. Further projections to the mammillary body region arose from cells in the anterior tegmental nucleus, which appears to be a rostral continuation of the infrafascicular part of the ventral tegmental nucleus. In the dorsal tegmental nucleus of Gudden, labeled cells were most evident when the tracer injection was more laterally placed in the mammillary bodies, consistent with a projection to the lateral mammillary nucleus. The present study not only demonstrates that the primate mammillary bodies receive parallel inputs from the dorsal and ventral tegmental nuclei of Gudden, but also helps to confirm the extent of these poorly distinguished nuclei in the monkey brain.

Saunders, Richard C.; Vann, Seralynne D.; Aggleton, John P.

2014-01-01

233

Tractography reveals diffuse white matter abnormalities in Myotonic Dystrophy Type 1.  

PubMed

Cerebral involvement in Myotonic Dystrophy Type 1 (DM1) is well-established but not well characterized. This study applied new Diffusion Tensor Imaging (DTI) tractography to characterize white matter disturbance in adults with DM1. Forty-five participants with DM1 and 44 control participants had MRIs on a Siemens 3T TIM Trio scanner. Data were processed with TRActs Constrained by UnderLying Anatomy (TRACULA) and 7 tracts were evaluated. Bilateral disturbances in white matter integrity were seen in all tracts in participants with DM1 compared to controls. There were no right-left hemisphere differences. The resulting DTI metrics were correlated with cognitive functioning, particularly working memory and processing speed. Motor speed was not significantly correlated with white matter microstructural integrity and, thus, was not the core explanation for the working memory and processing speed findings. White matter integrity was correlated with important clinical variables including the muscular impairment rating scale (MIRS). CTG repeat length was moderately associated with white matter status in corticospinal tract and cingulum. Sleepiness (Epworth Sleepiness Scale) was moderately associated with white matter status in the superior longitudinal fasciculus and cingulum. Overall, the results add to an emerging literature showing widespread white matter disturbances in both early-onset and adult-onset DM1. Results suggest that further investigation of white matter pathology is warranted in DM1 and that non-invasive measures such as DTI have a potentially important clinical value in characterizing the status of individuals with DM1. PMID:24768314

Wozniak, Jeffrey R; Mueller, Bryon A; Lim, Kelvin O; Hemmy, Laura S; Day, John W

2014-06-15

234

Development of Tectal Connectivity across Metamorphosis in the Bullfrog (Rana catesbeiana)  

PubMed Central

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 ? 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.

Horowitz, Seth S.; Simmons, Andrea Megela

2011-01-01

235

Correlation of diffusion tensor imaging with executive function measures after early childhood traumatic brain injury  

PubMed Central

Objective Examine relationships of diffusion tensor imaging (DTI) fractional anisotropy (FA) to executive function (EF) and attention measures following early childhood (3–7 years) traumatic brain injury (TBI). Design Exploratory correlation and comparison study. Setting Children’s hospital outpatient facilities. Participants 9 children with a history of TBI (age = 7.89 ± 1.00 years; Glasgow Coma Scale (GCS) = 10.11 ± 4.68) were compared to 12 children with OI (age = 7.51 ± 0.95). All children were at least 12 months post injury at time of evaluation. Main Outcome Measures FA in various regions of interest (ROI), EF and attention measures. Results FA values primarily in the frontal white matter tracks correlated with EF measures. Separate tasks of inhibition and switching correlated significantly with FA in bilateral frontal lobes. Tasks combining both inhibition and switching correlated significantly with FA values in the left frontal lobe. Tasks of attention negatively correlated with FA values in the right frontal white matter and the superior longitudinal fasciculus. Conclusions Associations between late measurement of FA and EF measures following early childhood TBI suggest that persistent white matter changes, especially in the frontal white matter, may provide an index of EF deficits.

Kurowski, Brad; Wade, Shari L.; Cecil, Kim M.; Walz, Nicolay C.; Yuan, Weihong; Rajagopal, Akila; Holland, Scott K.

2010-01-01

236

Angular smoothing and radial regularization of ODF fields: application on deterministic crossing fiber tractography.  

PubMed

The advent of high angular resolution diffusion imaging (HARDI) has opened up new perspectives for the delineation of crossing and branching fiber pathways. However, image acquisition under clinical conditions with limited measurement time faces the problem of poor spatial and angular resolution and the technique's high susceptibility to noise. In this paper we present a straightforward spatial filter for ODF fields that uses the data-inherent structural information around a voxel as part of a directionally selective method for angular smoothing and radial regularization (ASRR). Especially in regions where fibers cross (multimodal voxels), the method allows us to reduce noise, improve the accuracy of ODF diffusion peaks, and strengthen signals of non-dominant fibers. Moreover, we propose a dynamic scheme in which regularization is applied only to ODFs classified as multimodal. The approach is quantitatively evaluated on synthetic datasets of various configurations. With an in vivo dataset of a human subject, measured under clinical imaging conditions, we demonstrate the method's ability to improve tractography of non-dominant transcallosal fiber pathways and the long fibers of the superior longitudinal fasciculus. PMID:22051017

Otto, K M; Ehricke, H-H; Kumar, V; Klose, U

2013-01-01

237

Evaluation of fiber tracking from subsampled q-space data in diffusion spectrum imaging.  

PubMed

Diffusion spectrum imaging (DSI) is capable of resolving crossing and touching fiber bundles in a given voxel. Acquisition of DSI data involves sampling large number of points in the q-space which significantly increases scan times. The scan times can be reduced by exploiting the symmetry of the q-space. In this study the fiber pathways for five (fornix, cingulum, superior longitudinal fasciculus, corticospinal tract, and crossing fibers in the centrum semiovale region) fiber bundles derived using three subsampled data sets of different sizes derived from the 257 samples in the q-space are compared. The coefficient of variation of the ratio of the number of fiber pathways for each subsample data set to the original data points, averaged over all the 10 subjects, was used for quantitatively investigating the effect of subsampling on the tractography. The effect of threshold angles on tractography is also investigated. The effect of subsampling on the orientation distribution function (ODF) was quantitatively evaluated using both scalar and vector measures derived from the ODF. A streamline tractography method that improves the curvature problem and reduces the local truncation error to further improve the mapping of fiber pathways is adapted. Analysis of the fiber pathways in ten normal subjects, based on qualitative and quantitative methods, shows that the 129 and 198 q-space points provide very similar result with angle of threshold between 41° and 45°. Based on the scan time advantage, 129 subsampled points appear to be adequate for tractography. PMID:23602724

Tefera, Getaneh Bayu; Zhou, Yuxiang; Juneja, Vaibhav; Narayana, Ponnada A

2013-07-01

238

Cerebral white matter integrity and resting-state functional connectivity in middle-aged patients with type 2 diabetes.  

PubMed

Early detection of brain abnormalities at the preclinical stage can be useful for developing preventive interventions to abate cognitive decline. We examined whether middle-aged type 2 diabetic patients show reduced white matter integrity in fiber tracts important for cognition and whether this abnormality is related to preestablished altered resting-state functional connectivity in the default mode network (DMN). Diabetic and nondiabetic participants underwent diffusion tensor imaging, functional magnetic resonance imaging, and cognitive assessment. Multiple diffusion measures were calculated using streamline tractography, and correlations with DMN functional connectivity were determined. Diabetic patients showed lower fractional anisotropy (FA) (a measure of white matter integrity) in the cingulum bundle and uncinate fasciculus. Control subjects showed stronger functional connectivity than patients between the posterior cingulate and both left fusiform and medial frontal gyri. FA of the cingulum bundle was correlated with functional connectivity between the posterior cingulate and medial frontal gyrus for combined groups. Thus, middle-aged patients with type 2 diabetes show white matter abnormalities that correlate with disrupted functional connectivity in the DMN, suggesting that common mechanisms may underlie structural and functional connectivity. Detecting brain abnormalities in middle age enables implementation of therapies to slow progression of neuropathology. PMID:24203723

Hoogenboom, Wouter S; Marder, Thomas J; Flores, Veronica L; Huisman, Susanne; Eaton, Hana P; Schneiderman, Jason S; Bolo, Nicolas R; Simonson, Donald C; Jacobson, Alan M; Kubicki, Marek; Shenton, Martha E; Musen, Gail

2014-02-01

239

Detectability of Neural Tracts and Nuclei in the Brainstem Utilizing 3DAC-PROPELLER.  

PubMed

Despite clinical importance of identifying exact anatomical location of neural tracts and nuclei in the brainstem, no neuroimaging studies have validated the detectability of these structures. The aim of this study was to assess the detectability of the structures using three-dimensional anisotropy contrast-periodically rotated overlapping parallel lines with enhanced reconstruction (3DAC-PROPELLER) imaging. Forty healthy volunteers (21 males, 19 females; 19-53 years, average 23.4 years) participated in this study. 3DAC-PROPELLER axial images were obtained with a 3T-MR system at four levels of the brainstem: the lower midbrain, upper and lower pons, and medulla oblongata. Three experts independently judged whether five tracts (corticospinal tract, medial lemniscus, medial longitudinal fasciculus, central tegmental and spinothalamic tracts) and 10 nuclei (oculomotor and trochlear nuclei, spinal trigeminal, abducens, facial, vestibular, hypoglossal, prepositus, and solitary nuclei, locus ceruleus, superior and inferior olives) on each side could be identified. In total, 240 assessments were made. The five tracts and eight nuclei were identified in all the corresponding assessments, whereas the locus ceruleus and superior olive could not be identified in 3 (1.3%) and 16 (6.7%) assessments, respectively. 3DAC-PROPELLER seems extremely valuable imaging method for mapping out surgical strategies for brainstem lesions. PMID:23607742

Nishikawa, Taro; Okamoto, Kouichirou; Matsuzawa, Hitoshi; Terumitsu, Makoto; Nakada, Tsutomu; Fujii, Yukihiko

2014-05-01

240

Mapping joint grey and white matter reductions in Alzheimer's disease using joint independent component analysis  

PubMed Central

Alzheimer's disease (AD) is a neurodegenerative disease concomitant with grey and white matter damages. However, the interrelationship of volumetric changes between grey and white matter remains poorly understood in AD. Using joint independent component analysis, this study identified joint grey and white matter volume reductions based on structural magnetic resonance imaging data to construct the covariant networks in twelve AD patients and fourteen normal controls (NC). We found that three networks showed significant volume reductions in joint grey–white matter sources in AD patients, including (1) frontal/parietal/temporal-superior longitudinal fasciculus/corpus callosum, (2) temporal/parietal/occipital-frontal/occipital, and (3) temporal-precentral/postcentral. The corresponding expression scores distinguished AD patients from NC with 85.7%, 100% and 85.7% sensitivity for joint sources 1, 2 and 3, respectively; 75.0%, 66.7% and 75.0% specificity for joint sources 1, 2 and 3, respectively. Furthermore, the combined source of three significant joint sources best predicted the AD/NC group membership with 92.9% sensitivity and 83.3% specificity. Our findings revealed joint grey and white matter loss in AD patients, and these results can help elucidate the mechanism of grey and white matter reductions in the development of AD.

Guo, Xiaojuan; Han, Yuan; Chen, Kewei; Wang, Yan; Yao, Li

2013-01-01

241

Cryptic organisation within an apparently irregular rostrocaudal distribution of interneurons in the embryonic zebrafish spinal cord  

SciTech Connect

The molecules and mechanisms involved in patterning the dorsoventral axis of the developing vertebrate spinal cord have been investigated extensively and many are well known. Conversely, knowledge of mechanisms patterning cellular distributions along the rostrocaudal axis is relatively more restricted. Much is known about the rostrocaudal distribution of motoneurons and spinal cord cells derived from neural crest but there is little known about the rostrocaudal patterning of most of the other spinal cord neurons. Here we report data from our analyses of the distribution of dorsal longitudinal ascending (DoLA) interneurons in the developing zebrafish spinal cord. We show that, although apparently distributed irregularly, these cells have cryptic organisation. We present a novel cell-labelling technique that reveals that DoLA interneurons migrate rostrally along the dorsal longitudinal fasciculus of the spinal cord during development. This cell-labelling strategy may be useful for in vivo analysis of factors controlling neuron migration in the central nervous system. Additionally, we show that DoLA interneurons persist in the developing spinal cord for longer than previously reported. These findings illustrate the need to investigate factors and mechanisms that determine 'irregular' patterns of cell distribution, particularly in the central nervous system but also in other tissues of developing embryos.

Wells, Simon, E-mail: simon.wells@adelaide.edu.au [Discipline of Genetics, School of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, South Australia 5005 (Australia) [Discipline of Genetics, School of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, South Australia 5005 (Australia); The Special Research Centre for the Molecular Genetics of Development, University of Adelaide, Adelaide, South Australia 5005 (Australia); Conran, John G., E-mail: john.conran@adelaide.edu.au [Ecology and Evolutionary Biology, School of Earth and Environmental Sciences, University of Adelaide, Adelaide, South Australia 5005 (Australia); Tamme, Richard, E-mail: rtamme@ttu.ee [Discipline of Genetics, School of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, South Australia 5005 (Australia)] [Discipline of Genetics, School of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, South Australia 5005 (Australia); Gaudin, Arnaud, E-mail: a.gaudin@uq.edu.au [School of Biomedical Sciences, University of Queensland, Brisbane, Queensland 4072 (Australia)] [School of Biomedical Sciences, University of Queensland, Brisbane, Queensland 4072 (Australia); Webb, Jonathan, E-mail: jonathan.webb@worc.ox.ac.uk [Discipline of Genetics, School of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, South Australia 5005 (Australia)] [Discipline of Genetics, School of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, South Australia 5005 (Australia); Lardelli, Michael, E-mail: michael.lardelli@adelaide.edu.au [Discipline of Genetics, School of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, South Australia 5005 (Australia) [Discipline of Genetics, School of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, South Australia 5005 (Australia); The Special Research Centre for the Molecular Genetics of Development, University of Adelaide, Adelaide, South Australia 5005 (Australia)

2010-11-15

242

[Clinical study of two cases of traumatic cerebellar injury].  

PubMed

Two cases of traumatic cerebellar injury complicated with a traumatic medial longitudinal fasciculus (MLF) syndrome or cerebellar mutism were reported, and the cause of these mechanisms was discussed: Case 1: A 9-year-old boy who struck his head in the occipital region during an automobile accident was operated on for a delayed traumatic intracerebellar hematoma. The operation improved the level of his consciousness but MLF syndrome was noticed. The mechanism of traumatic MLF syndrome was discussed in relation to vascular injury and to neurovascular friction. The outcome of the syndrome including our case, which recovered spontaneously, seemed to support the theory of neurovascular injury. Case 2: A 6-year-old boy who struck his head in the temporooccipital region during an automobile accident was admitted to our hospital without conciousness. On admission, contusion of the temporal lobe and left cerebellar hemisphere was demonstrated by a computerized tomography (CT) and magnetic resonance imaging (MRI). A mute state (cerebellar mutism) was recognized after his recovery of consciousness. The cause of the cerebellar mutism was thought to be an injury of the cerebellar vermis or left cerebellar hemisphere. The findings of CT scan and MRI in our case suggested that the cause of the cerebellar mutism was the contusion of these areas. PMID:2406638

Yokota, H; Nakazawa, S; Kobayashi, S; Taniguchi, Y; Yukihide, T

1990-01-01

243

The relationship between executive functioning, processing speed, and white matter integrity in multiple sclerosis.  

PubMed

The primary purpose of the current study was to examine the relationship between performance on executive tasks and white matter integrity, assessed by diffusion tensor imaging (DTI) in multiple sclerosis (MS). A second aim was to examine how processing speed affects the relationship between executive functioning and fractional anisotropy (FA). This relationship was examined in two executive tasks that rely heavily on processing speed: the Color-Word Interference Test and the Trail Making Test (Delis-Kaplan Executive Function System). It was hypothesized that reduced FA is related to poor performance on executive tasks in MS, but that this relationship would be affected by the statistical correction of processing speed from the executive tasks. A total of 15 healthy controls and 25 persons with MS participated. Regression analyses were used to examine the relationship between executive functioning and FA, both before and after processing speed was removed from the executive scores. Before processing speed was removed from the executive scores, reduced FA was associated with poor performance on the Color-Word Interference Test and Trail Making Test in a diffuse network including corpus callosum and superior longitudinal fasciculus. However, once processing speed was removed, the relationship between executive functions and FA was no longer significant on the Trail Making Test, and significantly reduced and more localized on the Color-Word Interference Test. PMID:23777468

Genova, Helen M; DeLuca, John; Chiaravalloti, Nancy; Wylie, Glenn

2013-01-01

244

Evaluation of Fiber Tracking from Subsampled q-Space Data in Diffusion Spectrum Imaging  

PubMed Central

Diffusion spectrum imaging (DSI) is capable of resolving crossing and touching fiber bundles in a given voxel. Acquisition of DSI data involves sampling large number of points in the q-space which significantly increases scan times. The scan times can be reduced by exploiting the symmetry of the q-space. In this study the fiber pathways for five (fornix, cingulum, superior longitudinal fasciculus, corticospinal tract, and crossing fibers in the centrum semiovale region) fiber bundles derived using three subsampled data sets of different sizes derived from the 257 samples in the q-space are compared. The coefficient of variation of the ratio of the number of fiber pathways for each subsample data set to the original data points, averaged over all the 10 subjects, was used for quantitatively investigating the effect of subsampling on the tractography. The effect of threshold angles on tractography is also investigated. The effect of subsampling on the orientation distribution function (ODF) was quantitatively evaluated using both scalar and vector measures derived from the ODF. A streamline tractography method that improves the curvature problem and reduces the local truncation error to further improve the mapping of fiber pathways is adapted. Analysis of the fiber pathways in ten normal subjects, based on qualitative and quantitative methods, shows that the 129 and 198 q-space points provide very similar result with angle of threshold between 41° and 45°. Based on the scan time advantage, 129 subsampled points appear to be adequate for tractography.

Tefera, Getaneh Bayu; Zhou, Yuxiang; Juneja, Vaibhav; Narayana, Ponnada A.

2013-01-01

245

The Dide-Botcazo syndrome: Forgotten and misunderstood.  

PubMed

Bilateral infarcts of the posterior cerebral arteries are associated with a range of visual and memory deficits. In 1902, Dide and Botcazo presented a clinico-pathological case study linking visual field defects, topographical disorientation, retro-anterograde amnesia and alexia with bilateral medial occipito-temporal lesions. Based on the findings they suggested the occipital lobe and inferior longitudinal fasciculus played an important role in memory. The combination of deficits was subsequently referred to on occasion as Dide-Botcazo syndrome but the term was largely forgotten until revived in the 1980s. More recently, some authors have included visual anosognosia - Anton's syndrome - in the syndrome, a feature that was not in the original case report. Here we present a historical review of Dide-Botcazo syndrome, illustrated with a recent case with almost identical clinical features to that described by Dide and Botcazo. Although Dide and Botcazo's theory of occipital amnesia has been superseded by developments in our understanding of the neurobiology of memory, it seems fitting to remember in some way their description of a clinical association of visual and memory deficits. We suggest Dide-Botcazo syndrome be used to describe a variant of vascular dementia, where visual field deficits are associated with memory impairment and, depending on the location of the vascular lesions, visual perceptual dysfunction, topographic, imagery or dreaming deficits. PMID:23473855

Lazzarino De Lorenzo, Lucio G; Ffytche, Dominic H; Di Camillo, Eva; Buiatti, Tania

2013-02-10

246

Association between Severe Upper Limb Spasticity and Brain Lesion Location in Stroke Patients  

PubMed Central

Association between the site of brain injury and poststroke spasticity is poorly understood. The present study investigated whether lesion analysis could document brain regions associated with the development of severe upper limb poststroke spasticity. A retrospective analysis was conducted on 39 chronic stroke patients. Spasticity was assessed at the affected upper limb with the modified Ashworth scale (shoulder, elbow, wrist, and fingers). Brain lesions were traced from magnetic resonance imaging performed within the first 7 days after stroke and region of interest images were generated. The association between severe upper limb spasticity (modified Ashworth scale ?2) and lesion location was determined with the voxel-based lesion-symptom mapping method implemented in MRIcro software. Colored maps representing the z statistics were generated and overlaid onto the automated anatomical labeling and the Johns Hopkins University white matter templates provided with MRIcron. Thalamic nuclei were identified with the Talairach Daemon software. Injuries to the insula, the thalamus, the basal ganglia, and white matter tracts (internal capsule, corona radiata, external capsule, and superior longitudinal fasciculus) were significantly associated with severe upper limb poststroke spasticity. Further advances in our understanding of the neural correlates of spasticity may lead to early targeted rehabilitation when key regions are damaged.

Picelli, Alessandro; Tamburin, Stefano; Gajofatto, Francesca; Zanette, Giampietro; Praitano, Marialuigia; Saltuari, Leopold; Corradini, Claudio; Smania, Nicola

2014-01-01

247

Neurophysiology of Nicotine Addiction  

PubMed Central

Tobacco use is a major health problem, and nicotine is the main addictive component. Nicotine binds to nicotinic acetylcholine receptors (nAChR) to produce its initial effects. The nAChRs subtypes are composed of five subunits that can form in numerous combinations with varied functional and pharmacological characteristics. Diverse psychopharmacological effects contribute to the overall process of nicotine addiction, but two general neural systems are emerging as critical for the initiation and maintenance of tobacco use. Mesocorticolimbic circuitry that includes the dopaminergic pathway originating in the ventral tegmental area and projecting to the nucleus accumbens is recognized as vital for reinforcing behaviors during the initiation of nicotine addiction. In this neural system ?2, ?4, and ?6 are the most important nAChR subunits underlying the rewarding aspects of nicotine and nicotine self-administration. On the other hand, the epithalamic habenular complex and the interpeduncular nucleus, which are connected via the fasciculus retroflexus, are critical contributors regulating nicotine dosing and withdrawal symptoms. In this case, the ?5 and ?4 nAChR subunits have critical roles in combination with other subunits. In both of these neural systems, particular nAChR subtypes have roles that contribute to the overall nicotine addiction process

Dani, John A.; Jenson, Daniel; Broussard, John I.; De Biasi, Mariella

2012-01-01

248

The dorsal, posterodorsal, and ventral tegmental nuclei: a cyto- and chemoarchitectonic study in the human.  

PubMed

In order to verify the existence of the ventral and posterodorsal tegmental nuclei and to extend previous findings regarding the dorsal tegmental nucleus in the human brainstem, studies were conducted using cyto- and chemoarchitectonics, and computer reconstruction techniques. Serial sections of five brainstems from adults with no known neurological disorders were stained for Nissl substance, acetylcholinesterase, and substance P. The topography, cytoarchitecture, and acetylcholinesterase reactivity of the tegmental nuclei were presented in a mini-atlas depicting sections cut in transverse and sagittal planes. The dorsal and posterodorsal tegmental nuclei were identified fully within the central grey matter while the ventral tegmental nucleus extended across the medial longitudinal fasciculus into the pontine reticular formation. The dorsal tegmental nucleus featured a cell-poor pericentral part, strongly positive for acetylcholinesterase, and a central part comprised of densely packed small neurons that displayed moderate acetylcholinesterase reactivity and strong substance P-like immunoreactivity. The posterodorsal tegmental nucleus, located in the same transverse plane as the rostral part of the motor nucleus of the trigeminal nerve, was composed of diffusely arranged small to medium neurons with its neuropil displaying moderate acetylcholinesterase reactivity and strong substance P-like immunoreactivity. The ventral tegmental nucleus, identified as a prominent structure in the pontine tegmentum immediately rostral to the genu of the facial nerve, contained predominantly large neurons and displayed intensive acetylcholinesterase reactivity and substance P-like immunoreactivity. These studies showed that the tegmental nuclei, which displayed distinctive cyto- and chemoarchitectonic features, were fully present in adult human brainstem. PMID:1374765

Huang, X F; Törk, I; Halliday, G M; Paxinos, G

1992-04-01

249

A Brain Network Processing the Age of Faces  

PubMed Central

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.

Homola, Gyorgy A.; Jbabdi, Saad; Beckmann, Christian F.; Bartsch, Andreas J.

2012-01-01

250

"The Relationship between Executive Functioning, Processing Speed and White Matter Integrity in Multiple Sclerosis"  

PubMed Central

The primary purpose of the current study was to examine the relationship between performance on executive tasks and white matter integrity, assessed by diffusion tensor imaging (DTI) in Multiple Sclerosis (MS). A second aim was to examine how processing speed affects the relationship between executive functioning and FA. This relationship was examined in two executive tasks that rely heavily on processing speed: the Color-Word Interference Test and Trail-Making Test (Delis-Kaplan Executive Function System). It was hypothesized that reduced fractional anisotropy (FA) is related to poor performance on executive tasks in MS, but that this relationship would be affected by the statistical correction of processing speed from the executive tasks. 15 healthy controls and 25 persons with MS participated. Regression analyses were used to examine the relationship between executive functioning and FA, both before and after processing speed was removed from the executive scores. Before processing speed was removed from the executive scores, reduced FA was associated with poor performance on Color-Word Interference Test and Trail-Making Test in a diffuse network including corpus callosum and superior longitudinal fasciculus. However, once processing speed was removed, the relationship between executive functions and FA was no longer significant on the Trail Making test, and significantly reduced and more localized on the Color-Word Interference Test.

Genova, Helen M.; DeLuca, John; Chiaravalloti, Nancy; Wylie, Glenn

2014-01-01

251

Associations of white matter integrity and cortical thickness in patients with schizophrenia and healthy controls.  

PubMed

Typical brain development includes coordinated changes in both white matter (WM) integrity and cortical thickness (CT). These processes have been shown to be disrupted in schizophrenia, which is characterized by abnormalities in WM microstructure and by reduced CT. The aim of this study was to identify patterns of association between WM markers and cortex-wide CT in healthy controls (HCs) and patients with schizophrenia (SCZ). Using diffusion tensor imaging and structural magnetic resonance imaging data of the Mind Clinical Imaging Consortium study (130 HC and 111 SCZ), we tested for associations between (a) fractional anisotropy in selected manually labeled WM pathways (corpus callosum, anterior thalamic radiation, and superior longitudinal fasciculus) and CT, and (b) the number of lesion-like WM regions ("potholes") and CT. In HC, but not SCZ, we found highly significant negative associations between WM integrity and CT in several pathways, including frontal, temporal, and occipital brain regions. Conversely, in SCZ the number of WM potholes correlated with reduced CT in the left lateral temporal gyrus, left fusiform, and left lateral occipital brain area. Taken together, we found differential patterns of association between WM integrity and CT in HC and SCZ. Although the pattern in HC can be explained from a developmental perspective, the reduced gray matter CT in SCZ patients might be the result of focal but spatially heterogeneous disruptions of WM integrity. PMID:23661633

Ehrlich, Stefan; Geisler, Daniel; Yendiki, Anastasia; Panneck, Patricia; Roessner, Veit; Calhoun, Vince D; Magnotta, Vincent A; Gollub, Randy L; White, Tonya

2014-05-01

252

Whole brain functional connectivity using phase locking measures of resting state magnetoencephalography  

PubMed Central

The analysis of spontaneous functional connectivity (sFC) reveals the statistical connections between regions of the brain consistent with underlying functional communication networks within the brain. In this work, we describe the implementation of a complete all-to-all network analysis of resting state neuronal activity from magnetoencephalography (MEG). Using graph theory to define networks at the dipole level, we established functionally defined regions by k-means clustering cortical surface locations using Eigenvector centrality (EVC) scores from the all-to-all adjacency model. Permutation testing was used to estimate regions with statistically significant connections compared to empty room data, which adjusts for spatial dependencies introduced by the MEG inverse problem. In order to test this model, we performed a series of numerical simulations investigating the effects of the MEG reconstruction on connectivity estimates. We subsequently applied the approach to subject data to investigate the effectiveness of our method in obtaining whole brain networks. Our findings indicated that our model provides statistically robust estimates of functional region networks. Application of our phase locking network methodology to real data produced networks with similar connectivity to previously published findings, specifically, we found connections between contralateral areas of the arcuate fasciculus that have been previously investigated. The use of data-driven methods for neuroscientific investigations provides a new tool for researchers in identifying and characterizing whole brain functional connectivity networks.

Schmidt, Benjamin T.; Ghuman, Avniel S.; Huppert, Theodore J.

2014-01-01

253

Dissociable morphometric profiles of the affective and cognitive dimensions of alexithymia.  

PubMed

Alexithymia ("no words for feelings") is a psychological construct that can be divided in a cognitive and affective dimension. The cognitive dimension reflects the ability to identify, verbalize and analyze feelings, whereas the affective dimension reflects the degree to which individuals get aroused by emotional stimuli and their ability to fantasize. These two alexithymia dimensions may differentially put individuals at risk to develop psychopathology. However, their neural correlates have rarely been investigated. The aim of the current study was to investigate whether the cognitive and affective alexithymia dimension are associated with unique anatomical profiles. Structural MRI scans of 57 participants (29 males; mean age: 34) were processed using a voxel-based morphometry (VBM) - Diffeomorphic Anatomical Registration Through Exponentiated Lie algebra (DARTEL) approach. Multiple regression analyses were performed to examine the common and specific associations between gray and white matter volume and alexithymia subdimensions. The results revealed that the cognitive dimension was related to lower dorsal anterior cingulate volume. In contrast, the affective alexithymia was associated with lower gray matter volume in the medial orbitofrontal cortex (OFC) and lower white matter volume in the superior longitudinal fasciculus (SLF) near the angular gyrus. No relationship between corpus callosum volume and alexithymia was observed. These results are consistent with the idea that there are two separable neural systems underlying alexithymia. This finding might encourage future research into the link between specific alexithymia subtypes and the development of psychopathology. PMID:24699037

van der Velde, Jorien; van Tol, Marie-José; Goerlich-Dobre, Katharina Sophia; Gromann, Paula M; Swart, Marte; de Haan, Lieuwe; Wiersma, Durk; Bruggeman, Richard; Krabbendam, Lydia; Aleman, André

2014-05-01

254

Alcohol use and cerebral white matter compromise in adolescence.  

PubMed

Alcohol use is typically initiated during adolescence, a period known to be critical in neurodevelopment. The adolescent brain may be particularly susceptible to the harmful effects of alcohol. While the cognitive deficits associated with alcohol use during adolescence have been well-documented, the neural substrates underlying these effects remain inadequately understood. Cerebral white matter has been suggested as a primary site of alcohol-related damage and diffusion tensor imaging (DTI) allows for the quantification of white matter integrity in vivo. This review summarizes results from both cross-sectional and longitudinal studies employing DTI that indicate that white matter tracts, particularly those thought to be involved in executive functioning, continue to develop throughout adolescence and into adulthood. Numerous DTI studies reveal a positive correlation between white matter integrity and neurocognitive performance and, in adults, the detrimental effects of prolonged alcohol-dependence on white matter integrity. We provide a comprehensive review of the DTI studies exploring the relationship between alcohol use and white matter integrity in adolescents. Results from most of these studies suggest that alcohol use is associated with reduced white matter integrity, particularly in the superior longitudinal fasciculus (SLF), and some evidence suggests that this relationship may be influenced by sex. We conclude by highlighting confounds and limitations of the available research and suggesting directions for future research. PMID:23583835

Elofson, Jonathan; Gongvatana, Win; Carey, Kate B

2013-07-01

255

Alcohol Use and Cerebral White Matter Compromise in Adolescence  

PubMed Central

Alcohol use is typically initiated during adolescence, a period known to be critical in neurodevelopment. The adolescent brain may be particularly susceptible to the harmful effects of alcohol. While the cognitive deficits associated with alcohol use during adolescence have been well-documented, the neural substrates underlying these effects remain inadequately understood. Cerebral white matter has been suggested as a primary site of alcohol-related damage and diffusion tensor imaging (DTI) allows for the quantification of white matter integrity in vivo. This review summarizes results from both cross-sectional and longitudinal studies employing DTI that indicate that white matter tracts, particularly those thought to be involved in executive functioning, continue to develop throughout adolescence and into adulthood. Numerous DTI studies reveal a positive correlation between white matter integrity and neurocognitive performance and, in adults, the detrimental effects of prolonged alcohol-dependence on white matter integrity. We provide a comprehensive review of the DTI studies exploring the relationship between alcohol use and white matter integrity in adolescents. Results from most of these studies suggest that alcohol use is associated with reduced white matter integrity, particularly in the superior longitudinal fasciculus (SLF), and some evidence suggests that this relationship may be influenced by sex. We conclude by highlighting confounds and limitations of the available research and suggesting directions for future research.

Elofson, Jonathan; Gongvatana, Win; Carey, Kate B.

2013-01-01

256

Association between Severe Upper Limb Spasticity and Brain Lesion Location in Stroke Patients.  

PubMed

Association between the site of brain injury and poststroke spasticity is poorly understood. The present study investigated whether lesion analysis could document brain regions associated with the development of severe upper limb poststroke spasticity. A retrospective analysis was conducted on 39 chronic stroke patients. Spasticity was assessed at the affected upper limb with the modified Ashworth scale (shoulder, elbow, wrist, and fingers). Brain lesions were traced from magnetic resonance imaging performed within the first 7 days after stroke and region of interest images were generated. The association between severe upper limb spasticity (modified Ashworth scale ?2) and lesion location was determined with the voxel-based lesion-symptom mapping method implemented in MRIcro software. Colored maps representing the z statistics were generated and overlaid onto the automated anatomical labeling and the Johns Hopkins University white matter templates provided with MRIcron. Thalamic nuclei were identified with the Talairach Daemon software. Injuries to the insula, the thalamus, the basal ganglia, and white matter tracts (internal capsule, corona radiata, external capsule, and superior longitudinal fasciculus) were significantly associated with severe upper limb poststroke spasticity. Further advances in our understanding of the neural correlates of spasticity may lead to early targeted rehabilitation when key regions are damaged. PMID:24963473

Picelli, Alessandro; Tamburin, Stefano; Gajofatto, Francesca; Zanette, Giampietro; Praitano, Marialuigia; Saltuari, Leopold; Corradini, Claudio; Smania, Nicola

2014-01-01

257

The role of the habenula in drug addiction.  

PubMed

Interest in the habenula has greatly increased in recent years. The habenula is a small brain structure located posterior to the thalamus and adjacent to the third ventricle. Despite its small size, the habenula can be divided into medial habenula (MHb) and lateral habenula (LHb) nuclei that are anatomically and transcriptionally distinct. The habenula receives inputs from the limbic system and basal ganglia primarily via the stria medullaris. The fasciculus retroflexus is the primary habenular output from the habenula to the midbrain and governs release of glutamate onto gabaergic cells in the rostromedial tegmental nucleus (RMTg) and onto the interpeduncular nucleus. The resulting GABA released from RMTg neurons inactivates dopaminergic cells in the ventral tegmental area/substantia nigra compacta. Through this process, the habenula controls dopamine levels in the striatum. Thus, the habenula plays a critical role in reward and reward-associated learning. The LHb also modulates serotonin levels and norepinephrine release, while the MHb modulates acetylcholine. The habenula is a critical crossroad that influences the brain's response to pain, stress, anxiety, sleep, and reward. Dysfunction of the habenula has been linked to depression, schizophrenia, and the effects of drugs of abuse. This review focuses on the possible relationships between the habenula and drug abuse. PMID:24734015

Velasquez, Kenia M; Molfese, David L; Salas, Ramiro

2014-01-01

258

[A case of wall-eyed bilateral internuclear ophthalmoplegia (WEBINO) syndrome with cerebellar ataxia and facial dysesthesia].  

PubMed

We report an 85-year-old man presenting with wall-eyed bilateral internuclear ophthalmoplegia (WEBINO) syndrome with cerebellar ataxia and facial dysesthesia. He experienced an abrupt onset of double vision and exotropia of the right eye with unsteady gait and dysesthesia around upper lip. He was admitted to our hospital ten days after the onset of the double vision. On admission, he presented with WEBINO, left limb ataxia, and dysesthesia around upper lip on the right side. His exotropia was prominent on the right side. Diffusion weighted images of MRI revealed a high intensity lesion in the paramedian pontine tegmentum involving bilateral medial longitudinal fasciculus (MLF), consistent with acute ischemic lesion. Four months after the onset, the WEBINO persisted, without cerebellar ataxia and facial dysesthesia. Putative lesions of the WEBINO, cerebellar ataxia and facial dysesthesia were bilateral MLF, left superior cerebellar peduncle and trigeminothalamic tract, respectively, which were broader than the MRI lesion. Neurological examination is critical for evaluation of accurate ischemic area. PMID:24807275

Kadoya, Masato; Onoue, Hiroyuki; Kadoya, Akiko; Higashihara, Mana; Ikewaki, Katsunori; Kaida, Kenichi

2014-01-01

259

Research with rTMS in the treatment of aphasia  

PubMed Central

This review of our research with rTMS to treat aphasia contains four parts: Part 1 reviews functional brain imaging studies related to recovery of language in aphasia with emphasis on nonfluent aphasia. Part 2 presents the rationale for using rTMS to treat nonfluent aphasia patients (based on results from functional imaging studies). Part 2 also reviews our current rTMS treatment protocol used with nonfluent aphasia patients, and our functional 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 (CILT). Part 4 reviews our diffusion tensor imaging (DTI) study that examined white matter connections between the horizontal, midportion of the arcuate fasciculus (hAF) to different parts within Broca’s area (pars triangularis, PTr; pars opercularis, POp), and the ventral premotor cortex (vPMC) in the RH and in the LH. Part 4 also addresses some of the possible mechanisms involved with improved naming and speech, following rTMS with nonfluent aphasia patients.

Naeser, Margaret A.; Martin, Paula I; Treglia, Ethan; Ho, Michael; Kaplan, Elina; Bashir, Shahid; Hamilton, Roy; Coslett, H. Branch; Pascual-Leone, Alvaro

2013-01-01

260

Research with Transcranial Magnetic Stimulation in the Treatment of Aphasia  

PubMed Central

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.

Martin, Paula I; Naeser, Margaret A.; Ho, Michael; Treglia, Ethan; Kaplan, Elina; Baker, Errol H.; Pascual-Leone, Alvaro

2010-01-01

261

Intratelencephalic connections of the hippocampus in pigeons (Columba livia).  

PubMed

Behavioral experiments using ablation of the hippocampus are increasingly being used to address the hypothesis that the avian hippocampus plays a role in memory, as in mammals. However, the morphological basis of the avian hippocampus has been poorly understood. In the present study, the afferent and efferent connections of the hippocampus in the pigeon telencephalon were defined by injections, at various rostrocaudal sites, of neuronal tracers mainly into the triangular part located between its V-shaped layer of densely packed neurons. The major results obtained in the present study were as follows. 1) A topographical organization of the commissural projections was confirmed. These projections had two courses that projected to the contralateral side, one traveling through the fiber wall of the ventromedial telencephalon, which was the main path from neurons in the caudal hippocampus, and the other running down through the septohippocampal junction, which was the main path from neurons in the middle to rostral hippocampus. Both courses passed through the pallial commissure. 2) The hippocampus projected bilaterally to the septum, parahippocampal area (APH), and dorsolateral cortical area (CDL). These projections were also distributed topographically, with contralateral efferents crossing through the pallial commissure. 3) The hippocampus had ipsilateral reciprocal connections with APH, CDL, and the dorsal hyperstriatum. Septal afferents to the ipsilateral hippocampus were very small. 4) Intrinsic connections were found between the triangular part of the hippocampus and the lateral limb of the V-shaped layer of neurons. 5) The hippocampus projected ipsilaterally to the ventral basal ganglia and the fasciculus diagonalis Brocae. In sum, these connections of the hippocampus may form a neuronal circuit for the processing of spatial memory in pigeons. PMID:11977120

Atoji, Yasuro; Wild, J Martin; Yamamoto, Yoshio; Suzuki, Yoshitaka

2002-05-27

262

Subject-Specific Changes in Brain White Matter on Diffusion Tensor Imaging After Sports-Related Concussion  

PubMed Central

Background and Purpose Current approaches to diffusion tensor imaging (DTI) analysis do not permit identification of individual-level changes in DTI indices. We investigated the ability of wild bootstrapping analysis to detect subject-specific changes in brain white matter (WM) before and after sports-related concussion. Materials and Methods A prospective cohort study was performed in 9 high school athletes engaged in hockey or football, and 6 controls. Subjects underwent DTI pre- and post-season within a 3-month interval. One athlete was diagnosed with concussion (scanned within 72 hours) and 8 suffered between 26 and 399 sub-concussive head blows. Fractional anisotropy (FA) and mean diffusivity (MD) were measured in each white matter voxel. Bootstrap samples were generated and a permuted t test used to compare voxel-wise FA/MD changes in each subject pre- vs. post-season. Results The percentage of WM voxels with significant (p<0.05) pre-post FA changes was highest for the concussion subject (3.2%), intermediary for those with sub-concussive head blows (mean 1.05±.15%) and lowest for controls (mean 0.28±.01%). Similarly, the percentage of WM voxels with significant MD changes was highest for the concussion subject (3.44%), intermediary for those with sub-concussive head blows (mean 1.48±.17%) and lowest for controls (mean 0.48±.05%). Significantly changed FA and MD voxels co-localized in the concussion subject to the right corona radiata and right inferior longitudinal fasciculus. Conclusions Wild bootstrap analysis detected significantly changed WM in a single concussed athlete. Athletes with multiple sub-concussive head blows had significant changes in a percentage of their WM that was over 3 times higher than controls. Efforts to understand the significance of these WM changes, and their relationship to head impact forces appear warranted.

Zhu, Tong; Blyth, Brian; Borrino, Allyson; Zhong, Jianhui

2011-01-01

263

Pervasive microstructural abnormalities in autism: a DTI study  

PubMed Central

Background Recent studies have reported abnormal functional connectivity patterns in the brains of people with autism that may be accompanied by decreases in white matter integrity. Since autism is a developmental disorder, we aim to investigate the nature and location of decreases in white and grey matter integrity in an adolescent sample while accounting for age. Methods We used structural (T1) imaging to study brain volumetrics and diffusion tensor imaging (DTI) to investigate white and grey matter integrity in people with autism. We obtained magnetic resonance images for adolescents aged 12–18 years with high-functioning autism and from matched controls. Fractional anisotropy and mean diffusivity, as well as grey and white matter volumetrics were analyzed. Results There were 17 participants with autism and 25 matched controls included in this study. Participants with autism had lower fractional anisotropy in the left and right superior and inferior longitudinal fasciculus, but this effect was not significant after adjusting for age and intelligence quotient (IQ). The kurtosis of the white matter fractional anisotropy probability distribution was higher in this participant group, with and without adjustment for age and IQ. Most notably, however, the mean diffusivity levels were markedly increased in the autism group throughout the brain, and the mean diffusivity probability distributions of both grey and white matter were shifted toward a higher value, particularly with age and IQ adjustment. No volumetric differences in grey and white matter were found. Limitations We corrected for age and IQ using a linear model. The study was also limited by its sample size, investigated age range and cross-sectional design. Conclusion The findings suggest that autism is characterized by a generalized reduction of white matter integrity that is associated with an increase of interstitial space. The generalized manifestation of the white matter abnormalities provides an important new perspective on autism as a connectivity disorder.

Groen, Wouter B.; Buitelaar, Jan K.; van der Gaag, Rutger J.; Zwiers, Marcel P.

2011-01-01

264

Effects of chronic mild traumatic brain injury on white matter integrity in Iraq and Afghanistan war veterans.  

PubMed

Mild traumatic brain injury (TBI) is a common source of morbidity from the wars in Iraq and Afghanistan. With no overt lesions on structural MRI, diagnosis of chronic mild TBI in military veterans relies on obtaining an accurate history and assessment of behavioral symptoms that are also associated with frequent comorbid disorders, particularly posttraumatic stress disorder (PTSD) and depression. Military veterans from Iraq and Afghanistan with mild TBI (n = 30) with comorbid PTSD and depression and non-TBI participants from primary (n = 42) and confirmatory (n = 28) control groups were assessed with high angular resolution diffusion imaging (HARDI). White matter-specific registration followed by whole-brain voxelwise analysis of crossing fibers provided separate partial volume fractions reflecting the integrity of primary fibers and secondary (crossing) fibers. Loss of white matter integrity in primary fibers (P < 0.05; corrected) was associated with chronic mild TBI in a widely distributed pattern of major fiber bundles and smaller peripheral tracts including the corpus callosum (genu, body, and splenium), forceps minor, forceps major, superior and posterior corona radiata, internal capsule, superior longitudinal fasciculus, and others. Distributed loss of white matter integrity correlated with duration of loss of consciousness and most notably with "feeling dazed or confused," but not diagnosis of PTSD or depressive symptoms. This widespread spatial extent of white matter damage has typically been reported in moderate to severe TBI. The diffuse loss of white matter integrity appears consistent with systemic mechanisms of damage shared by blast- and impact-related mild TBI that involves a cascade of inflammatory and neurochemical events. PMID:22706988

Morey, Rajendra A; Haswell, Courtney C; Selgrade, Elizabeth S; Massoglia, Dino; Liu, Chunlei; Weiner, Jonathan; Marx, Christine E; Cernak, Ibolja; McCarthy, Gregory

2013-11-01

265

White matter structures associated with empathizing and systemizing in young adults.  

PubMed

Empathizing is defined as the drive to identify the mental states of others in order to predict their behavior and respond with an appropriate emotion. Systemizing is defined as the drive to analyze a system in terms of the rules that govern it to predict its behavior. We undertook voxel-by-voxel investigations of regional white matter volume (rWMV) and fractional anisotropy (FA) of diffusion tensor imaging to discover the WM structural correlates of empathizing, systemizing, and their difference (D score: systemizing-empathizing). Whole brain analyses of covariance revealed that across both sexes, the D score was negatively correlated with rWMV in the WM area in the bilateral temporal lobe, near the right inferior frontal gyrus, near the ventral medial prefrontal cortex, and near the posterior cingulate cortex and positively correlated with FA in an area involving the superior longitudinal fasciculus. Post-hoc analyses revealed that these associations were generally formed by both the correlation between WM structures and empathizing as well as the opposite correlation between WM structures and systemizing. A significant effect of interaction between sex and the D score on rWMV, which was mainly observed because of a positive correlation between rWMV and empathizing in females and a negative correlation between rWMV and systemizing in females, was found in an area close to the right inferior parietal lobule and temporoparietal junction. Our results suggest that WM structures involving the default mode network and the mirror neuron system support empathizing, and that a WM structure relating to the external attention system supports systemizing. Further, our results revealed an overlap between positive/negative WM structural correlates of empathizing and negative/positive WM structural correlates of systemizing despite little correlation between empathizing and systemizing, which supports the previously held idea that there is a trade-off between empathizing and systemizing in the brain. PMID:23578577

Takeuchi, Hikaru; Taki, Yasuyuki; Thyreau, Benjamin; Sassa, Yuko; Hashizume, Hiroshi; Sekiguchi, Atsushi; Nagase, Tomomi; Nouchi, Rui; Fukushima, Ai; Kawashima, Ryuta

2013-08-15

266

GENE NETWORK EFFECTS ON BRAIN MICROSTRUCTURE AND INTELLECTUAL PERFORMANCE IDENTIFIED IN 472 TWINS  

PubMed Central

A major challenge in neuroscience is finding which genes affect brain integrity, connectivity, and intellectual function. Discovering influential genes holds vast promise for neuroscience, but typical genome-wide searches assess around one million genetic variants one-by-one, leading to intractable false positive rates, even with vast samples of subjects. Even more intractable is the question of which genes interact and how they work together to affect brain connectivity. Here we report a novel approach that discovers which genes contribute to brain wiring and fiber integrity at all pairs of points in a brain scan. We studied genetic correlations between thousands of points in human brain images from 472 twins and their non-twin siblings (mean age: 23.7±2.1 SD years; 193 M/279 F). We combined clustering with genome-wide scanning to find brain systems with common genetic determination. We then filtered the image in a new way to boost power to find causal genes. Using network analysis, we found a network of genes that affect brain wiring in healthy young adults. Our new strategy makes it more computationally tractable to discover genes that affect brain integrity. The gene network showed small-world and scale-free topologies, suggesting efficiency in genetic interactions, and resilience to network disruption. Genetic variants at hubs of the network influence intellectual performance by modulating associations between performance intelligence quotient (IQ) and the integrity of major white matter tracts, such as the callosal genu and splenium, cingulum, optic radiations, and the superior longitudinal fasciculus.

Chiang, Ming-Chang; Barysheva, Marina; McMahon, Katie L.; de Zubicaray, Greig I.; Johnson, Kori; Montgomery, Grant W.; Martin, Nicholas G.; Toga, Arthur W.; Wright, Margaret J.; Shapshak, Paul; Thompson, Paul M.

2012-01-01

267

Abnormal water diffusivity in corticostriatal projections in children with Tourette syndrome.  

PubMed

The fronto-striato-thalamic circuit has been implicated in the pathomechanism of Tourette Syndrome (TS). To study white and gray matter comprehensively, we used a novel technique called Tract-Based Spatial Statistics (TBSS) combined with voxel-based analysis (VBA) of diffusion tensor MR images in children with TS as compared to typically developing controls. These automated and unbiased methods allow analysis of cerebral white matter and gray matter regions. We compared 15 right-handed children with TS (mean age: 11.6 ± 2.5 years, 12 males) to 14 age-matched right-handed healthy controls (NC; mean age: 12.29 ± 3.2 years, 6 males). Tic severity and neurobehavioral scores were correlated with FA and ADC values in regions found abnormal by these methods. For white matter, TBSS analysis showed regions of increased ADC in the corticostriatal projection pathways including left external capsule and left and right subcallosal fasciculus pathway in TS group compared to NC group. Within the TS group, ADC for the left external capsule was negatively associated with tic severity (r= -0.586, P = 0.02). For gray matter, VBA revealed increased ADC for bilateral orbitofrontal cortex, left putamen, and left insular cortex. ADC for the right and left orbitofrontal cortex was highly correlated with internalizing problems (r = 0.665; P = 0.009, r = 0.545; P = 0.04, respectively). Altogether, this analysis revealed focal diffusion abnormalities in the corticostriatal pathway and in gray matter structures involved in the fronto-striatal circuit in TS. These diffusion abnormalities could serve as a neuroimaging marker related to tic severity and neurobehavioral abnormalities in TS subjects. PMID:20162597

Govindan, Rajkumar Munian; Makki, Malek I; Wilson, Benjamin J; Behen, Michael E; Chugani, Harry T

2010-11-01

268

Neuropathology of chronic GM2 gangliosidosis due to hexosaminidase A deficiency.  

PubMed

Autopsy studies of late-onset GM2 gangliosidosis are sparse and only one adult case is on record. The case of partial Hex A deficiency presented here started in childhood as spinal muscular atrophy which progressed slowly over 4 decades. Cognitive function remained intact throughout the entire course, but during the last few years of life allodynia supervened. The patient died at 44 years of age. In good correlation with clinical observations the autopsy findings showed the most severe accumulation of lipid and consequent regressive change in the anterior horns of the spinal cord. Extensive but less severe storage was found in other spinal cord neurons, brain stem and selected basal ganglia. Cerebral cortex was virtually spared by storage but was the site of excessive formation of lipofuscin which was also present in many other neurons in the CNS. Marked storage and ganglionic loss was also found in the dorsal root ganglia, and the fasciculus gracilis was severely depleted of myelinated fibers. Electron microscopy showed accumulated gangliosides almost exclusively in the form of single and coalescing zebra bodies. In conclusion, the pathology in this case of chronic GM2 gangliosidosis, though in part conforming with previous observations, differed in several aspects. First, the cerebral cortex was--with only a few exceptions--free of ganglioside storage. Also spared was the cerebellum. In addition, homogeneous accumulation of zebra bodies contrasted with heterogeneity of neuronal inclusions found in other chronic cases. Finally, the involvement of sensory neurons was prominent and potentially related to allodynia. Molecular study of HEXA gene in this patient showed an TATC1278/? genotype. PMID:18808061

Kornfeld, M

2008-01-01

269

Relation between variants in the neurotrophin receptor gene, NTRK3, and white matter integrity in healthy young adults.  

PubMed

The NTRK3 gene (also known as TRKC) encodes a high affinity receptor for the neurotrophin 3'-nucleotidase (NT3), which is implicated in oligodendrocyte and myelin development. We previously found that white matter integrity in young adults is related to common variants in genes encoding neurotrophins and their receptors. This underscores the importance of neurotrophins for white matter development. NTRK3 variants are putative risk factors for schizophrenia, bipolar disorder, and obsessive-compulsive disorder hoarding, suggesting that some NTRK3 variants may affect the brain. To test this, we scanned 392 healthy adult twins and their siblings (mean age, 23.6 ± 2.2 years; range: 20-29 years) with 105-gradient 4-Tesla diffusion tensor imaging (DTI). We identified 18 single nucleotide polymorphisms (SNPs) in the NTRK3 gene that have been associated with neuropsychiatric disorders. We used a multi-SNP model, adjusting for family relatedness, age, and sex, to relate these variants to voxelwise fractional anisotropy (FA) - a DTI measure of white matter integrity. FA was optimally predicted (based on the highest false discovery rate critical p), by five SNPs (rs1017412, rs2114252, rs16941261, rs3784406, and rs7176429; overall FDR critical p=0.028). Gene effects were widespread and included the corpus callosum genu and inferior longitudinal fasciculus - regions implicated in several neuropsychiatric disorders and previously associated with other neurotrophin-related genetic variants in an overlapping sample of subjects. NTRK3 genetic variants, and neurotrophins more generally, may influence white matter integrity in brain regions implicated in neuropsychiatric disorders. PMID:23727532

Braskie, Meredith N; Kohannim, Omid; Jahanshad, Neda; Chiang, Ming-Chang; Barysheva, Marina; Toga, Arthur W; Ringman, John M; Montgomery, Grant W; McMahon, Katie L; de Zubicaray, Greig I; Martin, Nicholas G; Wright, Margaret J; Thompson, Paul M

2013-11-15

270

Spatiotemporal Expression of Repulsive Guidance Molecules (RGMs) and Their Receptor Neogenin in the Mouse Brain  

PubMed Central

Neogenin has been implicated in a variety of developmental processes such as neurogenesis, neuronal differentiation, apoptosis, migration and axon guidance. Binding of repulsive guidance molecules (RGMs) to Neogenin inhibits axon outgrowth of different neuronal populations. This effect requires Neogenin to interact with co-receptors of the uncoordinated locomotion-5 (Unc5) family to activate downstream Rho signaling. Although previous studies have reported RGM, Neogenin, and/or Unc5 expression, a systematic comparison of RGM and Neogenin expression in the developing nervous system is lacking, especially at later developmental stages. Furthermore, information on RGM and Neogenin expression at the protein level is limited. To fill this void and to gain further insight into the role of RGM-Neogenin signaling during mouse neural development, we studied the expression of RGMa, RGMb, Neogenin and Unc5A-D using in situ hybridization, immunohistochemistry and RGMa section binding. Expression patterns in the primary olfactory system, cortex, hippocampus, habenula, and cerebellum were studied in more detail. Characteristic cell layer-specific expression patterns were detected for RGMa, RGMb, Neogenin and Unc5A-D. Furthermore, strong expression of RGMa, RGMb and Neogenin protein was found on several major axon tracts such as the primary olfactory projections, anterior commissure and fasciculus retroflexus. These data not only hint at a role for RGM-Neogenin signaling during the development of different neuronal systems, but also suggest that Neogenin partners with different Unc5 family members in different systems. Overall, the results presented here will serve as a framework for further dissection of the role of RGM-Neogenin signaling during neural development.

van den Heuvel, Dianne M. A.; Hellemons, Anita J. C. G. M.; Pasterkamp, R. Jeroen

2013-01-01

271

Specific relations between neurodevelopmental abilities and white matter microstructure in children born preterm.  

PubMed

Survivors of preterm birth have a high incidence of neurodevelopmental impairment which is not explained by currently understood brain abnormalities. The aim of this study was to test the hypothesis that the neurodevelopmental abilities of 2-year-old children who were born preterm and who had no evidence of focal abnormality on conventional MR imaging were consistently linearly related to specific local changes in white matter microstructure. We studied 33 children, born at a median (range) gestational age of 28(+5) (24(+4)-32(+1)) weeks. The children were recruited as infants from the Neonatal Intensive Care Unit at Queen Charlotte's and Hammersmith Hospital in the early neonatal period and imaged at a median corrected age of 25.5 (24-27) months. The children underwent diffusion tensor imaging to measure fractional anisotropy (FA) as a measure of tissue microstructure, and neurodevelopmental assessment using the Griffiths Mental Development Scales [giving an overall developmental quotient (DQ) and sub-quotients scores for motor, personal-social, hearing-language, eye-hand coordination and performance scales] at 2 years corrected age. Tract-based spatial statistics with linear regression analysis of voxel-wise cross-subject statistics were used to assess the relationship between FA and DQ/sub-quotient scores and results confirmed by reduced major axis regression of regions with significant correlations. We found that DQ was linearly related to FA values in parts of the corpus callosum; performance sub-scores to FA values in the corpus callosum and right cingulum; and eye-hand coordination sub-scores to FA values in the cingulum, fornix, anterior commissure, corpus callosum and right uncinate fasciculus. This study shows that specific neurodevelopmental impairments in infants born preterm are precisely related to microstructural abnormalities in particular regions of cerebral white matter which are consistent between individuals. FA may aid prognostication and provide a biomarker for therapeutic or mechanistic studies of preterm brain injury. PMID:18952670

Counsell, Serena J; Edwards, A David; Chew, Andrew T M; Anjari, Mustafa; Dyet, Leigh E; Srinivasan, Latha; Boardman, James P; Allsop, Joanna M; Hajnal, Joseph V; Rutherford, Mary A; Cowan, Frances M

2008-12-01

272

Baseline Brain Metabolism in Resistant Depression and Response to Transcranial Magnetic Stimulation  

PubMed Central

Neuroimaging studies of patients with treatment-resistant depression (TRD) have reported abnormalities in the frontal and temporal regions. We sought to determine whether metabolism in these regions might be related to response to repetitive transcranial magnetic stimulation (TMS) in patients with TRD. Magnetic resonance images and baseline resting-state cerebral glucose uptake index (gluMI) obtained using 18F-fluorodeoxyglucose positron emission tomography were analyzed in TRD patients who had participated in a double-blind, randomized, sham-controlled trial of prefrontal 10?Hz TMS. Among the patients randomized to active TMS, 17 responders, defined as having 50% depression score decrease, and 14 nonresponders were investigated for prestimulation glucose metabolism and compared with 39 healthy subjects using a voxel-based analysis. In nonresponders relative to responders, gluMI was lower in left lateral orbitofrontal cortex (OFC), and higher in left amygdala and uncinate fasciculus. OFC and amygdala gluMI negatively correlated in nonresponders, positively correlated in responders, and did not correlate in healthy subjects. Relative to healthy subjects, both responders and nonresponders displayed lower gluMI in right dorsolateral prefrontal (DLPFC), right anterior cingulate (ACC), and left ventrolateral prefrontal cortices. Additionally, nonresponders had lower gluMI in left DLPFC, ACC, left and right insula, and higher gluMI in left amygdala and uncus. Hypometabolisms were partly explained by gray matter reductions, whereas hypermetabolisms were unrelated to structural changes. The findings suggest that different patterns of frontal–temporal–limbic abnormalities may distinguish responders and nonresponders to prefrontal magnetic stimulation. Both preserved OFC volume and amygdala metabolism might precondition response to TMS.

Martinot, Marie-Laure Paillere; Martinot, Jean-Luc; Ringuenet, Damien; Galinowski, Andre; Gallarda, Thierry; Bellivier, Frank; Lefaucheur, Jean-Pascal; Lemaitre, Herve; Artiges, Eric

2011-01-01

273

Double dissociation between syntactic gender and picture naming processing: a brain stimulation mapping study.  

PubMed

Neural foundations of syntactic gender processing remain poorly understood. We used electrostimulation mapping in nine right-handed awake patients during surgery for a glioma within the left hemisphere, to study whether the cortico-subcortical structures involved in naming versus syntactic gender processing are common or distinct. In French, the article determines the grammatical gender. Thus, the patient was asked to perform a picture naming task and to give the appropriate article for each picture, with and without stimulation. Cortical stimulation elicited reproducible syntactic gender disturbances in six patients, in the inferior frontal gyrus (three cases), and in the posterior middle temporal gyrus (three cases). Interestingly, no naming disorders were generated during stimulation of the syntactic sites, while cortical areas inducing naming disturbances never elicited grammatical gender errors when stimulated. Moreover, at the subcortical level, stimulation of the white matter lateral to the caudate nucleus induced gender errors in three patients, with no naming disorders. Using cortico-subcortical electrical mapping in awake patients, we demonstrate for the first time (1) a double dissociation between syntactic gender and naming processing, supporting independent network model rather than serial theory, (2) the involvement of the left inferior frontal gyrus, especially the pars triangularis, and the posterior left middle temporal gyrus in grammatical gender processing, (3) the existence of white matter pathways, likely a sub-part of the left superior longitudinal fasciculus, underlying a large-scale distributed cortico-subcortical circuit which might selectively sub-serve syntactic gender processing, even if interconnected with parallel sub-networks involved in naming (semantic and phonological) processing. PMID:21319264

Vidorreta, Jose Garbizu; Garcia, Roser; Moritz-Gasser, Sylvie; Duffau, Hugues

2011-03-01

274

Discriminating schizophrenia and bipolar disorder by fusing fMRI and DTI in a multimodal CCA+ joint ICA model.  

PubMed

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 that 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

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

2011-08-01

275

Afferent connections of the cerebellum in various types of reptiles.  

PubMed

The origin of cerebellar afferents was studied in various types of reptiles, viz., the turtles Pseudemys scripta elegans and Testudo hermanni, the lizard Varanus exanthematicus, and the snake Python regius, with retrograde tracers (the enzyme horseradish peroxidase and the fluorescent tracer "Fast Blue"). Projections to the cerebellum were demonstrated from the nucleus of the basal optic root, the interstitial nucleus of the fasciculus longitudinalis medialis, the vestibular ganglion, and the vestibular nuclear complex, two somatosensory nuclei, viz., the descending nucleus of the trigeminal nerve and the nucleus of the dorsal funiculus, the nucleus of the solitary tract, the reticular formation, and throughout the spinal cord. A distinct bilateral projection to the cerebellum was found to arise in a nucleus previously called nucleus parvocellularis medialis (Ebbesson, '67). In the present study this cell mass is termed the perihypoglossal nuclear complex, considering its comparable position and fiber connections to the perihypoglossal nuclei in mammals. In all reptilian species studied a contralateral cerebellar projection of a cell mass located in the caudal brainstem adjacent to the nucleus raphes inferior was observed. It seems likely that this cell mass represents the reptilian homologue of the mammalian inferior olive. Most of the spinocerebellar fibers appeared to arise in neurons located in area VII-VIII of the gray matter. In this respect the origin of the spinocerebellar projection in reptiles resembles the origin of the rostral and ventral spinocerebellar tracts in mammals. No indications for the existence of a column of Clarke or a central cervical nucleus in the reptilian spinal cord were obtained. On comparison of the cerebellum afferents in reptiles with the known connections of the cerebellum in amphibians, birds, and mammals, a basic pattern of cerebellar afferent projections appears to exist in these vertebrate classes, including retinal, vestibular, precerebellar, somatosensory, and spinal afferents. PMID:7107986

Bangma, G C; ten Donkelaar, H

1982-05-20

276

Dopaminergic innervation of human basal ganglia.  

PubMed

This paper summarises the results of some of our recent tyrosine hydroxylase (TH) immunohistochemical studies of the dopaminergic innervation of the human basal ganglia. It also reports new findings on the presence of TH-immunoreactive (ir) neurons in the striatum. Our data show the existence of nigrostriatal TH-ir axons that provide collaterals arborizing in the globus pallidus and subthalamic nucleus. These thin and varicose collaterals emerge from thick and smooth axons that course along the main output pathways of the basal ganglia, including the ansa lenticularis, the lenticular fasciculus and Wilson's pencils. We postulate that this extrastriatal innervation, which allows nigral dopaminergic neurons to directly affect the pallidum and subthalamic nucleus, plays a critical role in the functional organisation of human basal ganglia. The TH-ir fibres that reach the striatum arborize according to a highly heterogeneous pattern. At rostral striatal levels, numerous small TH-poor zones embedded in a TH-rich matrix correspond to calbindin-poor striosomes and calbindin-rich extrastriosomal matrix, respectively. At caudal striatal levels, in contrast, striosomes display a TH immunostaining that is more intense than that of the matrix. A significant number of small, oval, aspiny TH-ir neurons scattered throughout the rostrocaudal extent of the caudate nucleus and putamen, together with a few larger, multipolar, spiny TH-ir neurons lying principally within the ventral portion of the putamen, were disclosed in human. This potential source of intrinsic striatal dopamine might play an important role in the functional organisation of the human striatum, particularly in case of Parkinson's disease. PMID:11207419

Prensa, L; Cossette, M; Parent, A

2000-12-01

277

Prediction of individual subject's age across the human lifespan using diffusion tensor imaging: a machine learning approach.  

PubMed

Diffusion tensor imaging has the potential to be used as a neuroimaging marker of natural ageing and assist in elucidating trajectories of cerebral maturation and ageing. In this study, we applied a multivariate technique relevance vector regression (RVR) to predict individual subject's age using whole brain fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) from a cohort of 188 subjects aged 4-85 years. High prediction accuracy as derived from Pearson correlation coefficient of actual versus predicted age (FA - r=0.870 p<0.0001; MD - r=0.896 p<0.0001; AD - r=0.895 p<0.0001; RD - r=0.899 p<0.0001) was achieved. Cerebral white-matter regions that contributed to these predictions include; corpus callosum, cingulum bundles, posterior longitudinal fasciculus and the cerebral peduncle. A post-hoc analysis of these regions showed that FA follows a nonlinear rational-quadratic trajectory across the lifespan peaking at approximately 21.8 years. The MD, RD and AD volumes were particularly useful for making predictions using grey matter cerebral regions. These results suggest that diffusion tensor imaging measurements can reliably predict individual subject's age and demonstrate that FA cerebral maturation and ageing patterns follow a non-linear trajectory with a noteworthy peaking age. These data will contribute to the understanding of neurobiology of cerebral maturation and ageing. Most notably, from a neuropsychiatric perspective our results may allow differentiation of cerebral changes that may occur due to natural maturation and ageing, and those due to developmental or neuropsychiatric disorders. PMID:23501046

Mwangi, Benson; Hasan, Khader M; Soares, Jair C

2013-07-15

278

Neuroradiological and Neurophysiological Characteristics of Patients With Dyskinetic Cerebral Palsy  

PubMed Central

Objective To investigate neuroradiological and neurophysiological characteristics of patients with dyskinetic cerebral palsy (CP), by using magnetic resonance imaging (MRI), voxel-based morphometry (VBM), diffusion tensor tractography (DTT), and motor evoked potential (MEP). Methods Twenty-three patients with dyskinetic CP (13 males, 10 females; mean age 34 years, range 16-50 years) were participated in this study. Functional evaluation was assessed by the Gross Motor Functional Classification System (GMFCS) and Barry-Albright Dystonia Scale (BADS). Brain imaging was performed on 3.0 Tesla MRI, and volume change of the grey matter was assessed using VBM. The corticospinal tract (CST) and superior longitudinal fasciculus (SLF) were analyzed by DTT. MEPs were recorded in the first dorsal interossei, the biceps brachii and the deltoid muscles. Results Mean BADS was 16.4±5.0 in ambulatory group (GMFCS levels I, II, and III; n=11) and 21.3±3.9 in non-ambulatory group (GMFCS levels IV and V; n=12). Twelve patients showed normal MRI findings, and eleven patients showed abnormal MRI findings (grade I, n=5; grade II, n=2; grade III, n=4). About half of patients with dyskinetic CP showed putamen and thalamus lesions on MRI. Mean BADS was 20.3±5.7 in normal MRI group and 17.5±4.0 in abnormal MRI group. VBM showed reduced volume of the hippocampus and parahippocampal gyrus. In DTT, no abnormality was observed in CST, but not in SLF. In MEPs, most patients showed normal central motor conduction time. Conclusion These results support that extrapyramidal tract, related with basal ganglia circuitry, may be responsible for the pathophysiology of dyskinetic CP rather than CST abnormality.

Park, Byung-Hyun; Seo, Jeong-Hwan; Ko, Myoung-Hwan; Chung, Gyung-Ho

2014-01-01

279

Deterministic Diffusion Fiber Tracking Improved by Quantitative Anisotropy  

PubMed Central

Diffusion MRI tractography has emerged as a useful and popular tool for mapping connections between brain regions. In this study, we examined the performance of quantitative anisotropy (QA) in facilitating deterministic fiber tracking. Two phantom studies were conducted. The first phantom study examined the susceptibility of fractional anisotropy (FA), generalized factional anisotropy (GFA), and QA to various partial volume effects. The second phantom study examined the spatial resolution of the FA-aided, GFA-aided, and QA-aided tractographies. An in vivo study was conducted to track the arcuate fasciculus, and two neurosurgeons blind to the acquisition and analysis settings were invited to identify false tracks. The performance of QA in assisting fiber tracking was compared with FA, GFA, and anatomical information from T1-weighted images. Our first phantom study showed that QA is less sensitive to the partial volume effects of crossing fibers and free water, suggesting that it is a robust index. The second phantom study showed that the QA-aided tractography has better resolution than the FA-aided and GFA-aided tractography. Our in vivo study further showed that the QA-aided tractography outperforms the FA-aided, GFA-aided, and anatomy-aided tractographies. In the shell scheme (HARDI), the FA-aided, GFA-aided, and anatomy-aided tractographies have 30.7%, 32.6%, and 24.45% of the false tracks, respectively, while the QA-aided tractography has 16.2%. In the grid scheme (DSI), the FA-aided, GFA-aided, and anatomy-aided tractographies have 12.3%, 9.0%, and 10.93% of the false tracks, respectively, while the QA-aided tractography has 4.43%. The QA-aided deterministic fiber tracking may assist fiber tracking studies and facilitate the advancement of human connectomics.

Yeh, Fang-Cheng; Verstynen, Timothy D.; Wang, Yibao; Fernandez-Miranda, Juan C.; Tseng, Wen-Yih Isaac

2013-01-01

280

Maternal Pravastatin Prevents Altered Fetal Brain Development in a Preeclamptic CD-1 Mouse Model  

PubMed Central

Objective Using an animal model, we have previously shown that preeclampsia results in long-term adverse neuromotor outcomes in the offspring, and this phenotype was prevented by antenatal treatment with pravastatin. This study aims to localize the altered neuromotor programming in this animal model and to evaluate the role of pravastatin in its prevention. Materials and Methods For the preeclampsia model, pregnant CD-1 mice were randomly allocated to injection of adenovirus carrying sFlt-1 or its control virus carrying mFc into the tail vein. Thereafter they received pravastatin (sFlt-1-pra “experimental group”) or water (sFlt-1 “positive control”) until weaning. The mFc group (“negative control”) received water. Offspring at 6 months of age were sacrificed, and whole brains underwent magnetic resonance imaging (MRI). MRIs were performed using an 11.7 Tesla vertical bore MRI scanner. T2 weighted images were acquired to evaluate the volumes of 28 regions of interest, including areas involved in adaptation and motor, spatial and sensory function. Cytochemistry and cell quantification was performed using neuron-specific Nissl stain. One-way ANOVA with multiple comparison testing was used for statistical analysis. Results Compared with control offspring, male sFlt-1 offspring have decreased volumes in the fimbria, periaquaductal gray, stria medullaris, and ventricles and increased volumes in the lateral globus pallidus and neocortex; however, female sFlt-1 offspring showed increased volumes in the ventricles, stria medullaris, and fasciculus retroflexus and decreased volumes in the inferior colliculus, thalamus, and lateral globus pallidus. Neuronal quantification via Nissl staining exhibited decreased cell counts in sFlt-1 offspring neocortex, more pronounced in males. Prenatal pravastatin treatment prevented these changes. Conclusion Preeclampsia alters brain development in sex-specific patterns, and prenatal pravastatin therapy prevents altered neuroanatomic programming in this animal model.

Carver, Alissa R.; Andrikopoulou, Maria; Lei, Jun; Tamayo, Esther; Gamble, Phyllis; Hou, Zhipeng; Zhang, Jiangyang; Mori, Susumu; Saade, George R.; Costantine, Maged M.; Burd, Irina

2014-01-01

281

Altered interhemispheric and temporal lobe white matter microstructural organization in severe chronic schizophrenia.  

PubMed

Diffusion MRI investigations in schizophrenia provide evidence of abnormal white matter (WM) microstructural organization as indicated by reduced fractional anisotropy (FA) primarily in interhemispheric, left frontal and temporal WM. Using tract-based spatial statistics (TBSS), we examined diffusion parameters in a sample of patients with severe chronic schizophrenia. Diffusion MRI data were acquired on 19 patients with chronic severe schizophrenia and 19 age- and gender-matched healthy controls using a 64 gradient direction sequence, (b=1300 s/mm(2)) collected on a Siemens 1.5T MRI scanner. Diagnosis of schizophrenia was determined by Diagnostic and Statistical Manual for Mental Disorders 4th Edition (DSM-IV) Structured Clinical Interview for DSM disorder (SCID). Patients were treatment resistance, having failed to respond to at least two antipsychotic medications, and had prolonged periods of moderate to severe positive or negative symptoms. Analysis of diffusion parameters was carried out using TBSS. Individuals with chronic severe schizophrenia had significantly reduced FA with corresponding increased radial diffusivity in the genu, body, and splenium of the corpus callosum, the right posterior limb of the internal capsule, right external capsule, and the right temporal inferior longitudinal fasciculus. There were no voxels of significantly increased FA in patients compared with controls. A decrease in splenium FA was shown to be related to a longer illness duration. We detected widespread abnormal diffusivity properties in the callosal and temporal lobe WM regions in individuals with severe chronic schizophrenia who have not previously been exposed to clozapine. These deficits can be driven by a number of factors that are indistinguishable using in vivo diffusion-weighted imaging, but may be related to reduced axonal number or packing density, abnormal glial cell arrangement or function, and reduced myelin. PMID:24150571

Holleran, Laurena; Ahmed, Mohamed; Anderson-Schmidt, Heike; McFarland, John; Emsell, Louise; Leemans, Alexander; Scanlon, Cathy; Dockery, Peter; McCarthy, Peter; Barker, Gareth J; McDonald, Colm; Cannon, Dara M

2014-03-01

282

Criteria and Methodology for Identifying Respiratory Denitrifiers  

PubMed Central

Respiratory denitrification is not always adequately established when bacteria are characterized. We have tested a simple method that allows one to evaluate whether the two necessary criteria to claim denitrification have been met, namely, that N(inf2) or N(inf2)O is produced from nitrate or nitrite and that this reduction is coupled to a growth yield increase. Microorganisms were cultured in sealed tubes under a helium headspace and in the presence of 0, 2, 4, 7, and 10 mM nitrate or nitrite. After growth had ceased, N(inf2) and N(inf2)O were quantified by gas chromatography and the final protein concentration was measured. Net protein production was linearly related to nitrate concentration for all denitrifiers tested and ranged from 2 to 6 g of protein per mol of electron equivalent reduced. Nitrogen recovery as N(inf2) plus N(inf2)O from nitrate and nitrite transformed exceeded 80% for all denitrifiers. We also suggest that a rate of N gas production of >10 (mu)mol/min/g of protein can be used as an additional characteristic definitive of denitrification since this process produces gas more rapidly than other processes. These characteristics were established after evaluation of a variety of well-characterized respiratory denitrifiers and other N(inf2)O-producing nitrate reducers. Several poorly characterized denitrifiers were also tested and confirmed as respiratory denitrifiers, including Aquaspirillum itersonii, Aquaspirillum fasciculus, Bacillus azotoformans, and Corynebacterium nephridii. These criteria distinguished respiratory denitrifiers from other groups that reduce nitrate or produce N(inf2)O. Furthermore, they correctly identified respiratory denitrification in weak denitrifiers, a group in which the existence of this process may be overlooked.

Mahne, I.; Tiedje, J. M.

1995-01-01

283

Autoradiographic localization of putative nicotinic receptors in the rat brain using sup 125 I-neuronal bungarotoxin  

SciTech Connect

Neuronal bungarotoxin (NBT), a snake venom neurotoxin, selectively blocks nicotinic receptors in many peripheral and central neuronal preparations. alpha-Bungarotoxin (alpha BT), on the other hand, a second toxin isolated from the venom of the same snake, is an ineffective nicotinic antagonist in most vertebrate neuronal preparations studied thus far. To examine central nicotinic receptors recognized by NBT, we have characterized the binding of 125I-labeled NBT (125I-NBT) to rat brain membranes and have mapped the distribution of 125I-NBT binding in brain sections using quantitative light microscopic autoradiography. The binding of 125I-NBT was found to be saturable, of high affinity, and heterogeneously distributed in the brain. Pharmacological studies suggested that more than one population of sites is labeled by 125I-NBT. For example, one component of 125I-NBT binding was also recognized by alpha BT, while a second component, not recognized by alpha BT, was recognized by the nicotinic agonist nicotine. The highest densities of these alpha BT-insensitive, nicotine-sensitive sites were found in the fasciculus retroflexus, the lateral geniculate nucleus, the medial terminal nucleus of the accessory optic tract, and the olivary pretectal nucleus. alpha BT-sensitive NBT binding sites were found in highest density in the lateral geniculate nucleus, the subthalamic nucleus, the dorsal tegmental nucleus, and the medial mammillary nucleus (lateral part). The number of brain regions with a high density of 125I-NBT binding sites, blocked either by alpha BT or by nicotine, is low when compared with results obtained using other approaches to studying the central distribution of nicotinic receptors, such as labeling with 3H-nicotine or labeling with cDNA probes to mRNAs coding for putative receptor subunits.

Schulz, D.W.; Loring, R.H.; Aizenman, E.; Zigmond, R.E. (Harvard Medical School, Boston, MA (USA))

1991-01-01

284

Chemical transmission in the rat interpeduncular nucleus in vitro.  

PubMed Central

We have used a rat brain-slice preparation to study the effects of some cholinomimetic and amino acid agonists and antagonists on the discharge frequency of neurones in the interpeduncular nucleus (i.p.n.), and on the response of these neurones to electrical stimulation of their main excitatory input, the fasciculus retroflexus of Meynert (f.r.m.). A high proportion of i.p.n. neurones were excited by carbachol, acetylcholine (ACh) and muscarine, but methacholine was less effective. The amino acids L-glutamate and L-aspartate were highly effective stimulants of i.p.n. neurones. The responses to ACh or carbachol were greatly reduced by the nicotinic blocking agents hexamethonium, d-tubocurarine and mecamylamine but only slightly reduced by atropine. The response to muscarine was abolished by low doses of atropine. Alpha-Bungarotoxin did not block the response of i.p.n. neurones to f.r.m. stimulation or to cholinomimetic agonists. The response of i.p.n. neurones to f.r.m. stimulation was not appreciably affected by high doses of nicotinic antagonists or atropine nor was there any enhancement of the response by physostigmine. The amino acid antagonists gamma-D-glutamylglycine (gamma DGG) and 2-amino phosphonovalerate (2-APV) were effective blockers of the response to f.r.m. stimulation and preferentially reduced responses to aspartate while having little effect on responses to glutamate or cholinomimetic agonists. It is concluded that ACh is an unlikely candidate for transmitter in this pathway despite abundant neurochemical evidence in its favour. It is more likely that the transmitter is an excitatory amino acid, probably an aspartate-like substance.

Brown, D A; Docherty, R J; Halliwell, J V

1983-01-01

285

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

PubMed

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

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

286

Validating Serum S100B and Neuron-Specific Enolase as Biomarkers for the Human Brain - A Combined Serum, Gene Expression and MRI Study  

PubMed Central

Introduction Former studies have investigated the potential of serum biomarkers for diseases affecting the human brain. In particular the glial protein S100B, a neuro- and gliotrophin inducing plasticity, seems to be involved in the pathogenesis and treatment of psychiatric diseases such as major depression and schizophrenia. Neuron-specific enolase (NSE) is a specific serum marker for neuronal damage. However, the specificity of these biomarkers for cell type and brain region has not been investigated in vivo until now. Methods We acquired two magnetic resonance imaging parameters sensitive to changes in gray and white matter (T1-weighted/diffusion tensor imaging) and obtained serum S100B and NSE levels of 41 healthy subjects. Additionally, we analyzed whole brain gene expressions of S100B in another male cohort of three subjects using the Allen Brain Atlas. Furthermore, a female post mortal brain was investigated using double immunofluorescence labelling with oligodendrocyte markers. Results We show that S100B is specifically related to white matter structures, namely the corpus callosum, anterior forceps and superior longitudinal fasciculus in female subjects. This effect was observed in fractional anisotropy and radial diffusivity – the latest an indicator of myelin changes. Histological data confirmed a co-localization of S100B with oligodendrocyte markers in the human corpus callosum. S100B was most abundantly expressed in the corpus callosum according to the whole genome Allen Human Brain Atlas. In addition, NSE was related to gray matter structures, namely the amygdala. This effect was detected across sexes. Conclusion Our data demonstrates a very high S100B expression in white matter tracts, in particular in human corpus callosum. Our study is the first in vivo study validating the specificity of the glial marker S100B for the human brain, and supporting the assumption that radial diffusivity represents a myelin marker. Our results open a new perspective for future studies investigating major neuropsychiatric disorders.

Streitburger, Daniel-Paolo; Arelin, Katrin; Kratzsch, Jurgen; Thiery, Joachim; Steiner, Johann; Villringer, Arno

2012-01-01

287

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

PubMed Central

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.

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

288

Longitudinal diffusion tensor imaging and neuropsychological correlates in traumatic brain injury patients  

PubMed Central

Traumatic brain injury (TBI) often involves focal cortical injury and white matter (WM) damage that can be measured shortly after injury. Additionally, slowly evolving WM change can be observed but there is a paucity of research on the duration and spatial pattern of long-term changes several years post-injury. The current study utilized diffusion tensor imaging to identify regional WM changes in 12 TBI patients and nine healthy controls at three time points over a four year period. Neuropsychological testing was also administered to each participant at each time point. Results indicate that TBI patients exhibit longitudinal changes to WM indexed by reductions in fractional anisotropy (FA) in the corpus callosum, as well as FA increases in bilateral regions of the superior longitudinal fasciculus (SLF) and portions of the optic radiation (OR). FA changes appear to be driven by changes in radial (not axial) diffusivity, suggesting that observed longitudinal FA changes may be related to changes in myelin rather than to axons. Neuropsychological correlations indicate that regional FA values in the corpus callosum and sagittal stratum (SS) correlate with performance on finger tapping and visuomotor speed tasks (respectively) in TBI patients, and that longitudinal increases in FA in the SS, SLF, and OR correlate with improved performance on the visuomotor speed (SS) task as well as a derived measure of cognitive control (SLF, OR). The results of this study showing progressive WM deterioration for several years post-injury contribute to a growing literature supporting the hypothesis that TBI should be viewed not as an isolated incident but as a prolonged disease state. The observations of long-term neurological and functional improvement provide evidence that some ameliorative change may be occurring concurrently with progressive degeneration.

Farbota, Kimberly D.; Bendlin, Barbara B.; Alexander, Andrew L.; Rowley, Howard A.; Dempsey, Robert J.; Johnson, Sterling C.

2012-01-01

289

Structural correlates of skilled performance on a motor sequence task  

PubMed Central

The brain regions functionally engaged in motor sequence performance are well-established, but the structural characteristics of these regions and the fiber pathways involved have been less well studied. In addition, relatively few studies have combined multiple magnetic resonance imaging (MRI) and behavioral performance measures in the same sample. Therefore, the current study used diffusion tensor imaging (DTI), probabilistic tractography, and voxel-based morphometry (VBM) to determine the structural correlates of skilled motor performance. Further, we compared these findings with fMRI results in the same sample. We correlated final performance and rate of improvement measures on a temporal motor sequence task (TMST) with skeletonized fractional anisotropy (FA) and whole brain gray matter (GM) volume. Final synchronization performance was negatively correlated with FA in white matter (WM) underlying bilateral sensorimotor cortex—an effect that was mediated by a positive correlation with radial diffusivity. Multi-fiber tractography indicated that this region contained crossing fibers from the corticospinal tract (CST) and superior longitudinal fasciculus (SLF). The identified SLF pathway linked parietal and auditory cortical regions that have been shown to be functionally engaged in this task. Thus, we hypothesize that enhanced synchronization performance on this task may be related to greater fiber integrity of the SLF. Rate of improvement on synchronization was positively correlated with GM volume in cerebellar lobules HVI and V—regions that showed training-related decreases in activity in the same sample. Taken together, our results link individual differences in brain structure and function to motor sequence performance on the same task. Further, our study illustrates the utility of using multiple MR measures and analysis techniques to specify the interpretation of structural findings.

Steele, Christopher J.; Scholz, Jan; Douaud, Gwenaelle; Johansen-Berg, Heidi; Penhune, Virginia B.

2012-01-01

290

Mecamylamine-precipitated nicotine withdrawal syndrome and its prevention with baclofen: an autoradiographic study of ?4?2 nicotinic acetylcholine receptors in mice.  

PubMed

A previous study from our laboratory showed that baclofen (BAC, GABAB receptor agonist) was able to prevent the behavioral expression of nicotine (NIC) withdrawal syndrome. To further investigate the mechanisms underlying this effect, we conducted this study, with the aims of analyzing ?4?2 nicotinic receptor density during NIC withdrawal and, in case we found any changes, of determining whether they could be prevented by pretreatment with BAC. Swiss Webster albino mice received NIC (2.5 mg/kg, s.c.) 4 times daily, for 7 days. On the 8th day, NIC-treated mice received the nicotinic antagonist mecamylamine (MEC; 2 mg/kg, i.p.) 1 h after the last dose of NIC. A second group of NIC-treated mice received BAC (2 mg/kg, i.p.) prior to MEC administration. Thirty minutes after MEC, mice were sacrificed and brain autoradiography with [(3)H]epibatidine was carried out at five different anatomical levels. Autoradiographic mapping showed a significant increase of ?4?2 nicotinic receptor labeling during NIC withdrawal in the nucleus accumbens shell (AcbSh), medial habenular nucleus (HbM), thalamic nuclei, dorsal lateral geniculate (DLG) nucleus, fasciculus retroflexus (fr), ventral tegmental area, interpeduncular nucleus and superior colliculus. BAC pretreatment prevented the increased ?4?2 nicotinic receptor binding sites in the AcbSh, MHb, thalamic nuclei, DLG nucleus and fr. The present results suggest a relationship between BAC's preventive effect of the expression of NIC withdrawal signs, and its ability to restore the changes in ?4?2 nicotinic receptor labeling, evidenced in specific brain areas in NIC withdrawn animals. PMID:23500668

Varani, Andrés P; Antonelli, Marta C; Balerio, Graciela N

2013-07-01

291

Intraoperative dorsal language network mapping by using single-pulse electrical stimulation.  

PubMed

The preservation of language function during brain surgery still poses a challenge. No intraoperative methods have been established to monitor the language network reliably. We aimed to establish intraoperative language network monitoring by means of cortico-cortical evoked potentials (CCEPs). Subjects were six patients with tumors located close to the arcuate fasciculus (AF) in the language-dominant left hemisphere. Under general anesthesia, the anterior perisylvian language area (AL) was first defined by the CCEP connectivity patterns between the ventrolateral frontal and temporoparietal area, and also by presurgical neuroimaging findings. We then monitored the integrity of the language network by stimulating AL and by recording CCEPs from the posterior perisylvian language area (PL) consecutively during both general anesthesia and awake condition. High-frequency electrical stimulation (ES) performed during awake craniotomy confirmed language function at AL in all six patients. Despite an amplitude decline (?32%) in two patients, CCEP monitoring successfully prevented persistent language impairment. After tumor removal, single-pulse ES was applied to the white matter tract beneath the floor of the removal cavity in five patients, in order to trace its connections into the language cortices. In three patients in whom high-frequency ES of the white matter produced naming impairment, this "eloquent" subcortical site directly connected AL and PL, judging from the latencies and distributions of cortico- and subcortico-cortical evoked potentials. In conclusion, this study provided the direct evidence that AL, PL, and AF constitute the dorsal language network. Intraoperative CCEP monitoring is clinically useful for evaluating the integrity of the language network. Hum Brain Mapp 35:4345-4361, 2014. © 2014 Wiley Periodicals, Inc. PMID:24615889

Yamao, Yukihiro; Matsumoto, Riki; Kunieda, Takeharu; Arakawa, Yoshiki; Kobayashi, Katsuya; Usami, Kiyohide; Shibata, Sumiya; Kikuchi, Takayuki; Sawamoto, Nobukatsu; Mikuni, Nobuhiro; Ikeda, Akio; Fukuyama, Hidenao; Miyamoto, Susumu

2014-09-01

292

An Arbitrary Waveform Wearable Neuro-stimulator System for Neurophysiology Research on Freely Behaving Animals  

PubMed Central

Portable wireless neuro-stimulators have been developed to facilitate long-term cognitive and behavioral studies on the central nervous system in freely moving animals. These stimulators can provide precisely controllable input(s) to the nervous system, without distracting the animal attention with cables connected to its body. In this study, a low power backpack neuro-stimulator was developed for animal brain researches that can provides arbitrary stimulus waveforms for the stimulation, while it is small and light weight to be used for small animals including rats. The system consists of a controller that uses an RF link to program and activate a small and light microprocessor-based stimulator. A Howland current source was implemented to produce precise current controlled arbitrary waveform stimulations. The system was optimized for ultra-low power consumption and small size. The stimulator was first tested for its electrical specifications. Then its performance was evaluated in a rat experiment when electrical stimulation of medial longitudinal fasciculus induced circling behavior. The stimulator is capable of delivering programmed stimulations up to ± 2 mA with adjusting steps of 1 ?A, accuracy of 0.7% and compliance of 6 V. The stimulator is 15 mm × 20 mm × 40 mm in size, weights 13.5 g without battery and consumes a total power of only 5.l mW. In the experiment, the rat could easily carry the stimulator and demonstrated the circling behavior for 0.1 ms current pulses of above 400 ?A. The developed system has a competitive size and weight, whereas providing a wide range of operation and the flexibility of generating arbitrary stimulation patterns ideal for long-term experiments in the field of cognitive and neuroscience research.

Samani, Mohsen Mosayebi; Mahnam, Amin; Hosseini, Nasrin

2014-01-01

293

Profiles of white matter tract pathology in frontotemporal dementia.  

PubMed

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. Hum Brain Mapp 35:4163-4179, 2014. © 2014 The Authors. Human Brain Mapping Published by Wiley Periodicals, Inc. PMID:24510641

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

2014-08-01

294

White matter microstructural abnormalities in girls with chromosome 22q11.2 deletion syndrome, Fragile X or Turner syndrome as evidenced by diffusion tensor imaging.  

PubMed

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 14years 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

Villalon-Reina, Julio; Jahanshad, Neda; Beaton, Elliott; Toga, Arthur W; Thompson, Paul M; Simon, Tony J

2013-11-01

295

Effects of alcohol use initiation on brain structure in typically developing adolescents  

PubMed Central

Background Alcohol use in excessive quantities has deleterious effects on brain structure and behavior in adults and during periods of rapid neurodevelopment, such as prenatally. Whether similar outcomes characterize other developmental periods, such as adolescence, and in the context of less extensive use is unknown. Recent cross-sectional studies suggest that binge drinking as well as alcohol use disorders in adolescence are associated with disruptions in white matter microstructure and gray matter volumes. Objectives The current study followed typically developing adolescents from a baseline assessment, where no experience with alcohol was present, through two years, after which some individuals transitioned into regular use. Methods Participants (n = 55) completed MRI scans and behavioral assessments. Results Alcohol initiators (n = 30; mean baseline age 16.7 ± 1.3 years), compared to non-users (n = 25; mean baseline age 17.1 ± 1.2 years), showed altered patterns of neurodevelopment. They showed greater-than-expected decreases in cortical thickness in the right middle frontal gyrus from baseline to follow-up as well as blunted development of white matter in the right hemisphere precentral gyrus, lingual gyrus, middle temporal gyrus and anterior cingulate. Diffusion tensor imaging revealed a relative decrease over time in fractional anisotropy in the left caudate/thalamic region as well as in the right inferior frontal occipital fasciculus. Alcohol initiators did not differ from non-users at the baseline assessment; the groups were largely similar in other premorbid characteristics. Conclusions Subclinical alcohol use during mid-to-late adolescence is associated with deviations in neurodevelopment across several brain tissue classes. Implications for continued development and behavior are discussed.

Luciana, Monica; Collins, Paul F.; Muetzel, Ryan L.; Lim, Kelvin O.

2014-01-01

296

Longitudinal changes in patients with traumatic brain injury assessed with diffusion tensor and volumetric imaging  

PubMed Central

Traumatic brain injury (TBI) is associated with brain volume loss, but there is little information on the regional gray matter (GM) and white matter (WM) changes that contribute to overall loss. Since axonal injury is a common occurrence in TBI, imaging methods that are sensitive to WM damage such as diffusion-tensor imaging (DTI) may be useful for characterizing microstructural brain injury contributing to regional WM loss in TBI. High-resolution T1-weighted imaging and DTI were used to evaluate regional changes in TBI patients compared to matched controls. Patients received neuropsychological testing and were imaged approximately 2 months and 12.7 months post injury. Paradoxically, neuropsychological function improved from Visit 1 to Visit 2, while voxel-based analyses of fractional anisotropy (FA), and mean diffusivity (MD) from the DTI images, and voxel-based analyses of the GM and WM probability maps from the T1-weighted images, mainly revealed significantly greater deleterious GM and WM change over time in patients compared to controls. Cross-sectional comparisons of the DTI measures indicated that patients have decreased FA and increased MD compared to controls over large regions of the brain. TBI affected virtually all of the major fiber bundles in the brain including the corpus callosum, cingulum, the superior and inferior longitudinal fascicules, the uncinate fasciculus, and brain stem fiber tracts. The results indicate that both GM and WM degeneration are significant contributors to brain volume loss in the months following brain injury, and also suggest that DTI measures may be more useful than high-resolution anatomical images in assessment of group differences.

Bendlin, Barbara; Ries, Michele L.; Lazar, Mariana; Alexander, Andrew L.; Dempsey, Robert J.; Rowley, Howard A.; Sherman, Jack E.; Johnson, Sterling C.

2008-01-01

297

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

PubMed Central

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.

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

298

Problem solving, working memory, and motor correlates of association and commissural fiber bundles in normal aging  

PubMed Central

Normal aging is accompanied by decline in selective cognitive and motor functions. A concurrent decline in regional white matter integrity, detectable with diffusion tensor imaging (DTI), potentially contributes to waning function. DTI analysis of white matter loci indicates an anterior-to-posterior gradient distribution of declining fractional anisotropy (FA) and increasing diffusivity with age. Quantitative fiber tracking can be used to determine regional patterns of normal aging of fiber systems and test the functional ramifications of the DTI metrics. Here, we used quantitative fiber tracking to examine age effects on commissural (genu and splenium), bilateral association (cingulate, inferior longitudinal fasciculus and uncinate), and fornix fibers in 12 young and 12 elderly healthy men and women and tested functional correlates with concurrent assessment of a wide range of neuropsychological abilities. Principal component analysis of cognitive and motor tests on which the elderly achieved significantly lower scores than the young group was used for data reduction and yielded three factors: Problem Solving, Working Memory, and Motor. Age effects - lower FA or higher diffusivity - in the elderly were prominent in anterior tracts, specifically, genu, fornix, and uncinate fibers. Differential correlations between FA or diffusivity in fiber tracts and scores on Problem Solving, Working Memory, or Motor factors provide convergent validity to the biological meaningfulness of the integrity of the fibers tracked. The observed pattern of relations supports the possibility that regional degradation of white matter fiber integrity is a biological source of age-related functional compromise and may have the potential to limit accessibility to alternative neural systems to compensate for compromised function.

Zahr, Natalie M.; Rohlfing, Torsten; Pfefferbaum, Adolf; Sullivan, Edith V.

2009-01-01

299

An Arbitrary Waveform Wearable Neuro-stimulator System for Neurophysiology Research on Freely Behaving Animals.  

PubMed

Portable wireless neuro-stimulators have been developed to facilitate long-term cognitive and behavioral studies on the central nervous system in freely moving animals. These stimulators can provide precisely controllable input(s) to the nervous system, without distracting the animal attention with cables connected to its body. In this study, a low power backpack neuro-stimulator was developed for animal brain researches that can provides arbitrary stimulus waveforms for the stimulation, while it is small and light weight to be used for small animals including rats. The system consists of a controller that uses an RF link to program and activate a small and light microprocessor-based stimulator. A Howland current source was implemented to produce precise current controlled arbitrary waveform stimulations. The system was optimized for ultra-low power consumption and small size. The stimulator was first tested for its electrical specifications. Then its performance was evaluated in a rat experiment when electrical stimulation of medial longitudinal fasciculus induced circling behavior. The stimulator is capable of delivering programmed stimulations up to ± 2 mA with adjusting steps of 1 ?A, accuracy of 0.7% and compliance of 6 V. The stimulator is 15 mm × 20 mm × 40 mm in size, weights 13.5 g without battery and consumes a total power of only 5.l mW. In the experiment, the rat could easily carry the stimulator and demonstrated the circling behavior for 0.1 ms current pulses of above 400 ?A. The developed system has a competitive size and weight, whereas providing a wide range of operation and the flexibility of generating arbitrary stimulation patterns ideal for long-term experiments in the field of cognitive and neuroscience research. PMID:24761373

Samani, Mohsen Mosayebi; Mahnam, Amin; Hosseini, Nasrin

2014-04-01

300

Carbocyanine Dye Usage in Demarcating Boundaries of the Aged Human Red Nucleus  

PubMed Central

Background Though the adult human magnocellular Red nucleus (mNr) is essentially vestigial and its boundaries with neighbouring structures have never been well demarcated, human studies in utero have shown a well developed semilunar mNr wrapping around the caudal parvicellular Red nucleus (pNr), similar to what is seen in quadrupeds. In the present study, we have sought to better delineate the morphological determinants of the adult human Red nucleus (ahRn). Methods and Findings Serial sections of ahRn show fine myelinated fibers arising from pNr and turning toward the central tegmental tract. DiI was deposited within a well restricted region of ahRn at the fasciculus retroflexus level and the extent of label determined. Nissl-stained serial sections allowed production of a 3-D mNr model, showing rudimentary, vestigial morphology compared with its well developed infant homologue. DiI within this vestigial mNr region at the level of the oculomotor nerve showed labeled giant/large mNr neurons, coarse fiber bundles at the ventral tegmental decussation and lateral lemniscal label. Conclusions Large amounts of DiI and a long incubation time have proven useful in aged human brain as a marker of long axons and large cell bodies of projecting neurons such as the rubrospinal projection and for clarifying nuclear boundaries of closed nuclei (e.g., the large human pNr). Our 3D model of adult human mNr appeared shrunken in shape and axially rotated compared with the infant mNr, the rotation being a common feature among mammalian mNr.

Onodera, Satoru; Hicks, T. Philip

2010-01-01

301

Improved sensitivity to cerebral white matter abnormalities in Alzheimer's disease with spherical deconvolution based tractography.  

PubMed

Diffusion tensor imaging (DTI) based fiber tractography (FT) is the most popular approach for investigating white matter tracts in vivo, despite its inability to reconstruct fiber pathways in regions with "crossing fibers." Recently, constrained spherical deconvolution (CSD) has been developed to mitigate the adverse effects of "crossing fibers" on DTI based FT. Notwithstanding the methodological benefit, the clinical relevance of CSD based FT for the assessment of white matter abnormalities remains unclear. In this work, we evaluated the applicability of a hybrid framework, in which CSD based FT is combined with conventional DTI metrics to assess white matter abnormalities in 25 patients with early Alzheimer's disease. Both CSD and DTI based FT were used to reconstruct two white matter tracts: one with regions of "crossing fibers," i.e., the superior longitudinal fasciculus (SLF) and one which contains only one fiber orientation, i.e. the midsagittal section of the corpus callosum (CC). The DTI metrics, fractional anisotropy (FA) and mean diffusivity (MD), obtained from these tracts were related to memory function. Our results show that in the tract with "crossing fibers" the relation between FA/MD and memory was stronger with CSD than with DTI based FT. By contrast, in the fiber bundle where one fiber population predominates, the relation between FA/MD and memory was comparable between both tractography methods. Importantly, these associations were most pronounced after adjustment for the planar diffusion coefficient, a measure reflecting the degree of fiber organization complexity. These findings indicate that compared to conventionally applied DTI based FT, CSD based FT combined with DTI metrics can increase the sensitivity to detect functionally significant white matter abnormalities in tracts with complex white matter architecture. PMID:22952880

Reijmer, Yael D; Leemans, Alexander; Heringa, Sophie M; Wielaard, Ilse; Jeurissen, Ben; Koek, Huiberdina L; Biessels, Geert Jan

2012-01-01

302

Electroconvulsive therapy mediates neuroplasticity of white matter microstructure in major depression  

PubMed Central

Whether plasticity of white matter (WM) microstructure relates to therapeutic response in major depressive disorder (MDD) remains uncertain. We examined diffusion tensor imaging (DTI) correlates of WM structural connectivity in patients receiving electroconvulsive therapy (ECT), a rapidly acting treatment for severe MDD. Tract-Based Spatial Statistics (TBSS) applied to DTI data (61 directions, 2.5?mm3 voxel size) targeted voxel-level changes in fractional anisotropy (FA), and radial (RD), axial (AD) and mean diffusivity (MD) in major WM pathways in MDD patients (n=20, mean age: 41.15 years, 10.32 s.d.) scanned before ECT, after their second ECT and at transition to maintenance therapy. Comparisons made at baseline with demographically similar controls (n=28, mean age: 39.42 years, 12.20 s.d.) established effects of diagnosis. Controls were imaged twice to estimate scanning-related variance. Patients showed significant increases of FA in dorsal fronto-limbic circuits encompassing the anterior cingulum, forceps minor and left superior longitudinal fasciculus between baseline and transition to maintenance therapy (P<0.05, corrected). Decreases in RD and MD were observed in overlapping regions and the anterior thalamic radiation (P<0.05, corrected). Changes in DTI metrics associated with therapeutic response in tracts showing significant ECT effects differed between patients and controls. All measures remained stable across time in controls. Altered WM microstructure in pathways connecting frontal and limbic areas occur in MDD, are modulated by ECT and relate to therapeutic response. Increased FA together with decreased MD and RD, which trend towards normative values with treatment, suggest increased fiber integrity in dorsal fronto-limbic pathways involved in mood regulation.

Lyden, H; Espinoza, R T; Pirnia, T; Clark, K; Joshi, S H; Leaver, A M; Woods, R P; Narr, K L

2014-01-01

303

White Matter Tract Damage in the Behavioral Variant of Frontotemporal and Corticobasal Dementia Syndromes  

PubMed Central

The phenotypes of the behavioral variant of frontotemporal dementia and the corticobasal syndrome present considerable clinical and anatomical overlap. The respective patterns of white matter damage in these syndromes have not been directly contrasted. Beyond cortical involvement, damage to white matter pathways may critically contribute to both common and specific symptoms in both conditions. Here we assessed patients with the behavioral variant of frontotemporal dementia and corticobasal syndrome with whole-brain diffusion tensor imaging to identify the white matter networks underlying these pathologies. Twenty patients with the behavioral variant of frontotemporal dementia, 19 with corticobasal syndrome, and 15 healthy controls were enrolled in the study. Differences in tract integrity between (i) patients and controls, and (ii) patients with the corticobasal syndrome and the behavioral variant of frontotemporal dementia were assessed with whole brain tract-based spatial statistics and analyses of regions of interest. Behavioral variant of frontotemporal dementia and the corticobasal syndrome shared a pattern of bilaterally decreased white matter integrity in the anterior commissure, genu and body of the corpus callosum, corona radiata and in the long intrahemispheric association pathways. Patients with the behavioral variant of frontotemporal dementia showed greater damage to the uncinate fasciculus, genu of corpus callosum and forceps minor. In contrast, corticobasal syndrome patients had greater damage to the midbody of the corpus callosum and perirolandic corona radiata. Whereas several compact white matter pathways were damaged in both the behavioral variant of frontotemporal dementia and corticobasal syndrome, the distribution and degree of white matter damage differed between them. These findings concur with the distinctive clinical manifestations of these conditions and may improve the in vivo neuroanatomical and diagnostic characterization of these disorders.

Tovar-Moll, Fernanda; de Oliveira-Souza, Ricardo; Bramati, Ivanei Edson; Zahn, Roland; Cavanagh, Alyson; Tierney, Michael; Moll, Jorge; Grafman, Jordan

2014-01-01

304

Diffusion tractography of post-mortem human brains: Optimization and comparison of spin echo and steady-state free precession techniques  

PubMed Central

Diffusion imaging of post-mortem brains could provide valuable data for validation of diffusion tractography of white matter pathways. Long scans (e.g., overnight) may also enable high-resolution diffusion images for visualization of fine structures. However, alterations to post-mortem tissue (T2 and diffusion coefficient) present significant challenges to diffusion imaging with conventional diffusion-weighted spin echo (DW-SE) acquisitions, particularly for imaging human brains on clinical scanners. Diffusion-weighted steady-state free precession (DW-SSFP) has been proposed as an alternative acquisition technique to ameliorate this tradeoff in large-bore clinical scanners. In this study, both DWSE and DW-SSFP are optimized for use in fixed white matter on a clinical 3-Tesla scanner. Signal calculations predict superior performance from DW-SSFP across a broad range of protocols and conditions. DW-SE and DW-SSFP data in a whole, post-mortem human brain are compared for 6- and 12-hour scan durations. Tractography is performed in major projection, commissural and association tracts (corticospinal tract, corpus callosum, superior longitudinal fasciculus and cingulum bundle). The results demonstrate superior tract-tracing from DW-SSFP data, with 6-hour DW-SSFP data performing as well as or better than 12-hour DW-SE scans. These results suggest that DW-SSFP may be a preferred method for diffusion imaging of post-mortem human brains. The ability to estimate multiple fibers in imaging voxels is also demonstrated, again with greater success in DW-SSFP data.

Miller, Karla L.; McNab, Jennifer A.; Jbabdi, Saad; Douaud, Gwenaelle

2012-01-01

305

Quantitative diffusion tensor imaging and intellectual outcomes in spina bifida  

PubMed Central

Object Patients with spina bifida (SB) have variable intellectual outcomes. The authors used diffusion tensor (DT) imaging to quantify whole-brain volumes of gray matter, white matter, and cerebrospinal fluid (CSF), and perform regional quantitative microstructural assessments of gray matter nuclei and white matter tracts in relation to intellectual outcomes in patients with SB. Methods Twenty-nine children with myelomeningoceles and 20 age- and sex-matched children with normal neural tube development underwent MR imaging with DT image acquisition and assessments of intelligence. The DT imaging-derived metrics were the fractional anisotropy (FA), axial (parallel), and transverse (perpendicular) diffusivities. These metrics were also used to segment the brain into white matter, gray matter, and CSF. A region-of-interest analysis was conducted of the white and gray matter structures implicated in hydrocephalus. Results The amount of whole-brain gray matter was decreased in patients with SB, with a corresponding increase in CSF (p < 0.0001). Regional transverse diffusivity in the caudate nucleus was decreased (p < 0.0001), and the corresponding FA was increased (p < 0.0001), suggesting reduced dendritic branching and connectivity. Fractional anisotropy in the posterior limb of the internal capsule increased in the myelomeningocele group (p = 0.02), suggesting elimination of some divergent fascicles; in contrast, the FA in several white matter structures (such as the corpus callosum genu [p < 0.001] and arcuate fasciculus) was reduced, suggesting disruption of myelination. Diffusion tensor imaging-metrics involving gray matter volume and the caudate nucleus, but not other structures, predicted variations in IQ (r = 0.37-0.50; p < 0.05). Conclusions Diffusion tensor imaging-derived metrics provide noninvasive neuronal surrogate markers of the pathogenesis of SB and predict variations in general intellectual outcomes in children with this condition.

Hasan, Khader M.; Sankar, Ambika; Halphen, Christopher; Kramer, Larry A.; Ewing-Cobbs, Linda; Dennis, Maureen; Fletcher, Jack M.

2011-01-01

306

Diffusion tractography of post-mortem human brains: optimization and comparison of spin echo and steady-state free precession techniques.  

PubMed

Diffusion imaging of post-mortem brains could provide valuable data for validation of diffusion tractography of white matter pathways. Long scans (e.g., overnight) may also enable high-resolution diffusion images for visualization of fine structures. However, alterations to post-mortem tissue (T2 and diffusion coefficient) present significant challenges to diffusion imaging with conventional diffusion-weighted spin echo (DW-SE) acquisitions, particularly for imaging human brains on clinical scanners. Diffusion-weighted steady-state free precession (DW-SSFP) has been proposed as an alternative acquisition technique to ameliorate this tradeoff in large-bore clinical scanners. In this study, both DWSE and DW-SSFP are optimized for use in fixed white matter on a clinical 3-Tesla scanner. Signal calculations predict superior performance from DW-SSFP across a broad range of protocols and conditions. DW-SE and DW-SSFP data in a whole, post-mortem human brain are compared for 6- and 12-hour scan durations. Tractography is performed in major projection, commissural and association tracts (corticospinal tract, corpus callosum, superior longitudinal fasciculus and cingulum bundle). The results demonstrate superior tract-tracing from DW-SSFP data, with 6-hour DW-SSFP data performing as well as or better than 12-hour DW-SE scans. These results suggest that DW-SSFP may be a preferred method for diffusion imaging of post-mortem human brains. The ability to estimate multiple fibers in imaging voxels is also demonstrated, again with greater success in DW-SSFP data. PMID:22008372

Miller, Karla L; McNab, Jennifer A; Jbabdi, Saad; Douaud, Gwenaëlle

2012-02-01

307

Pioneer midbrain longitudinal axons navigate using a balance of Netrin attraction and Slit repulsion  

PubMed Central

Background Longitudinal axons grow parallel to the embryonic midline to connect distant regions of the central nervous system. Previous studies suggested that repulsive midline signals guide pioneer longitudinal axons by blocking their entry into the floor plate; however, the role of midline attractants, and whether attractant signals may cooperate with repulsive signals, remains unclear. In this study we investigated the navigation of a set of pioneer longitudinal axons, the medial longitudinal fasciculus, in mouse embryos mutant for the Netrin/Deleted in Colorectal Cancer (DCC) attractants, and for Slit repellents, as well as the responses of explanted longitudinal axons in vitro. Results In mutants for Netrin1 chemoattractant or DCC receptor signaling, longitudinal axons shifted away from the ventral midline, suggesting that Netrin1/DCC signals act attractively to pull axons ventrally. Analysis of mutants in the three Slit genes, including Slit1/2/3 triple mutants, suggest that concurrent repulsive Slit/Robo signals push pioneer axons away from the ventral midline. Combinations of mutations between the Netrin and Slit guidance systems provided genetic evidence that the attractive and repulsive signals balance against each other. This balance is demonstrated in vitro using explant culture, finding that the cues can act directly on longitudinal axons. The explants also reveal an unexpected synergy of Netrin1 and Slit2 that promotes outgrowth. Conclusions These results support a mechanism in which longitudinal trajectories are positioned by a push-pull balance between opposing Netrin and Slit signals. Our evidence suggests that longitudinal axons respond directly and simultaneously to both attractants and repellents, and that the combined signals constrain axons to grow longitudinally.

2014-01-01

308

The Evolution of Syntax: An Exaptationist Perspective  

PubMed Central

The evolution of language required elaboration of a number of independent mechanisms in the hominin lineage, including systems involved in signaling, semantics, and syntax. Two perspectives on the evolution of syntax can be contrasted. The “continuist” perspective seeks the evolutionary roots of complex human syntax in simpler combinatory systems used in animal communication systems, such as iteration and sequencing. The “exaptationist” perspective posits evolutionary change of function, so that systems today used for linguistic communication might previously have served quite different functions in earlier hominids. I argue that abundant biological evidence supports an exaptationist perspective, in general, and that it must be taken seriously when considering language evolution. When applied to syntax, this suggests that core computational components used today in language could have originally served non-linguistic functions such as motor control, non-verbal thought, or spatial reasoning. I outline three specific exaptationist hypotheses for spoken language. These three hypotheses each posit a change of functionality in a precursor circuit, and its transformation into a neural circuit or region specifically involved in language today. Hypothesis 1 suggests that the precursor mechanism for intentional vocal control, specifically direct cortical control over the larynx, was manual motor control subserved by the cortico-spinal tract. The second is that the arcuate fasciculus, which today connects syntactic and lexical regions, had its origin in intracortical connections subserving vocal imitation. The third is that the specialized components of Broca’s area, specifically BA 45, had their origins in non-linguistic motor control, and specifically hierarchical planning of action. I conclude by illustrating the importance of both homology (studied via primates) and convergence (typically analyzed in birds) for testing such evolutionary hypotheses.

Fitch, W. Tecumseh

2011-01-01

309

A novel approach with "skeletonised MTR" measures tract-specific microstructural changes in early primary-progressive MS.  

PubMed

We combined tract-based spatial statistics (TBSS) and magnetization transfer (MT) imaging to assess white matter (WM) tract-specific short-term changes in early primary-progressive multiple sclerosis (PPMS) and their relationships with clinical progression. Twenty-one PPMS patients within 5 years from onset underwent MT and diffusion tensor imaging (DTI) at baseline and after 12 months. Patients' disability was assessed. DTI data were processed to compute fractional anisotropy (FA) and to generate a common WM "skeleton," which represents the tracts that are "common" to all subjects using TBSS. The MT ratio (MTR) was computed from MT data and co-registered with the DTI. The skeletonization procedure derived for FA was applied to each subject's MTR image to obtain a "skeletonised" MTR map for every subject. Permutation tests were used to assess (i) changes in FA, principal diffusivities, and MTR over the follow-up, and (ii) associations between changes in imaging parameters and changes in disability. Patients showed significant decreases in MTR over one year in the corpus callosum (CC), bilateral corticospinal tract (CST), thalamic radiations, and superior and inferior longitudinal fasciculi. These changes were located both within lesions and the normal-appearing WM. No significant longitudinal change in skeletonised FA was found, but radial diffusivity (RD) significantly increased in several regions, including the CST bilaterally and the right inferior longitudinal fasciculus. MTR decreases, RD increases, and axial diffusivity decreases in the CC and CST correlated with a deterioration in the upper limb function. We detected tract-specific multimodal imaging changes that reflect the accrual of microstructural damage and possibly contribute to clinical impairment in PPMS. We propose a novel methodology that can be extended to other diseases to map cross-subject and tract-specific changes in MTR. PMID:23616276

Bodini, Benedetta; Cercignani, Mara; Toosy, Ahmed; De Stefano, Nicola; Miller, David H; Thompson, Alan J; Ciccarelli, Olga

2014-02-01

310

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

PubMed Central

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.

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

2011-01-01

311

Descending projections of the hamster intergeniculate leaflet: relationship to the sleep/arousal and visuomotor systems  

NASA Technical Reports Server (NTRS)

The intergeniculate leaflet (IGL), homolog of the primate pregeniculate nucleus, modulates circadian rhythms. However, its extensive anatomical connections suggest that it may regulate other systems, particularly those for visuomotor function and sleep/arousal. Here, descending IGL-efferent pathways are identified with the anterograde tracer, Phaseolus vulgaris leucoagglutinin, with projections to over 50 brain stem nuclei. Projections of the ventral lateral geniculate are similar, but more limited. Many of the nuclei with IGL afferents contribute to circuitry governing visuomotor function. These include the oculomotor, trochlear, anterior pretectal, Edinger-Westphal, and the terminal nuclei; all layers of the superior colliculus, interstitial nucleus of the medial longitudinal fasciculus, supraoculomotor periaqueductal gray, nucleus of the optic tract, the inferior olive, and raphe interpositus. Other target nuclei are known to be involved in the regulation of sleep, including the lateral dorsal and pedunculopontine tegmentum. The dorsal raphe also receives projections from the IGL and may contribute to both sleep/arousal and visuomotor function. However, the locus coeruleus and medial vestibular nucleus, which contribute to sleep and eye movement regulation and which send projections to the IGL, do not receive reciprocal projections from it. The potential involvement of the IGL with the sleep/arousal system is further buttressed by existing evidence showing IGL-efferent projections to the ventrolateral preoptic area, dorsomedial, and medial tuberal hypothalamus. In addition, the great majority of all regions receiving IGL projections also receive input from the orexin/hypocretin system, suggesting that this system contributes not only to the regulation of sleep, but to eye movement control as well.

Morin, Lawrence P.; Blanchard, Jane H.

2005-01-01

312

Grey and white matter abnormalities in temporal lobe epilepsy with and without mesial temporal sclerosis  

PubMed Central

Temporal lobe epilepsy with (TLE-mts) and without (TLE-no) mesial temporal sclerosis display different patterns of cortical neuronal loss, suggesting that the distribution of white matter damage may also differ between the sub-groups. The purpose of this study was to examine patterns of white matter damage in TLE-mts and TLE-no and to determine if identified changes are related to neuronal loss at the presumed seizure focus. The 4 T diffusion tensor imaging (DTI) and T1-weighted data were acquired for 22 TLE-mts, 21 TLE-no and 31 healthy controls. Tract-based spatial statistics (TBSS) was used to compare fractional anisotropy (FA) maps and voxel-based morphometry (VBM) was used to identify grey matter (GM) volume atrophy. Correlation analysis was conducted between the FA maps and neuronal loss at the presumed seizure focus. In TLE-mts, reduced FA was identified in the genu, body and splenium of the corpus callosum, bilateral corona radiata, cingulum, external capsule, ipsilateral internal capsule and uncinate fasciculus. In TLE-no, FA decreases were identified in the genu, the body of the corpus callosum and ipsilateral anterior corona radiata. The FA positively correlated with ipsilateral hippocampal volume. Widespread extra-focal GM atrophy was associated with both sub-groups. Despite widespread and extensive GM atrophy displaying different anatomical patterns in both sub-groups, TLE-mts demonstrated more extensive FA abnormalities than TLE-no. The microstructural organization in the corpus callosum was related to hippocampal volume in both patients and healthy subjects demonstrating the association of these distal regions.

Scanlon, Cathy; Mueller, Susanne G.; Cheong, Ian; Hartig, Miriam; Weiner, Michael W.

2013-01-01

313

White matter microstructural changes in psychogenic erectile dysfunction patients.  

PubMed

Brain dysfunction in erectile dysfunction (ED) has been identified by multiple neuroimaging studies. A recent MRI study indicated grey matter alterations in ED patients. This study aims to investigate the microstructural changes of cerebral white matter (WM) in psychological ED patients and their possible correlations with clinical variables. Twenty-seven psychological ED patients and 27 healthy subjects (HS) were included and underwent a magnetic resonance (MR) diffusion tensor imaging (DTI) scan. The tract-based spatial statistics were employed to identify the WM structure alterations in psychological ED patients. The multiple DTI-derived indices' [fractional anisotropy (FA), axial diffusivity (AD) and mean diffusivity (MD)] correlations with the symptoms and their durations, respectively, were analysed. The IIEF-5, quality of erection questionnaire (QEQ) and the self-esteem and relationship (SEAR) questionnaire were used to assess the symptoms of psychological ED patients. Compared with HS, the psychological ED patients showed increased FA values, reduced MD values and reduced AD values in multiple WM tracts including the corpus callosum (genu, body and splenium), corticospinal tract, internal capsule, corona radiata, external capsule and superior longitudinal fasciculus (p < 0.05, threshold-free cluster enhancement corrected). Both of the IIEF scores and QEQ scores of ED patients showed a significantly negative correlation with the average FA values, and positive correlation with average AD values and MD values in the splenium of the corpus callosum (p < 0.05). The results provided preliminary evidence of WM microstructural changes in patients with psychological ED. The morphological alterations in the splenium of the corpus callosum were related to the symptom severity. PMID:24711250

Zhang, P; Liu, J; Li, G; Pan, J; Li, Z; Liu, Q; Qin, W; Dong, M; Sun, J; Huang, X; Wu, T; Chang, D

2014-05-01

314

Repeatability and variation of region-of-interest methods using quantitative diffusion tensor MR imaging of the brain  

PubMed Central

Background Diffusion tensor imaging (DTI) is increasingly used in various diseases as a clinical tool for assessing the integrity of the brain’s white matter. Reduced fractional anisotropy (FA) and an increased apparent diffusion coefficient (ADC) are nonspecific findings in most pathological processes affecting the brain’s parenchyma. At present, there is no gold standard for validating diffusion measures, which are dependent on the scanning protocols, methods of the softwares and observers. Therefore, the normal variation and repeatability effects on commonly-derived measures should be carefully examined. Methods Thirty healthy volunteers (mean age 37.8 years, SD 11.4) underwent DTI of the brain with 3T MRI. Region-of-interest (ROI) -based measurements were calculated at eleven anatomical locations in the pyramidal tracts, corpus callosum and frontobasal area. Two ROI-based methods, the circular method (CM) and the freehand method (FM), were compared. Both methods were also compared by performing measurements on a DTI phantom. The intra- and inter-observer variability (coefficient of variation, or CV%) and repeatability (intra-class correlation coefficient, or ICC) were assessed for FA and ADC values obtained using both ROI methods. Results The mean FA values for all of the regions were 0.663 with the CM and 0.621 with the FM. For both methods, the FA was highest in the splenium of the corpus callosum. The mean ADC value was 0.727 ×10-3 mm2/s with the CM and 0.747 ×10-3 mm2/s with the FM, and both methods found the ADC to be lowest in the corona radiata. The CV percentages of the derived measures were < 13% with the CM and < 10% with the FM. In most of the regions, the ICCs were excellent or moderate for both methods. With the CM, the highest ICC for FA was in the posterior limb of the internal capsule (0.90), and with the FM, it was in the corona radiata (0.86). For ADC, the highest ICC was found in the genu of the corpus callosum (0.93) with the CM and in the uncinate fasciculus (0.92) with FM. Conclusions With both ROI-based methods variability was low and repeatability was moderate. The circular method gave higher repeatability, but variation was slightly lower using the freehand method. The circular method can be recommended for the posterior limb of the internal capsule and splenium of the corpus callosum, and the freehand method for the corona radiata.

2012-01-01

315

Characterizing a neurodegenerative syndrome: primary progressive apraxia of speech  

PubMed Central

Apraxia of speech is a disorder of speech motor planning and/or programming that is distinguishable from aphasia and dysarthria. It most commonly results from vascular insults but can occur in degenerative diseases where it has typically been subsumed under aphasia, or it occurs in the context of more widespread neurodegeneration. The aim of this study was to determine whether apraxia of speech can present as an isolated sign of neurodegenerative disease. Between July 2010 and July 2011, 37 subjects with a neurodegenerative speech and language disorder were prospectively recruited and underwent detailed speech and language, neurological, neuropsychological and neuroimaging testing. The neuroimaging battery included 3.0 tesla volumetric head magnetic resonance imaging, [18F]-fluorodeoxyglucose and [11C] Pittsburg compound B positron emission tomography scanning. Twelve subjects were identified as having apraxia of speech without any signs of aphasia based on a comprehensive battery of language tests; hence, none met criteria for primary progressive aphasia. These subjects with primary progressive apraxia of speech included eight females and four males, with a mean age of onset of 73 years (range: 49–82). There were no specific additional shared patterns of neurological or neuropsychological impairment in the subjects with primary progressive apraxia of speech, but there was individual variability. Some subjects, for example, had mild features of behavioural change, executive dysfunction, limb apraxia or Parkinsonism. Voxel-based morphometry of grey matter revealed focal atrophy of superior lateral premotor cortex and supplementary motor area. Voxel-based morphometry of white matter showed volume loss in these same regions but with extension of loss involving the inferior premotor cortex and body of the corpus callosum. These same areas of white matter loss were observed with diffusion tensor imaging analysis, which also demonstrated reduced fractional anisotropy and increased mean diffusivity of the superior longitudinal fasciculus, particularly the premotor components. Statistical parametric mapping of the [18F]-fluorodeoxyglucose positron emission tomography scans revealed focal hypometabolism of superior lateral premotor cortex and supplementary motor area, although there was some variability across subjects noted with CortexID analysis. [11C]-Pittsburg compound B positron emission tomography binding was increased in only one of the 12 subjects, although it was unclear whether the increase was actually related to the primary progressive apraxia of speech. A syndrome characterized by progressive pure apraxia of speech clearly exists, with a neuroanatomic correlate of superior lateral premotor and supplementary motor atrophy, making this syndrome distinct from primary progressive aphasia.

Duffy, Joseph R.; Strand, Edythe A.; Machulda, Mary M.; Senjem, Matthew L.; Master, Ankit V.; Lowe, Val J.; Jack, Clifford R.; Whitwell, Jennifer L.

2012-01-01

316

Dissociated repetition deficits in aphasia can reflect flexible interactions between left dorsal and ventral streams and gender-dimorphic architecture of the right dorsal stream.  

PubMed

Assessment of brain-damaged subjects presenting with dissociated repetition deficits after selective injury to either the left dorsal or ventral auditory pathways can provide further insight on their respective roles in verbal repetition. We evaluated repetition performance and its neural correlates using multimodal imaging (anatomical MRI, DTI, fMRI, and(18)FDG-PET) in a female patient with transcortical motor aphasia (TCMA) and in a male patient with conduction aphasia (CA) who had small contiguous but non-overlapping left perisylvian infarctions. Repetition in the TCMA patient was fully preserved except for a mild impairment in nonwords and digits, whereas the CA patient had impaired repetition of nonwords, digits and word triplet lists. Sentence repetition was impaired, but he repeated novel sentences significantly better than clichés. The TCMA patient had tissue damage and reduced metabolism in the left sensorimotor cortex and insula. DTI showed damage to the left temporo-frontal and parieto-frontal segments of the arcuate fasciculus (AF) and part of the left ventral stream together with well-developed right dorsal and ventral streams, as has been reported in more than one-third of females. The CA patient had tissue damage and reduced metabolic activity in the left temporoparietal cortex with additional metabolic decrements in the left frontal lobe. DTI showed damage to the left temporo-parietal and temporo-frontal segments of the AF, but the ventral stream was spared. The direct segment of the AF in the right hemisphere was also absent with only vestigial remains of the other dorsal subcomponents present, as is often found in males. fMRI during word and nonword repetition revealed bilateral perisylvian activation in the TCMA patient suggesting recruitment of spared segments of the left dorsal stream and right dorsal stream with propagation of signals to temporal lobe structures suggesting a compensatory reallocation of resources via the ventral streams. The CA patient showed a greater activation of these cortical areas than the TCMA patient, but these changes did not result in normal performance. Repetition of word triplet lists activated bilateral perisylvian cortices in both patients, but activation in the CA patient with very poor performance was restricted to small frontal and posterior temporal foci bilaterally. These findings suggest that dissociated repetition deficits in our cases are probably reliant on flexible interactions between left dorsal stream (spared segments, short tracts remains) and left ventral stream and on gender-dimorphic architecture of the right dorsal stream. PMID:24391569

Berthier, Marcelo L; Froudist Walsh, Seán; Dávila, Guadalupe; Nabrozidis, Alejandro; Juárez Y Ruiz de Mier, Rocío; Gutiérrez, Antonio; De-Torres, Irene; Ruiz-Cruces, Rafael; Alfaro, Francisco; García-Casares, Natalia

2013-01-01

317

Predicting speech fluency and naming abilities in aphasic patients.  

PubMed

There is a need to identify biomarkers that predict degree of chronic speech fluency/language impairment and potential for improvement after stroke. We previously showed that the Arcuate Fasciculus lesion load (AF-LL), a combined variable of lesion site and size, predicted speech fluency in patients with chronic aphasia. In the current study, we compared lesion loads of such a structural map (i.e., AF-LL) with those of a functional map [i.e., the functional gray matter lesion load (fGM-LL)] in their ability to predict speech fluency and naming performance in a large group of patients. The fGM map was constructed from functional brain images acquired during an overt speaking task in a group of healthy elderly controls. The AF map was reconstructed from high-resolution diffusion tensor images also from a group of healthy elderly controls. In addition to these two canonical maps, a combined AF-fGM map was derived from summing fGM and AF maps. Each canonical map was overlaid with individual lesion masks of 50 chronic aphasic patients with varying degrees of impairment in speech production and fluency to calculate a functional and structural lesion load value for each patient, and to regress these values with measures of speech fluency and naming. We found that both AF-LL and fGM-LL independently predicted speech fluency and naming ability; however, AF lesion load explained most of the variance for both measures. The combined AF-fGM lesion load did not have a higher predictability than either AF-LL or fGM-LL alone. Clustering and classification methods confirmed that AF lesion load was best at stratifying patients into severe and non-severe outcome groups with 96% accuracy for speech fluency and 90% accuracy for naming. An AF-LL of greater than 4 cc was the critical threshold that determined poor fluency and naming outcomes, and constitutes the severe outcome group. Thus, surrogate markers of impairments have the potential to predict outcomes and can be used as a stratifier in experimental studies. PMID:24339811

Wang, Jasmine; Marchina, Sarah; Norton, Andrea C; Wan, Catherine Y; Schlaug, Gottfried

2013-01-01

318

Hereditary spastic paraplegia: clinico-pathologic features and emerging molecular mechanisms  

PubMed Central

Hereditary spastic paraplegia (HSP) is a syndrome designation describing inherited disorders in which lower extremity weakness and spasticity are the predominant symptoms. There are more than 50 genetic types of HSP. HSP affects individuals diverse ethnic groups with prevalence estimates ranging from 1.2 to 9.6 per 100,000 [39, 70, 77, 154, 185]. Symptoms may begin at any age. Gait impairment that begins after childhood usually worsens very slowly over many years. Gait impairment that begins in infancy and early childhood may not worsen significantly. Post mortem studies consistently identify degeneration of corticospinal tract axons (maximal in the thoracic spinal cord) and degeneration of fasciculus gracilis fibers (maximal in the cervico-medullary region). HSP syndromes thus appear to involve motor-sensory axon degeneration affecting predominantly (but not exclusively) the distal ends of long central nervous system (CNS) axons. In general, proteins encoded by HSP genes have diverse functions including axon transport (e.g. SPG30/KIF1A, SPG10/KIF5A and possibly SPG4/Spastin); endoplasmic reticulum morphology (e.g. SPG3A/Atlastin, SPG4/Spastin, SPG12/reticulon 2, and SPG31/REEP1, all of which interact); mitochondrial function (e.g. SPG13/chaperonin 60/heat shock protein 60, SPG7/paraplegin; and mitochondrial ATP6; 4) myelin formation (e.g. SPG2/Proteolipid protein and SPG42/Connexin 47); 5) protein folding and ER-stress response (SPG6/NIPA1, SPG8/K1AA0196 (Strumpellin), SGP17/BSCL2 (Seipin) [113-115], “mutilating sensory neuropathy with spastic paraplegia” due to CcT5 mutation and presumably SPG18/ERLIN2); 6) corticospinal tract and other neurodevelopment (e.g. SPG1/L1 cell adhesion molecule and SPG22/thyroid transporter MCT8); 7) fatty acid and phospholipid metabolism (e.g. SPG28/DDHD1, SPG35/FA2H, SPG39/NTE, SPG54/DDHD2, and SPG56/CYP2U1); and 8) endosome membrane trafficking and vesicle formation (e.g. SPG47/AP4B1, SPG48/KIAA0415, SPG50/AP4M1, SPG51/AP4E, SPG52/AP4S1, and VSPG53/VPS37A). The availability of animal models (including bovine, murine, zebrafish, Drosophila, and C. elegans) for many types of HSP permits exploration of disease mechanisms and potential treatments. This review highlights emerging concepts of this large group of clinically similar disorders. For recent review of HSP including historical descriptions, differential diagnosis, and additional references see [78].

Fink, John K.

2014-01-01

319

Transneuronal transport in the vestibular and auditory systems of the squirrel monkey and the arctic ground squirrel. I. Vestibular system.  

PubMed

Transneuronal transport of [3H]proline, [3H]fucose, and [3H]leucine in various combinations from pledgets implanted in the ampulla of a single semicircular duct was studied in the squirrel monkey and arctic ground squirrel after long survival periods. Tritiated amino acids implanted in any single ampulla resulted in labeling of nearly all vestibular and auditory receptors, nearly all cells of the vestibular and spiral ganglia and central transport via nearly all root fibers of both nerves. Primary vestibular fibers were distributed to the vestibular nuclei (VN) and specific parts of the cerebellum in the pattern previously described. Transneuronal transport of [3H]proline by vestibular neurons was present in all known secondary pathways, except those projecting to thalamic nuclei. Observations were similar in both species, except for small differences in commissural vestibular projections. Major commissural transport was to all parts of the opposite medial vestibular nucleus (MVN) and to peripheral parts of the superior vestibular nucleus (SVN), but some transport was present in all contralateral VN, including ventral cell group y. Descending transneuronal transport was evident in vestibulospinal tract (VST) ipsilaterally and in the medial longitudinal fasciculus (MLF) bilaterally. Both [3H]proline and [3]fucose were transported transneuronally to the ipsilateral abducens nucleus (AN); with long survivals [3H]proline was transported peripherally via the ipsilateral abducens nerve root. Ascending transport in the MLF was bilateral, asymmetric and greatest contralaterally. Fibers entered the contralateral MLF near the AN and the lateral wing of the ipsilateral MLF rostral to most of the VN. Terminals in the trochlear nuclei (TN) were bilateral and greatest contralaterally. In the monkey terminals in ipsilateral oculomotor complex (OMC) were distributed uniformly in all subdivisions, except for the medial rectus subdivision (MRS), where terminals were more numerous. The greatest density of terminals was present contralaterally in the superior rectus subdivision (SRS) of the OMC; only sparse terminals were present in the MRS on that side. Transport in the ipsilateral abducens nerve roots in the monkey and the virtual absence of transport to the MRS of the contralateral OMC suggested transneuronal transport to abducens motor neurons, but not to internuclear neurons (AIN). The AIN project only to the MRS of the contralateral OMC and do not appear to receive vestibular input. Comparable observations were made in the AN, TN and OMC of the ground squirrel, although the representation of the extraocular muscles in the OMC is unknown.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:4075118

Carpenter, M B; Cowie, R J

1985-12-01

320

Predicting speech fluency and naming abilities in aphasic patients  

PubMed Central

There is a need to identify biomarkers that predict degree of chronic speech fluency/language impairment and potential for improvement after stroke. We previously showed that the Arcuate Fasciculus lesion load (AF-LL), a combined variable of lesion site and size, predicted speech fluency in patients with chronic aphasia. In the current study, we compared lesion loads of such a structural map (i.e., AF-LL) with those of a functional map [i.e., the functional gray matter lesion load (fGM-LL)] in their ability to predict speech fluency and naming performance in a large group of patients. The fGM map was constructed from functional brain images acquired during an overt speaking task in a group of healthy elderly controls. The AF map was reconstructed from high-resolution diffusion tensor images also from a group of healthy elderly controls. In addition to these two canonical maps, a combined AF-fGM map was derived from summing fGM and AF maps. Each canonical map was overlaid with individual lesion masks of 50 chronic aphasic patients with varying degrees of impairment in speech production and fluency to calculate a functional and structural lesion load value for each patient, and to regress these values with measures of speech fluency and naming. We found that both AF-LL and fGM-LL independently predicted speech fluency and naming ability; however, AF lesion load explained most of the variance for both measures. The combined AF-fGM lesion load did not have a higher predictability than either AF-LL or fGM-LL alone. Clustering and classification methods confirmed that AF lesion load was best at stratifying patients into severe and non-severe outcome groups with 96% accuracy for speech fluency and 90% accuracy for naming. An AF-LL of greater than 4 cc was the critical threshold that determined poor fluency and naming outcomes, and constitutes the severe outcome group. Thus, surrogate markers of impairments have the potential to predict outcomes and can be used as a stratifier in experimental studies.

Wang, Jasmine; Marchina, Sarah; Norton, Andrea C.; Wan, Catherine Y.; Schlaug, Gottfried

2013-01-01

321

Dissociated repetition deficits in aphasia can reflect flexible interactions between left dorsal and ventral streams and gender-dimorphic architecture of the right dorsal stream  

PubMed Central

Assessment of brain-damaged subjects presenting with dissociated repetition deficits after selective injury to either the left dorsal or ventral auditory pathways can provide further insight on their respective roles in verbal repetition. We evaluated repetition performance and its neural correlates using multimodal imaging (anatomical MRI, DTI, fMRI, and18FDG-PET) in a female patient with transcortical motor aphasia (TCMA) and in a male patient with conduction aphasia (CA) who had small contiguous but non-overlapping left perisylvian infarctions. Repetition in the TCMA patient was fully preserved except for a mild impairment in nonwords and digits, whereas the CA patient had impaired repetition of nonwords, digits and word triplet lists. Sentence repetition was impaired, but he repeated novel sentences significantly better than clichés. The TCMA patient had tissue damage and reduced metabolism in the left sensorimotor cortex and insula. DTI showed damage to the left temporo-frontal and parieto-frontal segments of the arcuate fasciculus (AF) and part of the left ventral stream together with well-developed right dorsal and ventral streams, as has been reported in more than one-third of females. The CA patient had tissue damage and reduced metabolic activity in the left temporoparietal cortex with additional metabolic decrements in the left frontal lobe. DTI showed damage to the left temporo-parietal and temporo-frontal segments of the AF, but the ventral stream was spared. The direct segment of the AF in the right hemisphere was also absent with only vestigial remains of the other dorsal subcomponents present, as is often found in males. fMRI during word and nonword repetition revealed bilateral perisylvian activation in the TCMA patient suggesting recruitment of spared segments of the left dorsal stream and right dorsal stream with propagation of signals to temporal lobe structures suggesting a compensatory reallocation of resources via the ventral streams. The CA patient showed a greater activation of these cortical areas than the TCMA patient, but these changes did not result in normal performance. Repetition of word triplet lists activated bilateral perisylvian cortices in both patients, but activation in the CA patient with very poor performance was restricted to small frontal and posterior temporal foci bilaterally. These findings suggest that dissociated repetition deficits in our cases are probably reliant on flexible interactions between left dorsal stream (spared segments, short tracts remains) and left ventral stream and on gender-dimorphic architecture of the right dorsal stream.

Berthier, Marcelo L.; Froudist Walsh, Sean; Davila, Guadalupe; Nabrozidis, Alejandro; Juarez y Ruiz de Mier, Rocio; Gutierrez, Antonio; De-Torres, Irene; Ruiz-Cruces, Rafael; Alfaro, Francisco; Garcia-Casares, Natalia

2013-01-01

322

Alterations in brain structure and functional connectivity in prescription opioid-dependent patients  

PubMed Central

A dramatic increase in the use and dependence of prescription opioids has occurred within the last 10 years. The consequences of long-term prescription opioid use and dependence on the brain are largely unknown, and any speculation is inferred from heroin and methadone studies. Thus, no data have directly demonstrated the effects of prescription opioid use on brain structure and function in humans. To pursue this issue, we used structural magnetic resonance imaging, diffusion tensor imaging and resting-state functional magnetic resonance imaging in a highly enriched group of prescription opioid-dependent patients [(n?=??10); from a larger study on prescription opioid dependent patients (n?=??133)] and matched healthy individuals (n?=??10) to characterize possible brain alterations that may be caused by long-term prescription opioid use. Criteria for patient selection included: (i) no dependence on alcohol or other drugs; (ii) no comorbid psychiatric or neurological disease; and (iii) no medical conditions, including pain. In comparison to control subjects, individuals with opioid dependence displayed bilateral volumetric loss in the amygdala. Prescription opioid-dependent subjects had significantly decreased anisotropy in axonal pathways specific to the amygdala (i.e. stria terminalis, ventral amygdalofugal pathway and uncinate fasciculus) as well as the internal and external capsules. In the patient group, significant decreases in functional connectivity were observed for seed regions that included the anterior insula, nucleus accumbens and amygdala subdivisions. Correlation analyses revealed that longer duration of prescription opioid exposure was associated with greater changes in functional connectivity. Finally, changes in amygdala functional connectivity were observed to have a significant dependence on amygdala volume and white matter anisotropy of efferent and afferent pathways of the amygdala. These findings suggest that prescription opioid dependence is associated with structural and functional changes in brain regions implicated in the regulation of affect and impulse control, as well as in reward and motivational functions. These results may have important clinical implications for uncovering the effects of long-term prescription opioid use on brain structure and function.

Upadhyay, Jaymin; Maleki, Nasim; Potter, Jennifer; Elman, Igor; Rudrauf, David; Knudsen, Jaime; Wallin, Diana; Pendse, Gautam; McDonald, Leah; Griffin, Margaret; Anderson, Julie; Nutile, Lauren; Renshaw, Perry; Weiss, Roger; Becerra, Lino

2010-01-01

323

Damage to white matter pathways in subacute and chronic spatial neglect: a group study and 2 single-case studies with complete virtual "in vivo" tractography dissection.  

PubMed

The exact anatomical localization of right hemisphere lesions that lead to left spatial neglect is still debated. The effect of confounding factors such as acute diaschisis and hypoperfusion, visual field defects, and lesion size may account for conflicting results that have been reported in the literature. Here, we present a comprehensive anatomical investigation of the gray- and white matter lesion correlates of left spatial neglect, which was run in a sample 58 patients with subacute or chronic vascular strokes in the territory of the right middle cerebral artery. Standard voxel-based correlates confirmed the role played by lesions in the posterior parietal cortex (supramarginal gyrus, angular gyrus, and temporal-parietal junction), in the frontal cortex (frontal eye field, middle and inferior frontal gyrus), and in the underlying parietal-frontal white matter. Using a new diffusion tensor imaging-based atlas of the human brain, we were able to run, for the first time, a detailed analysis of the lesion involvement of subcortical white matter pathways. The results of this analysis revealed that, among the different pathways linking parietal with frontal areas, damage to the second branch of the superior longitudinal fasciculus (SLF II) was the best predictor of left spatial neglect. The group study also revealed a subsample of patients with neglect due to focal lesion in the lateral-dorsal portion of the thalamus, which connects the premotor cortex with the inferior parietal lobule. The relevance of fronto-parietal disconnection was further supported by complete in vivo tractography dissection of white matter pathways in 2 patients, one with and the other without signs of neglect. These 2 patients were studied both in the acute phase and 1 year after stroke and were perfectly matched for age, handedness, stroke onset, lesion size, and for cortical lesion involvement. Taken together, the results of the present study support the hypothesis that anatomical disconnections leading to a functional breakdown of parietal-frontal networks are an important pathophysiological factor leading to chronic left spatial neglect. Here, we propose that different loci of SLF disconnection on the rostro-caudal axis can also be associated with disconnection of short-range white matter pathways within the frontal or parietal areas. Such different local disconnection patterns can play a role in the important clinical variability of the neglect syndrome. PMID:23162045

Thiebaut de Schotten, Michel; Tomaiuolo, Francesco; Aiello, Marilena; Merola, Sheila; Silvetti, Massimo; Lecce, Francesca; Bartolomeo, Paolo; Doricchi, Fabrizio

2014-03-01

324

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

PubMed Central

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.

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

325

Development of Cerebral Fiber Pathways in Cats revealed by Diffusion Spectrum Imaging  

PubMed Central

Examination of the three-dimensional axonal pathways in the developing brain is key to understanding the formation of cerebral connectivity. By tracing fiber pathways throughout the entire brain, diffusion tractography provides information that cannot be achieved by conventional anatomical MR imaging or histology. However, standard diffusion tractography (based on diffusion tensor imaging, or DTI) tends to terminate in brain areas with low water diffusivity, indexed by low diffusion fractional anisotropy (FA), which can be caused by crossing fibers as well as fibers with less myelin. For this reason, DTI tractography is not effective for delineating the structural changes that occur in the developing brain, where the process of myelination is incomplete, and where crossing fibers exist in greater numbers than in the adult brain. Unlike DTI, diffusion spectrum imaging (DSI) can define multiple directions of water diffusivity; as such, diffusion tractography based on DSI provides marked flexibility for delineation of fiber tracts in areas where the fiber architecture is complex and multidirectional, even in areas of low FA. In this study, we showed that FA values were lower in the white matter of newborn (postnatal day 0; P0) cat brains than in the white matter of infant (P35) and juvenile (P100) cat brains. These results correlated well with histological myelin stains of the white matter: the newborn kitten brain has much less myelin than that found in cat brains at later stages of development. Using DSI tractography, we successfully identified structural changes in thalamo-cortical and cortico-cortical association tracts in cat brains from one stage of development to another. In newborns, the main body of the thalamo-cortical tract was smooth, and fibers branching from it were almost straight, while the main body became more complex and branching fibers became curved reflecting gyrification in the older cats. Cortico-cortical tracts in the temporal lobe were smooth in newborns, and they formed a sharper angle in the later stages of development. The cingulum bundle and superior longitudinal fasciculus became more visible with time. Within the first month after birth, structural changes occurred in these tracts that coincided with the formation of the gyri. These results show that DSI tractography has the potential for mapping morphological changes in low FA areas associated with growth and development. The technique may also be applicable to the study of other forms of brain plasticity, including future studies in vivo.

Takahashi, Emi; Dai, Guangping; Wang, Ruopeng; Ohki, Kenichi; Rosen, Glenn D.; Galaburda, Albert M.; Grant, P. Ellen; Wedeen, Van J.

2009-01-01

326

Voxel-based structural magnetic resonance imaging (MRI) study of patients with early onset schizophrenia  

PubMed Central

Background Investigation into the whole brain morphology of early onset schizophrenia (EOS) to date has been sparse. We studied the regional brain volumes in EOS patients, and the correlations between regional volume measures and symptom severity. Methods A total of 18 EOS patients (onset under 16 years) and 18 controls matched for age, gender, parental socioeconomic status, and height were examined. Voxel-based morphometric analysis using the Brain Analysis Morphological Mapping (BAMM) software package was employed to explore alterations of the regional grey (GM) and white matter (WM) volumes in EOS patients. Symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS). Results EOS patients had significantly reduced GM volume in the left parahippocampal, inferior frontal, and superior temporal gyri, compared with the controls. They also had less WM volume in the left posterior limb of the internal capsule and the left inferior longitudinal fasciculus. The positive symptom score of PANSS (higher values corresponding to more severe symptoms) was negatively related to GM volume in the bilateral posterior cingulate gyrus. The negative symptom score was positively correlated with GM volume in the right thalamus. As for the association with WM volume, the positive symptom score of PANSS was positively related to cerebellar WM (vermis region), and negatively correlated with WM in the brain stem (pons) and in the bilateral cerebellum (hemisphere region). Conclusion Our findings of regional volume alterations of GM and WM in EOS patients coincide with those of previous studies of adult onset schizophrenia patients. However, in brain regions that had no overall structural differences between EOS patients and controls (that is, the bilateral posterior cingulate gyrus, the right thalamus, the cerebellum, and the pons), within-subject analysis of EOS patients alone revealed that there were significant associations of the volume in these areas and the symptom severity. These findings suggest that at an early stage of the illness, especially for those with onset before brain maturation, a wide range of disturbed neural circuits, including these brain regions that show no apparent morphological changes, may contribute to the formation of the symptomatology.

Yoshihara, Yujiro; Sugihara, Genichi; Matsumoto, Hideo; Suckling, John; Nishimura, Katsuhiko; Toyoda, Takao; Isoda, Haruo; Tsuchiya, Kenji J; Takebayashi, Kiyokazu; Suzuki, Katsuaki; Sakahara, Harumi; Nakamura, Kazuhiko; Mori, Norio; Takei, Nori

2008-01-01

327

Quantification of white matter fibre pathways disruption in frontal transcortical approach to the lateral ventricle or the interventricular foramen in diffusion tensor tractography.  

PubMed

Pathologies occupying the interventricular foramen (foramen of Monro - FM) or the anterior part of lateral ventricle (LV) are accessed by the transcortical or transcallosal route. As severing of rostral corpus callosum has been deemed inferior to cortical incision, the approaches through various points of frontal lobe have been developed. Superior (F1), middle (F2) frontal gyrus or occasionally superior frontal sulcus are used as an entry of neurosurgical corridor. In spite of the fact that every approach to LV or FM causes its characteristic irreversible damage to white matter, to date all of transcortical routes are regarded as equivalent. The current study compared the damage of main neural bundles between virtualtrans-F1 and trans-F2 corridors by means of diffusion tensor tractography method (DTT) in 11 magnetic resonance imaging (MRI) exams from clinical series (22 hemispheres, regardless of dominance). Corpus callosum, cingulum, subdivisions I and II of superior longitudinal fasciculus (SLF I and SLF II), corticoreticular as well as pyramidal tracts crossing both approaches were subjected to surgical violation. Both approaches served a similar total number of fibres (0.94 to 1.78 [× 103]).Trans-F1 route caused significantly greater damage of total white matter volume(F1: 8.26 vs. F2: 7.16 mL), percentage of SLF I fibres (F1: 78.6% vs. F2: 28.6%)and cingulum (F1: 49.4% vs. F2: 10.6%), whereas trans-F2 route interrupted morecorticoreticular fibres (F1: 4.5% vs. F2: 30.7%). Pyramidal tract (F1: 0.6% vs. F2:1.3%) and SLF II (F1: 15.9% vs. F2: 26.2%) were marginally more vulnerable incase of the access via middle frontal gyrus. Both approaches destroyed 7% of callosal fibres. Summarising the above DTT findings, trans-F2 route disrupted a greater number of fibres from eloquent neural bundles (SLF II, pyramidal and corticoreticular tracts), therefore is regarded as inferior to trans-F1 one. Due to lack of up-to-date guidelines with recommendations of the approaches to LV or FM, an individual preoperative planning based on DTT should precede a surgery. PMID:24902089

Szmuda, T; S?oniewski, P; Szmuda, M; Waszak, P M; Starzy?ska, A

2014-05-01