Science.gov

Sample records for fronto-occipital fasciculus revisited

  1. Q-Ball of Inferior Fronto-Occipital Fasciculus and Beyond

    PubMed Central

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

    2014-01-01

    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. PMID:24945305

  2. Phenotypic and Genetic Correlations Between the Lobar Segments of the Inferior Fronto-occipital Fasciculus and Attention

    PubMed Central

    Leng, Yuan; Shi, Yonggang; Yu, Qiaowen; Van Horn, John Darrell; Tang, Haiyan; Li, Junning; Xu, Wenjian; Ge, Xinting; Tang, Yuchun; Han, Yan; Zhang, Dong; Xiao, Min; Zhang, Huaqiang; Pang, Zengchang; Toga, Arthur W.; Liu, Shuwei

    2016-01-01

    Attention deficits may present dysfunctions in any one or two components of attention (alerting, orienting, and executive control (EC)). However, these various forms of attention deficits generally have abnormal microstructure integrity of inferior fronto-occipital fasciculus (IFOF). In this work, we aim to deeply explore: (1) associations between microstructure integrities of IFOF (including frontal, parietal, temporal, occipital, and insular segments) and attention by means of structural equation models and multiple regression analyses; (2) genetic/environmental effects on IFOF, attention, and their correlations using bivariate genetic analysis. EC function was attributed to the fractional anisotropy (FA) of left (correlation was driven by genetic and environmental factors) and right IFOF (correlation was driven by environmental factors), especially to left frontal part and right occipital part (correlation was driven by genetic factors). Alerting was associated with FA in parietal and insular parts of left IFOF. No significant correlation was found between orienting and IFOF. This study revealed the advantages of lobar-segmental analysis in structure-function correlation study and provided the anatomical basis for kinds of attention deficits. The common genetic/environmental factors implicated in the certain correlations suggested the common physiological mechanisms for two traits, which should promote the discovery of single-nucleotide polymorphisms affecting IFOF and attention. PMID:27597294

  3. Phenotypic and Genetic Correlations Between the Lobar Segments of the Inferior Fronto-occipital Fasciculus and Attention.

    PubMed

    Leng, Yuan; Shi, Yonggang; Yu, Qiaowen; Van Horn, John Darrell; Tang, Haiyan; Li, Junning; Xu, Wenjian; Ge, Xinting; Tang, Yuchun; Han, Yan; Zhang, Dong; Xiao, Min; Zhang, Huaqiang; Pang, Zengchang; Toga, Arthur W; Liu, Shuwei

    2016-01-01

    Attention deficits may present dysfunctions in any one or two components of attention (alerting, orienting, and executive control (EC)). However, these various forms of attention deficits generally have abnormal microstructure integrity of inferior fronto-occipital fasciculus (IFOF). In this work, we aim to deeply explore: (1) associations between microstructure integrities of IFOF (including frontal, parietal, temporal, occipital, and insular segments) and attention by means of structural equation models and multiple regression analyses; (2) genetic/environmental effects on IFOF, attention, and their correlations using bivariate genetic analysis. EC function was attributed to the fractional anisotropy (FA) of left (correlation was driven by genetic and environmental factors) and right IFOF (correlation was driven by environmental factors), especially to left frontal part and right occipital part (correlation was driven by genetic factors). Alerting was associated with FA in parietal and insular parts of left IFOF. No significant correlation was found between orienting and IFOF. This study revealed the advantages of lobar-segmental analysis in structure-function correlation study and provided the anatomical basis for kinds of attention deficits. The common genetic/environmental factors implicated in the certain correlations suggested the common physiological mechanisms for two traits, which should promote the discovery of single-nucleotide polymorphisms affecting IFOF and attention. PMID:27597294

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2016-01-01

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

  6. Normal variation in fronto-occipital circuitry and cerebellar structure with an autism-associated polymorphism of CNTNAP2

    PubMed Central

    Tan, Geoffrey C.Y.; Doke, Thomas F.; Ashburner, John; Wood, Nicholas W.; Frackowiak, Richard S.J.

    2010-01-01

    Recent genetic studies have implicated a number of candidate genes in the pathogenesis of Autism Spectrum Disorder (ASD). Polymorphisms of CNTNAP2 (contactin-associated like protein-2), a member of the neurexin family, have already been implicated as a susceptibility gene for autism by at least 3 separate studies. We investigated variation in white and grey matter morphology using structural MRI and diffusion tensor imaging. We compared volumetric differences in white and grey matter and fractional anisotropy values in control subjects characterised by genotype at rs7794745, a single nucleotide polymorphism in CNTNAP2. Homozygotes for the risk allele showed significant reductions in grey and white matter volume and fractional anisotropy in several regions that have already been implicated in ASD, including the cerebellum, fusiform gyrus, occipital and frontal cortices. Male homozygotes for the risk alleles showed greater reductions in grey matter in the right frontal pole and in FA in the right rostral fronto-occipital fasciculus compared to their female counterparts who showed greater reductions in FA of the anterior thalamic radiation. Thus a risk allele for autism results in significant cerebral morphological variation, despite the absence of overt symptoms or behavioural abnormalities. The results are consistent with accumulating evidence of CNTNAP2's function in neuronal development. The finding suggests the possibility that the heterogeneous manifestations of ASD can be aetiologically characterised into distinct subtypes through genetic-morphological analysis. PMID:20176116

  7. The role of left inferior fronto-occipital fascicle in verbal perseveration: a brain electrostimulation mapping study.

    PubMed

    Khan, Osaama H; Herbet, Guillaume; Moritz-Gasser, Sylvie; Duffau, Hugues

    2014-05-01

    The subcortical connectivity underlying verbal perseveration (VP) remains poorly understood. We have previously reported that intraoperative electrical stimulation of the caudate nucleus during awake surgery resulted in VP. Here, our purpose is to study the white matter pathway underlying VP using subcortical stimulation mapping in a series of patients who underwent glioma resection. Eleven patients with a left hemispheric low grade glioma were operated on while awake. Intraoperative direct electrical stimulation was used both at cortical and subcortical levels while the patients carried out motor and naming tasks during the resection. All patients experienced VP during electrical stimulation performed at the level of different subcortical locations, which corresponded in the 11 cases to different parts of the left inferior fronto-occipital fascicle. Perseveration persisted into the postoperative days, but resolved completely by three months.Our original findings provide further insight into the neuroanatomical basis of VP, by supporting the role of left inferior fronto-occipital fascicle. Such data may have both fundamental and clinical implications. PMID:24347130

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

    PubMed

    Duffau, Hugues

    2012-01-01

    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

  9. The Role of the Arcuate Fasciculus in Conduction Aphasia

    ERIC Educational Resources Information Center

    Bernal, Byron; Ardila, Alfredo

    2009-01-01

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

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

    PubMed Central

    Von Der Heide, Rebecca J.; Skipper, Laura M.; Klobusicky, Elizabeth

    2013-01-01

    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

  11. Analysis of the volumetric relationship among human ocular, orbital and fronto-occipital cortical morphology.

    PubMed

    Masters, Michael; Bruner, Emiliano; Queer, Sarah; Traynor, Sarah; Senjem, Jess

    2015-10-01

    Recent research on the visual system has focused on investigating the relationship among eye (ocular), orbital, and visual cortical anatomy in humans. This issue is relevant in evolutionary and medical fields. In terms of evolution, only in modern humans and Neandertals are the orbits positioned beneath the frontal lobes, with consequent structural constraints. In terms of medicine, such constraints can be associated with minor deformation of the eye, vision defects, and patterns of integration among these features, and in association with the frontal lobes, are important to consider in reconstructive surgery. Further study is therefore necessary to establish how these variables are related, and to what extent ocular size is associated with orbital and cerebral cortical volumes. Relationships among these anatomical components were investigated using magnetic resonance images from a large sample of 83 individuals, which also included each subject's body height, age, sex, and uncorrected visual acuity score. Occipital and frontal gyri volumes were calculated using two different cortical parcellation tools in order to provide a better understanding of how the eye and orbit vary in relation to visual cortical gyri, and frontal cortical gyri which are not directly related to visual processing. Results indicated that ocular and orbital volumes were weakly correlated, and that eye volume explains only a small proportion of the variance in orbital volume. Ocular and orbital volumes were also found to be equally and, in most cases, more highly correlated with five frontal lobe gyri than with occipital lobe gyri associated with V1, V2, and V3 of the visual cortex. Additionally, after accounting for age and sex variation, the relationship between ocular and total visual cortical volume was no longer statistically significant, but remained significantly related to total frontal lobe volume. The relationship between orbital and visual cortical volumes remained significant for a number of occipital lobe gyri even after accounting for these cofactors, but was again found to be more highly correlated with the frontal cortex than with the occipital cortex. These results indicate that eye volume explains only a small amount of variation in orbital and visual cortical volume, and that the eye and orbit are generally more structurally associated with the frontal lobes than they are functionally associated with the visual cortex of the occipital lobes. Results also demonstrate that these components of the visual system are highly complex and influenced by a multitude of factors in humans. PMID:26250048

  12. Ideomotor Apraxia Due to Injury of the Superior Longitudinal Fasciculus.

    PubMed

    Jang, Sung Ho; Jang, Woo Hyuk

    2016-08-01

    We report on a patient who showed ideomotor apraxia due to injury of the superior longitudinal fasciculus following brain tumor and tumor bleeding, which was demonstrated by diffusion tensor tractography (DTT). A 60-yr-old, right-handed male patient underwent removal of brain meningioma and drainage of intraventricular hemorrhage and intracerebral hemorrhage in the left fronto-parietal lobe. At the time of DTT scanning (5 wk after onset), he was able to move the right upper extremity against gravity. The patient exhibited an intact ideational plan for motor performance. In addition, he was able to use actual objects (scissors, eraser) using his right wrist and hand. However, he had difficulty in using his right upper extremity for pantomime of object use, imitating gestures (meaningless or meaningful), and movement of his right upper extremity proximal. Score on the ideomotor apraxia test for the right side was 4 (cut-off score < 32). DTTs for the left superior longitudinal fasciculus to the left premotor cortex and left inferior parietal lobule showed partial injury, compared with the right superior longitudinal fasciculus. These injuries appeared to be the reason for ideomotor apraxia in this patient. PMID:27003199

  13. Decoding the superior parietal lobule connections of the superior longitudinal fasciculus/arcuate fasciculus in the human brain.

    PubMed

    Kamali, A; Sair, H I; Radmanesh, A; Hasan, K M

    2014-09-26

    The temporo-parietal (TP) white matter connections between the inferior parietal lobule and superior temporal gyrus as part of the superior longitudinal fasciculus/arcuate fasciculus (SLF/AF) or middle longitudinal fasciculus (MdLF) have been studied in prior diffusion tensor tractography (DTT) studies. However, few studies have been focusing on the higher TP connections of the superior parietal lobule with the temporal lobe. These higher TP connections have been shown to have a role in core processes such as attention, memory, emotions, and language. Our most recent study, for the first time, hinted to the possibility of a long white matter connection interconnecting the superior parietal lobule (SPL) with the posterior temporal lobe in human brain which we call the SLF/AF TP-SPL and for a shorter abbreviation, the TP-SPL. We decided to further investigate this white matter connection using fiber assignment by continuous tracking deterministic tractography and high spatial resolution diffusion tensor imaging on 3T. Five healthy right-handed men (age range 24-37 years) were studied. We delineated the SPL connections of the SLF/AF TP bilaterally in five normal adult human brains. Using a high resolution DTT technique, we demonstrate for the first time, the trajectory of a long fiber bundle connectivity between the SPL and posterior temporal lobe, called the SLF/AF TP-SPL (or the TP-SPL), bilaterally in five healthy adult human brains. We also demonstrate the trajectory of the vertically oriented posterior TP connections, interconnecting the inferior parietal lobule (IPL) with the posterior temporal lobe (TP-IPL) in relation to the TP-SPL, arcuate fasciculus and other major language pathways. In the current study, for the first time, we categorized the TP connections into the anterior and posterior connectivity groups and subcategorized each one into the SPL or IPL connections. PMID:25086308

  14. The superior longitudinal fasciculus in typically developing children and adolescents: diffusion tensor imaging and neuropsychological correlates.

    PubMed

    Urger, Sacide E; De Bellis, Michael D; Hooper, Stephen R; Woolley, Donald P; Chen, Steven D; Provenzale, James

    2015-01-01

    The relationship between superior longitudinal fasciculus microstructural integrity and neuropsychological functions were examined in 49 healthy children (range: 5-17 years) using diffusion tensor imaging. Seven major cognitive domains (intelligence, fine-motor, attention, language, visual-spatial, memory, executive function) were assessed. Data analyses used correlational methods. After adjusting for age and gender, fractional anisotropy and axial diffusivity values in the superior longitudinal fasciculus were positively correlated with executive functions of set shifting, whereas left superior longitudinal fasciculus fractional anisotropy values correlated with attention and language. Apparent diffusion coefficient values in the left superior longitudinal fasciculus negatively correlated with inhibitory control. In the left arcuate fasciculus, fractional anisotropy correlated with IQ and attention, whereas radial diffusivity values negatively correlated with IQ, fine-motor skills, and expressive language. Findings from this study provide an examination of the relationship between superior longitudinal fasciculus integrity and children's neuropsychological abilities that can be useful in monitoring pediatric neurologic diseases. PMID:24556549

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

    ERIC Educational Resources Information Center

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

    2007-01-01

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

  16. Reading impairment in a patient with missing arcuate fasciculus

    PubMed Central

    Rauschecker, Andreas M.; Deutsch, Gayle K.; Ben-Shachar, Michal; Schwartzman, Armin; Perry, Lee M.; Dougherty, Robert F.

    2009-01-01

    We describe the case of a child (“S”) who was treated with radiation therapy at age 5 for a recurrent malignant brain tumor. Radiation successfully abolished the tumor but caused radiation-induced tissue necrosis, primarily affecting cerebral white matter. S was introduced to us at age 15 because of her profound dyslexia. We assessed cognitive abilities and performed diffusion tensor imaging (DTI) to measure cerebral white matter pathways. Diffuse white matter differences were evident in T1-weighted, T2-weighted, diffusion anisotropy, and mean diffusivity measures in S compared to a group of 28 normal female controls. In addition, we found specific white matter pathway deficits by comparing tensor orientation directions in S’s brain with those of the control brains. While her principal diffusion direction maps appeared consistent with those of controls over most of the brain, there were tensor orientation abnormalities in the fiber tracts that form the superior longitudinal fasciculus (SLF) in both hemispheres. Tractography analysis indicated that the left and right arcuate fasciculus (AF), as well as other tracts within the SLF, were missing in S. Other major white matter tracts, such as the corticospinal and inferior occipitofrontal pathways, were intact. Functional MRI measurements indicated left-hemisphere dominanance for language with a normal activation pattern. Despite the left AF abnormality, S had preserved oral language with average sentence repetition skills. In addition to profound dyslexia, S exhibited visuospatial, calculation, and rapid naming deficits and was impaired in both auditory and spatial working memory. We propose that the reading and visuospatial deficits were due to the abnormal left and right SLF pathways, respectively. These results advance our understanding of the functional significance of the SLF and are the first to link radiation necrosis with selective damage to a specific set of fiber tracts. PMID:18775735

  17. Right inferior longitudinal fasciculus lesions disrupt visual-emotional integration.

    PubMed

    Fischer, David B; Perez, David L; Prasad, Sashank; Rigolo, Laura; O'Donnell, Lauren; Acar, Diler; Meadows, Mary-Ellen; Baslet, Gaston; Boes, Aaron D; Golby, Alexandra J; Dworetzky, Barbara A

    2016-06-01

    The mechanism by which the brain integrates visual and emotional information remains incompletely understood, and can be studied through focal lesions that selectively disrupt this process. To date, three reported cases of visual hypoemotionality, a vision-specific form of derealization, have resulted from lesions of the temporo-occipital junction. We present a fourth case of this rare phenomenon, and investigate the role of the inferior longitudinal fasciculus (ILF) in the underlying pathophysiology. A 50-year-old right-handed male was found to have a right medial temporal lobe tumor following new-onset seizures. Interstitial laser ablation of the lesion was complicated by a right temporo-parieto-occipital intraparenchymal hemorrhage. The patient subsequently experienced emotional estrangement from visual stimuli. A lesion overlap analysis was conducted to assess involvement of the ILF by this patient's lesion and those of the three previously described cases, and diffusion tensor imaging was acquired in our case to further investigate ILF disruption. All four lesions specifically overlapped with the expected trajectory of the right ILF, and diminished structural integrity of the right ILF was observed in our case. These findings implicate the ILF in visual hypoemotionality, suggesting that the ILF is critical for integrating visual information with its emotional content. PMID:26940563

  18. Correlating Function and Imaging Measures of the Medial Longitudinal Fasciculus

    PubMed Central

    Sakaie, Ken; Takahashi, Masaya; Remington, Gina; Wang, Xiaofeng; Conger, Amy; Conger, Darrel; Dimitrov, Ivan; Jones, Stephen; Frohman, Ashley; Frohman, Teresa; Sagiyama, Koji; Togao, Osamu

    2016-01-01

    Objective To test the validity of diffusion tensor imaging (DTI) measures of tissue injury by examining such measures in a white matter structure with well-defined function, the medial longitudinal fasciculus (MLF). Injury to the MLF underlies internuclear ophthalmoparesis (INO). Methods 40 MS patients with chronic INO and 15 healthy controls were examined under an IRB-approved protocol. Tissue integrity of the MLF was characterized by DTI parameters: longitudinal diffusivity (LD), transverse diffusivity (TD), mean diffusivity (MD) and fractional anisotropy (FA). Severity of INO was quantified by infrared oculography to measure versional disconjugacy index (VDI). Results LD was significantly lower in patients than in controls in the medulla-pons region of the MLF (p < 0.03). FA was also lower in patients in the same region (p < 0.0004). LD of the medulla-pons region correlated with VDI (R = -0.28, p < 0.05) as did FA in the midbrain section (R = 0.31, p < 0.02). Conclusions This study demonstrates that DTI measures of brain tissue injury can detect injury to a functionally relevant white matter pathway, and that such measures correlate with clinically accepted evaluation indices for INO. The results validate DTI as a useful imaging measure of tissue integrity. PMID:26800522

  19. Volumetric associations between uncinate fasciculus, amygdala, and trait anxiety

    PubMed Central

    2012-01-01

    Background Recent investigations of white matter (WM) connectivity suggest an important role of the uncinate fasciculus (UF), connecting anterior temporal areas including the amygdala with prefrontal-/orbitofrontal cortices, for anxiety-related processes. Volume of the UF, however, has rarely been investigated, but may be an important measure of structural connectivity underlying limbic neuronal circuits associated with anxiety. Since UF volumetric measures are newly applied measures, it is necessary to cross-validate them using further neural and behavioral indicators of anxiety. Results In a group of 32 subjects not reporting any history of psychiatric disorders, we identified a negative correlation between left UF volume and trait anxiety, a finding that is in line with previous results. On the other hand, volume of the left amygdala, which is strongly connected with the UF, was positively correlated with trait anxiety. In addition, volumes of the left UF and left amygdala were inversely associated. Conclusions The present study emphasizes the role of the left UF as candidate WM fiber bundle associated with anxiety-related processes and suggests that fiber bundle volume is a WM measure of particular interest. Moreover, these results substantiate the structural relatedness of UF and amygdala by a non-invasive imaging method. The UF-amygdala complex may be pivotal for the control of trait anxiety. PMID:22217209

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

    ERIC Educational Resources Information Center

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

    2011-01-01

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

  1. Ventral and dorsal visual streams in posterior cortical atrophy: A DT MRI study

    PubMed Central

    Migliaccio, Raffaella; Agosta, Federica; Scola, Elisa; Magnani, Giuseppe; Cappa, Stefano F.; Pagani, Elisabetta; Canu, Elisa; Comi, Giancarlo; Falini, Andrea; Gorno-Tempini, Maria Luisa; Bartolomeo, Paolo; Filippi, Massimo

    2016-01-01

    Using diffusion tensor magnetic resonance imaging tractography, ventral (inferior longitudinal fasciculus) and fronto-occipital (inferior fronto-occipital fasciculus) and dorsal (fronto-parietal superior longitudinal fasciculus) visual pathways were assessed in 7 patients with posterior cortical atrophy (PCA), showing either predominantly ventral or additional dorsal cognitive deficits. Corpus callosum and corticospinal tracts were also studied. Gray and white matter atrophy was assessed using voxel-based morphometry. In all PCA patients, abnormal diffusivity indexes were found in bilateral inferior longitudinal fasciculus and inferior fronto-occipital fasciculus, with a left-side predominance. Patients also had mild microstructural damage to the corpus callosum. The 2 patients with more dorsal symptoms also showed right fronto-parietal superior longitudinal fasciculus abnormalities. Corticospinal tracts were normal, bilaterally. When studied separately, patients with ventral clinical impairment showed a pattern of atrophy mainly located in the ventral occipitotemporal regions, bilaterally; patients with both ventral and dorsal clinical deficits showed additional atrophy of the bilateral inferior parietal lobe. Magnetic resonance imaging patterns of abnormalities mirror closely the clinical phenotypes and could provide reliable ante mortem markers of tissue damage in PCA. PMID:22277261

  2. The Relationship between Uncinate Fasciculus White Matter Integrity and Verbal Memory Proficiency in Children

    PubMed Central

    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.

    2014-01-01

    During childhood, verbal learning and memory are important for academic performance. Recent fMRI 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

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

    PubMed

    Coppens, Christian

    2009-01-01

    The article deals with the Dutch translation of the Fasciculus medicinae based on the Latin edition, Venice 1495, with the famous woodcuts created in 1494 for the Italian translation of the original Latin edition of 1491. The woodcuts are compared with the Venetian model. New features in the Antwerp edition include the Skeleton and the Zodiac Man, bot originally based on German models. The text also deals with other woodcuts in the Low Countries based on these Venetian illustrations. The Appendices provide a short title catalog of all the editions and translations based on the Venetian edition and a stemma. PMID:19642255

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

    ERIC Educational Resources Information Center

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

    2010-01-01

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

  5. Left Hemisphere Diffusivity of the Arcuate Fasciculus: Influences of Autism Spectrum Disorder and Language Impairment

    PubMed Central

    Roberts, T.P.L.; Heiken, K.; Zarnow, D.; Dell, J.; Nagae, L.; Blaskey, L.; Solot, C.; Levy, S.E.; Berman, J.I.; Edgar, J.C.

    2014-01-01

    BACKGROUND AND PURPOSE There has been much discussion whether brain abnormalities associated with specific language impairment and autism with language impairment are shared or are disorder specific. Although white matter tract abnormalities are observed in both specific language impairment and autism spectrum disorders, the similarities and differences in the white matter abnormalities in these 2 disorders have not been fully determined. MATERIALS AND METHODS Diffusion tensor imaging diffusion parameters of the arcuate fasciculus were measured in 14 children with specific language impairment as well as in 16 children with autism spectrum disorder with language impairment, 18 with autism spectrum disorder without language impairment, and 25 age-matched typically developing control participants. RESULTS Language impairment and autism spectrum disorder both had (elevating) main effects on mean diffusivity of the left arcuate fasciculus, initially suggesting a shared white matter substrate abnormality. Analysis of axial and radial diffusivity components, however, indicated that autism spectrum disorder and language impairment differentially affect white matter microstructural properties, with a main effect of autism spectrum disorder on axial diffusivity and a main effect of language impairment on radial diffusivity. CONCLUSIONS Although white matter abnormalities appear similar in language impairment and autism spectrum disorder when examining broad white matter measures, a more detailed analysis indicates different mechanisms for the white matter microstructural anomalies associated with language impairment and autism spectrum disorder. PMID:24335547

  6. Virtual dissection and comparative connectivity of the superior longitudinal fasciculus in chimpanzees and humans.

    PubMed

    Hecht, Erin E; Gutman, David A; Bradley, Bruce A; Preuss, Todd M; Stout, Dietrich

    2015-03-01

    Many of the behavioral capacities that distinguish humans from other primates rely on fronto-parietal circuits. The superior longitudinal fasciculus (SLF) is the primary white matter tract connecting lateral frontal with lateral parietal regions; it is distinct from the arcuate fasciculus, which interconnects the frontal and temporal lobes. Here we report a direct, quantitative comparison of SLF connectivity using virtual in vivo dissection of the SLF in chimpanzees and humans. SLF I, the superior-most branch of the SLF, showed similar patterns of connectivity between humans and chimpanzees, and was proportionally volumetrically larger in chimpanzees. SLF II, the middle branch, and SLF III, the inferior-most branch, showed species differences in frontal connectivity. In humans, SLF II showed greater connectivity with dorsolateral prefrontal cortex, whereas in chimps SLF II showed greater connectivity with the inferior frontal gyrus. SLF III was right-lateralized and proportionally volumetrically larger in humans, and human SLF III showed relatively reduced connectivity with dorsal premotor cortex and greater extension into the anterior inferior frontal gyrus, especially in the right hemisphere. These results have implications for the evolution of fronto-parietal functions including spatial attention to observed actions, social learning, and tool use, and are in line with previous research suggesting a unique role for the right anterior inferior frontal gyrus in the evolution of human fronto-parietal network architecture. PMID:25534109

  7. Virtual dissection and comparative connectivity of the superior longitudinal fasciculus in chimpanzees and humans

    PubMed Central

    Hecht, Erin E.; Gutman, David A.; Bradley, Bruce A.; Preuss, Todd M.; Stout, Dietrich

    2015-01-01

    Many of the behavioral capacities that distinguish humans from other primates rely on fronto-parietal circuits. The superior longitudinal fasciculus (SLF) is the primary white matter tract connecting lateral frontal with lateral parietal regions; it is distinct from the arcuate fasciculus, which interconnects the frontal and temporal lobes. Here we report a direct, quantitative comparison of SLF connectivity using virtual in vivo dissection of the SLF in chimpanzees and humans. SLF I, the superior-most branch of the SLF, showed similar patterns of connectivity between humans and chimpanzees, and was proportionally volumetrically larger in chimpanzees. SLF II, the middle branch, and SLF III, the inferior-most branch, showed species differences in frontal connectivity. In humans, SLF II showed greater connectivity with dorsolateral prefrontal cortex, whereas in chimps SLF II showed greater connectivity with the inferior frontal gyrus. SLF III was right-lateralized and proportionally volumetrically larger in humans, and human SLF III showed relatively reduced connectivity with dorsal premotor cortex and greater extension into the anterior inferior frontal gyrus, especially in the right hemisphere. These results have implications for the evolution of fronto-parietal functions including spatial attention to observed actions, social learning, and tool use, and are in line with previous research suggesting a unique role for the right anterior inferior frontal gyrus in the evolution of human fronto-parietal network architecture. PMID:25534109

  8. Lakatos Revisited.

    ERIC Educational Resources Information Center

    Court, Deborah

    1999-01-01

    Revisits and reviews Imre Lakatos' ideas on "Falsification and the Methodology of Scientific Research Programmes." Suggests that Lakatos' framework offers an insightful way of looking at the relationship between theory and research that is relevant not only for evaluating research programs in theoretical physics, but in the social sciences as…

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

    PubMed Central

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

    2014-01-01

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

  10. Bilateral agenesis of arcuate fasciculus demonstrated by fiber tractography in congenital bilateral perisylvian syndrome.

    PubMed

    Kilinc, Ozden; Ekinci, Gazanfer; Demirkol, Ezgi; Agan, Kadriye

    2015-03-01

    Congenital bilateral perisylvian syndrome (CBPS) is a type of cortical developmental abnormality associated with distinctive clinical and imaging features. Clinical spectrum of this syndrome is quite heterogeneous, with different degrees of neurological impairment in affected individuals. High-definition magnetic resonance imaging (MRI) has a great importance in revealing the presence of CBPS, but is limited in elucidating the heterogeneous clinical spectrum. The arcuate fasciculus (AF) is a prominent language tract in the perisylvian region interconnecting Broca and Wernicke areas, and has a high probability of being affected developmentally in CBPS. Herein, we report a case of CBPS with investigation of AF using diffusion tensor imaging (DTI) and fiber tractography in relation to clinical findings. We postulated that proven absence of AF on DTI and fiber tractography would correlate with a severe phenotype of CBPS. PMID:24852949

  11. Evidence of slow maturation of the superior longitudinal fasciculus in early childhood by diffusion tensor imaging.

    PubMed

    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

    2007-11-01

    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 5 years. The result is attributed to slow axonal and/or myelin maturation of this tract, which is believed to be involved in language functions. PMID:17826183

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

    PubMed

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

    2015-01-01

    Individuals with psychopathy possess emotional and behavioral abnormalities. Two neural regions, involved in behavioral control and emotion regulation, are often implicated: amygdala and ventromedial prefrontal cortex (VMPFC). Recently, in studies using adult criminal populations, reductions in microstructural integrity of the white matter connections (i.e., uncinate fasciculus (UF)) between these two neural regions have been discovered in criminals with psychopathy, supporting the notion of neural dysfunction in the amygdala-VMPFC circuit. Here, a young adult, community sample is used to assess whether psychopathic traits modulate microstructural integrity of UF, and whether this relationship is dependent upon levels of trait anxiety, which is sometimes used to distinguish subtypes of psychopathy. Results reveal a negative association between psychopathic traits and microstructural integrity of UF, supporting previous findings. However, no moderation of the relationship by trait anxiety was discovered. Findings provide further support for the notion of altered amygdala-VMPFC connectivity in association with higher psychopathic traits. PMID:26106525

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

    PubMed Central

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

    2015-01-01

    Individuals with psychopathy possess emotional and behavioral abnormalities. Two neural regions, involved in behavioral control and emotion regulation, are often implicated: amygdala and ventromedial prefrontal cortex (VMPFC). Recently, in studies using adult criminal populations, reductions in microstructural integrity of the white matter connections (i.e., uncinate fasciculus (UF)) between these two neural regions have been discovered in criminals with psychopathy, supporting the notion of neural dysfunction in the amygdala–VMPFC circuit. Here, a young adult, community sample is used to assess whether psychopathic traits modulate microstructural integrity of UF, and whether this relationship is dependent upon levels of trait anxiety, which is sometimes used to distinguish subtypes of psychopathy. Results reveal a negative association between psychopathic traits and microstructural integrity of UF, supporting previous findings. However, no moderation of the relationship by trait anxiety was discovered. Findings provide further support for the notion of altered amygdala–VMPFC connectivity in association with higher psychopathic traits. PMID:26106525

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

    PubMed

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

    2015-10-01

    Psychopathy is a personality disorder characterized by callous lack of empathy, impulsive antisocial behavior, and criminal recidivism. Here, we performed the largest diffusion tensor imaging (DTI) study of incarcerated criminal offenders to date (N = 147) to determine whether psychopathy severity is linked to the microstructural integrity of major white matter tracts in the brain. Consistent with the results of previous studies in smaller samples, we found that psychopathy was associated with reduced fractional anisotropy in the right uncinate fasciculus (UF; the major white matter tract connecting ventral frontal and anterior temporal cortices). We found no such association in the left UF or in adjacent frontal or temporal white matter tracts. Moreover, the right UF finding was specifically related to the interpersonal features of psychopathy (glib superficial charm, grandiose sense of self-worth, pathological lying, manipulativeness), rather than the affective, antisocial, or lifestyle features. These results indicate a neural marker for this key dimension of psychopathic symptomatology. PMID:26219745

  15. Diffusion MRI properties of the human uncinate fasciculus correlate with the ability to learn visual associations.

    PubMed

    Thomas, Cibu; Avram, Alexandru; Pierpaoli, Carlo; Baker, Chris

    2015-11-01

    The uncinate fasciculus (UF) is a cortico-cortico white matter pathway that links the anterior temporal and the orbitofrontal cortex (OFC). In the monkey, transection of the UF causes significant impairments in learning conditional visual-visual associations, while object discrimination remains intact, suggesting an important role for the UF in mediating the learning of complex visual associations. Whether this functional role extends to the human UF has not been tested directly. Here, we used diffusion tensor magnetic resonance imaging (dMRI) and behavioral experiments to examine the relation between learning visual associations and the structural properties of the human UF. In a group of healthy adults, we segmented the UF and the inferior longitudinal fasciculus (ILF) and derived dMRI measures of the structural properties of the two pathways. We also used a behavioral experiment adapted from the monkey studies to characterize the ability of these individuals to learn to associate a person's face with a group of specific scenes (conditional visual-visual association). We then tested whether the variability in the dMRI measures of the two pathways correlated with variability in the ability to rapidly learn the face-place associations. Our study suggests that in the human, the left UF may be important for mediating the rapid learning of conditional visual-visual associations whereas the right UF may play an important role in the immediate retrieval of visual-visual associations. These results provide preliminary evidence suggesting similarities and differences in the functional role of the UF in monkeys compared to humans. The findings presented here contribute to our understanding of the functional role of the UF in humans and the functional neuroanatomy of the brain networks involved in visual cognition. PMID:25742710

  16. The White Matter Microintegrity Alterations of Neocortical and Limbic Association Fibers in Major Depressive Disorder and Panic Disorder

    PubMed Central

    Lai, Chien-Han; Wu, Yu-Te

    2016-01-01

    Abstract The studies regarding to the comparisons between major depressive disorder (MDD) and panic disorder (PD) in the microintegrity of white matter (WM) are uncommon. Therefore, we tried to a way to classify the MDD and PD. Fifty-three patients with 1st-episode medication-naive PD, 54 healthy controls, and 53 patients with 1st-episode medication-naive MDD were enrolled in this study. The controls and patients were matched for age, gender, education, and handedness. The diffusion tensor imaging scanning was also performed. The WM microintegrity was analyzed and compared between 3 groups of participants (ANOVA analysis) with age and gender as covariates. The MDD group had lower WM microintegrity than the PD group in the left anterior thalamic radiation, left uncinate fasciculus, left inferior fronto-occipital fasciculus, and bilateral corpus callosum. The MDD group had reductions in the microintegrity when compared to controls in the bilateral superior longitudinal fasciculi, inferior longitudinal fasciculi, inferior fronto-occipital fasciculi, and corpus callosum. The PD group had lower microintegrity in bilateral superior longitudinal fasciculi and left inferior fronto-occipital fasciculus when compared to controls. The widespread pattern of microintegrity alterations in fronto-limbic WM circuit for MDD was different from restrictive pattern of alterations for PD. PMID:26945417

  17. White matter and reading deficits after pediatric traumatic brain injury: A diffusion tensor imaging study

    PubMed Central

    Johnson, Chad Parker; Juranek, Jenifer; Swank, Paul R.; Kramer, Larry; Cox, Charles S.; Ewing-Cobbs, Linda

    2015-01-01

    Pediatric traumatic brain injury often results in significant long-term deficits in mastery of reading ability. This study aimed to identify white matter pathways that, when damaged, predicted reading deficits in children. Based on the dual-route model of word reading, we predicted that integrity of the inferior fronto-occipital fasciculus would be related to performance in sight word identification while integrity of the superior longitudinal fasciculus would be related to performance in phonemic decoding. Reading fluency and comprehension were hypothesized to relate to the superior longitudinal fasciculus, inferior fronto-occipital fasciculus, and cingulum bundle. The connectivity of white matter pathways was used to predict reading deficits in children aged 6 to 16 years with traumatic brain injury (n = 29) and those with orthopedic injury (n = 27) using tract-based spatial statistics. Results showed that children with traumatic brain injury and reduced microstructural integrity of the superior longitudinal fasciculus demonstrated reduced word-reading ability on sight word and phonemic decoding tasks. Additionally, children with traumatic brain injury and microstructural changes involving the cingulum bundle demonstrated reduced reading fluency. Results support the association of a dorsal pathway via the superior longitudinal fasciculus with both sight word reading and phonemic decoding. No association was identified between the inferior fronto-occipital fasciculus and sight word reading or phonemic decoding. Reading fluency was associated with the integrity of the cingulum bundle. These findings support dissociable pathways predicting word reading and fluency using Diffusion Tensor Imaging and provide additional information for developing models of acquired reading deficits by specifying areas of brain damage which may predict reading deficits following recovery from the acute phase of TBI. PMID:26740920

  18. Developmental process of the arcuate fasciculus from infancy to adolescence: a diffusion tensor imaging study

    PubMed Central

    Tak, Hyeong Jun; Kim, Jin Hyun; Son, Su Min

    2016-01-01

    We investigated the radiologic developmental process of the arcuate fasciculus (AF) using subcomponent diffusion tensor imaging (DTI) analysis in typically developing volunteers. DTI data were acquired from 96 consecutive typically developing children, aged 0–14 years. AF subcomponents, including the posterior, anterior, and direct AF tracts were analyzed. Success rates of analysis (AR) and fractional anisotropy (FA) values of each subcomponent tract were measured and compared. AR of all subcomponent tracts, except the posterior, showed a significant increase with aging (P < 0.05). Subcomponent tracts had a specific developmental sequence: First, the posterior AF tract, second, the anterior AF tract, and last, the direct AF tract in identical hemispheres. FA values of all subcomponent tracts, except right direct AF tract, showed correlation with subject's age (P < 0.05). Increased AR and FA values were observed in female subjects in young age (0–2 years) group compared with males (P < 0.05). The direct AF tract showed leftward hemispheric asymmetry and this tendency showed greater consolidation in older age (3–14 years) groups (P < 0.05). These findings demonstrated the radiologic developmental patterns of the AF from infancy to adolescence using subcomponent DTI analysis. The AF showed a specific developmental sequence, sex difference in younger age, and hemispheric asymmetry in older age. PMID:27482222

  19. Developmental process of the arcuate fasciculus from infancy to adolescence: a diffusion tensor imaging study.

    PubMed

    Tak, Hyeong Jun; Kim, Jin Hyun; Son, Su Min

    2016-06-01

    We investigated the radiologic developmental process of the arcuate fasciculus (AF) using subcomponent diffusion tensor imaging (DTI) analysis in typically developing volunteers. DTI data were acquired from 96 consecutive typically developing children, aged 0-14 years. AF subcomponents, including the posterior, anterior, and direct AF tracts were analyzed. Success rates of analysis (AR) and fractional anisotropy (FA) values of each subcomponent tract were measured and compared. AR of all subcomponent tracts, except the posterior, showed a significant increase with aging (P < 0.05). Subcomponent tracts had a specific developmental sequence: First, the posterior AF tract, second, the anterior AF tract, and last, the direct AF tract in identical hemispheres. FA values of all subcomponent tracts, except right direct AF tract, showed correlation with subject's age (P < 0.05). Increased AR and FA values were observed in female subjects in young age (0-2 years) group compared with males (P < 0.05). The direct AF tract showed leftward hemispheric asymmetry and this tendency showed greater consolidation in older age (3-14 years) groups (P < 0.05). These findings demonstrated the radiologic developmental patterns of the AF from infancy to adolescence using subcomponent DTI analysis. The AF showed a specific developmental sequence, sex difference in younger age, and hemispheric asymmetry in older age. PMID:27482222

  20. Development of the Uncinate Fasciculus: Implications for Theory and Developmental Disorders

    PubMed Central

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

    2016-01-01

    The uncinate fasciculus (UF) is a long-range white matter tract that connects limbic regions in the temporal lobe to the frontal lobe. The UF is one of the latest developing tracts, and continues maturing into the third decade of life. As such, individual differences in the maturational profile of the UF may serve to explain differences in behavior. Indeed, atypical macrostructure and microstructure of the UF have been reported in numerous studies of individuals with developmental and psychiatric disorders such as social deprivation and maltreatment, autism spectrum disorders, conduct disorder, risk taking, and substance abuse. The present review evaluates what we currently know about the UF’s developmental trajectory and reviews the literature relating UF abnormalities to specific disorders. Additionally, we take a dimensional approach and critically examine symptoms and behavioral impairments that have been demonstrated to cluster with UF aberrations, in an effort to relate these impairments to our speculations regarding the functionality of the UF. We suggest that developmental disorders with core problems relating to memory retrieval, reward and valuation computation, and impulsive decision making may be linked to aberrations in uncinate microstructure. PMID:26143154

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

    PubMed Central

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

    2014-01-01

    The vertical occipital fasciculus (VOF) is the only major fiber bundle connecting dorsolateral and ventrolateral visual cortex. Only a handful of studies have examined the anatomy of the VOF or its role in cognition in the living human brain. Here, we trace the contentious history of the VOF, beginning with its original discovery in monkey by Wernicke (1881) and in human by Obersteiner (1888), to its disappearance from the literature, and recent reemergence a century later. We introduce an algorithm to identify the VOF in vivo using diffusion-weighted imaging and tractography, and show that the VOF can be found in every hemisphere (n = 74). Quantitative T1 measurements demonstrate that tissue properties, such as myelination, in the VOF differ from neighboring white-matter tracts. The terminations of the VOF are in consistent positions relative to cortical folding patterns in the dorsal and ventral visual streams. Recent findings demonstrate that these same anatomical locations also mark cytoarchitectonic and functional transitions in dorsal and ventral visual cortex. We conclude that the VOF is likely to serve a unique role in the communication of signals between regions on the ventral surface that are important for the perception of visual categories (e.g., words, faces, bodies, etc.) and regions on the dorsal surface involved in the control of eye movements, attention, and motion perception. PMID:25404310

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

    PubMed

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

    2014-12-01

    The vertical occipital fasciculus (VOF) is the only major fiber bundle connecting dorsolateral and ventrolateral visual cortex. Only a handful of studies have examined the anatomy of the VOF or its role in cognition in the living human brain. Here, we trace the contentious history of the VOF, beginning with its original discovery in monkey by Wernicke (1881) and in human by Obersteiner (1888), to its disappearance from the literature, and recent reemergence a century later. We introduce an algorithm to identify the VOF in vivo using diffusion-weighted imaging and tractography, and show that the VOF can be found in every hemisphere (n = 74). Quantitative T1 measurements demonstrate that tissue properties, such as myelination, in the VOF differ from neighboring white-matter tracts. The terminations of the VOF are in consistent positions relative to cortical folding patterns in the dorsal and ventral visual streams. Recent findings demonstrate that these same anatomical locations also mark cytoarchitectonic and functional transitions in dorsal and ventral visual cortex. We conclude that the VOF is likely to serve a unique role in the communication of signals between regions on the ventral surface that are important for the perception of visual categories (e.g., words, faces, bodies, etc.) and regions on the dorsal surface involved in the control of eye movements, attention, and motion perception. PMID:25404310

  3. Dissociable roles of the inferior longitudinal fasciculus and fornix in face and place perception

    PubMed Central

    Hodgetts, Carl J; Postans, Mark; Shine, Jonathan P; Jones, Derek K; Lawrence, Andrew D; Graham, Kim S

    2015-01-01

    We tested a novel hypothesis, generated from representational accounts of medial temporal lobe (MTL) function, that the major white matter tracts converging on perirhinal cortex (PrC) and hippocampus (HC) would be differentially involved in face and scene perception, respectively. Diffusion tensor imaging was applied in healthy participants alongside an odd-one-out paradigm sensitive to PrC and HC lesions in animals and humans. Microstructure of inferior longitudinal fasciculus (ILF, connecting occipital and ventro-anterior temporal lobe, including PrC) and fornix (the main HC input/output pathway) correlated with accuracy on odd-one-out judgements involving faces and scenes, respectively. Similarly, blood oxygen level-dependent (BOLD) response in PrC and HC, elicited during oddity judgements, was correlated with face and scene oddity performance, respectively. We also observed associations between ILF and fornix microstructure and category-selective BOLD response in PrC and HC, respectively. These striking three-way associations highlight functionally dissociable, structurally instantiated MTL neurocognitive networks for complex face and scene perception. DOI: http://dx.doi.org/10.7554/eLife.07902.001 PMID:26319355

  4. Detection of the arcuate fasciculus in congenital amusia depends on the tractography algorithm

    PubMed Central

    Chen, Joyce L.; Kumar, Sukhbinder; Williamson, Victoria J.; Scholz, Jan; Griffiths, Timothy D.; Stewart, Lauren

    2015-01-01

    The advent of diffusion magnetic resonance imaging (MRI) allows researchers to virtually dissect white matter fiber pathways in the brain in vivo. This, for example, allows us to characterize and quantify how fiber tracts differ across populations in health and disease, and change as a function of training. Based on diffusion MRI, prior literature reports the absence of the arcuate fasciculus (AF) in some control individuals and as well in those with congenital amusia. The complete absence of such a major anatomical tract is surprising given the subtle impairments that characterize amusia. Thus, we hypothesize that failure to detect the AF in this population may relate to the tracking algorithm used, and is not necessarily reflective of their phenotype. Diffusion data in control and amusic individuals were analyzed using three different tracking algorithms: deterministic and probabilistic, the latter either modeling two or one fiber populations. Across the three algorithms, we replicate prior findings of a left greater than right AF volume, but do not find group differences or an interaction. We detect the AF in all individuals using the probabilistic 2-fiber model, however, tracking failed in some control and amusic individuals when deterministic tractography was applied. These findings show that the ability to detect the AF in our sample is dependent on the type of tractography algorithm. This raises the question of whether failure to detect the AF in prior studies may be unrelated to the underlying anatomy or phenotype. PMID:25653637

  5. Diffusivity of the uncinate fasciculus in heroin users relates to their levels of anxiety

    PubMed Central

    Wong, N M L; Cheung, S-H; Chan, C C H; Zeng, H; Liu, Y-P; So, K-F; Lee, T M C

    2015-01-01

    Heroin use is closely associated with emotional dysregulation, which may explain its high comorbidity with disorders such as anxiety and depression. However, the understanding of the neurobiological etiology of the association between heroin use and emotional dysregulation is limited. Previous studies have suggested an impact of heroin on diffusivity in white matter involving the emotional regulatory system, but the specificity of this finding remains to be determined. Therefore, this study investigated the association between heroin use and diffusivity of white matter tracts in heroin users and examined whether the tracts were associated with their elevated anxiety and depression levels. A sample of 26 right-handed male abstinent heroin users (25 to 42 years of age) and 32 matched healthy controls (19 to 55 years of age) was recruited for this study. Diffusion tensor imaging data were collected, and their levels of anxiety and depression were assessed using the Hospital Anxiety and Depression Scale. Our findings indicated that heroin users exhibited higher levels of anxiety and depression, but the heroin use-associated left uncinate fasciculus was only related to their anxiety level, suggesting that association between heroin and anxiety has an incremental organic basis but that for depression could be a threshold issue. This finding improves our understanding of heroin addiction and its comorbid affective disorder and facilitates future therapeutic development. PMID:25918991

  6. Microstructural abnormalities of uncinate fasciculus as a function of impaired cognition in schizophrenia: A DTI study.

    PubMed

    Singh, Sadhana; Singh, Kavita; Trivedi, Richa; Goyal, Satnam; Kaur, Prabhjot; Singh, Namita; Bhatia, Triptish; Deshpande, Smita N; Khushu, Subash

    2016-09-01

    Neuropsychological studies have reported that attention, memory, language, motor and emotion processing are impaired in schizophrenia. It is known that schizophrenia involves structural alterations in the white matter of brain that contribute to the pathophysiology of the disorder. Uncinate fasciculus (UNC), a bundle of white matter fibres, plays an important role in the pathology of this disorder and involved in cognitive functions such as memory, language and emotion processing. Therefore, the present study aimed to investigate microstructural changes in UNC fibre in schizophrenia patients relative to controls and its correlation with neuropsychological scores. Diffusion tensor imaging (DTI) and Hindi version of Penn Computerised Neuropsychological Battery test was performed in 14 schizophrenia patients and 14 controls. DTI measures [fractional anisotropy (FA) and mean diffusivity (MD)] from UNC fibre were calculated and a comparison was made between patients and controls. Pearson's correlation was performed between neuropsychological scores and DTI measures.Schizophrenia patients showed significantly reduced FA values in UNC fibre compared to controls. In schizophrenia patients, a positive correlation of attention, spatial memory, sensorimotor dexterity and emotion with FA was observed. These findings suggest that microstructural changes in UNC fibre may contribute to underlying dysfunction in the cognitive functions associated with schizophrenia. PMID:27581933

  7. Atypical hemispheric asymmetry in the arcuate fasciculus of completely nonverbal children with autism.

    PubMed

    Wan, Catherine Y; Marchina, Sarah; Norton, Andrea; Schlaug, Gottfried

    2012-04-01

    Despite the fact that as many as 25% of the children diagnosed with autism spectrum disorders are nonverbal, surprisingly little research has been conducted on this population. In particular, the mechanisms that underlie their absence of speech remain unknown. Using diffusion tensor imaging, we compared the structure of a language-related white matter tract (the arcuate fasciculus, AF) in five completely nonverbal children with autism to that of typically developing children. We found that, as a group, the nonverbal children did not show the expected left-right AF asymmetry--rather, four of the five nonverbal children actually showed the reversed pattern. It is possible that this unusual pattern of asymmetry may underlie some of the severe language deficits commonly found in autism, particularly in children whose speech fails to develop. Furthermore, novel interventions (such as auditory-motor mapping training) designed to engage brain regions that are connected via the AF may have important clinical potential for facilitating expressive language in nonverbal children with autism. PMID:22524376

  8. White matter alterations in temporal lobe epilepsy

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

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

  9. Mindfulness-Based Stress Reduction, Fear Conditioning, and The Uncinate Fasciculus: A Pilot Study.

    PubMed

    Hölzel, Britta K; Brunsch, Vincent; Gard, Tim; Greve, Douglas N; Koch, Kathrin; Sorg, Christian; Lazar, Sara W; Milad, Mohammed R

    2016-01-01

    Mindfulness has been suggested to impact emotional learning, but research on these processes is scarce. The classical fear conditioning/extinction/extinction retention paradigm is a well-known method for assessing emotional learning. The present study tested the impact of mindfulness training on fear conditioning and extinction memory and further investigated whether changes in white matter fiber tracts might support such changes. The uncinate fasciculus (UNC) was of particular interest in the context of emotional learning. In this pilot study, 46 healthy participants were quasi-randomized to a Mindfulness-Based Stress Reduction (MBSR, N = 23) or waitlist control (N = 23) group and underwent a two-day fear conditioning, extinction learning, and extinction memory protocol before and after the course or control period. Skin conductance response (SCR) data served to measure the physiological response during conditioning and extinction memory phases. Diffusion tensor imaging (DTI) data were analyzed with probabilistic tractography and analyzed for changes of fractional anisotropy in the UNC. During conditioning, participants were able to maintain a differential response to conditioned vs. not conditioned stimuli following the MBSR course (i.e., higher sensitivity to the conditioned stimuli), while controls dropped the response. Extinction memory results were not interpretable due to baseline differences. MBSR participants showed a significant increase in fractional anisotropy in the UNC, while controls did not (group by time interaction missed significance). Pre-post changes in UNC were correlated with changes in the response to the conditioned stimuli. The findings suggest effects of mindfulness practice on the maintenance of sensitivity of emotional responses and suggest underlying neural plasticity. (ClinicalTrials.gov, Identifier NCT01320969, https://clinicaltrials.gov/ct2/show/NCT01320969). PMID:27378875

  10. Mindfulness-Based Stress Reduction, Fear Conditioning, and The Uncinate Fasciculus: A Pilot Study

    PubMed Central

    Hölzel, Britta K.; Brunsch, Vincent; Gard, Tim; Greve, Douglas N.; Koch, Kathrin; Sorg, Christian; Lazar, Sara W.; Milad, Mohammed R.

    2016-01-01

    Mindfulness has been suggested to impact emotional learning, but research on these processes is scarce. The classical fear conditioning/extinction/extinction retention paradigm is a well-known method for assessing emotional learning. The present study tested the impact of mindfulness training on fear conditioning and extinction memory and further investigated whether changes in white matter fiber tracts might support such changes. The uncinate fasciculus (UNC) was of particular interest in the context of emotional learning. In this pilot study, 46 healthy participants were quasi-randomized to a Mindfulness-Based Stress Reduction (MBSR, N = 23) or waitlist control (N = 23) group and underwent a two-day fear conditioning, extinction learning, and extinction memory protocol before and after the course or control period. Skin conductance response (SCR) data served to measure the physiological response during conditioning and extinction memory phases. Diffusion tensor imaging (DTI) data were analyzed with probabilistic tractography and analyzed for changes of fractional anisotropy in the UNC. During conditioning, participants were able to maintain a differential response to conditioned vs. not conditioned stimuli following the MBSR course (i.e., higher sensitivity to the conditioned stimuli), while controls dropped the response. Extinction memory results were not interpretable due to baseline differences. MBSR participants showed a significant increase in fractional anisotropy in the UNC, while controls did not (group by time interaction missed significance). Pre-post changes in UNC were correlated with changes in the response to the conditioned stimuli. The findings suggest effects of mindfulness practice on the maintenance of sensitivity of emotional responses and suggest underlying neural plasticity. (ClinicalTrials.gov, Identifier NCT01320969, https://clinicaltrials.gov/ct2/show/NCT01320969). PMID:27378875

  11. Subcomponents and connectivity of the superior longitudinal fasciculus in the human brain.

    PubMed

    Wang, Xuhui; Pathak, Sudhir; Stefaneanu, Lucia; Yeh, Fang-Cheng; Li, Shiting; Fernandez-Miranda, Juan C

    2016-05-01

    The subcomponents of the human superior longitudinal fasciculus (SLF) are disputed. The objective of this study was to investigate the segments, connectivity and asymmetry of the SLF. We performed high angular diffusion spectrum imaging (DSI) analysis on ten healthy adults. We also conducted fiber tracking on a 30-subject DSI template (CMU-30) and 488-subject template from the Human Connectome Project (HCP-488). In addition, five normal brains obtained at autopsy were microdissected. Based on tractography and microdissection results, we show that the human SLF differs significantly from that of monkey. The fibers corresponding to SLF-I found in 6 out of 20 hemispheres proved to be part of the cingulum fiber system in all cases and confirmed on both DSI and HCP-488 template. The most common patterns of connectivity bilaterally were as follows: from angular gyrus to caudal middle frontal gyrus and dorsal precentral gyrus representing SLF-II (or dorsal SLF), and from supramarginal gyrus to ventral precentral gyrus and pars opercularis to form SLF-III (or ventral SLF). Some connectivity features were, however, clearly asymmetric. Thus, we identified a strong asymmetry of the dorsal SLF (SLF-II), where the connectivity between the supramarginal gyrus with the dorsal precentral gyrus and the caudal middle frontal gyrus was only present in the left hemisphere. Contrarily, the ventral SLF (SLF-III) showed fairly constant connectivity with pars triangularis only in the right hemisphere. The results provide a novel neuroanatomy of the SLF that may help to better understand its functional role in the human brain. PMID:25782434

  12. Reduced Volume of the Arcuate Fasciculus in Adults with High-Functioning Autism Spectrum Conditions.

    PubMed

    Moseley, Rachel L; Correia, Marta M; Baron-Cohen, Simon; Shtyrov, Yury; Pulvermüller, Friedemann; Mohr, Bettina

    2016-01-01

    Atypical language is a fundamental feature of autism spectrum conditions (ASC), but few studies have examined the structural integrity of the arcuate fasciculus, the major white matter tract connecting frontal and temporal language regions, which is usually implicated as the main transfer route used in processing linguistic information by the brain. Abnormalities in the arcuate have been reported in young children with ASC, mostly in low-functioning or non-verbal individuals, but little is known regarding the structural properties of the arcuate in adults with ASC or, in particular, in individuals with ASC who have intact language, such as those with high-functioning autism or Asperger syndrome. We used probabilistic tractography of diffusion-weighted imaging to isolate and scrutinize the arcuate in a mixed-gender sample of 18 high-functioning adults with ASC (17 Asperger syndrome) and 14 age- and IQ-matched typically developing controls. Arcuate volume was significantly reduced bilaterally with clearest differences in the right hemisphere. This finding remained significant in an analysis of all male participants alone. Volumetric reduction in the arcuate was significantly correlated with the severity of autistic symptoms as measured by the Autism-Spectrum Quotient. These data reveal that structural differences are present even in high-functioning adults with ASC, who presented with no clinically manifest language deficits and had no reported developmental language delay. Arcuate structural integrity may be useful as an index of ASC severity and thus as a predictor and biomarker for ASC. Implications for future research are discussed. PMID:27242478

  13. Arcuate fasciculus asymmetry has a hand in language function but not handedness.

    PubMed

    Allendorfer, Jane B; Hernando, Kathleen A; Hossain, Shyla; Nenert, Rodolphe; Holland, Scott K; Szaflarski, Jerzy P

    2016-09-01

    The importance of relationships between handedness, language lateralization and localization, and white matter tracts for language performance is unclear. The goal of the study was to investigate these relationships by examining arcuate fasciculus (AF) structural asymmetry (DTI) and functional asymmetry (fMRI) in language circuits, handedness, and linguistic performance. A large sample of right-handed (n = 158) and atypical-handed (n = 82) healthy adults underwent DTI at 3 T to assess number of streamlines and fractional anisotropy (FA) of the AF, and language fMRI. Language functions were assessed using standard tests of vocabulary, naming, verbal fluency, and complex ideation. Laterality indices (LIs) illustrated degree of asymmetry and lateralization patterns for the AF (streamlines and FA) and verb generation fMRI. Both handedness groups showed leftward lateralization bias for streamline and fMRI LIs and symmetry for FA LI. The proportion of subjects with left, right, or symmetric lateralization were similar between groups if based on AF LIs, but differed if based on fMRI LIs (p = 0.0016). Degree of right-handedness was not associated with AF lateralization, but was associated with fMRI language lateralization (p = 0.0014). FA LI was not associated with performance on language assessments, but streamline LI was associated with better vocabulary and complex ideation performance in atypical-handed subjects (p = 0.022 and p = 0.0098, respectively), and better semantic fluency in right-handed subjects (p = 0.047); however, these did not survive multiple comparisons correction. We provide evidence that AF asymmetry is independent of hand preference, and while degree of right-handedness is associated with hemispheric language lateralization, the majority of atypical-handed individuals are left-lateralized for language. Hum Brain Mapp 37:3297-3309, 2016. © 2016 Wiley Periodicals, Inc. PMID:27144738

  14. Injury of the Arcuate Fasciculus in the Dominant Hemisphere in Patients With Mild Traumatic Brain Injury

    PubMed Central

    Jang, Sung Ho; Lee, Ah Young; Shin, So Min

    2016-01-01

    Abstract Little is known about injury of the arcuate fasciculus (AF) in patients with mild traumatic brain injury (TBI). We investigated injury of the AF in the dominant hemisphere in patients with mild TBI, using diffusion tensor tractography (DTT). We recruited 25 patients with injury of the left AF among 64 right-handed consecutive patients with mild TBI and 20 normal control subjects. DTTs of the left AF were reconstructed, and fractional anisotropy (FA), apparent diffusion coefficient (ADC), and fiber number of the AF were measured. Among 64 consecutive patients, 25 (39%) patients showed injury of the left AF. The patient group showed lower FA value and fiber number with higher ADC value than the control group (P < 0.05). On K-WAB evaluation, aphasia quotient and language quotient were 95.9 ± 4.1 (range 85–100) and 95.0 ± 5.4 (range 80–100), respectively. However, 23 (92.0%) of 25 patients complained of language-related symptoms after TBI; paraphasia in 12 (48.0%) patients, deficits of comprehension in 4 (16.0%) patients, deficits of speech production in 1 (4.0%) patient, and >2 language symptoms in 6 (24.0%) patients. We found that a significant number (39%) of patients with mild TBI had injury of the AF in the dominant hemisphere and these patients had mild language deficit. These results suggest that DTT could provide useful information in detecting injury of the AF and evaluation of the AF using DTT would be necessary even in the case of a patient with mild TBI who complains of mild language deficit. PMID:26945425

  15. Reduced Volume of the Arcuate Fasciculus in Adults with High-Functioning Autism Spectrum Conditions

    PubMed Central

    Moseley, Rachel L.; Correia, Marta M.; Baron-Cohen, Simon; Shtyrov, Yury; Pulvermüller, Friedemann; Mohr, Bettina

    2016-01-01

    Atypical language is a fundamental feature of autism spectrum conditions (ASC), but few studies have examined the structural integrity of the arcuate fasciculus, the major white matter tract connecting frontal and temporal language regions, which is usually implicated as the main transfer route used in processing linguistic information by the brain. Abnormalities in the arcuate have been reported in young children with ASC, mostly in low-functioning or non-verbal individuals, but little is known regarding the structural properties of the arcuate in adults with ASC or, in particular, in individuals with ASC who have intact language, such as those with high-functioning autism or Asperger syndrome. We used probabilistic tractography of diffusion-weighted imaging to isolate and scrutinize the arcuate in a mixed-gender sample of 18 high-functioning adults with ASC (17 Asperger syndrome) and 14 age- and IQ-matched typically developing controls. Arcuate volume was significantly reduced bilaterally with clearest differences in the right hemisphere. This finding remained significant in an analysis of all male participants alone. Volumetric reduction in the arcuate was significantly correlated with the severity of autistic symptoms as measured by the Autism-Spectrum Quotient. These data reveal that structural differences are present even in high-functioning adults with ASC, who presented with no clinically manifest language deficits and had no reported developmental language delay. Arcuate structural integrity may be useful as an index of ASC severity and thus as a predictor and biomarker for ASC. Implications for future research are discussed. PMID:27242478

  16. Selective neurotoxic effects of nicotine on axons in fasciculus retroflexus further support evidence that this a weak link in brain across multiple drugs of abuse.

    PubMed

    Carlson, J; Armstrong, B; Switzer, R C; Ellison, G

    2000-10-01

    When administered continuously for several days at relatively low plasma levels, a variety of drugs of abuse with strong dopaminergic actions induce degeneration in axons traveling from the lateral habenula through the sheath of fasciculus retroflexus to midbrain monoaminergic nuclei. With some of these drugs, such as cocaine, this is virtually the only degeneration induced in brain. Nicotine given continuously also selectively induces degeneration in fasciculus retroflexus, but in the other half of the tract: the cholinergic axons running from medial habenula in the core of the tract to the interpeduncular nucleus. Fasciculus retroflexus appears to be a weak link in brain for diverse drugs of abuse when administered incessantly for several days. Alterations in this tract would be predicted to be especially important for the genesis of the symptomatology which develops during drug binges, residual effects of such binges, and the processes underlying relapse. PMID:11044749

  17. Vertical gaze palsy and selective unilateral infarction of the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF).

    PubMed Central

    Bogousslavsky, J; Miklossy, J; Regli, F; Janzer, R

    1990-01-01

    We report a clinico-pathological correlation study in a patient with basilar artery thrombosis, who developed tetraplegia and combined up- and downgaze palsy involving voluntary saccades and visually-guided movements, but sparing the oculocephalic responses. At necropsy, apart from bilateral infarction in the basis pontis, there was a single unilateral infarct selectively destroying the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) on the right. The posterior commissure and its nucleus, the nucleus of Cajal, the nucleus of Darkschewitsch and the pontine tegmentum were spared. We suggest that the unilateral riMLF lesion may have disrupted bilateral upgaze excitatory and inhibitory inputs and unilateral downgaze excitatory inputs. The functional anatomy of inhibitory and excitatory vertical gaze circuitry, which remains speculative, may explain why a unilateral lesion of the upper midbrain tegmentum may be sufficient to generate an upgaze palsy or a combined up- and downgaze palsy, while an isolated downgaze palsy requires bilateral lesions. Images PMID:2303833

  18. Tract specific analysis in patients with sickle cell disease

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  19. Lower structural integrity of the uncinate fasciculus is associated with a history of child maltreatment and future psychological vulnerability to stress

    PubMed Central

    Hanson, Jamie L; Knodt, Annchen R; Brigidi, Bartholomew D.; Hariri, Ahmad R.

    2015-01-01

    The experience of child maltreatment is a significant risk factor for the development of later internalizing disorders such as depression and anxiety. This risk is particularly heightened after exposure to additional, more contemporaneous stress. While behavioral evidence exists for such “stress sensitization,” little is known about the mechanisms mediating such relationships, particularly within the brain. Here we report that the experience of child maltreatment independent of recent life stress, gender, and age is associated with reduced structural integrity of the uncinate fasciculus, a major white matter pathway between the amygdala and ventromedial prefrontal cortex, in young adults. We further demonstrate that individuals with lower uncinate fasciculus integrity at baseline who subsequently experience stressful life events report higher levels of internalizing symptomatology at follow-up. Our findings suggest a novel neurobiological mechanism linking child maltreatment with later internalizing symptoms, specifically altered structural connectivity within the brain’s threat-detection and emotion regulation circuitry. PMID:26535947

  20. Lower structural integrity of the uncinate fasciculus is associated with a history of child maltreatment and future psychological vulnerability to stress.

    PubMed

    Hanson, Jamie L; Knodt, Annchen R; Brigidi, Bartholomew D; Hariri, Ahmad R

    2015-11-01

    The experience of child maltreatment is a significant risk factor for the development of later internalizing disorders such as depression and anxiety. This risk is particularly heightened after exposure to additional, more contemporaneous stress. While behavioral evidence exists for such "stress sensitization," little is known about the mechanisms mediating such relationships, particularly within the brain. Here we report that the experience of child maltreatment independent of recent life stress, gender, and age is associated with reduced structural integrity of the uncinate fasciculus, a major white matter pathway between the amygdala and ventromedial prefrontal cortex, in young adults. We further demonstrate that individuals with lower uncinate fasciculus integrity at baseline who subsequently experience stressful life events report higher levels of internalizing symptomatology at follow-up. Our findings suggest a novel neurobiological mechanism linking child maltreatment with later internalizing symptoms, specifically altered structural connectivity within the brain's threat-detection and emotion-regulation circuitry. PMID:26535947

  1. The plasticity of the superior longitudinal fasciculus as a function of musical expertise: a diffusion tensor imaging study.

    PubMed

    Oechslin, Mathias S; Imfeld, Adrian; Loenneker, Thomas; Meyer, Martin; Jäncke, Lutz

    2009-01-01

    Previous neuroimaging studies have demonstrated that musical expertise leads to functional alterations in language processing. We utilized diffusion tensor imaging (DTI) to investigate white matter plasticity in musicians with absolute pitch (AP), relative pitch and non-musicians. Using DTI, we analysed the fractional anisotropy (FA) of the superior longitudinal fasciculus (SLF), which is considered the most primary pathway for processing and production of speech and music. In association with different levels of musical expertise, we found that AP is characterized by a greater left than right asymmetry of FA in core fibres of the SLF. A voxel-based analysis revealed three clusters within the left hemisphere SLF that showed significant positive correlations with error rates only for AP-musicians in an AP-test, but not for musicians without AP. We therefore conclude that the SLF architecture in AP musicians is related to AP acuity. In order to reconcile our observations with general aspects of development of fibre bundles, we introduce the Pioneer Axon Thesis, a theoretical approach to formalize axonal arrangements of major white matter pathways. PMID:20161812

  2. Language, aging, and cognition: frontal aslant tract and superior longitudinal fasciculus contribute toward working memory performance in older adults.

    PubMed

    Rizio, Avery A; Diaz, Michele T

    2016-06-15

    Previous research has documented change in white matter tract integrity with increasing age. Both interhemispheric and intrahemispheric tracts that underlie language processing are susceptible to these age-related changes. The aim of the current study was to explore age and white matter integrity in language-related tracts as predictors of cognitive task performance in younger and older adults. To this end, we carried out principal component analyses of white matter tracts and confirmatory factor analysis of neuropsychological measures. We next carried out a series of regression analyses that used white matter components to predict scores on each of the neuropsychological components. For both younger and older adults, age was a significant predictor of processing speed and working memory. However, white matter integrity did not contribute independently toward these models. In older adults only, both age and a white matter component that included the bilateral frontal aslant tract and left superior longitudinal fasciculus were significant predictors of working memory. Taken together, these results extend our understanding of the contributions of language-related white matter structure to cognitive processing and highlight the effects of age-related differences in both frontal and dorsal tracts. PMID:27138951

  3. The Plasticity of the Superior Longitudinal Fasciculus as a Function of Musical Expertise: A Diffusion Tensor Imaging Study

    PubMed Central

    Oechslin, Mathias S.; Imfeld, Adrian; Loenneker, Thomas; Meyer, Martin; Jäncke, Lutz

    2009-01-01

    Previous neuroimaging studies have demonstrated that musical expertise leads to functional alterations in language processing. We utilized diffusion tensor imaging (DTI) to investigate white matter plasticity in musicians with absolute pitch (AP), relative pitch and non-musicians. Using DTI, we analysed the fractional anisotropy (FA) of the superior longitudinal fasciculus (SLF), which is considered the most primary pathway for processing and production of speech and music. In association with different levels of musical expertise, we found that AP is characterized by a greater left than right asymmetry of FA in core fibres of the SLF. A voxel-based analysis revealed three clusters within the left hemisphere SLF that showed significant positive correlations with error rates only for AP-musicians in an AP-test, but not for musicians without AP. We therefore conclude that the SLF architecture in AP musicians is related to AP acuity. In order to reconcile our observations with general aspects of development of fibre bundles, we introduce the Pioneer Axon Thesis, a theoretical approach to formalize axonal arrangements of major white matter pathways. PMID:20161812

  4. Asymmetric projections of the arcuate fasciculus to the temporal cortex underlie lateralized language function in the human brain

    PubMed Central

    Takaya, Shigetoshi; Kuperberg, Gina R.; Liu, Hesheng; Greve, Douglas N.; Makris, Nikos; Stufflebeam, Steven M.

    2015-01-01

    The arcuate fasciculus (AF) in the human brain has asymmetric structural properties. However, the topographic organization of the asymmetric AF projections to the cortex and its relevance to cortical function remain unclear. Here we mapped the posterior projections of the human AF in the inferior parietal and lateral temporal cortices using surface-based structural connectivity analysis based on diffusion MRI and investigated their hemispheric differences. We then performed the cross-modal comparison with functional connectivity based on resting-state functional MRI (fMRI) and task-related cortical activation based on fMRI using a semantic classification task of single words. Structural connectivity analysis showed that the left AF connecting to Broca's area predominantly projected in the lateral temporal cortex extending from the posterior superior temporal gyrus to the mid part of the superior temporal sulcus and the middle temporal gyrus, whereas the right AF connecting to the right homolog of Broca's area predominantly projected to the inferior parietal cortex extending from the mid part of the supramarginal gyrus to the anterior part of the angular gyrus. The left-lateralized projection regions of the AF in the left temporal cortex had asymmetric functional connectivity with Broca's area, indicating structure-function concordance through the AF. During the language task, left-lateralized cortical activation was observed. Among them, the brain responses in the temporal cortex and Broca's area that were connected through the left-lateralized AF pathway were specifically correlated across subjects. These results suggest that the human left AF, which structurally and functionally connects the mid temporal cortex and Broca's area in asymmetrical fashion, coordinates the cortical activity in these remote cortices during a semantic decision task. The unique feature of the left AF is discussed in the context of the human capacity for language. PMID:26441551

  5. Swedish Successful Schools Revisited

    ERIC Educational Resources Information Center

    Hoog, Jonas; Johansson, Olof; Olofsson, Anders

    2009-01-01

    Purpose: The purpose of this paper is to describe the results of a follow-up study of two Swedish schools in which, five years previously, the principals had been successful leaders. Had this success been maintained? Design/methodology/approach: Two schools were revisited to enable the authors to interview principals and teachers as well as…

  6. The Linguistic Repertoire Revisited

    ERIC Educational Resources Information Center

    Busch, Brigitta

    2012-01-01

    This article argues for the relevance of poststructuralist approaches to the notion of a linguistic repertoire and introduces the notion of language portraits as a basis for empirical study of the way in which speakers conceive and represent their heteroglossic repertoires. The first part of the article revisits Gumperz's notion of a linguistic…

  7. A Hydrostatic Paradox Revisited

    ERIC Educational Resources Information Center

    Ganci, Salvatore

    2012-01-01

    This paper revisits a well-known hydrostatic paradox, observed when turning upside down a glass partially filled with water and covered with a sheet of light material. The phenomenon is studied in its most general form by including the mass of the cover. A historical survey of this experiment shows that a common misunderstanding of the phenomenon…

  8. Revisiting Bioaccumulation Criteria

    EPA Science Inventory

    The objective of workgroup 5 was to revisit the B(ioaccumulation) criteria that are currently being used to identify POPs under the Stockholm Convention and PBTs under CEPA, TSCA, REACh and other programs. Despite the lack of a recognized definition for a B substance, we defined ...

  9. Colloquial Hebrew Imperatives Revisited

    ERIC Educational Resources Information Center

    Bolozky, Shmuel

    2009-01-01

    In revisiting Bolozky's [Bolozky, Shmuel, 1979. "On the new imperative in colloquial Hebrew." "Hebrew Annual Review" 3, 17-24] and Bat-El's [Bat-El, Outi, 2002. "True truncation in colloquial Hebrew imperatives." "Language" 78(4), 651-683] analyses of colloquial Hebrew imperatives, the article argues for restricting Imperative Truncation to the…

  10. Revisiting Curriculum Potential

    ERIC Educational Resources Information Center

    Deng, Zongyi

    2011-01-01

    This article analyzes the notion of curriculum potential by revisiting the ideas of Miriam Ben-Peretz and Joseph Schwab. Invoking the German "Didaktik" tradition and by way of a curriculum-making framework, the paper argues that interpreting curriculum materials for curriculum potential requires a careful analysis and unpacking of the meanings and…

  11. Anodic Polarization Curves Revisited

    ERIC Educational Resources Information Center

    Liu, Yue; Drew, Michael G. B.; Liu, Ying; Liu, Lin

    2013-01-01

    An experiment published in this "Journal" has been revisited and it is found that the curve pattern of the anodic polarization curve for iron repeats itself successively when the potential scan is repeated. It is surprising that this observation has not been reported previously in the literature because it immediately brings into…

  12. Revisiting the Rhetorical Curriculum

    ERIC Educational Resources Information Center

    Rutten, Kris; Soetaert, Ronald

    2012-01-01

    The aim of the special strand on "Revisiting the rhetorical curriculum" is to explore the educational potential of a new rhetorical perspective, specifically in relation to different traditions within educational and rhetorical studies. This implies that we do not only look at education "in" rhetoric, but that we position education also "as" a…

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

    PubMed

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

    2016-06-01

    Auditory verbal hallucinations (AVH) have been proposed to result from altered connectivity between frontal speech production regions and temporal speech perception regions. Whilst the dorsal language pathway, serviced by the arcuate fasciculus, has been extensively studied in relation to AVH, the ventral language pathway, serviced by the inferior occipito-frontal fasciculus (IOFF) has been rarely studied in relation to AVH. This study examined whether structural changes in anatomically defined subregions of the IOFF were associated with AVH in patients with schizophrenia. Diffusion tensor imaging scans and clinical data were obtained from the Australian Schizophrenia Research Bank for 113 schizophrenia patients, of whom 39 had lifetime experience of AVH (18 had current AVH, 21 had remitted AVH), 74 had no lifetime experience of AVH, and 40 healthy controls. Schizophrenia patients with a lifetime experience of AVH exhibited reduced fractional anisotropy (FA) in the fronto-temporal fibers of the left IOFF compared to both healthy controls and schizophrenia patients without AVH. In contrast, structural abnormalities in the temporal and occipital regions of the IOFF were observed bilaterally in both patient groups, relative to the healthy controls. These results suggest that while changes in the structural integrity of the bilateral IOFF are associated with schizophrenia per se, integrity reductions in the fronto-temporal fibers of the left IOFF may be specifically associated with AVH. PMID:26112051

  14. Revisiting Dialogues and Monologues

    ERIC Educational Resources Information Center

    Kvernbekk, Tone

    2012-01-01

    In educational discourse dialogue tends to be viewed as being (morally) superior to monologue. When we look at them as basic forms of communication, we find that dialogue is a two-way, one-to-one form and monologue is a one-way, one-to-many form. In this paper I revisit the alleged (moral) superiority of dialogue. First, I problematize certain…

  15. Time functions revisited

    NASA Astrophysics Data System (ADS)

    Fathi, Albert

    2015-07-01

    In this paper we revisit our joint work with Antonio Siconolfi on time functions. We will give a brief introduction to the subject. We will then show how to construct a Lipschitz time function in a simplified setting. We will end with a new result showing that the Aubry set is not an artifact of our proof of existence of time functions for stably causal manifolds.

  16. Cerebral white matter deficiencies in pedophilic men.

    PubMed

    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

    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

  17. Reframing in dentistry: revisited.

    PubMed

    Nuvvula, Sivakumar; Kamatham, Rekalakshmi; Challa, Ramasubbareddy; Asokan, Sharath

    2013-01-01

    The successful practice of dentistry involves a good combination of technical skills and soft skills. Soft skills or communication skills are not taught extensively in dental schools and it can be challenging to learn and at times in treating dental patients. Guiding the child's behavior in the dental operatory is one of the preliminary steps to be taken by the pediatric dentist and one who can successfully modify the behavior can definitely pave the way for a life time comprehensive oral care. This article is an attempt to revisit a simple behavior guidance technique, reframing and explain the possible psychological perspectives behind it for better use in the clinical practice. PMID:24021326

  18. Bottomonium spectrum revisited

    NASA Astrophysics Data System (ADS)

    Segovia, Jorge; Ortega, Pablo G.; Entem, David R.; Fernández, Francisco

    2016-04-01

    We revisit the bottomonium spectrum motivated by the recently exciting experimental progress in the observation of new bottomonium states, both conventional and unconventional. Our framework is a nonrelativistic constituent quark model which has been applied to a wide range of hadronic observables from the light to the heavy quark sector, and thus the model parameters are completely constrained. Beyond the spectrum, we provide a large number of electromagnetic, strong and hadronic decays in order to discuss the quark content of the bottomonium states and give more insights about a better way to determine their properties experimentally.

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

    PubMed Central

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

    2010-01-01

    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 (5M) 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

  20. Lower white matter microstructure in the superior longitudinal fasciculus is associated with increased response time variability in adults with attention-deficit/hyperactivity disorder

    PubMed Central

    Wolfers, Thomas; Onnink, A. Marten H.; Zwiers, Marcel P.; Arias-Vasquez, Alejandro; Hoogman, Martine; Mostert, Jeanette C.; Kan, Cornelis C.; Slaats-Willemse, Dorine; Buitelaar, Jan K.; Franke, Barbara

    2015-01-01

    Background Response time variability (RTV) is consistently increased in patients with attention-deficit/hyperactivity disorder (ADHD). A right-hemispheric frontoparietal attention network model has been implicated in these patients. The 3 main connecting fibre tracts in this network, the superior longitudinal fasciculus (SLF), inferior longitudinal fasciculus (ILF) and the cingulum bundle (CB), show microstructural abnormalities in patients with ADHD. We hypothesized that the microstructural integrity of the 3 white matter tracts of this network are associated with ADHD and RTV. Methods We examined RTV in adults with ADHD by modelling the reaction time distribution as an exponentially modified Gaussian (ex-Gaussian) function with the parameters μ, σ and τ, the latter of which has been attributed to lapses of attention. We assessed adults with ADHD and healthy controls using a sustained attention task. Diffusion tensor imaging–derived fractional anisotropy (FA) values were determined to quantify bilateral microstructural integrity of the tracts of interest. Results We included 100 adults with ADHD and 96 controls in our study. Increased τ was associated with ADHD diagnosis and was linked to symptoms of inattention. An inverse correlation of τ with mean FA was seen in the right SLF of patients with ADHD, but no direct association between the mean FA of the 6 regions of interest with ADHD could be observed. Limitations Regions of interest were defined a priori based on the attentional network model for ADHD and thus we might have missed effects in other networks. Conclusion This study suggests that reduced microstructural integrity of the right SLF is associated with elevated τ in patients with ADHD. PMID:26079698

  1. Altered hemispheric lateralization of white matter pathways in developmental dyslexia: Evidence from spherical deconvolution tractography.

    PubMed

    Zhao, Jingjing; Thiebaut de Schotten, Michel; Altarelli, Irene; Dubois, Jessica; Ramus, Franck

    2016-03-01

    This study examines the structural integrity and the hemispheric lateralization patterns of four major association fiber pathways in a group of French dyslexic children and age-matched controls (from 9 to 14 years), using high angular diffusion imaging combined with spherical deconvolution tractography. Compared with age-matched controls, dyslexic children show increased hindrance-modulated oriented anisotropy (HMOA) in the right superior longitudinal fasciculus (SLF). They also show a reduced leftward asymmetry of the inferior fronto-occipital fasciculus (IFOF) and an increased rightward asymmetry of the second branch of the SLF (SLF II). The lateralization pattern of IFOF and SLF II also accounts for individual differences in dyslexic children's reading abilities. These data provide evidence for an abnormal lateralization of occipito-frontal and parieto-frontal pathways in developmental dyslexia. PMID:26859852

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

    PubMed Central

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

    2013-01-01

    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

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

    PubMed Central

    Ben-Shachar, Michal; Feldman, Heidi M.

    2015-01-01

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

  4. Satellite failures revisited

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2012-12-01

    In January 1994, the two geostationary satellites known as Anik-E1 and Anik-E2, operated by Telesat Canada, failed one after the other within 9 hours, leaving many northern Canadian communities without television and data services. The outage, which shut down much of the country's broadcast television for hours and cost Telesat Canada more than $15 million, generated significant media attention. Lam et al. used publicly available records to revisit the event; they looked at failure details, media coverage, recovery effort, and cost. They also used satellite and ground data to determine the precise causes of those satellite failures. The researchers traced the entire space weather event from conditions on the Sun through the interplanetary medium to the particle environment in geostationary orbit.

  5. Anonymous Signatures Revisited

    NASA Astrophysics Data System (ADS)

    Saraswat, Vishal; Yun, Aaram

    We revisit the notion of the anonymous signature, first formalized by Yang, Wong, Deng and Wang [10], and then further developed by Fischlin [4] and Zhang and Imai [11]. We present a new formalism of anonymous signature, where instead of the message, a part of the signature is withheld to maintain anonymity. We introduce the notion unpretendability to guarantee infeasibility for someone other than the correct signer to pretend authorship of the message and signature. Our definition retains applicability for all previous applications of the anonymous signature, provides stronger security, and is conceptually simpler. We give a generic construction from any ordinary signature scheme, and also show that the short signature scheme by Boneh and Boyen [2] can be naturally regarded as such a secure anonymous signature scheme according to our formalism.

  6. Revisiting Lambert's problem

    NASA Astrophysics Data System (ADS)

    Izzo, Dario

    2015-01-01

    The orbital boundary value problem, also known as Lambert problem, is revisited. Building upon Lancaster and Blanchard approach, new relations are revealed and a new variable representing all problem classes, under L-similarity, is used to express the time of flight equation. In the new variable, the time of flight curves have two oblique asymptotes and they mostly appear to be conveniently approximated by piecewise continuous lines. We use and invert such a simple approximation to provide an efficient initial guess to an Householder iterative method that is then able to converge, for the single revolution case, in only two iterations. The resulting algorithm is compared, for single and multiple revolutions, to Gooding's procedure revealing to be numerically as accurate, while having a significantly smaller computational complexity.

  7. Quantum duel revisited

    NASA Astrophysics Data System (ADS)

    Schmidt, Alexandre G. M.; Paiva, Milena M.

    2012-03-01

    We revisit the quantum two-person duel. In this problem, both Alice and Bob each possess a spin-1/2 particle which models dead and alive states for each player. We review the Abbott and Flitney result—now considering non-zero α1 and α2 in order to decide if it is better for Alice to shoot or not the second time—and we also consider a duel where players do not necessarily start alive. This simple assumption allows us to explore several interesting special cases, namely how a dead player can win the duel shooting just once, or how can Bob revive Alice after one shot, and the better strategy for Alice—being either alive or in a superposition of alive and dead states—fighting a dead opponent.

  8. Multinomial pattern matching revisited

    NASA Astrophysics Data System (ADS)

    Horvath, Matthew S.; Rigling, Brian D.

    2015-05-01

    Multinomial pattern matching (MPM) is an automatic target recognition algorithm developed for specifically radar data at Sandia National Laboratories. The algorithm is in a family of algorithms that first quantizes pixel value into Nq bins based on pixel amplitude before training and classification. This quantization step reduces the sensitivity of algorithm performance to absolute intensity variation in the data, typical of radar data where signatures exhibit high variation for even small changes in aspect angle. Our previous work has focused on performance analysis of peaky template matching, a special case of MPM where binary quantization is used (Nq = 2). Unfortunately references on these algorithms are generally difficult to locate and here we revisit the MPM algorithm and illustrate the underlying statistical model and decision rules for two algorithm interpretations: the 1-of-K vector form and the scalar. MPM can also be used as a detector and specific attention is given to algorithm tuning where "peak pixels" are chosen based on their underlying empirical probabilities according to a reward minimization strategy aimed at reducing false alarms in the detection scenario and false positives in a classification capacity. The algorithms are demonstrated using Monte Carlo simulations on the AFRL civilian vehicle dataset for variety of choices of Nq.

  9. Lorentz violation naturalness revisited

    NASA Astrophysics Data System (ADS)

    Belenchia, Alessio; Gambassi, Andrea; Liberati, Stefano

    2016-06-01

    We revisit here the naturalness problem of Lorentz invariance violations on a simple toy model of a scalar field coupled to a fermion field via a Yukawa interaction. We first review some well-known results concerning the low-energy percolation of Lorentz violation from high energies, presenting some details of the analysis not explicitly discussed in the literature and discussing some previously unnoticed subtleties. We then show how a separation between the scale of validity of the effective field theory and that one of Lorentz invariance violations can hinder this low-energy percolation. While such protection mechanism was previously considered in the literature, we provide here a simple illustration of how it works and of its general features. Finally, we consider a case in which dissipation is present, showing that the dissipative behaviour does not percolate generically to lower mass dimension operators albeit dispersion does. Moreover, we show that a scale separation can protect from unsuppressed low-energy percolation also in this case.

  10. Stacking Global Seismograms Revisited

    NASA Astrophysics Data System (ADS)

    Shearer, P. M.; Buehler, J. S.; Denolle, M.; Fan, W.; Ma, Z.; Mancinelli, N. J.; Matoza, R. S.; Wang, W.; Wang, Y.; Zhan, Z.

    2014-12-01

    Over 20 years ago, stacks of global seismograms produced direct images of the global seismic wavefield highlighting the visibility, frequency content, and polarity of known seismic phases, and also identified a host of new phases associated with reflections and phase conversions from upper-mantle discontinuities. Two different stacking methods proved particularly useful: (1) STA/LTA-filtered stacks that describe the local signal-to-noise characteristics of the major seismic phases. These serve to image the entire wavefield in a uniform way for educational purposes and to show which phases are observed most clearly as a guide to future research. These stacks also resolve SH versus SV timing differences consistent with radial anisotropy. (2) Reference-phase stacks that preserve the polarity, amplitude, and timing of traces with respect to a specified target phase. These show a large number of top-side and bottom-side reflections and phase conversions from the 410- and 660-km discontinuities that create weak phases with a characteristic "railroad track" appearance both preceding and following many of the main seismic phases. Reference-phase stacking can also be used to produce coherent surface-wave stacks at very long periods, which directly show the dispersive character of the surface waves. Here we revisit and update these stacks by exploiting the vastly increased data now available from the IRIS DMC to produce greatly improved wavefield images. We present several examples of the different stacking approaches and point out their various features, including promising targets for future research.

  11. CGL description revisited

    NASA Astrophysics Data System (ADS)

    Hunana, P.; Zank, G. P.; Goldstein, M. L.; Webb, G. M.; Adhikari, L.

    2016-03-01

    Solar wind observational studies have emphasized that the solar wind plasma data is bounded by the mirror and firehose instabilities, and it is often believed that these instabilities are of a purely kinetic nature. The simplest fluid model that generalizes magnetohydrodynamics with anisotropic temperatures is the Chew-Goldberger-Low model (CGL). Here we briefly revisit the CGL description and discuss its (otherwise well-documented) linear firehose and mirror instability thresholds; namely that the firehose instability threshold is identical to the one found from linear kinetic theory and that the mirror threshold contains a factor of 6 error. We consider a simple higher-order fluid model with time dependent heat flux equations and show that the mirror instability threshold is correctly reproduced. We also present fully nonlinear three-dimensional simulations of freely decaying turbulence for the Hall-CGL model with isothermal electrons. The spatial resolution of these simulations is 5123 and the formation of a spectral break in magnetic and velocity field spectra around the proton inertial length is found.

  12. Searle's"Dualism Revisited"

    SciTech Connect

    P., Henry

    2008-11-20

    A recent article in which John Searle claims to refute dualism is examined from a scientific perspective. John Searle begins his recent article 'Dualism Revisited' by stating his belief that the philosophical problem of consciousness has a scientific solution. He then claims to refute dualism. It is therefore appropriate to examine his arguments against dualism from a scientific perspective. Scientific physical theories contain two kinds of descriptions: (1) Descriptions of our empirical findings, expressed in an every-day language that allows us communicate to each other our sensory experiences pertaining to what we have done and what we have learned; and (2) Descriptions of a theoretical model, expressed in a mathematical language that allows us to communicate to each other certain ideas that exist in our mathematical imaginations, and that are believed to represent, within our streams of consciousness, certain aspects of reality that we deem to exist independently of their being perceived by any human observer. These two parts of our scientific description correspond to the two aspects of our general contemporary dualistic understanding of the total reality in which we are imbedded, namely the empirical-mental aspect and the theoretical-physical aspect. The duality question is whether this general dualistic understanding of ourselves should be regarded as false in some important philosophical or scientific sense.

  13. Revisiting caspases in sepsis

    PubMed Central

    Aziz, M; Jacob, A; Wang, P

    2014-01-01

    Sepsis is a life-threatening illness that occurs due to an abnormal host immune network which extends through the initial widespread and overwhelming inflammation, and culminates at the late stage of immunosupression. Recently, interest has been shifted toward therapies aimed at reversing the accompanying periods of immune suppression. Studies in experimental animals and critically ill patients have demonstrated that increased apoptosis of lymphoid organs and some parenchymal tissues contributes to this immune suppression, anergy and organ dysfunction. Immediate to the discoveries of the intracellular proteases, caspases for the induction of apoptosis and inflammation, and their striking roles in sepsis have been focused elaborately in a number of original and review articles. Here we revisited the different aspects of caspases in terms of apoptosis, pyroptosis, necroptosis and inflammation and focused their links in sepsis by reviewing several recent findings. In addition, we have documented striking perspectives which not only rewrite the pathophysiology, but also modernize our understanding for developing novel therapeutics against sepsis. PMID:25412304

  14. Cats protecting birds revisited.

    PubMed

    Fan, Meng; Kuang, Yang; Feng, Zhilan

    2005-09-01

    In this paper, we revisit the dynamical interaction among prey (bird), mesopredator (rat), and superpredator (cat) discussed in [Courchamp, F., Langlais, M., Sugihara, G., 1999. Cats protecting birds: modelling the mesopredator release effect. Journal of Animal Ecology 68, 282-292]. First, we develop a prey-mesopredator-superpredator (i.e., bird-rat-cat, briefly, BRC) model, where the predator's functional responses are derived based on the classical Holling's time budget arguments. Our BRC model overcomes several model construction problems in Courchamp et al. (1999), and admits richer, reasonable and realistic dynamics. We explore the possible control strategies to save or restore the bird by controlling or eliminating the rat or the cat when the bird is endangered. We establish the existence of two types of mesopredator release phenomena: severe mesopredator release, where once superpredators are suppressed, a burst of mesopredators follows which leads their shared prey to extinction; and mild mesopredator release, where the mesopredator release could assert more negative impact on the endemic prey but does not lead the endemic prey to extinction. A sharp sufficient criterion is established for the occurrence of severe mesopredator release. We also show that, in a prey-mesopredator-superpredator trophic food web, eradication of introduced superpredators such as feral domestic cats in the BRC model, is not always the best solution to protect endemic insular prey. The presence of a superpredator may have a beneficial effect in such systems. PMID:15998496

  15. Adding insult to injury: childhood and adolescent risk factors for psychosis predict lower fractional anisotropy in the superior longitudinal fasciculus in healthy adults.

    PubMed

    DeRosse, Pamela; Ikuta, Toshikazu; Peters, Bart D; Karlsgodt, Katherine H; Szeszko, Philip R; Malhotra, Anil K

    2014-12-30

    Although epidemiological studies provide strong support for demographic and environmental risk factors in psychotic disorders, few data examine how these risk factors relate to the putative aberrant neurodevelopment associated with illness. The present study examined how the accumulation of risk factors including low IQ, low parental socioeconomic status (SES), history of adolescent cannabis use and childhood trauma, and high levels of subclinical psychotic-like experiences (PLEs) contributed to aberrant neurodevelopmental outcomes in 112 otherwise healthy adults recruited from the community. Participants were studied with diffusion tensor imaging (DTI), and voxel-wise statistical analysis of fractional anisotropy (FA) using tract-based spatial statistics (TBSS) was used to examine the relation between cumulative risk (CR) for psychosis and white matter (WM) integrity across the whole brain. Analyses revealed that higher CR was significantly associated with lower FA in a cluster in the left superior longitudinal fasciculus (SLF). These results suggest that risk factors previously associated with psychotic disorders are associated with WM integrity even in otherwise healthy adults and may provide insight into how previously identified risk factors contribute to the structural brain abnormalities associated with psychotic illness. Prospective longitudinal studies examining the effect of risk factors on the developmental trajectory of brain WM are warranted. PMID:25277095

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

    PubMed

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

    2014-07-01

    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

  17. Adding insult to injury: childhood and adolescent risk factors for psychosis predict lower fractional anisotropy in the superior longitudinal fasciculus in healthy adults

    PubMed Central

    DeRosse, Pamela; Ikuta, Toshikazu; Peters, Bart D.; Karlsgodt, Katherine H.; Szeszko, Philip R.; Malhotra, Anil K.

    2014-01-01

    Although epidemiological studies provide strong support for demographic and environmental risk factors in psychotic disorders, few data examine how these risk factors relate to the putative aberrant neurodevelopment associated with illness. The present study examined how the accumulation of risk factors including low IQ, low parental socioeconomic status, history of adolescent cannabis use and childhood trauma, and high levels of subclinical psychotic-like experiences contributed to aberrant neurodevelopmental outcomes in 112 otherwise healthy adults recruited from the community. Participants were studied with diffusion tensor imaging, and voxel-wise statistical analysis of fractional anisotropy (FA) using tract-based spatial statistics was used to examine the relation between cumulative risk (CR) for psychosis and white matter (WM) integrity across the whole brain. Analyses revealed that higher CR was significantly associated with lower FA in a cluster in the left superior longitudinal fasciculus. These results suggest that risk factors previously associated with psychotic disorders are associated with WM integrity even in otherwise healthy adults and may provide insight into how previously identified risk factors contribute to the structural brain abnormalities associated with psychotic illness. Prospective longitudinal studies examining the effect of risk factors on the developmental trajectory of brain WM are warranted. PMID:25277095

  18. White matter microstructure of the uncinate fasciculus is associated with subthreshold posttraumatic stress disorder symptoms and fear potentiated startle during early extinction in recently deployed Service Members.

    PubMed

    Costanzo, Michelle E; Jovanovic, Tanja; Pham, Dzung; Leaman, Suzanne; Highland, Krista B; Norrholm, Seth Davin; Roy, Michael J

    2016-04-01

    Early intervention following combat deployment has the potential to prevent posttraumatic stress disorder (PTSD), but there is a need for greater understanding of the factors that contribute to PTSD symptom progression. This study investigated: (1) fear-potentiated startle during a fear extinction, (2) white matter microstructure, and (3) PTSD symptom severity, in 48 recently deployed service members (SMs) who did not have sufficient PTSD symptoms to meet criteria for a clinical diagnosis. Electromyography startle during a conditional discrimination paradigm, diffusion tensor imaging, and the Clinician Administered PTSD Scale were assessed in a cohort of SMs within 2 months after their return from Iraq or Afghanistan. Significant correlations were found between left uncinate fasciculus (UF) white matter tract integrity and total PTSD symptoms, r=-0.343, p=0.018; the left UF and hyperarousal symptoms, r=-0.29, p=0.047; right UF integrity and total PTSD symptoms r=-0.3371, p=0.01; right UF integrity and hyperarousal symptoms r=-0.332, p=0.023; left UF and startle during early extinction, r=.31, p=0.033. Our results indicate that compromise of UF tract frontal-limbic connections are associated with greater PTSD symptom severity and lower startle response during extinction. In a subthreshold population, such a relationship between brain structure, physiological reactivity, and behavioral expression may reveal vulnerabilities that could have significant implications for PTSD symptom development. PMID:26923670

  19. Injury of the Arcuate Fasciculus in the Nondominant Hemisphere by Subfalcine Herniation in Patients with Intracerebral Hemorrhage : Two Case Reports and Literature Review

    PubMed Central

    Jang, Sung Ho; Kim, Seong Ho

    2016-01-01

    Using diffusion tensor tractography (DTT), we demonstrated injury of the arcuate fasciculus (AF) in the nondominant hemisphere in two patients who showed subfalcine herniation after intracerebral hemorrhage (ICH) in the dominant hemisphere. Two patients (patient 1 and patient 2) with ICH and six age-matched control patients who have ICH on the left corona radiata and basal ganglia without subfalcine herniation were recruited for this study. DTT was performed at one month after onset in patient 1 and patient 2. AFs of both hemispheres in both patients were disrupted between Wernicke's and Broca's areas. The fractional anisotropy value and tract numbers of the right AFs in both patients were found to be more than two standard deviations lower than those of control patients. In contrast, the apparent diffusion coefficient value was more than two standard deviations higher than those of control patients. Using the configuration and parameters of DTT, we confirmed injury of the AF in the nondominant hemisphere in two patients with subfalcine herniation following ICH in the dominant hemisphere. Therefore, DTT would be a useful tool for detection of underlying injury of the AF in the nondominant hemisphere in patients with subfalcine herniation. PMID:27226866

  20. 42 CFR 488.30 - Revisit user fee for revisit surveys.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 5 2012-10-01 2012-10-01 false Revisit user fee for revisit surveys. 488.30 Section 488.30 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES General Provisions § 488.30 Revisit user fee...

  1. Erratum: Interstellar Abundance Standards Revisited

    NASA Astrophysics Data System (ADS)

    Sofia, U. J.; Meyer, D. M.

    2001-09-01

    In the Letter ``Interstellar Abundance Standards Revisited'' by U. J. Sofia and D. M. Meyer (ApJ, 554, L221 [2001]), Table 2 and its footnotes contain several typographical errors. The corrected table is shown below. We note that the solar reference standard now implies a positive abundance of nitrogen in halo dust.

  2. Cultural Warping of Childbirth, Revisited

    PubMed Central

    Budin, Wendy C.

    2007-01-01

    In this column, the editor of The Journal of Perinatal Education revisits Doris Haire's classic 1972 article, “The Cultural Warping of Childbirth,” and describes the birth culture of today. The editor also describes the contents of this issue, which offer a broad range of resources, research, and inspiration for childbirth educators in their efforts to promote normal birth.

  3. The "Mushroom Cloud" Demonstration Revisited

    ERIC Educational Resources Information Center

    Panzarasa, Guido; Sparnacci, Katia

    2013-01-01

    A revisitation of the classical "mushroom cloud" demonstration is described. Instead of aniline and benzoyl peroxide, the proposed reaction involves household chemicals such as alpha-pinene (turpentine oil) and trichloroisocyanuric acid ("Trichlor") giving an impressive demonstration of oxidation and combustion reactions that…

  4. Frontotemporal networks and behavioral symptoms in primary progressive aphasia

    PubMed Central

    Mesulam, Marsel M.; Thiebaut de Schotten, Michel; Dell'Acqua, Flavio; Murphy, Declan; Wieneke, Christina; Martersteck, Adam; Cobia, Derin; Rogalski, Emily

    2016-01-01

    Objective: To determine if behavioral symptoms in patients with primary progressive aphasia (PPA) were associated with degeneration of a ventral frontotemporal network. Methods: We used diffusion tensor imaging tractography to quantify abnormalities of the uncinate fasciculus that connects the anterior temporal lobe and the ventrolateral frontal cortex. Two additional ventral tracts were studied: the inferior fronto-occipital fasciculus and the inferior longitudinal fasciculus. We also measured cortical thickness of anterior temporal and orbitofrontal regions interconnected by these tracts. Thirty-three patients with PPA and 26 healthy controls were recruited. Results: In keeping with the PPA diagnosis, behavioral symptoms were distinctly less prominent than the language deficits. Although all 3 tracts had structural pathology as determined by tractography, significant correlations with scores on the Frontal Behavioral Inventory were found only for the uncinate fasciculus. Cortical atrophy of the orbitofrontal and anterior temporal lobe cortex was also correlated with these scores. Conclusions: Our findings indicate that damage to a frontotemporal network mediated by the uncinate fasciculus may underlie the emergence of behavioral symptoms in patients with PPA. PMID:26992858

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

    PubMed Central

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

    2013-01-01

    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. PMID:23582873

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

    PubMed

    Amemiya, Kaoru; Naito, Eiichi

    2016-05-01

    It is generally believed that the human right cerebral hemisphere plays a dominant role in corporeal awareness, which is highly associated with conscious experience of the physical self. Prompted by our previous findings, we examined whether the right frontoparietal activations often observed when people experience kinesthetic illusory limb movement are supported by a large-scale brain network connected by a specific branch of the superior longitudinal fasciculus fiber tracts (SLF I, II, and III). We scanned brain activity with functional magnetic resonance imaging (MRI) while nineteen blindfolded healthy volunteers experienced illusory movement of the right stationary hand elicited by tendon vibration, which was replicated after the scanning. We also scanned brain activity when they executed and imagined right hand movement, and identified the active brain regions during illusion, execution, and imagery in relation to the SLF fiber tracts. We found that illusion predominantly activated the right inferior frontoparietal regions connected by SLF III, which were not substantially recruited during execution and imagery. Among these regions, activities in the right inferior parietal cortices and inferior frontal cortices showed right-side dominance and correlated well with the amount of illusion (kinesthetic illusory awareness) experienced by the participants. The results illustrated the predominant involvement of the right inferior frontoparietal network connected by SLF III when people recognize postural changes of their limb. We assume that the network bears a series of functions, specifically, monitoring the current status of the musculoskeletal system, and building-up and updating our postural model (body schema), which could be a basis for the conscious experience of the physical self. PMID:26986838

  7. Injury of the Arcuate Fasciculus in the Dominant Hemisphere in Patients With Mild Traumatic Brain Injury: A Retrospective Cross-Sectional Study.

    PubMed

    Jang, Sung Ho; Lee, Ah Young; Shin, So Min

    2016-03-01

    Little is known about injury of the arcuate fasciculus (AF) in patients with mild traumatic brain injury (TBI). We investigated injury of the AF in the dominant hemisphere in patients with mild TBI, using diffusion tensor tractography (DTT). We recruited 25 patients with injury of the left AF among 64 right-handed consecutive patients with mild TBI and 20 normal control subjects. DTTs of the left AF were reconstructed, and fractional anisotropy (FA), apparent diffusion coefficient (ADC), and fiber number of the AF were measured. Among 64 consecutive patients, 25 (39%) patients showed injury of the left AF. The patient group showed lower FA value and fiber number with higher ADC value than the control group (P < 0.05). On K-WAB evaluation, aphasia quotient and language quotient were 95.9 ± 4.1 (range 85-100) and 95.0 ± 5.4 (range 80-100), respectively. However, 23 (92.0%) of 25 patients complained of language-related symptoms after TBI; paraphasia in 12 (48.0%) patients, deficits of comprehension in 4 (16.0%) patients, deficits of speech production in 1 (4.0%) patient, and >2 language symptoms in 6 (24.0%) patients. We found that a significant number (39%) of patients with mild TBI had injury of the AF in the dominant hemisphere and these patients had mild language deficit. These results suggest that DTT could provide useful information in detecting injury of the AF and evaluation of the AF using DTT would be necessary even in the case of a patient with mild TBI who complains of mild language deficit. PMID:26945425

  8. 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

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

    2014-01-01

    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. PMID:24808828

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

    PubMed Central

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

    2015-01-01

    Background Diffusion imaging tractography is increasingly used to trace critical fiber tracts in brain tumor patients to reduce the risk of post-operative neurological deficit. However, the effects of peritumoral edema pose a challenge to conventional tractography using the standard diffusion tensor model. The aim of this study was to present a novel technique using a two-tensor unscented Kalman filter (UKF) algorithm to track the arcuate fasciculus (AF) in brain tumor patients with peritumoral edema. Methods Ten right-handed patients with left-sided brain tumors in the vicinity of language-related cortex and evidence of significant peritumoral edema were retrospectively selected for the study. All patients underwent 3-Tesla magnetic resonance imaging (MRI) including a diffusion-weighted dataset with 31 directions. Fiber tractography was performed using both single-tensor streamline and two-tensor UKF tractography. A two-regions-of-interest approach was applied to perform the delineation of the AF. Results from the two different tractography algorithms were compared visually and quantitatively. Results Using single-tensor streamline tractography, the AF appeared disrupted in four patients and contained few fibers in the remaining six patients. Two-tensor UKF tractography delineated an AF that traversed edematous brain areas in all patients. The volume of the AF was significantly larger on two-tensor UKF than on single-tensor streamline tractography (p < 0.01). Conclusions Two-tensor UKF tractography provides the ability to trace a larger volume AF than single-tensor streamline tractography in the setting of peritumoral edema in brain tumor patients. PMID:26082890

  10. Dynamic Topography Revisited

    NASA Astrophysics Data System (ADS)

    Moresi, Louis

    2015-04-01

    Dynamic Topography Revisited Dynamic topography is usually considered to be one of the trinity of contributing causes to the Earth's non-hydrostatic topography along with the long-term elastic strength of the lithosphere and isostatic responses to density anomalies within the lithosphere. Dynamic topography, thought of this way, is what is left over when other sources of support have been eliminated. An alternate and explicit definition of dynamic topography is that deflection of the surface which is attributable to creeping viscous flow. The problem with the first definition of dynamic topography is 1) that the lithosphere is almost certainly a visco-elastic / brittle layer with no absolute boundary between flowing and static regions, and 2) the lithosphere is, a thermal / compositional boundary layer in which some buoyancy is attributable to immutable, intrinsic density variations and some is due to thermal anomalies which are coupled to the flow. In each case, it is difficult to draw a sharp line between each contribution to the overall topography. The second definition of dynamic topography does seem cleaner / more precise but it suffers from the problem that it is not measurable in practice. On the other hand, this approach has resulted in a rich literature concerning the analysis of large scale geoid and topography and the relation to buoyancy and mechanical properties of the Earth [e.g. refs 1,2,3] In convection models with viscous, elastic, brittle rheology and compositional buoyancy, however, it is possible to examine how the surface topography (and geoid) are supported and how different ways of interpreting the "observable" fields introduce different biases. This is what we will do. References (a.k.a. homework) [1] Hager, B. H., R. W. Clayton, M. A. Richards, R. P. Comer, and A. M. Dziewonski (1985), Lower mantle heterogeneity, dynamic topography and the geoid, Nature, 313(6003), 541-545, doi:10.1038/313541a0. [2] Parsons, B., and S. Daly (1983), The

  11. First Grade Writers Revisit Their Work

    ERIC Educational Resources Information Center

    Hansen, Jane A.

    2007-01-01

    In this article, the author focuses on first grade readers and writers who revisit their work and describes what first-graders do when they revisit their writing about science and literature and review collections of their work. The first-graders discussed here are in Elaine O'Connor's classroom at Clark Elementary School in Charlottesville. In a…

  12. Benjamin Franklin and Mesmerism, revisited.

    PubMed

    McConkey, Kevin M; Perry, Campbell

    2002-10-01

    The authors revisit and update their previous historiographical note (McConkey & Perry, 1985) on Benjamin Franklin's involvement with and investigation of animal magnetism or mesmerism. They incorporate more recent literature and offer additional comment about Franklin's role in and views about mesmerism. Franklin had a higher degree of personal involvement with and a more detailed opinion of mesmerism than has been previously appreciated. PMID:12362950

  13. Radiolytic Cryovolcanism Revisited

    NASA Astrophysics Data System (ADS)

    Cooper, J. F.; Cooper, P. D.; Sittler, E. C.; Wesenberg, R. P.

    2013-12-01

    Active geysers of water vapor and ice grains from the south pole of Enceladus are not yet definitively explained in terms of energy sources and processes. Other instances of hot (Io) and cold (Mars, Triton) volcanism beyond Earth are known if not fully understood. We revisit, in comparison to other models, the 'Old Faithful' theory of radiolytic gas-driven cryovolcanism first proposed by Cooper et al. [Plan. Sp. Sci. 2009]. In the energetic electron irradiation environment of Enceladus within Saturn's magnetosphere, a 10-percent duty cycle could be maintained for current geyser activity driven by gases from oxidation of ammonia to N2 and methane to CO2 in the thermal margins of a south polar sea. Much shorter duty cycles down to 0.01 percent would be required to account for thermal power output up to 16 GW, Steady accumulation of oxidant energy over four billion years could have powered all Enceladus emissions over the past four hundred thousand to four hundred million years. There could be separate energy sources driving mass flow and thermal emission over vastly different time scales. Since episodic tidal dissipation on 10 Myr time scales at 0.1 - 1 Gyr intervals [O'Neill and Nimmo, Nature 2010], and thus duty cycles 1 - 10 percent, could heat the polar sea to the current level, the radiolytic energy source could easily power and modulate the geyser mass flow on million-year time scales. Maximum thermal emission temperature 223 K [Abramov and Spencer, Icarus 2009] hints at thermal buffering in the basal and vent wall layers by a 1:1 H2O:H2O2 radiolytic eutectic, assuming deep ice crust saturation with H2O2 from long cumulative surface irradiation and downward ice convection. Due to density stratification the peroxide eutectic and salt water layers could separate, so that the denser peroxide layer (1.2 g/cc) descends to the polar sea while the lighter salt water (1.05 g/cc) rises along separate channels. Methane reservoirs could be found dissolved into the polar

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

    PubMed

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

    2014-06-01

    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

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

    PubMed Central

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

    2014-01-01

    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

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

    PubMed

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

    2015-06-15

    Amblyopia is a neurological disorder of vision that follows abnormal binocular interaction or visual deprivation during early life. Previous studies have reported multiple functional or structural cortical alterations. Although white matter was also studied, it still cannot be clarified clearly which fasciculus was affected by amblyopia. In the present study, tract-based spatial statistics analysis was applied to diffusion tensor imaging (DTI) to investigate potential diffusion changes of neural tracts in anisometropic amblyopia. Fractional anisotropy (FA) value was calculated and compared between 20 amblyopic children and 18 healthy age-matched controls. In contrast to the controls, significant decreases in FA values were found in right optic radiation (OR), left inferior longitudinal fasciculus/inferior fronto-occipital fasciculus (ILF/IFO) and right superior longitudinal fasciculus (SLF) in the amblyopia. Furthermore, FA values of these identified tracts showed positive correlation with visual acuity. It can be inferred that abnormal visual input not only hinders OR from well developed, but also impairs fasciculi associated with dorsal and ventral visual pathways, which may be responsible for the amblyopic deficiency in object discrimination and stereopsis. Increased FA was detected in right posterior part of corpus callosum (CC) with a medium effect size, which may be due to compensation effect. DTI with subsequent measurement of FA is a useful tool for investigating neuronal tract involvement in amblyopia. PMID:25899779

  17. Doppler ultrasound--basics revisited.

    PubMed

    Eagle, Mary

    Palpation of pedal pulses alone is known to be an unreliable indicator for the presence of arterial disease. Using portable Doppler ultrasound to measure the resting ankle brachial pressure index is superior to palpation of peripheral pulses as an assessment of the adequacy pf the arterial supply in the lower limb. Revisiting basics, this article aims to aid the clinician to understand and perform hand-held Doppler ultrasound effectively while involving the client or patient in the process. The author describes the basics of Doppler ultrasound, how to select correct equipment for the process, and interpretation of results to further enhance clinicians' knowledge. PMID:16835512

  18. Concurrent white and gray matter degeneration of disease-specific networks in early-stage Alzheimer's disease and behavioral variant frontotemporal dementia.

    PubMed

    Steketee, Rebecca M E; Meijboom, Rozanna; de Groot, Marius; Bron, Esther E; Niessen, Wiro J; van der Lugt, Aad; van Swieten, John C; Smits, Marion

    2016-07-01

    This study investigates regional coherence between white matter (WM) microstructure and gray matter (GM) volume and perfusion measures in Alzheimer's disease (AD) and behavioral variant frontotemporal dementia (bvFTD) using a correlational approach. WM-GM coherence, compared with controls, was stronger between cingulum WM and frontotemporal GM in AD, and temporoparietal GM in bvFTD. In addition, in AD compared with controls, coherence was stronger between inferior fronto-occipital fasciculus WM microstructure and occipital GM perfusion. In this first study assessing regional WM-GM coherence in AD and bvFTD, we show that WM microstructure and GM volume and perfusion measures are coherent, particularly in regions implicated in AD and bvFTD pathology. This indicates concurrent degeneration in disease-specific networks. Our methodology allows for the detection of incipient abnormalities that go undetected in conventional between-group analyses. PMID:27255821

  19. Delayed early developmental trajectories of white matter tracts of functional pathways in preterm-born infants: Longitudinal diffusion tensor imaging data

    PubMed Central

    Chang, Linda; Akazawa, Kentaro; Yamakawa, Robyn; Hayama, Sara; Buchthal, Steven; Alicata, Daniel; Andres, Tamara; Castillo, Deborrah; Oishi, Kumiko; Skranes, Jon; Ernst, Thomas; Oishi, Kenichi

    2016-01-01

    Probabilistic maps of white matter pathways related to motor, somatosensory, auditory, visual, and limbic functions, and major white matter tracts (the corpus callosum, the inferior fronto-occipital fasciculus, and the middle cerebellar peduncle) were applied to evaluate the developmental trajectories of these tracts, using longitudinal diffusion tensor imaging (DTI) obtained in term-born and preterm-born healthy infants. Nineteen term-born and 30 preterm-born infants completed MR scans at three time points: Time-point 1, 41.6±2.7 postmenstrual weeks; Time-point 2, 46.0±2.9 postmenstrual weeks; and Time-point 3, 50.8±3.7 postmenstrual weeks. The DTI-derived scalar values (fractional anisotropy, eigenvalues, and radial diffusivity) of the three time points are available in this Data article. PMID:26958632

  20. SLIM--An Early Work Revisited

    SciTech Connect

    Chao, Alex; /SLAC

    2008-07-25

    An early, but at the time illuminating, piece of work on how to deal with a general, linearly coupled accelerator lattice is revisited. This work is based on the SLIM formalism developed in 1979-1981.

  1. Neuroanatomical Abnormalities and Cognitive Impairments Are Shared by Adults with Attention-Deficit/Hyperactivity Disorder and Their Unaffected First-Degree Relatives

    PubMed Central

    Pironti, Valentino Antonio; Lai, Meng-Chuan; Müller, Ulrich; Dodds, Chris Martin; Suckling, John; Bullmore, Edward Thomas; Sahakian, Barbara Jacquelyn

    2014-01-01

    Background Attention-deficit/hyperactivity disorder (ADHD) is a highly heritable neurodevelopmental disorder, yet the search for genes with a definitive role in its etiology has been elusive. Deconstructing the disorder in its endophenotypic traits, where the variance is thought to be associated with a fewer number of genes, should boost the statistical power of molecular genetic studies and clarify the pathophysiology of ADHD. In this study, we tested for neuroanatomical and cognitive endophenotypes in a group of adults with ADHD, their unaffected first-degree relatives, and typically developing control subjects. Methods Sixty participants, comprising 20 adults with ADHD, 20 unaffected first-degree relatives, and 20 typically developing control subjects matched for age and gender undertook structural magnetic resonance imaging scans. Voxel-based morphometry with DARTEL was performed to obtain regional gray and white matter volumes. General linear analyses of the volumes of brain regions, adjusting for age and total intracranial volume, were used to compare groups. Sustained attention and response inhibition were also investigated as cognitive endophenotypes. Results Neuroanatomical abnormalities in gray matter volume in the right inferior frontal gyrus and white matter volume in the caudal portion of the right inferior fronto-occipital fasciculus were shared between ADHD probands and their unaffected first-degree relatives. In addition, impairments in sustained attention were also found to be shared between ADHD patients and their relatives. Conclusions Cognitive impairments in sustained attention and neuroanatomical abnormalities in the right inferior frontal gyrus and the posterior part of right inferior fronto-occipital fasciculus are putative neurocognitive endophenotypes in adult ADHD. PMID:24199662

  2. White matter microstructure and the variable adult outcome of childhood attention deficit hyperactivity disorder.

    PubMed

    Shaw, Philip; Sudre, Gustavo; Wharton, Amy; Weingart, Daniel; Sharp, Wendy; Sarlls, Joelle

    2015-02-01

    Changes in cerebral cortical anatomy have been tied to the clinical course of attention deficit hyperactivity disorder (ADHD). We now ask if alterations in white matter tract microstructure are likewise linked with the adult outcome of childhood ADHD. Seventy-five young adults, 32 with ADHD persisting from childhood and 43 with symptom remission were contrasted against 74 never-affected comparison subjects. Using diffusion tensor imaging, we defined fractional anisotropy, a metric related to white matter microstructure, along with measures of diffusion perpendicular (radial) and parallel (axial) to the axon. Analyses were adjusted for head motion, age and sex, and controlled for multiple comparisons and medication history. Tract-based analyses showed that greater adult inattention, but not hyperactivity-impulsivity, was associated with significantly lower fractional anisotropy in the left uncinate (standardized β=-0.37, t=3.28, p=0.002) and inferior fronto-occipital fasciculi (standardized β=-0.37, t=3.29, p=0.002). The ADHD group with symptoms persisting into adulthood had significantly lower fractional anisotropy than the never-affected controls in these tracts, differences associated with medium to large effect sizes. By contrast, the ADHD group that remitted by adulthood did not differ significantly from controls. The anomalies were found in tracts that connect components of neural systems pertinent to ADHD, such as attention control (inferior fronto-occipital fasciculus) and emotion regulation and the processing of reward (the uncinate fasciculus). Change in radial rather than axial diffusivity was the primary driver of this effect, suggesting pathophysiological processes including altered myelination as future targets for pharmacological and behavioral interventions. PMID:25241803

  3. Delineation of Early and Later Adult Onset Depression by Diffusion Tensor Imaging

    PubMed Central

    Yu, Hongjun; Nie, Binbin; Li, Na; Luo, Chunrong; Li, Haijun; Liu, Fang; Bai, Yan; Shan, Baoci; Xu, Lin; Xu, Xiufeng

    2014-01-01

    Background Due to a lack of evidence, there is no consistent age of onset to define early onset (EO) versus later onset (LO) major depressive disorder (MDD). Fractional anisotropy (FA), derived from diffusion tensor imaging (DTI), has been widely used to study neuropsychiatric disorders by providing information about the brain circuitry, abnormalities of which might facilitate the delineation of EO versus LO MDD. Method In this study, 61 pairs of untreated, non-elderly, first-episode MDD patients and healthy controls (HCs) aged 18–45 years old received DTI scans. The voxel-based analysis method (VBM), classification analysis, using the Statistical Package for the Social Sciences (SPSS), and regression analyses were used to determine abnormal FA clusters and their correlations with age of onset and clinical symptoms. Results Classification analysis suggested in the best model that there were two subgroups of MDD patients, delineated by an age of onset of 30 years old, by which MDD patients could be divided into EO (18–29 years old) and LO (30–45 years old) groups. LO MDD was characterized by decreased FA, especially in the white matter (WM) of the fronto-occipital fasciculus and posterior limb of internal capsule, with a negative correlation with the severity of depressive symptoms; in marked contrast, EO MDD showed increased FA, especially in the WM of the corpus callosum, corticospinal midbrain and inferior fronto-occipital fasciculus, while FA of the WM near the midbrain had a positive correlation with the severity of depressive symptoms. Conclusion Specific abnormalities of the brain circuitry in EO vs. LO MDD were delineated by an age of onset of 30 years old, as demonstrated by distinct abnormal FA clusters with opposite correlations with clinical symptoms. This DTI study supported the evidence of an exact age for the delineation of MDD, which could have broad multidisciplinary importance. Trial Registration ClinicalTrials.gov NCT00703742 PMID:25393297

  4. White Matter Microstructure and the Variable Adult Outcome of Childhood Attention Deficit Hyperactivity Disorder

    PubMed Central

    Shaw, Philip; Sudre, Gustavo; Wharton, Amy; Weingart, Daniel; Sharp, Wendy; Sarlls, Joelle

    2015-01-01

    Changes in cerebral cortical anatomy have been tied to the clinical course of attention deficit hyperactivity disorder (ADHD). We now ask if alterations in white matter tract microstructure are likewise linked with the adult outcome of childhood ADHD. Seventy-five young adults, 32 with ADHD persisting from childhood and 43 with symptom remission were contrasted against 74 never-affected comparison subjects. Using diffusion tensor imaging, we defined fractional anisotropy, a metric related to white matter microstructure, along with measures of diffusion perpendicular (radial) and parallel (axial) to the axon. Analyses were adjusted for head motion, age and sex, and controlled for multiple comparisons and medication history. Tract-based analyses showed that greater adult inattention, but not hyperactivity–impulsivity, was associated with significantly lower fractional anisotropy in the left uncinate (standardized β=−0.37, t=3.28, p=0.002) and inferior fronto-occipital fasciculi (standardized β=−0.37, t=3.29, p=0.002). The ADHD group with symptoms persisting into adulthood had significantly lower fractional anisotropy than the never-affected controls in these tracts, differences associated with medium to large effect sizes. By contrast, the ADHD group that remitted by adulthood did not differ significantly from controls. The anomalies were found in tracts that connect components of neural systems pertinent to ADHD, such as attention control (inferior fronto-occipital fasciculus) and emotion regulation and the processing of reward (the uncinate fasciculus). Change in radial rather than axial diffusivity was the primary driver of this effect, suggesting pathophysiological processes including altered myelination as future targets for pharmacological and behavioral interventions. PMID:25241803

  5. Secret Public Key Protocols Revisited

    NASA Astrophysics Data System (ADS)

    Lim, Hoon Wei; Paterson, Kenneth G.

    Password-based protocols are important and popular means of providing human-to-machine authentication. The concept of secret public keys was proposed more than a decade ago as a means of securing password-based authentication protocols against off-line password guessing attacks, but was later found vulnerable to various attacks. In this paper, we revisit the concept and introduce the notion of identity-based secret public keys. Our new identity-based approach allows secret public keys to be constructed in a very natural way using arbitrary random strings, eliminating the structure found in, for example, RSA or ElGamal keys. We examine identity-based secret public key protocols and give informal security analyses, indicating that they are secure against off-line password guessing and other attacks.

  6. Extended equal area criterion revisited

    SciTech Connect

    Xue, X.; Wehenkel, L.; Belhomme, R.; Rousseaux, P.; Pavella, M. ); Euxibie, E.; Heilbronn, B.; Lesigne, J.F. )

    1992-08-01

    This paper reports on a case study conducted on the EHV French power system in order to revisit the extended equal area criterion and test its suitability as a fast transient stability indicator. The assumptions underlying the method are reexamined, causes liable to invalidate them are identified, and indices are devised to automatically circumvent them. The selection of candidate critical machines is also reconsidered and an augmented criterion is proposed. The various improvements are developed and tested on about 1000 stability scenarios, covering the entire 400-kV system; the severity of the scenarios, resulting from the combination of weakened both pre- and post-fault configurations, subjects the method to particularly stringent conditions. The obtained results show that the devised tools contribute to significantly reinforce its robustness and reliability.

  7. 42 CFR 488.30 - Revisit user fee for revisit surveys.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... SERVICES (CONTINUED) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES General... be subject to user fees unless otherwise exempted. Revisit survey means a survey performed with..., or substantiated complaint survey and that is designed to evaluate the extent to which...

  8. 42 CFR 488.30 - Revisit user fee for revisit surveys.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... SERVICES (CONTINUED) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES General... be subject to user fees unless otherwise exempted. Revisit survey means a survey performed with..., or substantiated complaint survey and that is designed to evaluate the extent to which...

  9. 42 CFR 488.30 - Revisit user fee for revisit surveys.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... SERVICES (CONTINUED) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES General... be subject to user fees unless otherwise exempted. Revisit survey means a survey performed with..., or substantiated complaint survey and that is designed to evaluate the extent to which...

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

    PubMed Central

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

    2015-01-01

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

  11. Adverse childhood experiences influence white matter microstructure in patients with schizophrenia.

    PubMed

    Poletti, Sara; Mazza, Elena; Bollettini, Irene; Locatelli, Clara; Cavallaro, Roberto; Smeraldi, Enrico; Benedetti, Francesco

    2015-10-30

    Integrity of brain white matter (WM) tracts in adulthood could be detrimentally affected by exposure to adverse childhood experiences (ACE). Changes of diffusion tensor imaging (DTI) measures suggesting WM disruption have been reported in patients with schizophrenia together with a history of childhood maltreatment. We therefore hypothesized that ACE could be associated with altered DTI measures of WM integrity in patients with schizophrenia. We tested this hypothesis in 83 schizophrenia patients using whole brain tract-based spatial statistics in the WM skeleton with threshold-free cluster enhancement of DTI measures of WM microstructure: axial, radial, and mean diffusivity (MD), and fractional anisotropy (FA). We observed an inverse correlation between severity of ACE and DTI measures of FA, and a positive correlation with MD in several WM tracts including corona radiata, thalamic radiations, corpus callosum, cingulum bundle, superior longitudinal fasciculus, inferior fronto-occipital fasciculus, uncinate fasciculus. Lower FA and higher MD are indexes of a reduction in fibre coherence and integrity. The association of ACE to reduced FA and increased MD in key WM tracts contributing to the functional integrity of the brain suggests that ACE might contribute to the pathophysiology of schizophrenia through a detrimental action on structural connectivity in critical cortico-limbic networks. PMID:26341951

  12. Role of Frontotemporal Fiber Tract Integrity in Task-Switching Performance of Healthy Controls and Patients with Temporal Lobe Epilepsy

    PubMed Central

    Kucukboyaci, N. Erkut; Girard, H.M.; Hagler, D.J.; Kuperman, J.; Tecoma, E.S.; Iragui, V.J.; Halgren, E.; McDonald, C.R.

    2012-01-01

    The objective of this study is to investigate the relationships among frontotemporal fiber tract compromise and task-switching performance in healthy controls and patients with temporal lobe epilepsy (TLE). We performed diffusion tensor imaging (DTI) on 30 controls and 32 patients with TLE (15 left TLE). Fractional anisotropy (FA) was calculated for four fiber tracts [uncinate fasciculus (UncF), arcuate fasciculus (ArcF), dorsal cingulum (CING), and inferior fronto-occipital fasciculus (IFOF)]. Participants completed the Trail Making Test-B (TMT-B) and Verbal Fluency Category Switching (VFCS) test. Multivariate analyses of variances (MANOVAs) were performed to investigate group differences in fiber FA and set-shifting performances. Canonical correlations were used to examine the overall patterns of structural-cognitive relationships and were followed by within-group bivariate correlations. We found a significant canonical correlation between fiber FA and task-switching performance. In controls, TMT-B correlated with left IFOF, whereas VFCS correlated with FA of left ArcF and left UncF. These correlations were not significant in patients with TLE. We report significant correlations between frontotemporal fiber tract integrity and set-shifting performance in healthy controls that appear to be absent or attenuated in patients with TLE. These findings suggest a breakdown of typical structure-function relationships in TLE that may reflect aberrant developmental or degenerative processes. PMID:22014246

  13. Microstructure and Cerebral Blood Flow within White Matter of the Human Brain: A TBSS Analysis

    PubMed Central

    Giezendanner, Stéphanie; Fisler, Melanie Sarah; Soravia, Leila Maria; Andreotti, Jennifer; Walther, Sebastian; Wiest, Roland; Dierks, Thomas; Federspiel, Andrea

    2016-01-01

    Background White matter (WM) fibers connect different brain regions and are critical for proper brain function. However, little is known about the cerebral blood flow in WM and its relation to WM microstructure. Recent improvements in measuring cerebral blood flow (CBF) by means of arterial spin labeling (ASL) suggest that the signal in white matter may be detected. Its implications for physiology needs to be extensively explored. For this purpose, CBF and its relation to anisotropic diffusion was analyzed across subjects on a voxel-wise basis with tract-based spatial statistics (TBSS) and also across white matter tracts within subjects. Methods Diffusion tensor imaging and ASL were acquired in 43 healthy subjects (mean age = 26.3 years). Results CBF in WM was observed to correlate positively with fractional anisotropy across subjects in parts of the splenium of corpus callosum, the right posterior thalamic radiation (including the optic radiation), the forceps major, the right inferior fronto-occipital fasciculus, the right inferior longitudinal fasciculus and the right superior longitudinal fasciculus. Furthermore, radial diffusivity correlated negatively with CBF across subjects in similar regions. Moreover, CBF and FA correlated positively across white matter tracts within subjects. Conclusion The currently observed findings on a macroscopic level might reflect the metabolic demand of white matter on a microscopic level involving myelination processes or axonal function. However, the exact underlying physiological mechanism of this relationship needs further evaluation. PMID:26942763

  14. Gray- and white-matter anatomy of absolute pitch possessors.

    PubMed

    Dohn, Anders; Garza-Villarreal, Eduardo A; Chakravarty, M Mallar; Hansen, Mads; Lerch, Jason P; Vuust, Peter

    2015-05-01

    Absolute pitch (AP), the ability to identify a musical pitch without a reference, has been examined behaviorally in numerous studies for more than a century, yet only a few studies have examined the neuroanatomical correlates of AP. Here, we used MRI and diffusion tensor imaging to investigate structural differences in brains of musicians with and without AP, by means of whole-brain vertex-wise cortical thickness (CT) analysis and tract-based spatial statistics (TBSS) analysis. APs displayed increased CT in a number of areas including the bilateral superior temporal gyrus (STG), the left inferior frontal gyrus, and the right supramarginal gyrus. Furthermore, we found higher fractional anisotropy in APs within the path of the inferior fronto-occipital fasciculus, the uncinate fasciculus, and the inferior longitudinal fasciculus. The findings in gray matter support previous studies indicating an increased left lateralized posterior STG in APs, yet they differ from previous findings of thinner cortex for a number of areas in APs. Finally, we found a relation between the white-matter results and the CT in the right parahippocampal gyrus. In this study, we present novel findings in AP research that may have implications for the understanding of the neuroanatomical underpinnings of AP ability. PMID:24304583

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

    PubMed

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

    2015-01-01

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

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

    PubMed Central

    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

    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. PMID:20541839

  17. Clinical correlations of microstructural changes in progressive supranuclear palsy.

    PubMed

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

    2014-10-01

    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

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

    PubMed Central

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

    2013-01-01

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

  19. Involuntary switching into the native language induced by electrocortical stimulation of the superior temporal gyrus: a multimodal mapping study.

    PubMed

    Tomasino, Barbara; Marin, Dario; Canderan, Cinzia; Maieron, Marta; Budai, Riccardo; Fabbro, Franco; Skrap, Miran

    2014-09-01

    We describe involuntary language switching from L2 to L1 evoked by electro-stimulation in the superior temporal gyrus in a 30-year-old right-handed Serbian (L1) speaker who was also a late Italian learner (L2). The patient underwent awake brain surgery. Stimulation of other portions of the exposed cortex did not cause language switching as did not stimulation of the left inferior frontal gyrus, where we evoked a speech arrest. Stimulation effects on language switching were selective, namely, interfered with counting behaviour but not with object naming. The coordinates of the positive site were combined with functional and fibre tracking (DTI) data. Results showed that the language switching site belonged to a significant fMRI cluster in the left superior temporal gyrus/supramarginal gyrus found activated for both L1 and L2, and for both the patient and controls, and did not overlap with the inferior fronto-occipital fasciculus (IFOF), the inferior longitudinal fasciculus (ILF) and the superior longitudinal fasciculus (SLF). This area, also known as Stp, has a role in phonological processing. Language switching phenomenon we observed can be partly explained by transient dysfunction of the feed-forward control mechanism hypothesized by the DIVA (Directions Into Velocities of Articulators) model (Golfinopoulos, E., Tourville, J. A., & Guenther, F. H. (2010). The integration of large-scale neural network modeling and functional brain imaging in speech motor control. PMID:25058058

  20. Revisiting Bohr's semiclassical quantum theory.

    PubMed

    Ben-Amotz, Dor

    2006-10-12

    Bohr's atomic theory is widely viewed as remarkable, both for its accuracy in predicting the observed optical transitions of one-electron atoms and for its failure to fully correspond with current electronic structure theory. What is not generally appreciated is that Bohr's original semiclassical conception differed significantly from the Bohr-Sommerfeld theory and offers an alternative semiclassical approximation scheme with remarkable attributes. More specifically, Bohr's original method did not impose action quantization constraints but rather obtained these as predictions by simply matching photon and classical orbital frequencies. In other words, the hydrogen atom was treated entirely classically and orbital quantized emerged directly from the Planck-Einstein photon quantization condition, E = h nu. Here, we revisit this early history of quantum theory and demonstrate the application of Bohr's original strategy to the three quintessential quantum systems: an electron in a box, an electron in a ring, and a dipolar harmonic oscillator. The usual energy-level spectra, and optical selection rules, emerge by solving an algebraic (quadratic) equation, rather than a Bohr-Sommerfeld integral (or Schroedinger) equation. However, the new predictions include a frozen (zero-kinetic-energy) state which in some (but not all) cases lies below the usual zero-point energy. In addition to raising provocative questions concerning the origin of quantum-chemical phenomena, the results may prove to be of pedagogical value in introducing students to quantum mechanics. PMID:17020371

  1. Revisiting and Rethinking the Reading Process.

    ERIC Educational Resources Information Center

    Kucer, Stephen B.; Tuten, Jenny

    2003-01-01

    Reports on the authors' revisiting of the reading process using proficient adult readers (advanced graduate students in a school of education) as their informants. Begins with a brief overview of the current debate concerning the nature of reading and explains how they went about investigating the issue. Discusses what they learned from their…

  2. Phenomenology of n - n ¯ oscillations revisited

    DOE PAGESBeta

    Gardner, S.; Jafari, E.

    2015-05-22

    We revisit the phenomenology of n-n¯ oscillations in the presence of external magnetic fields, highlighting the role of spin. We show, contrary to long-held belief, that the n-n¯ transition rate need not be suppressed, opening new opportunities for its empirical study.

  3. The Evil of Banality: Arendt Revisited

    ERIC Educational Resources Information Center

    Minnich, Elizabeth

    2014-01-01

    "The banality of evil" (Arendt) remains controversial and useful. Ironically, the concept is now itself a banality. To revisit and extend it, we consider the "evil of banality", the profound dangers of cliched thoughtlessness. A distinction is proposed: "intensive" versus "extensive evils". The former takes…

  4. Fine structure of the butterfly diagram revisited

    NASA Astrophysics Data System (ADS)

    Major, Balázs

    The latitudinal time distribution of sunspots (butterfly diagram) was studied by Becker (1959) and Antalová & Gnevyshev (1985). Our goal is to revisit these studies. In the first case we check whether there is a poleward migration in sunspot activity. In the second case we confirm the results, and make more quantitative statements concerning their significance and the position of the activity peaks.

  5. Revisiting the Regenerative Possibilities of Ortiz

    ERIC Educational Resources Information Center

    Duques, Matthew

    2004-01-01

    The author of this article revisits Simon Ortiz's poem, "From Sand Creek," in which the latter can in so few words convey both the horrific tragedy of conquest and colonization, while at the same time find a space for possibility, a means for recovery that is never about forgetting but always occurs as a kind of recuperative remembering. Ortiz…

  6. Revisiting separation properties of convex fuzzy sets

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Separation of convex sets by hyperplanes has been extensively studied on crisp sets. In a seminal paper separability and convexity are investigated, however there is a flaw on the definition of degree of separation. We revisited separation on convex fuzzy sets that have level-wise (crisp) disjointne...

  7. The Rotating Morse-Pekeris Oscillator Revisited

    ERIC Educational Resources Information Center

    Zuniga, Jose; Bastida, Adolfo; Requena, Alberto

    2008-01-01

    The Morse-Pekeris oscillator model for the calculation of the vibration-rotation energy levels of diatomic molecules is revisited. This model is based on the realization of a second-order exponential expansion of the centrifugal term about the minimum of the vibrational Morse oscillator and the subsequent analytical resolution of the resulting…

  8. Revisiting the 1761 Transatlantic Tsunami

    NASA Astrophysics Data System (ADS)

    Baptista, Maria Ana; Wronna, Martin; Miranda, Jorge Miguel

    2016-04-01

    The tsunami catalogs of the Atlantic include two transatlantic tsunamis in the 18th century the well known 1st November 1755 and the 31st March 1761. The 31st March 1761 earthquake struck Portugal, Spain, and Morocco. The earthquake occurred around noontime in Lisbon alarming the inhabitants and throwing down ruins of the past 1st November 1755 earthquake. According to several sources, the earthquake was followed by a tsunami observed as far as Cornwall (United Kingdom), Cork (Ireland) and Barbados (Caribbean). The analysis of macroseismic information and its compatibility with tsunami travel time information led to a source area close to the Ampere Seamount with an estimated epicenter circa 34.5°N 13°W. The estimated magnitude of the earthquake was 8.5. In this study, we revisit the tsunami observations, and we include a report from Cadiz not used before. We use the results of the compilation of the multi-beam bathymetric data, that covers the area between 34°N - 38°N and 12.5°W - 5.5°W and use the recent tectonic map published for the Southwest Iberian Margin to select among possible source scenarios. Finally, we use a non-linear shallow water model that includes the discretization and explicit leap-frog finite difference scheme to solve the shallow water equations in the spherical or Cartesian coordinate to compute tsunami waveforms and tsunami inundation and check the results against the historical descriptions to infer the source of the event. This study received funding from project ASTARTE- Assessment Strategy and Risk Reduction for Tsunamis in Europe a collaborative project Grant 603839, FP7-ENV2013 6.4-3

  9. The flow along an external corner revisited

    NASA Astrophysics Data System (ADS)

    Denier, Jim; Jewell, Nathaniel

    2013-11-01

    We revisit the problem of the flow of an almost inviscid fluid along an external corner made from the junction of two quarter infinite plates joined at an angle 0 < α < π / 2 . The structure of the boundary layer which develops along the corner is explored using a computational approach based upon a spectral element discretisation of the steady two-dimensional boundary-layer equations. We pay particular attention to the case when the angle α is small, thus approximating the semi-infinte quarter plate problem considered by Stewartson (1961) and recently revisited by Duck & Hewitt (2012). Our results, which demonstrate a thickening of the boundary-layer near the sharp corner, will be discussed in the context of the asymptotic theory developed in the aforementioned papers.

  10. Quasar X-Ray Spectra Revisited: Erratum

    NASA Astrophysics Data System (ADS)

    Shastri, P.; Wilkes, B. J.; Elvis, M.; McDowell, J.

    1994-08-01

    In the paper "Quasar X-Ray Spectra Revisited " by P. Shastri, B. J. Wilkes, M. Elvis, and J. McDowell (ApJ, 410,29 [1993]), there is an error in the flux density levels in Figures 4a and 4b. As a result of an error during rebinning of the optical spectrophotometry data, the flux density levels in those two figures are a factor of 5 lower then their actual value.

  11. BHQ revisited (2): Texture development

    NASA Astrophysics Data System (ADS)

    Kilian, Rüdiger; Heilbronner, Renée

    2016-04-01

    appears that grains can be unfavourably oriented for glide despite their c-axis direction falling in those positions which were used in the "classical" interpretation. Additionally, it turns out that grain-scale dispersion axes can be used to describe the kinematic behaviour in a more consistent way compared to the rotations axes obtained from intragranular misorientations in the range of 2-10°. The implications derived from the experimental data set will be compared to data obtained from natural quartz mylonites which formed in a comparable recrystallization regime. This is the companion poster to "BHQ revisited (I) looking at grain size" where the development of the dynamically recrystallized grain size is addressed. Reference cited: Heilbronner, R., and J. Tullis (2006), Evolution of c axis pole figures and grain size during dynamic recrystallization: Results from experimentally sheared quartzite, J. Geophys. Res., 111, B10202, doi:10.1029/2005JB004194.

  12. 42 CFR 488.30 - Revisit user fee for revisit surveys.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... SERVICES (CONTINUED) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES General... subject to user fees unless otherwise exempted. Revisit survey means a survey performed with respect to a... substantiated complaint survey and that is designed to evaluate the extent to which...

  13. Early cerebral volume reductions and their associations with reduced lupus disease activity in patients with newly-diagnosed systemic lupus erythematosus

    PubMed Central

    Mak, Anselm; Ho, Roger Chun-Man; Tng, Han-Ying; Koh, Hui Li; Chong, Joanna Su Xian; Zhou, Juan

    2016-01-01

    We examined if cerebral volume reduction occurs very early during the course of systemic lupus erythematosus (SLE), and observed prospectively whether gray (GMV) and white matter volumes (WMV) of the brain would improve with lowered SLE disease activity. T1-weighted MRI brain images were obtained from 14 healthy controls (HC) and 14 newly-diagnosed SLE patients within 5 months of diagnosis (S1) and after achieving low disease activity (S2). Whole brain voxel-based morphometry was used to detect differences in the GMV and WMV between SLE patients and HC and those between SLE patients at S1 and S2. SLE patients were found to have lower GMV than HC in the middle cingulate cortex, middle frontal gyrus and right supplementary motor area, and lower WMV in the superior longitudinal fasciculus, cingulum cingulate gyrus and inferior fronto-occipital fasciculus at both S1 and S2. Whole-brain voxel-wise analysis revealed increased GMV chiefly in the prefrontal regions at S2 compared to S1 in SLE patients. The GMV increase in the left superior frontal gyrus was significantly associated with lowered SLE disease activity. In conclusion, GMV and WMV reduced very early in SLE patients. Reduction of SLE disease activity was accompanied by region-specific GMV improvement in the prefrontal regions. PMID:26928214

  14. Emerging structure-function relations in the developing face processing system.

    PubMed

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

    2014-11-01

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

  15. Diffusion tensor imaging of idiopathic normal-pressure hydrocephalus and the cerebrospinal fluid tap test.

    PubMed

    Kang, Kyunghun; Yoon, Uicheul; Choi, Woohyuk; Lee, Ho-Won

    2016-05-15

    We evaluated relationships between diffusion tensor imaging (DTI) findings and clinical profiles in idiopathic normal-pressure hydrocephalus (INPH) patients, along with differences in DTI parameters between cerebrospinal fluid tap test (CSFTT) responders and non-responders. Fifty-four INPH patients constituted the final group for analysis. Fractional anisotropy (FA), axial diffusivity, radial diffusivity, and mean diffusivity were assessed using atlas-based tract-mapping methods on 20 different fiber tracts. Uncorrected results revealed that CSFTT non-responders, when compared to responders, exhibited lower FA in the left anterior thalamic radiation (ATR), left cingulum-hippocampus (CgH), and left inferior fronto-occipital fasciculus (IFO) and higher axial diffusivity, radial diffusivity, and mean diffusivity in the left CgH and left inferior longitudinal fasciculus (ILF). FA values in the ATR (bilateral), corticospinal tract (right), IFO (bilateral), and ILF (bilateral) were negatively correlated with Unified Parkinson's Disease Rating Scale motor scores. In the right CgH, FA values showed significant positive correlations with Korean-Mini Mental State Examination scores and negative correlations with Clinical Dementia Rating Scale scores. Our findings may suggest a possibility for considering microstructural changes of white matter in patients with ventriculomegaly as potential imaging markers for the prediction of CSFTT responders. Unique patterns of white matter microstructural changes, as measured using DTI, might underlie impairments in distinct symptom domains in patients with INPH. PMID:27084223

  16. Cognitive Processing Speed in Older Adults: Relationship with White Matter Integrity

    PubMed Central

    Kerchner, Geoffrey A.; Racine, Caroline A.; Hale, Sandra; Wilheim, Reva; Laluz, Victor; Miller, Bruce L.; Kramer, Joel H.

    2012-01-01

    Cognitive processing slows with age. We sought to determine the importance of white matter integrity, assessed by diffusion tensor imaging (DTI), at influencing cognitive processing speed among normal older adults, assessed using a novel battery of computerized, non-verbal, choice reaction time tasks. We studied 131 cognitively normal adults aged 55–87 using a cross-sectional design. Each participant underwent our test battery, as well as MRI with DTI. We carried out cross-subject comparisons using tract-based spatial statistics. As expected, reaction time slowed significantly with age. In diffuse areas of frontal and parietal white matter, especially the anterior corpus callosum, fractional anisotropy values correlated negatively with reaction time. The genu and body of the corpus callosum, superior longitudinal fasciculus, and inferior fronto-occipital fasciculus were among the areas most involved. This relationship was not explained by gray or white matter atrophy or by white matter lesion volume. In a statistical mediation analysis, loss of white matter integrity mediated the relationship between age and cognitive processing speed. PMID:23185621

  17. Exploratory analysis of diffusion tensor imaging in children with attention deficit hyperactivity disorder: evidence of abnormal white matter structure.

    PubMed

    Pastura, Giuseppe; Doering, Thomas; Gasparetto, Emerson Leandro; Mattos, Paulo; Araújo, Alexandra Prüfer

    2016-06-01

    Abnormalities in the white matter microstructure of the attentional system have been implicated in the aetiology of attention deficit hyperactivity disorder (ADHD). Diffusion tensor imaging (DTI) is a promising magnetic resonance imaging (MRI) technology that has increasingly been used in studies of white matter microstructure in the brain. The main objective of this work was to perform an exploratory analysis of white matter tracts in a sample of children with ADHD versus typically developing children (TDC). For this purpose, 13 drug-naive children with ADHD of both genders underwent MRI using DTI acquisition methodology and tract-based spatial statistics. The results were compared to those of a sample of 14 age- and gender-matched TDC. Lower fractional anisotropy was observed in the splenium of the corpus callosum, right superior longitudinal fasciculus, bilateral retrolenticular part of the internal capsule, bilateral inferior fronto-occipital fasciculus, left external capsule and posterior thalamic radiation (including right optic radiation). We conclude that white matter tracts in attentional and motor control systems exhibited signs of abnormal microstructure in this sample of drug-naive children with ADHD. PMID:26620714

  18. Aberrant structural and functional connectivity in the salience network and central executive network circuit in schizophrenia.

    PubMed

    Chen, Quan; Chen, Xingui; He, Xiaoxuan; Wang, Lu; Wang, Kai; Qiu, Bensheng

    2016-08-01

    Consistent structural and functional abnormities have been detected in the salience network (SN) and the central-executive network (CEN) in schizophrenia. SN, known for its critical role in switching CEN and default-mode network (DMN) during cognitively demanding tasks, is proved to show aberrant regulation on the interaction between DMN and CEN in schizophrenia. However, it has not been elucidated whether there is a direct alteration of structural and functional connectivity between SN and CEN. 22 schizophrenia patients and 21 healthy controls were recruited for functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) in present study. The results show that schizophrenia patients had lower fractional anisotropy (FA) in right inferior long fasciculus (ILF), left inferior fronto-occipital fasciculus (IFOF) and callosal body than healthy controls. Significantly reduced functional connectivity was also found between right fronto-insular cortex (rFIC) and right posterior parietal cortex (rPPC). FA in right ILF was positively correlated with the functional connectivity of rFIC-rPPC. Therefore, we proposed a disruption of structural and functional connectivity and a positive anatomo-functional relationship in SN-CEN circuit, which might account for a core feature of schizophrenia. PMID:27233217

  19. The ins and outs of meaning: Behavioral and neuroanatomical dissociation of semantically-driven word retrieval and multimodal semantic recognition in aphasia.

    PubMed

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

    2015-09-01

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

  20. Emerging Structure–Function Relations in the Developing Face Processing System

    PubMed Central

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

    2014-01-01

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

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

    PubMed Central

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

    2016-01-01

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

  2. Impact of reading habit on white matter structure: Cross-sectional and longitudinal analyses.

    PubMed

    Takeuchi, Hikaru; Taki, Yasuyuki; Hashizume, Hiroshi; Asano, Kohei; Asano, Michiko; Sassa, Yuko; Yokota, Susumu; Kotozaki, Yuka; Nouchi, Rui; Kawashima, Ryuta

    2016-06-01

    Psychological studies showed the quantity of reading habit affects the development of their reading skills, various language skills, and knowledge. However, despite a vast amount of literature, the effects of reading habit on the development of white matter (WM) structures critical to language and reading processes have never been investigated. In this study, we used the fractional anisotropy (FA) measure of diffusion tensor imaging to measure WM microstructural properties and examined cross-sectional and longitudinal correlations between reading habit and FA of the WM bundles in a large sample of normal children. In both cross-sectional and longitudinal analyses, we found that greater strength of reading habit positively affected FA in the left arcuate fasciculus (AF), in the left inferior fronto-occipital fasciculus (IFOF), and in the left posterior corona radiata (PCR). Consistent with previous studies, we also confirmed the significance or a tendency for positive correlation between the strength of reading habit and the Verbal Comprehension score in cross-sectional and longitudinal analyses. These cross-sectional and longitudinal findings indicate that a healthy reading habit may be directly or indirectly associated with the advanced development of WM critical to reading and language processes. Future intervention studies are needed to determine the causal effects of reading habits on WM in normal children. PMID:27033689

  3. Lifelong Bilingualism Contributes to Cognitive Reserve against White Matter Integrity Declines in Aging

    PubMed Central

    Gold, Brian T.; Johnson, Nathan F.; Powell, David K.

    2013-01-01

    Recent evidence suggests that lifelong bilingualism may contribute to cognitive reserve (CR) in normal aging. However, there is currently no neuroimaging evidence to suggest that lifelong bilinguals can retain normal cognitive functioning in the face of age-related neurodegeneration. Here we explored this issue by comparing white matter (WM) integrity and gray matter (GM) volumetric patterns of older adult lifelong bilinguals (N = 20) and monolinguals (N = 20). The groups were matched on a range of relevant cognitive test scores and on the established CR variables of education, socioeconomic status and intelligence. Participants underwent high-resolution structural imaging for assessment of GM volume and diffusion tensor imaging (DTI) for assessment of WM integrity. Results indicated significantly lower microstructural integrity in the bilingual group in several WM tracts. In particular, compared to their monolingual peers, the bilingual group showed lower fractional anisotropy and/or higher radial diffusivity in the inferior longitudinal fasciculus/inferior fronto-occipital fasciculus bilaterally, the fornix, and multiple portions of the corpus callosum. There were no group differences in GM volume. Our results suggest that lifelong bilingualism contributes to CR against WM integrity declines in aging. PMID:24103400

  4. Orthorhombic Zr2Co11 phase revisited

    SciTech Connect

    Li, X. -Z.; Zhang, W. Y.; Sellmyer, D. J.; Zhao, X.; Nguyen, M. C.; Wang, C. Z.; Ho, K. M.

    2014-10-01

    The structure of the orthorhombic Zr2Co11 phase was revisited in the present work. Selected-area electron diffraction (SAED) and high-resolution electron microscopy (HREM) techniques were used to investigate the structure. They show the orthorhombic Zr2Co11 phase has a 1-D incommensurate modulated structure. The structure can be approximately described as a B-centered orthorhombic lattice. The lattice parameters of the orthorhombic Zr2Co11 phase have been determined by a tilt series of SAED patterns. A hexagonal network with a modulation wave has been observed in the HREM image and the hexagonal motif is considered as the basic structural unit.

  5. Sloan Digital Sky Survey Photometric Calibration Revisited

    SciTech Connect

    Marriner, John; /Fermilab

    2012-06-29

    The Sloan Digital Sky Survey calibration is revisited to obtain the most accurate photometric calibration. A small but significant error is found in the flat-fielding of the Photometric telescope used for calibration. Two SDSS star catalogs are compared and the average difference in magnitude as a function of right ascension and declination exhibits small systematic errors in relative calibration. The photometric transformation from the SDSS Photometric Telescope to the 2.5 m telescope is recomputed and compared to synthetic magnitudes computed from measured filter bandpasses.

  6. Sloan Digital Sky Survey Photometric Calibration Revisited

    NASA Astrophysics Data System (ADS)

    Marriner, J.

    2016-05-01

    The Sloan Digital Sky Survey calibration is revisited to obtain the most accurate photometric calibration. A small but significant error is found in the flat-fielding of the Photometric telescope used for calibration. Two SDSS star catalogs are compared and the average difference in magnitude as a function of right ascension and declination exhibits small systematic errors in relative calibration. The photometric transformation from the SDSS Photometric Telescope to the 2.5 m telescope is recomputed and compared to synthetic magnitudes computed from measured filter bandpasses.

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

    PubMed Central

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

    2014-01-01

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

  8. Measuring Hospital Quality Using Pediatric Readmission and Revisit Rates

    PubMed Central

    Vittinghoff, Eric; Asteria-Peñaloza, Renée; Edwards, Jeffrey D.; Yazdany, Jinoos; Lee, Henry C.; Boscardin, W. John; Cabana, Michael D.; Dudley, R. Adams

    2013-01-01

    OBJECTIVE: To assess variation among hospitals on pediatric readmission and revisit rates and to determine the number of high- and low-performing hospitals. METHODS: In a retrospective analysis using the State Inpatient and Emergency Department Databases from the Healthcare Cost and Utilization Project with revisit linkages available, we identified pediatric (ages 1–20 years) visits with 1 of 7 common inpatient pediatric conditions (asthma, dehydration, pneumonia, appendicitis, skin infections, mood disorders, and epilepsy). For each condition, we calculated rates of all-cause readmissions and rates of revisits (readmission or presentation to the emergency department) within 30 and 60 days of discharge. We used mixed logistic models to estimate hospital-level risk-standardized 30-day revisit rates and to identify hospitals that had performance statistically different from the group mean. RESULTS: Thirty-day readmission rates were low (<10.0%) for all conditions. Thirty-day rates of revisit to the inpatient or emergency department setting ranged from 6.2% (appendicitis) to 11.0% (mood disorders). Study hospitals (n = 958) had low condition-specific visit volumes (37.0%–82.8% of hospitals had <25 visits). The only condition with >1% of hospitals labeled as different from the mean on 30-day risk-standardized revisit rates was mood disorders (4.2% of hospitals [n = 15], range of hospital performance 6.3%–15.9%). CONCLUSIONS: We found that when comparing hospitals’ performances to the average, few hospitals that care for children are identified as high- or low-performers for revisits, even for common pediatric diagnoses, likely due to low hospital volumes. This limits the usefulness of condition-specific readmission or revisit measures in pediatric quality measurement. PMID:23979094

  9. Revisits within 48 Hours to a Thai Emergency Department

    PubMed Central

    Nithimathachoke, Adisak; Tirrell, Gregory Philip; Surawongwattana, Sataporn; Liu, Shan Woo

    2016-01-01

    Objective. Emergency department (ED) revisits are a common ED quality measure. This study was undertaken to ascertain the contributing factors of revisits within 48 hours to a Thai ED and to explore physician-related, illness-related, and patient-related factors behind those revisits. Methods. This study was a chart review from one tertiary care, urban Thai hospital from October 1, 2009, to September 31, 2010. We identified patients who returned to the ED within 48 hours for the same or related complaints after their initial discharge. Three physicians classified revisit as physician-related, illness-related, and patient-related factors. Results. Our study included 172 ED patients' charts. 86/172 (50%) were male and the mean age was 38 ± 5.6 (SD) years. The ED revisits contributing factors were physician-related factors [86/172 (50.0%)], illness-related factors [61/172 (35.5%)], and patient-related factor [25/172 (14.5%)], respectively. Among revisits classified as physician-related factors, 40/86 (46.5%) revisits were due to misdiagnosis and 36/86 (41.9%) were due to suboptimal management. Abdominal pain [27/86 (31.4%)] was the majority of physician-related chief complaints, followed by fever [16/86 (18.6%)] and dyspnea [15/86 (17.4%)]. Conclusion. Misdiagnosis and suboptimal management contributed to half of the 48-hour repeat ED visits in this Thai hospital. PMID:27478642

  10. Electron heating in capacitively coupled plasmas revisited

    NASA Astrophysics Data System (ADS)

    Lafleur, T.; Chabert, P.; Booth, J. P.

    2014-06-01

    We revisit the problem of electron heating in capacitively coupled plasmas (CCPs), and propose a method for quantifying the level of collisionless and collisional heating in plasma simulations. The proposed procedure, based on the electron mechanical energy conservation equation, is demonstrated with particle-in-cell simulations of a number of single and multi-frequency CCPs operated in regimes of research and industrial interest. In almost all cases tested, the total electron heating is comprised of collisional (ohmic) and pressure heating parts. This latter collisionless component is in qualitative agreement with the mechanism of electron heating predicted from the recent re-evaluation of theoretical models. Finally, in very electrically asymmetric plasmas produced in multi-frequency discharges, we observe an additional collisionless heating mechanism associated with electron inertia.

  11. Seasonal dating of Sappho's 'Midnight Poem' revisited

    NASA Astrophysics Data System (ADS)

    Cuntz, Manfred; Gurdemir, Levent; George, Martin

    2016-04-01

    Sappho was a Greek lyric poet who composed a significant array of pristine poetry. Although much of it has been lost, her reputation has endured thanks to numerous surviving fragments. One of her contributions includes the so-called 'Midnight Poem', which contains a line about the Pleiades, setting sometime before midnight, and supposedly observed from the island of Lesbos. This poem also refers to the setting of the Moon. Sappho's Midnight Poem thus represents a prime example of where ancient poetry and astronomy merge, and it also offers the possibility of seasonal dating. Previously, Herschberg and Mebius (1990) estimated that the poem was composed in late winter/early spring, a time frame that is not unusual for lyrics of an amorous nature. The aim of our paper is to revisit this earlier finding by using modern-day software. Our study confirms Herschberg and Mebius' result, but also conveys further information.

  12. Revisiting a magneto-elastic strange attractor

    NASA Astrophysics Data System (ADS)

    Tam, Jee Ian; Holmes, Philip

    2014-03-01

    We revisit an early example of a nonlinear oscillator that exhibits chaotic motions when subjected to periodic excitation: the magneto-elastically buckled beam. In the paper of Moons and Holmes (1980) [1] magnetic field calculations were outlined but not carried through; instead the nonlinear forces responsible for creation of a two-well potential and buckling were fitted to a polynomial function after reduction to a single mode model. In the present paper we compute the full magnetic field and use it to approximate the forces acting on the beam, also using a single mode reduction. This provides a complete model that accurately predicts equilibria, bifurcations, and free oscillation frequencies of an experimental device. We also compare some periodic, transient and chaotic motions with those obtained by numerical simulations of the single mode model, further illustrating the rich dynamical behavior of this simple electromechanical system.

  13. Linear stability of a vortex ring revisited

    NASA Astrophysics Data System (ADS)

    Fukumoto, Yasuhide; Hattori, Yuji

    We revisit the stability of an elliptically strained vortex and a thin axisymmetric vortex ring, embedded in an inviscid incompressible fluid, to three-dimensional disturbances of infinitesimal amplitude. The results of Tsai & Widnall (1976) for an elliptically strained vortex are simplified by providing an explicit expression for the disturbance flow field. A direct relation is established with the elliptical instability. For Kelvin's vortex ring, the primary perturbation to the Rankine vortex is a dipole field. We show that the dipole field causes a parametric resonance instability between axisymmetric and bending waves at intersection points of the dispersion curves. It is found that the dipole effect predominates over the straining effect for a very thin core. The mechanism is attributable to stretching of the disturbance vortex lines in the toroidal direction.

  14. The Doppler spread theory and parameterization revisited

    NASA Astrophysics Data System (ADS)

    Hines, Colin O.

    2004-07-01

    The author's earlier Doppler Spread Theory (DST) and Doppler Spread Parameterization (DSP) are revisited with a new understanding of the dichotomous roles played by nonlinearity in Eulerian and Lagrangian coordinates, respectively. An embryo Lagrangian DST is introduced and employed to assess the original DST. Earlier results near the Eulerian spectral peak are found to be reasonably valid, whereas those at greater vertical wavenumber are confirmed to have produced too much spreading. The earlier DSP is found to need little if any change, though specific values are suggested for its two most important ``fudge factors''. In a more general context, the continuing identity of a wave undergoing certain nonlinear interactions with other waves is discussed.

  15. Biofluiddynamics of balistiform and gymnotiform locomotion: Revisited

    NASA Astrophysics Data System (ADS)

    Sprinkle, Brennan; Bale, Rahul; Singh, Amneet; Chen, Nelson; Maciver, Malcom; Patankar, Neelesh

    2015-11-01

    Gymnotiform and balistiform swimmers are those which have an undulatory fin affixed to a rigid body unlike anguilliforms who undulate their entire body. Is there a mechanical advantage to gymnotiform and balistiform swimming? This question was investigated by Lighthill & Blake in a four paper series Biofluiddynamics of balistiform and gymnotiform locomotion. We revisit this work using fully resolved numerical simulations of the types of swimmers considered by Lighthill & Blake to interrogate the issue of mechanical advantage for rigid body swimmers. In doing so, we find that while there is advantage to rigid body swimming, the mechanism of `momentum enhancement,' proposed by Lighthill and Blake, is not the cause. Further, we use our results and simulations to explain why some gymnotiform and balistiform swimmers have their propulsor attached to their bodies at an angle. This work was supported in part by NSF grants CBET-0828749, CMMI-0941674 and CBET-1066575. Computational resources were provided by Northwestern University High Performance Computing System-Quest.

  16. The Species Problem in Myxomycetes Revisited.

    PubMed

    Walker, Laura M; Stephenson, Steven L

    2016-08-01

    Species identification in the myxomycetes (plasmodial slime molds or myxogastrids) poses particular challenges to researchers as a result of their morphological plasticity and frequent alteration between sexual and asexual life strategies. Traditionally, myxomycete morphology has been used as the primary method of species delimitation. However, with the increasing availability of genetic information, traditional myxomycete taxonomy is being increasingly challenged, and new hypotheses continue to emerge. Due to conflicts that sometimes occur between traditional and more modern species concepts that are based largely on molecular data, there is a pressing need to revisit the discussion surrounding the species concept used for myxomycetes. Biological diversity is being increasingly studied with molecular methods and data accumulates at ever-faster rates, making resolution of this matter urgent. In this review, currently used and potentially useful species concepts (biological, morphological, phylogenetic and ecological) are reviewed, and an integrated approach to resolve the myxomycete species problem is discussed. PMID:27351595

  17. Visser's massive graviton bimetric theory revisited

    SciTech Connect

    Roany, Alain de; Chauvineau, Bertrand; Freitas Pacheco, Jose A. de

    2011-10-15

    A massive gravity theory was proposed by Visser in the late 1990s. This theory, based on a background metric b{sub {alpha}{beta}} and on an usual dynamical metric g{sub {alpha}{beta}} has the advantage of being free of ghosts as well as discontinuities present in other massive theories proposed in the past. In the present investigation, the equations of Visser's theory are revisited with particular care on the related conservation laws. It will be shown that a multiplicative factor is missing in the graviton tensor originally derived by Visser, which has no incidence on the weak field approach but becomes important in the strong field regime when, for instance, cosmological applications are considered. In this case, contrary to some previous claims found in the literature, we conclude that a nonstatic background metric is required in order to obtain a solution able to mimic the {Lambda}CDM cosmology.

  18. Revisiting the R νMDM models

    NASA Astrophysics Data System (ADS)

    Cai, Yi; Schmidt, Michael A.

    2016-05-01

    Combining neutrino mass generation and a dark matter candidate in a unified model has always been intriguing. We revisit the class of R νMDM models, which incorporate minimal dark matter in radiative neutrino mass models based on the one-loop ultraviolet completions of the Weinberg operator. The possibility of an exact accidental Z 2 is completely ruled out in this scenario. We study the phenomenology of one of the models with an approximate Z 2 symmetry. In addition to the Standard Model particles, it contains two real scalar quintuplets, one vector-like quadruplet fermion and a fermionic quintuplet. The neutral component of the fermionic quintuplet serves as a good dark matter candidate which can be tested by the future direct and indirect detection experiments. The constraints from flavor physics and electroweak-scale naturalness are also discussed.

  19. Predator-prey interactions, resource depression and patch revisitation

    USGS Publications Warehouse

    Erwin, R.M.

    1989-01-01

    Generalist predators may be confronted by different types of prey in different patches: sedentary and conspicuous, cryptic (with or without refugia), conspicuous and nonsocial, or conspicuous and social. I argue that, where encounter rates with prey are of most importance, patch revisitation should be a profitable tactic where prey have short 'recovery' times (conspicuous, nonsocial prey), or where anti-predator response (e.g. shoaling) may increase conspicuousness. Predictions are made for how temporal changes in prey encounter rates should affect revisit schedules and feeding rates for the 4 different prey types.

  20. The right hemisphere is dominant in organization of visual search-A study in stroke patients.

    PubMed

    Ten Brink, Antonia F; Matthijs Biesbroek, J; Kuijf, Hugo J; Van der Stigchel, Stefan; Oort, Quirien; Visser-Meily, Johanna M A; Nijboer, Tanja C W

    2016-05-01

    Cancellation tasks are widely used for diagnosis of lateralized attentional deficits in stroke patients. A disorganized fashion of target cancellation has been hypothesized to reflect disturbed spatial exploration. In the current study we aimed to examine which lesion locations result in disorganized visual search during cancellation tasks, in order to determine which brain areas are involved in search organization. A computerized shape cancellation task was administered in 78 stroke patients. As an index for search organization, the amount of intersections of paths between consecutive crossed targets was computed (i.e., intersections rate). This measure is known to accurately depict disorganized visual search in a stroke population. Ischemic lesions were delineated on CT or MRI images. Assumption-free voxel-based lesion-symptom mapping and region of interest-based analyses were used to determine the grey and white matter anatomical correlates of the intersections rate as a continuous measure. The right lateral occipital cortex, superior parietal lobule, postcentral gyrus, superior temporal gyrus, middle temporal gyrus, supramarginal gyrus, inferior longitudinal fasciculus, first branch of the superior longitudinal fasciculus (SLF I), and the inferior fronto-occipital fasciculus, were related to search organization. To conclude, a clear right hemispheric dominance for search organization was revealed. Further, the correlates of disorganized search overlap with regions that have previously been associated with conjunctive search and spatial working memory. This suggests that disorganized visual search is caused by disturbed spatial processes, rather than deficits in high level executive function or planning, which would be expected to be more related to frontal regions. PMID:26876010

  1. Development of human white matter fiber pathways: From newborn to adult ages.

    PubMed

    Cohen, Andrew H; Wang, Rongpin; Wilkinson, Molly; MacDonald, Patrick; Lim, Ashley R; Takahashi, Emi

    2016-05-01

    Major long-range white matter pathways (cingulum, fornix, uncinate fasciculus [UF], inferior fronto-occipital fasciculus [IFOF], inferior longitudinal fasciculus [ILF], thalamocortical [TC], and corpus callosal [CC] pathways) were identified in eighty-three healthy humans ranging from newborn to adult ages. We tracked developmental changes using high-angular resolution diffusion MR tractography. Fractional anisotropy (FA), apparent diffusion coefficient, number, length, and volume were measured in pathways in each subject. Newborns had fewer, and more sparse, pathways than those of the older subjects. FA, number, length, and volume of pathways gradually increased with age and reached a plateau between 3 and 5 years of age. Data were further analyzed by normalizing with mean adult values as well as with each subject's whole brain values. Comparing subjects of 3 years old and under to those over 3 years old, the studied pathways showed differential growth patterns. The CC, bilateral cingulum, bilateral TC, and the left IFOF pathways showed significant growth both in volume and length, while the bilateral fornix, bilateral ILF and bilateral UF showed significant growth only in volume. The TC and CC took similar growth patterns with the whole brain. FA values of the cingulum and IFOF, and the length of ILF showed leftward asymmetry. The fornix, ILF and UF occupied decreased space compared to the whole brain during development with higher FA values, likely corresponding to extensive maturation of the pathways compared to the mean whole brain maturation. We believe that the outcome of this study will provide an important database for future reference. PMID:26948153

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

    PubMed Central

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

    2012-01-01

    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 < 0.05, fully corrected for multiple comparisons across space. Results: Areas with FA reduction in patients were identified in both hemispheres, mainly in the frontal lobes, cingulum, and forceps minor (p = 0.014), caudate e anterior thalamic radiation (p = 0.034), superior longitudinal 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. PMID:22855684

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

    PubMed

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

    2013-01-01

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

  4. Revisiting the argument from fetal potential

    PubMed Central

    Manninen, Bertha Alvarez

    2007-01-01

    One of the most famous, and most derided, arguments against the morality of abortion is the argument from potential, which maintains that the fetus' potential to become a person and enjoy the valuable life common to persons, entails that its destruction is prima facie morally impermissible. In this paper, I will revisit and offer a defense of the argument from potential. First, I will criticize the classical arguments proffered against the importance of fetal potential, specifically the arguments put forth by philosophers Peter Singer and David Boonin, by carefully unpacking the claims made in these arguments and illustrating why they are flawed. Secondly, I will maintain that fetal potential is morally relevant when it comes to the morality of abortion, but that it must be accorded a proper place in the argument. This proper place, however, cannot be found until we first answer a very important and complex question: we must first address the issue of personal identity, and when the fetus becomes the type of being who is relevantly identical to a future person. I will illustrate why the question of fetal potential can only be meaningfully addressed after we have first answered the question of personal identity and how it relates to the human fetus. PMID:17509146

  5. No-scale ripple inflation revisited

    SciTech Connect

    Li, Tianjun; Li, Zhijin; Nanopoulos, Dimitri V. E-mail: lizhijin@physics.tamu.edu

    2014-04-01

    We revisit the no-scale ripple inflation model, where no-scale supergravity is modified by an additional term for the inflaton field in the Kähler potential. This term not only breaks one SU(N,1) symmetry explicitly, but also plays an important role for inflation. We generalize the superpotential in the no-scale ripple inflation model slightly. There exists a discrete Z{sub 2} symmetry/parity in the scalar potential in general, which can be preserved or violated by the non-canonical nomalized inflaton kinetic term. Thus, there are three inflation paths: one parity invariant path, and the left and right paths for parity violating scenario. We show that the inflations along the parity invariant path and right path are consistent with the Planck results. However, the gavitino mass for the parity invariant path is so large that the inflation results will be invalid if we consider the inflaton supersymmetry breaking soft mass term. Thus, only the inflation along the right path gives the correct and consistent results. Notably, the tensor-to-scalar ratio in such case can be large, with a value around 0.05, which may be probed by the future Planck experiment.

  6. Targeting Cancer Metabolism - Revisiting the Warburg Effects

    PubMed Central

    Tran, Quangdon; Lee, Hyunji; Park, Jisoo; Kim, Seon-Hwan; Park, Jongsun

    2016-01-01

    After more than half of century since the Warburg effect was described, this atypical metabolism has been standing true for almost every type of cancer, exhibiting higher glycolysis and lactate metabolism and defective mitochondrial ATP production. This phenomenon had attracted many scientists to the problem of elucidating the mechanism of, and reason for, this effect. Several models based on oncogenic studies have been proposed, such as the accumulation of mitochondrial gene mutations, the switch from oxidative phosphorylation respiration to glycolysis, the enhancement of lactate metabolism, and the alteration of glycolytic genes. Whether the Warburg phenomenon is the consequence of genetic dysregulation in cancer or the cause of cancer remains unknown. Moreover, the exact reasons and physiological values of this peculiar metabolism in cancer remain unclear. Although there are some pharmacological compounds, such as 2-deoxy-D-glucose, dichloroacetic acid, and 3-bromopyruvate, therapeutic strategies, including diet, have been developed based on targeting the Warburg effect. In this review, we will revisit the Warburg effect to determine how much scientists currently understand about this phenomenon and how we can treat the cancer based on targeting metabolism. PMID:27437085

  7. Carbon emission from global hydroelectric reservoirs revisited.

    PubMed

    Li, Siyue; Zhang, Quanfa

    2014-12-01

    Substantial greenhouse gas (GHG) emissions from hydropower reservoirs have been of great concerns recently, yet the significant carbon emitters of drawdown area and reservoir downstream (including spillways and turbines as well as river reaches below dams) have not been included in global carbon budget. Here, we revisit GHG emission from hydropower reservoirs by considering reservoir surface area, drawdown zone and reservoir downstream. Our estimates demonstrate around 301.3 Tg carbon dioxide (CO2)/year and 18.7 Tg methane (CH4)/year from global hydroelectric reservoirs, which are much higher than recent observations. The sum of drawdown and downstream emission, which is generally overlooked, represents 42 % CO2 and 67 % CH4 of the total emissions from hydropower reservoirs. Accordingly, the global average emissions from hydropower are estimated to be 92 g CO2/kWh and 5.7 g CH4/kWh. Nonetheless, global hydroelectricity could currently reduce approximate 2,351 Tg CO2eq/year with respect to fuel fossil plant alternative. The new findings show a substantial revision of carbon emission from the global hydropower reservoirs. PMID:24943886

  8. Revisiting Twomey's approximation for peak supersaturation

    NASA Astrophysics Data System (ADS)

    Shipway, B. J.

    2015-04-01

    Twomey's seminal 1959 paper provided lower and upper bound approximations to the estimation of peak supersaturation within an updraft and thus provides the first closed expression for the number of nucleated cloud droplets. The form of this approximation is simple, but provides a surprisingly good estimate and has subsequently been employed in more sophisticated treatments of nucleation parametrization. In the current paper, we revisit the lower bound approximation of Twomey and make a small adjustment that can be used to obtain a more accurate calculation of peak supersaturation under all potential aerosol loadings and thermodynamic conditions. In order to make full use of this improved approximation, the underlying integro-differential equation for supersaturation evolution and the condition for calculating peak supersaturation are examined. A simple rearrangement of the algebra allows for an expression to be written down that can then be solved with a single lookup table with only one independent variable for an underlying lognormal aerosol population. While multimodal aerosol with N different dispersion characteristics requires 2N+1 inputs to calculate the activation fraction, only N of these one-dimensional lookup tables are needed. No additional information is required in the lookup table to deal with additional chemical, physical or thermodynamic properties. The resulting implementation provides a relatively simple, yet computationally cheap, physically based parametrization of droplet nucleation for use in climate and Numerical Weather Prediction models.

  9. Nursing knowledge, theory and method revisited.

    PubMed

    Booth, K; Kenrick, M; Woods, S

    1997-10-01

    With the approach of the 21st century, nursing is having to respond to diverse influences which are remoulding the professional landscape. Not least of these is the changing status of western economies which underpins a drive towards evidence-based practice and an increased emphasis on multidisciplinary approaches to health care delivery. Certainty in health care is now a thing of the past. Central to the way the nursing profession embraces the future is its underlying philosophy: that which articulates professional values and shapes practice, research, education and management. In a time of change it is therefore essential to revisit the philosophical framework which underpins nursing. The debate in nursing research and theory appears to have stressed the polarization of viewpoints. It may be the case that feminist writers, ethnographers, positivist researchers and nursing theorists, in defending their own points of view, diminish rather than enhance professional dialogue. This paper reviews the nature of this debate within nursing and considers the implications that a dichotomous position may have for knowledge, theory and research method within the current context of health care. It then suggests a philosophical framework which could be relevant and accessible across the whole spectrum of nursing activity. In so doing, the paper aims to contribute to the discussion around epistemology and method in a way which encompasses the diversity found within the broad church of nursing. PMID:9354995

  10. Targeting Cancer Metabolism - Revisiting the Warburg Effects.

    PubMed

    Tran, Quangdon; Lee, Hyunji; Park, Jisoo; Kim, Seon-Hwan; Park, Jongsun

    2016-07-01

    After more than half of century since the Warburg effect was described, this atypical metabolism has been standing true for almost every type of cancer, exhibiting higher glycolysis and lactate metabolism and defective mitochondrial ATP production. This phenomenon had attracted many scientists to the problem of elucidating the mechanism of, and reason for, this effect. Several models based on oncogenic studies have been proposed, such as the accumulation of mitochondrial gene mutations, the switch from oxidative phosphorylation respiration to glycolysis, the enhancement of lactate metabolism, and the alteration of glycolytic genes. Whether the Warburg phenomenon is the consequence of genetic dysregulation in cancer or the cause of cancer remains unknown. Moreover, the exact reasons and physiological values of this peculiar metabolism in cancer remain unclear. Although there are some pharmacological compounds, such as 2-deoxy-D-glucose, dichloroacetic acid, and 3-bromopyruvate, therapeutic strategies, including diet, have been developed based on targeting the Warburg effect. In this review, we will revisit the Warburg effect to determine how much scientists currently understand about this phenomenon and how we can treat the cancer based on targeting metabolism. PMID:27437085

  11. Role of iron in synthetic tetrahedrites revisited

    NASA Astrophysics Data System (ADS)

    Nasonova, Daria I.; Presniakov, Igor A.; Sobolev, Alexei V.; Verchenko, Valeriy Yu.; Tsirlin, Alexander A.; Wei, Zheng; Dikarev, Evgeny V.; Shevelkov, Andrei V.

    2016-03-01

    The valence state of iron in Cu12-xFexSb4S13 tetrahedrites have been revisited by the combination of the crystallographic results, Mössbauer spectroscopy, and magnetization measurements. The crystal structure solution for Cu11.0Fe1.0Sb4S13 (space group I 4 bar 3m, a=10.3253(12), z=2, R=0.011) proved that iron substitutes for copper only in the Cu1 position. At the iron content of x=0.8, 1.0, and 1.2, the presence of two nonequivalent and non-interacting Fe3+ cations was inferred from Mössbauer spectra. At higher levels of substitution (x=1.5 and 2.0), room-temperature Mössbauer spectra indicate the electron hopping between part of Fe3+ and Fe2+ centers, whereas the rest of iron atoms exists as valence-localized Fe3+ and Fe2+ cations. Electron transfer is frozen out at 77 K, where a combination of two Fe3+ sites and one high-spin Fe2+ site is observed. Paramagnetic effective moments extracted from the magnetic susceptibility data point at the Fe3+ state of iron at x=0.8, while a mixture of Fe2+ and Fe3+ is presumed in the samples with higher Fe content.

  12. The Sakharov Experiment Revisited for Granular Materials

    NASA Astrophysics Data System (ADS)

    Vogler, Tracy

    2013-06-01

    Sakharov and co-workers in 1965 proposed an experiment in which a sinusoidal perturbation in a planar wave evolves as it travels through a material. More recent, Liu and co-workers utilized gas gun techniques rather than explosives to drive the shock wave, resulting in a better defined input. The technique has been applied to liquids such as water and mercury as well as solids such as aluminum. All analyses of the experiments conducted to date have utilized a viscous fluid approach, even for the solids. Here, the concept of the decay of a perturbation in a shock wave is revisited and applied to granular materials. Simulations utilizing continuum models for the granular materials as well as mesoscale models in which individual particles are resolved are utilized. It is found that the perturbation decay is influenced by the strength (deviatoric behavior) used in the continuum model. In the mesocale calculations, the simulation parameters as well as the computational approach influence the results. Finally, initial experimental results for the technique using granular tungsten carbide are presented. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin company, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  13. Revisiting the phase diagram of hard ellipsoids.

    PubMed

    Odriozola, Gerardo

    2012-04-01

    In this work, the well-known Frenkel-Mulder phase diagram of hard ellipsoids of revolution [D. Frenkel and B. M. Mulder, Mol. Phys. 55, 1171 (1985)] is revisited by means of replica exchange Monte Carlo simulations. The method provides good sampling of dense systems and so, solid phases can be accessed without the need of imposing a given structure. At high densities, we found plastic solids and fcc-like crystals for semi-spherical ellipsoids (prolates and oblates), and SM2 structures [P. Pfleiderer and T. Schilling, Phys. Rev. E 75, 020402 (2007)] for x : 1-prolates and 1 : x-oblates with x ≥ 3. The revised fluid-crystal and isotropic-nematic transitions reasonably agree with those presented in the Frenkel-Mulder diagram. An interesting result is that, for small system sizes (100 particles), we obtained 2:1- and 1.5:1-prolate equations of state without transitions, while some order is developed at large densities. Furthermore, the symmetric oblate cases are also reluctant to form ordered phases. PMID:22482570

  14. Charge symmetry breaking in Λ hypernuclei revisited

    NASA Astrophysics Data System (ADS)

    Gal, Avraham

    2015-05-01

    The large charge symmetry breaking (CSB) implied by the Λ binding energy difference Δ BΛ4 (0g.s.+) ≡BΛ (He4Λ) -BΛ (H4Λ) = 0.35 ± 0.06 MeV of the A = 4 mirror hypernuclei ground states, determined from emulsion studies, has defied theoretical attempts to reproduce it in terms of CSB in hyperon masses and in hyperon-nucleon interactions, including one pion exchange arising from Λ-Σ0 mixing. Using a schematic strong-interaction ΛN ↔ ΣN coupling model developed by Akaishi and collaborators for s-shell Λ hypernuclei, we revisit the evaluation of CSB in the A = 4 Λ hypernuclei and extend it to p-shell mirror Λ hypernuclei. The model yields values of Δ BΛ4 (0g.s.+) ∼ 0.25 MeV. Smaller size and mostly negative p-shell binding energy differences are calculated for the A = 7- 10 mirror hypernuclei, in rough agreement with the few available data. CSB is found to reduce by almost 30 keV the 110 keV B10Λ g.s. doublet splitting anticipated from the hyperon-nucleon strong-interaction spin dependence, thereby explaining the persistent experimental failure to observe the 2exc- → 1g.s.- γ-ray transition.

  15. Scaling Relationships for Spherical Polymer Brushes Revisited.

    PubMed

    Chen, Guang; Li, Hao; Das, Siddhartha

    2016-06-16

    In this short paper, we revisit the scaling relationships for spherical polymer brushes (SPBs), i.e., polymer brushes grafted to rigid, spherical particles. Considering that the brushes can be described to be encased in a series of hypothetical spherical blobs, we identify significant physical discrepancies in the model of Daoud and Cotton (Journal of Physics, 1982), which is considered to be the state of the art in scaling modeling of SPBs. We establish that the "brush" configuration of the polymer molecules forming the SPBs is possible only if the swelling ratio (which is the ratio of the end-to-end length of the blob-encased polymer segment to the corresponding coil-like polymer segment) is always less than unity-a notion that has been erroneously overlooked in the model of Daoud and Cotton. We also provide new scaling arguments that (a) establish this swelling (or more appropriately shrinking) ratio as a constant (less than unity) for the case of "good" solvent, (b) recover the scaling predictions for blob dimension and monomer number and monomer concentration distributions within the blob, and PMID:27232497

  16. Revisiting the phase diagram of hard ellipsoids

    NASA Astrophysics Data System (ADS)

    Odriozola, Gerardo

    2012-04-01

    In this work, the well-known Frenkel-Mulder phase diagram of hard ellipsoids of revolution [D. Frenkel and B. M. Mulder, Mol. Phys. 55, 1171 (1985), 10.1080/00268978500101971] is revisited by means of replica exchange Monte Carlo simulations. The method provides good sampling of dense systems and so, solid phases can be accessed without the need of imposing a given structure. At high densities, we found plastic solids and fcc-like crystals for semi-spherical ellipsoids (prolates and oblates), and SM2 structures [P. Pfleiderer and T. Schilling, Phys. Rev. E 75, 020402 (2007)] for x : 1-prolates and 1 : x-oblates with x ≥ 3. The revised fluid-crystal and isotropic-nematic transitions reasonably agree with those presented in the Frenkel-Mulder diagram. An interesting result is that, for small system sizes (100 particles), we obtained 2:1- and 1.5:1-prolate equations of state without transitions, while some order is developed at large densities. Furthermore, the symmetric oblate cases are also reluctant to form ordered phases.

  17. Revisiting the Role of Communication in Adolescent Intimate Partner Violence

    ERIC Educational Resources Information Center

    Messinger, Adam M.; Rickert, Vaughn I.; Fry, Deborah A.; Lessel, Harriet; Davidson, Leslie L.

    2012-01-01

    A growing literature suggests that communication strategies can promote or inhibit intimate partner violence (IPV). Research on communication is still needed on a group ripe for early IPV intervention: high school-aged adolescents. This article revisits our previous analyses of young female reproductive clinic patients (Messinger, Davidson, &…

  18. Revisiting the Trust Effect in Urban Elementary Schools

    ERIC Educational Resources Information Center

    Adams, Curt M.; Forsyth, Patrick B.

    2013-01-01

    More than a decade after Goddard, Tschannen-Moran, and Hoy (2001) found that collective faculty trust in clients predicts student achievement in urban elementary schools, we sought to identify a plausible link for this relationship. Our purpose in revisiting the trust effect was twofold: (1) to test the main effect of collective faculty trust on…

  19. The Importance of Being a Complement: CED Effects Revisited

    ERIC Educational Resources Information Center

    Jurka, Johannes

    2010-01-01

    This dissertation revisits subject island effects (Ross 1967, Chomsky 1973) cross-linguistically. Controlled acceptability judgment studies in German, English, Japanese and Serbian show that extraction out of specifiers is consistently degraded compared to extraction out of complements, indicating that the Condition on Extraction domains (CED,…

  20. Educational Administration and the Management of Knowledge: 1980 Revisited

    ERIC Educational Resources Information Center

    Bates, Richard

    2013-01-01

    This paper revisits the thesis of a 1980 paper that suggested a new approach to educational administration based upon the New Sociology of Education. In particular it updates answers to the six key questions asked by that paper: what counts as knowledge; how is what counts as knowledge organised; how is what counts as knowledge transmitted; how is…

  1. Revisiting the Role of Organizational Effectiveness in Educational Evaluation.

    ERIC Educational Resources Information Center

    Lotto, Linda S.

    Organizational effectiveness ought to play a role in educational evaluation, and the development of alternative perspectives for viewing organizations could be a starting point for revisiting organizational evaluation in education. Five possible perspectives and criteria for evaluating organizations have been developed. If an organization is…

  2. Threshold Concepts and Student Engagement: Revisiting Pedagogical Content Knowledge

    ERIC Educational Resources Information Center

    Zepke, Nick

    2013-01-01

    This article revisits the notion that to facilitate quality learning requires teachers in higher education to have pedagogical content knowledge. It constructs pedagogical content knowledge as a teaching and learning space that brings content and pedagogy together. On the content knowledge side, it suggests that threshold concepts, akin to a…

  3. Language Transmission Revisited: Family Type, Linguistic Environment and Language Attitudes

    ERIC Educational Resources Information Center

    Schupbach, Doris

    2009-01-01

    This article revisits factors in intergenerational language maintenance and shift within the family. It does so through an in-depth analysis of what 14 migrants to Australia from German-speaking Switzerland reported in written life stories and subsequent life story interviews. The participants represent four family types and a wide age range, and…

  4. Facilitating Grade Acceleration: Revisiting the Wisdom of John Feldhusen

    ERIC Educational Resources Information Center

    Culross, Rita R.; Jolly, Jennifer L.; Winkler, Daniel

    2013-01-01

    This article revisits the 1986 Feldhusen, Proctor, and Black recommendations on grade skipping. These recommendations originally appeared as 12 guidelines. In this article, the guidelines are grouped into three general categories: how to screen accelerant candidates, how to engage with the adults in the acceleration process (e.g., teachers,…

  5. Bohr’s ‘Light and Life’ revisited

    NASA Astrophysics Data System (ADS)

    Nussenzveig, H. M.

    2015-11-01

    I revisit Niels Bohr’s famous 1932 ‘Light and Life’ lecture, confronting it with current knowledge. Topics covered include: life origin and evolution, quantum mechanics and life, brain and mind, consciousness and free will, and light as a tool for biology, with special emphasis on optical tweezers and their contributions to biophysics. Specialized knowledge of biology is not assumed.

  6. Antidote for Zero Tolerance: Revisiting a "Reclaiming" School.

    ERIC Educational Resources Information Center

    Farner, Conrad D.

    2002-01-01

    Reports on a revisit to the Frank Lloyd Wright Middle School, which implemented strategies to deal with disciplinary problems. The school continues to progress towards creating the type of reclaiming environment necessary to ensure the needs of all students. Strategies used include alternatives to zero tolerance policy; smaller teams of students;…

  7. Revisiting Constructivist Teaching Methods in Ontario Colleges Preparing for Accreditation

    ERIC Educational Resources Information Center

    Schultz, Rachel A.

    2015-01-01

    At the time of writing, the first community colleges in Ontario were preparing for transition to an accreditation model from an audit system. This paper revisits constructivist literature, arguing that a more pragmatic definition of constructivism effectively blends positivist and interactionist philosophies to achieve both student centred…

  8. WAC Revisited: You Get What You Pay for

    ERIC Educational Resources Information Center

    Perelman, Les

    2011-01-01

    In 1982, the author wrote an essay for the second issue of "The Writing Instructor," "Approaches to Comprehensive Writing: Integrating Writing into the College Curriculum," reviewing the early stages of the modern Writing Across the Curriculum (WAC)/Writing in the Disciplines (WID) movement. In this article, the author revisits his essay and…

  9. Revisiting Jack Goody to Rethink Determinisms in Literacy Studies

    ERIC Educational Resources Information Center

    Collin, Ross

    2013-01-01

    This article revisits Goody's arguments about literacy's influence on social arrangements, culture, cognition, economics, and other domains of existence. Whereas some of his arguments tend toward technological determinism (i.e., literacy causes change in the world), other of his arguments construe literacy as a force that shapes and is shaped by…

  10. Closing Achievement Gaps: Revisiting Benjamin S. Bloom's "Learning for Mastery"

    ERIC Educational Resources Information Center

    Guskey, Thomas R.

    2007-01-01

    The problem of achievement gaps among different subgroups of students has been evident in education for many years. This manuscript revisits the work of renowned educator Benjamin S. Bloom, who saw reducing gaps in the achievement of various groups of students as a simple problem of reducing variation in student learning outcomes. Bloom observed…

  11. Moral Judgment Development across Cultures: Revisiting Kohlberg's Universality Claims

    ERIC Educational Resources Information Center

    Gibbs, John C.; Basinger, Karen S.; Grime, Rebecca L.; Snarey, John R.

    2007-01-01

    This article revisits Kohlberg's cognitive developmental claims that stages of moral judgment, facilitative processes of social perspective-taking, and moral values are commonly identifiable across cultures. Snarey [Snarey, J. (1985). "The cross-cultural universality of social-moral development: A critical review of Kohlbergian research."…

  12. Revisiting the Continua of Biliteracy: International and Critical Perspectives.

    ERIC Educational Resources Information Center

    Hornberger, Nancy H.; Skilton-Sylvester, Ellen

    2000-01-01

    The continua model of biliteracy offers a framework to situate research, teaching, and language planning in linguistically diverse settings. The continua model is revisited from the perspective of international cases of educational policy and practice in linguistically diverse settings, and from a critical perspective that seeks to make explicit…

  13. A Multi-Level Model of Moral Functioning Revisited

    ERIC Educational Resources Information Center

    Reed, Don Collins

    2009-01-01

    The model of moral functioning scaffolded in the 2008 "JME" Special Issue is here revisited in response to three papers criticising that volume. As guest editor of that Special Issue I have formulated the main body of this response, concerning the dynamic systems approach to moral development, the problem of moral relativism and the role of…

  14. High Resolution Rapid Revisits Insar Monitoring of Surface Deformation

    NASA Astrophysics Data System (ADS)

    Singhroy, V.; Li, J.; Charbonneau, F.

    2014-12-01

    Monitoring surface deformation on strategic energy and transportation corridors requires high resolution spatial and temporal InSAR images for mitigation and safety purposes. High resolution air photos, lidar and other satellite images are very useful in areas where the landslides can be fatal. Recently, radar interferometry (InSAR) techniques using more rapid revisit images from several radar satellites are increasingly being used in active deformation monitoring. The Canadian RADARSAT Constellation (RCM) is a three-satellite mission that will provide rapid revisits of four days interferometric (InSAR) capabilities that will be very useful for complex deformation monitoring. For instance, the monitoring of surface deformation due to permafrost activity, complex rock slide motion and steam assisted oil extraction will benefit from this new rapid revisit capability. This paper provide examples of how the high resolution (1-3 m) rapid revisit InSAR capabilities will improve our monitoring of surface deformation and provide insights in understanding triggering mechanisms. We analysed over a hundred high resolution InSAR images over a two year period on three geologically different sites with various configurations of topography, geomorphology, and geology conditions. We show from our analysis that the more frequent InSAR acquisitions are providing more information in understanding the rates of movement and failure process of permafrost triggered retrogressive thaw flows; the complex motion of an asymmetrical wedge failure of an active rock slide and the identification of over pressure zones related to oil extraction using steam injection. Keywords: High resolution, InSAR, rapid revisits, triggering mechanisms, oil extraction.

  15. A Revisit of the Masuda Flare

    NASA Astrophysics Data System (ADS)

    Liu, Rui; Xu, Yan; Wang, Haimin

    2011-03-01

    We revisit the flare that occurred on 13 January 1992, which is now universally termed the “Masuda flare”. The new analysis is motivated not just by its uniqueness despite the increasing number of coronal observations in hard X-rays, but also by the improvement of Yohkoh hard X-ray image processing, which was achieved after the intensive investigations on this celebrated event. Using an uncertainty analysis, we show that the hard X-ray coronal source is located closer to the soft X-ray loop by about 5000 km (or 7 arcsec) in the re-calibrated Hard X-ray Telescope (HXT) images than in the original ones. Specifically, the centroid of the M1-band (23 - 33 keV) coronal source is above the maximum brightness of the Soft X-ray Telescope (SXT) loop by 5000±1000 km (9600 km in the original data) and above the apex of the SXT loop represented by the 30% brightness contour by 2000±1000 km (˜ 7000 km in the original data). The change is obviously significant, because most coronal sources are above the thermal loop by less than 6 arcsec. We suggest that this change may account for the discrepancy in the literature, i.e., the spectrum of the coronal emission was reported to be extremely hard below ˜ 20 keV in the pre-calibration investigations, whereas it was reported to be considerably softer in the literature after the re-calibration done by Sato, Kosugi, and Makishima ( Pub. Astron. Soc. Japan 51, 127, 1999). Still, the coronal spectrum is flatter at lower energies than at higher energies, due to the lack of a similar, co-spatial source in the L-band (14 - 23 keV), for which a convincing explanation is absent.

  16. Active Nuclear Import of Membrane Proteins Revisited

    PubMed Central

    Laba, Justyna K.; Steen, Anton; Popken, Petra; Chernova, Alina; Poolman, Bert; Veenhoff, Liesbeth M.

    2015-01-01

    It is poorly understood how membrane proteins destined for the inner nuclear membrane pass the crowded environment of the Nuclear Pore Complex (NPC). For the Saccharomyces cerevisiae proteins Src1/Heh1 and Heh2, a transport mechanism was proposed where the transmembrane domains diffuse through the membrane while the extralumenal domains encoding a nuclear localization signal (NLS) and intrinsically disordered linker (L) are accompanied by transport factors and travel through the NPC. Here, we validate the proposed mechanism and explore and discuss alternative interpretations of the data. First, to disprove an interpretation where the membrane proteins become membrane embedded only after nuclear import, we present biochemical and localization data to support that the previously used, as well as newly designed reporter proteins are membrane-embedded irrespective of the presence of the sorting signals, the specific transmembrane domain (multipass or tail anchored), independent of GET, and also under conditions that the proteins are trapped in the NPC. Second, using the recently established size limit for passive diffusion of membrane proteins in yeast, and using an improved assay, we confirm active import of polytopic membrane protein with extralumenal soluble domains larger than those that can pass by diffusion on similar timescales. This reinforces that NLS-L dependent active transport is distinct from passive diffusion. Thirdly, we revisit the proposed route through the center of the NPC and conclude that the previously used trapping assay is, unfortunately, poorly suited to address the route through the NPC, and the route thus remains unresolved. Apart from the uncertainty about the route through the NPC, the data confirm active, transport factor dependent, nuclear transport of membrane-embedded mono- and polytopic membrane proteins in baker’s yeast. PMID:26473931

  17. Machining as a mechanical property test revisited

    NASA Astrophysics Data System (ADS)

    Smith, David L.

    There is much need for data on mechanical behavior of metals at high strains and strain rates. This need is dictated by modeling of processes like forming and machining, wherein the material in the deformation zone is subjected to severe deformation conditions atypical of conventional material property tests such as tension and torsion. Accurate flow stress data is an essential input for robust prediction of process outputs. Similar requirements arise from applications in high speed ballistic penetration and design of materials for armor. Since the deformation zone in cutting of metals is characterized by unique and extreme combinations of strain, strain rate and temperature, an opportunity exists for using plane-strain cutting as a mechanical property test for measuring flow properties of metals. The feasibility of using plane-strain cutting to measure flow properties of metals is revisited in the light of recent data showing controllability of the deformation conditions in chip formation by systematic variation of process input parameters. A method is outlined as to how the deformation conditions can be varied by changing the process parameters. The method is applied to cutting of commercially pure copper (FCC), iron (BCC) and zinc (HCP). Forces and chip geometries are measured, in conjunction with particle image velocimetry characterization of the deformation using high speed image sequences. The flow stresses are estimated from these measurements. The measured flow stress and its dependence on strain are shown to agree well with prior measurements of these parameters using conventional tests, and flow stress inferred from hardness characterization. The method is also demonstrated to be able to measure properties of metals that recrystallize at room temperature (zinc), wherein quasi-static tests predict much lower strength. Sources of variability and uncertainty in the application of this measurement technique are discussed. Future work in the context of further

  18. Active Nuclear Import of Membrane Proteins Revisited.

    PubMed

    Laba, Justyna K; Steen, Anton; Popken, Petra; Chernova, Alina; Poolman, Bert; Veenhoff, Liesbeth M

    2015-01-01

    It is poorly understood how membrane proteins destined for the inner nuclear membrane pass the crowded environment of the Nuclear Pore Complex (NPC). For the Saccharomyces cerevisiae proteins Src1/Heh1 and Heh2, a transport mechanism was proposed where the transmembrane domains diffuse through the membrane while the extralumenal domains encoding a nuclear localization signal (NLS) and intrinsically disordered linker (L) are accompanied by transport factors and travel through the NPC. Here, we validate the proposed mechanism and explore and discuss alternative interpretations of the data. First, to disprove an interpretation where the membrane proteins become membrane embedded only after nuclear import, we present biochemical and localization data to support that the previously used, as well as newly designed reporter proteins are membrane-embedded irrespective of the presence of the sorting signals, the specific transmembrane domain (multipass or tail anchored), independent of GET, and also under conditions that the proteins are trapped in the NPC. Second, using the recently established size limit for passive diffusion of membrane proteins in yeast, and using an improved assay, we confirm active import of polytopic membrane protein with extralumenal soluble domains larger than those that can pass by diffusion on similar timescales. This reinforces that NLS-L dependent active transport is distinct from passive diffusion. Thirdly, we revisit the proposed route through the center of the NPC and conclude that the previously used trapping assay is, unfortunately, poorly suited to address the route through the NPC, and the route thus remains unresolved. Apart from the uncertainty about the route through the NPC, the data confirm active, transport factor dependent, nuclear transport of membrane-embedded mono- and polytopic membrane proteins in baker's yeast. PMID:26473931

  19. Applying a free-water correction to diffusion imaging data uncovers stress-related neural pathology in depression

    PubMed Central

    Bergamino, Maurizio; Pasternak, Ofer; Farmer, Madison; Shenton, Martha E.; Paul Hamilton, J.

    2015-01-01

    Diffusion tensor imaging (DTI) holds promise for developing our understanding of white-matter pathology in major depressive disorder (MDD). Variable findings in DTI-based investigations of MDD, however, have thwarted development of this literature. Effects of extra-cellular free-water on the sensitivity of DTI metrics could account for some of this inconsistency. Here we investigated whether applying a free-water correction algorithm to DTI data could improve the sensitivity to detect clinical effects using DTI metrics. Only after applying this correction, we found: a) significantly decreased fractional anisotropy and axial diffusivity (AD) in the left inferior fronto-occipital fasciculus (IFOF) in MDD; and b) increased self-reported stress that significantly correlated with decreased IFOF AD in depression. We estimated and confirmed the robustness of differences observed between free-water corrected and uncorrected approaches using bootstrapping. We conclude that applying a free-water correction to DTI data increases the sensitivity of DTI-based metrics to detect clinical effects in MDD. PMID:27006903

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

    PubMed Central

    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

    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. PMID:21498054

  1. White Matter Integrity is Reduced in Bulimia Nervosa

    PubMed Central

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

    2013-01-01

    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. PMID:23354827

  2. Blindness alters the microstructure of the ventral but not the dorsal visual stream.

    PubMed

    Reislev, Nina L; Kupers, Ron; Siebner, Hartwig R; Ptito, Maurice; Dyrby, Tim B

    2016-07-01

    Visual deprivation from birth leads to reorganisation of the brain through cross-modal plasticity. Although there is a general agreement that the primary afferent visual pathways are altered in congenitally blind individuals, our knowledge about microstructural changes within the higher-order visual streams, and how this is affected by onset of blindness, remains scant. We used diffusion tensor imaging and tractography to investigate microstructural features in the dorsal (superior longitudinal fasciculus) and ventral (inferior longitudinal and inferior fronto-occipital fasciculi) visual pathways in 12 congenitally blind, 15 late blind and 15 normal sighted controls. We also studied six prematurely born individuals with normal vision to control for the effects of prematurity on brain connectivity. Our data revealed a reduction in fractional anisotropy in the ventral but not the dorsal visual stream for both congenitally and late blind individuals. Prematurely born individuals, with normal vision, did not differ from normal sighted controls, born at term. Our data suggest that although the visual streams are structurally developing without normal visual input from the eyes, blindness selectively affects the microstructure of the ventral visual stream regardless of the time of onset. We suggest that the decreased fractional anisotropy of the ventral stream in the two groups of blind subjects is the combined result of both degenerative and cross-modal compensatory processes, affecting normal white matter development. PMID:26134685

  3. BDNF GENE EFFECTS ON BRAIN CIRCUITRY REPLICATED IN 455 TWINS

    PubMed Central

    Chiang, Ming-Chang; Barysheva, Marina; Toga, Arthur W.; Medland, Sarah E.; Hansell, Narelle K.; James, Michael R.; McMahon, Katie L.; de Zubicaray, Greig I.; Martin, Nicholas G.; Wright, Margaret J.; Thompson, Paul M.

    2011-01-01

    Brain-derived neurotrophic factor (BDNF) plays a key role in learning and memory, but its effects on the fiber architecture of the living brain are unknown. We genotyped 455 healthy adult twins and their non-twin siblings (188 males/267 females; age: 23.7±2.1 years, mean±SD) and scanned them with high angular resolution diffusion tensor imaging (DTI), to assess how the BDNF Val66Met polymorphism affects white matter microstructure. By applying genetic association analysis to every 3D point in the brain images, we found that the Val-BDNF genetic variant was associated with lower white matter integrity in the splenium of the corpus callosum, left optic radiation, inferior fronto-occipital fasciculus, and superior corona radiata. Normal BDNF variation influenced the association between subjects’ performance intellectual ability (as measured by Object Assembly subtest) and fiber integrity (as measured by fractional anisotropy; FA) in the callosal splenium, and pons. The BDNF gene may affect intellectual performance by modulating white matter development. This combination of genetic association analysis and large-scale diffusion imaging directly relates a specific gene to the fiber microstructure of the living brain and to human intelligence. PMID:21195196

  4. DTI-MR tractography of white matter damage in stroke patients with neglect.

    PubMed

    Urbanski, M; Thiebaut de Schotten, M; Rodrigo, S; Oppenheim, C; Touzé, E; Méder, J-F; Moreau, K; Loeper-Jeny, C; Dubois, B; Bartolomeo, P

    2011-02-01

    Left visual neglect is a dramatic neurological condition that impairs awareness of left-sided events. Neglect has been classically reported after strokes in the territory of the right middle cerebral artery. However, the precise lesional correlates of neglect within this territory remain discussed. Recent evidence strongly suggests an implication of dysfunction of large-scale perisylvian networks in chronic neglect, but the quantitative relationships between neglect signs and damage to white matter (WM) tracts have never been explored. In this prospective study, we used diffusion tensor imaging (DTI) tractography in twelve patients with a vascular stroke in the right hemisphere. Six of these patients showed signs of neglect. Nonparametric voxel-based comparisons between neglect and controls on fractional anisotropy maps revealed clusters in the perisylvian WM and in the external capsule. Individual DTI tractography identified specific disconnections of the fronto-parietal and fronto-occipital pathways in the neglect group. Voxel-based correlation statistics highlighted correlations between patients' performance on two visual search tasks and damage to WM clusters. These clusters were located in the anterior limb of the internal capsule and in the WM underlying the inferior frontal gyrus, along the trajectory of the anterior segment of the arcuate fasciculus (asAF). These results indicate that chronic visual neglect can result from, and correlate with, damage to fronto-parietal connections in the right hemisphere, within large-scale cortical networks important for orienting of spatial attention, arousal and spatial working memory. PMID:21113581

  5. Cardiorespiratory fitness and white matter integrity in Alzheimer's disease.

    PubMed

    Perea, R D; Vidoni, E D; Morris, J K; Graves, R S; Burns, J M; Honea, R A

    2016-09-01

    The objective of this study was to investigate the relationship between cardiorespiratory (CR) fitness and the brain's white matter tract integrity using diffusion tensor imaging (DTI) in the Alzheimer's disease (AD) population. We recruited older adults in the early stages of AD (n = 37; CDR = 0.5 and 1) and collected cross-sectional fitness and diffusion imaging data. We examined the association between CR fitness (peak oxygen consumption [VO2peak]) and fractional anisotropy (FA) in AD-related white matter tracts using two processing methodologies: a tract-of-interest approach and tract-based spatial statistic (TBSS). Subsequent diffusivity metrics (radial diffusivity [RD], mean diffusivity [MD], and axial diffusivity [A × D]) were also correlated with VO2peak. The tract-of-interest approach showed that higher VO2peak was associated with preserved white matter integrity as measured by increased FA in the right inferior fronto-occipital fasciculus (p = 0.035, r = 0.36). We did not find a significant correlation using TBSS, though there was a trend for a positive association between white matter integrity and higher VO2peak measures (p < 0.01 uncorrected). Our findings indicate that higher CR fitness levels in early AD participants may be related to preserved white matter integrity. However to draw stronger conclusions, further study on the relationship between fitness and white matter deterioration in AD is necessary. PMID:26239997

  6. Microstructural brain differences predict functional hemodynamic responses in a reward processing task.

    PubMed

    Camara, Estela; Rodriguez-Fornells, Antoni; Münte, Thomas F

    2010-08-25

    Many aspects of human behavior are driven by rewards, yet different people are differentially sensitive to rewards and punishment. In this study, we show that white matter microstructure in the uncinate/inferior fronto-occipital fasciculus, defined by fractional anisotropy values derived from diffusion tensor magnetic resonance images, correlates with both short-term (indexed by the fMRI blood oxygenation level-dependent response to reward in the nucleus accumbens) and long-term (indexed by the trait measure sensitivity to punishment) reactivity to rewards. Moreover, trait measures of reward processing were also correlated with reward-related functional activation in the nucleus accumbens. The white matter tract revealed by the correlational analysis connects the anterior temporal lobe with the medial and lateral orbitofrontal cortex and also supplies the ventral striatum. The pattern of strong correlations suggests an intimate relationship between white matter structure and reward-related behavior that may also play a role in a number of pathological conditions, such as addiction and pathological gambling. PMID:20739561

  7. Connectomic Insights into Topologically Centralized Network Edges and Relevant Motifs in the Human Brain

    PubMed Central

    Xia, Mingrui; Lin, Qixiang; Bi, Yanchao; He, Yong

    2016-01-01

    White matter (WM) tracts serve as important material substrates for information transfer across brain regions. However, the topological roles of WM tracts in global brain communications and their underlying microstructural basis remain poorly understood. Here, we employed diffusion magnetic resonance imaging and graph-theoretical approaches to identify the pivotal WM connections in human whole-brain networks and further investigated their wiring substrates (including WM microstructural organization and physical consumption) and topological contributions to the brain's network backbone. We found that the pivotal WM connections with highly topological-edge centrality were primarily distributed in several long-range cortico-cortical connections (including the corpus callosum, cingulum and inferior fronto-occipital fasciculus) and some projection tracts linking subcortical regions. These pivotal WM connections exhibited high levels of microstructural organization indicated by diffusion measures (the fractional anisotropy, the mean diffusivity and the axial diffusivity) and greater physical consumption indicated by streamline lengths, and contributed significantly to the brain's hubs and the rich-club structure. Network motif analysis further revealed their heavy participations in the organization of communication blocks, especially in routes involving inter-hemispheric heterotopic and extremely remote intra-hemispheric systems. Computational simulation models indicated the sharp decrease of global network integrity when attacking these highly centralized edges. Together, our results demonstrated high building-cost consumption and substantial communication capacity contributions for pivotal WM connections, which deepens our understanding of the topological mechanisms that govern the organization of human connectomes. PMID:27148015

  8. Altered tract-specific white matter microstructure is related to poorer cognitive performance: The Rotterdam Study.

    PubMed

    Cremers, Lotte G M; de Groot, Marius; Hofman, Albert; Krestin, Gabriel P; van der Lugt, Aad; Niessen, Wiro J; Vernooij, Meike W; Ikram, M Arfan

    2016-03-01

    White matter microstructural integrity has been related to cognition. Yet, the potential role of specific white matter tracts on top of a global white matter effect remains unclear, especially when considering specific cognitive domains. Therefore, we determined the tract-specific effect of white matter microstructure on global cognition and specific cognitive domains. In 4400 nondemented and stroke-free participants (mean age 63.7 years, 55.5% women), we obtained diffusion magnetic resonance imaging parameters (fractional anisotropy and mean diffusivity) in 14 white matter tracts using probabilistic tractography and assessed cognitive performance with a cognitive test battery. Tract-specific white matter microstructure in all supratentorial tracts was associated with poorer global cognition. Lower fractional anisotropy in association tracts, primarily the inferior fronto-occipital fasciculus, and higher mean diffusivity in projection tracts, in particular the posterior thalamic radiation, most strongly related to poorer cognition. Altered white matter microstructure related to poorer information processing speed, executive functioning, and motor speed, but not to memory. Tract-specific microstructural changes may aid in better understanding the mechanism of cognitive impairment and neurodegenerative diseases. PMID:26923407

  9. Finite frequency tomography: the checkerboard test revisited

    NASA Astrophysics Data System (ADS)

    Mercerat, E. D.; Zaroli, C.; Nolet, G.

    2011-12-01

    We address some consequences of the application of finite frequency theory for seismic tomography by revisiting the classical checkerboard test. We use a simple borehole-to-borehole experiment set-up in order to have complete control of the situation and to avoid complicating factors such as crustal corrections that still hamper global tomography. We are particularly interested in the feasibility of using ray-based finite frequency kernels in the inversion of travel time perturbations measured by crosscorrelation, in the cross-dependence between S wave velocity perturbations and the measured P travel times, and in the benefits of using finite-frequency theory on one or multiple frequency bands. We have done a 3D checkerboard test to assess the influence of these issues. Full-waveform synthetic seismograms are calculated using the spectral elements method up to 2 kHz maximum frequency. The computational domain extends 200 m x 120 m x 120 m and the target velocity model is a checkerboard with 12 m x 12 m x 12 m blocks of velocities 5% slower and faster than the background (homogeneous, Vp=6 km/s) model. First, we make a comparison between finite-frequency kernels calculated by ray theory with those based on the spectral elements method (adjoint technique), in terms of resolution, accuracy, but also computational cost. From synthetic seismograms calculated for the 3D checkerboard model as well as for the homogeneous model, we measure crosscorrelation travel times at different frequency bands and invert them with classical ray theory as well as with finite frequency theory. Several interesting features are highlighted in our multi-band data set, such as the wavefront healing effect. For instance, we observe that the delay times, in absolute value, are usually larger at short (0.5 ms) than long (4 ms) periods. This can be explained by the presence of the "doughnut hole" along the geometrical ray path in the sensitivity kernels, whose diameter is proportional to the

  10. Five years on: Revisiting GSN data quality

    NASA Astrophysics Data System (ADS)

    Gee, L. S.; Nettles, M.; Ekstrom, G.; Davis, J. P.; Ringler, A. T.; Storm, T. L.; Wilson, D.; Anderson, K. R.

    2014-12-01

    In 2010, the Lamont Waveform Quality Center (WQC) conducted an in-depth review of ten stations in the Global Seismographic Network (GSN). IU stations (CASY, DAV, KIP, KONO, WCI), IC stations (SSE, XAN), and II stations (ALE, DGAR, RPN) were analyzed using a scaling analysis based on data-synthetic comparisons, evaluation of noise levels, assessment of inter-sensor coherence, and polarization analysis. These reports (available from http://www.ldeo.columbia.edu/~ekstrom/Projects/WQC.html) highlighted a number of significant problems in GSN data quality, including the frequency-dependent loss of gain in the STS-1 seismometer (Ekström et al., 2006) that has been attributed to the presence of humidity in the electronics, cables, and connectors (Yuki and Ishihara, 2002; Hutt and Ringler, 2011). The reports from the WQC spurred a number of changes in the operation of the GSN, including the adoption of the policy of annual calibrations and the development of new tools and metrics to monitor, evaluate, and communicate data quality. In parallel, the USGS' Albuquerque Seismological Laboratory (ASL) and UCSD's Project IDA worked with the IRIS Consortium to upgrade GSN stations with new data acquisition systems, to refurbish the STS-1 seismometers with new electronics, and to expand the deployment of secondary broadband sensors. We revisit the 2010 reports, using the tools of the WQC as well as a number of newly developed tools such as the USGS' Data Quality Analyzer and IRIS' MUSTANG, and provide an update on GSN data quality. Our initial focus is on CASY and KIP, the first two stations reviewed by the WQC. Our goal is to evaluate progress in the last five years and assess our ability to quantify data quality as well as to identify potential problems that could compromise data quality in the future. Ekström, G., C. A. Dalton, and M. Nettles (2006). Observations of time-dependent errors in long-period instrument gain at global seismic stations. Seismological Research Letters

  11. Unwarranted Return: A Response to McVee, Dunsmore, and Gavelek's (2005) "Schema Theory Revisited"

    ERIC Educational Resources Information Center

    Krasny, Karen A.; Sadoski, Mark; Paivio, Allan

    2007-01-01

    This article presents the authors' response to McVee, Dunsmore, and Gavelek's "Schema Theory Revisited." In "Schema Theory Revisited," McVee, Dunsmore, and Gavelek (2005) proposed a rearticulation of schema theory intended to encompass the ideas that schemata and other cognitive processes are embodied, that knowledge is situated in the transaction…

  12. Enthalpy-Entropy Compensation (EEC) Effect: A Revisit.

    PubMed

    Pan, Animesh; Biswas, Tapas; Rakshit, Animesh K; Moulik, Satya P

    2015-12-31

    A short account of the developments and perspectives of IKR (iso-kinetic relation) and EEC (enthalpy (H) - entropy (S) compensation) has been presented. The IKR and EEC are known to be extra thermodynamic or empirical correlations though linear H-S correlation can be thermodynamically deduced. Attempt has also been made to explain the phenomena in terms of statistical thermodynamics. In this study, we have briefly revisited the fundamentals of both IKR and EEC from kinetic and thermodynamic grounds. A detailed revisit of the EEC phenomenon on varied kinetic and equilibrium processes has been also presented. Possible correlations among the free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) changes of different similar and nonsimilar chemical processes under varied conditions have been discussed with possible future projections. PMID:26641279

  13. Topological Twisted Sigma Model with H-flux Revisited

    SciTech Connect

    Chuang, Wu-yen

    2006-08-18

    In this paper we revisit the topological twisted sigma model with H-flux. We explicitly expand and then twist the worldsheet Lagrangian for bi-Hermitian geometry. we show that the resulting action consists of a BRST exact term and pullback terms, which only depend on one of the two generalized complex structures and the B-field. We then discuss the topological feature of the model.

  14. (Pseudo)issue of the conformal frame revisited

    SciTech Connect

    Faraoni, Valerio; Nadeau, Shahn

    2007-01-15

    The issue of the equivalence between Jordan and Einstein conformal frames in scalar-tensor gravity is revisited, with the emphasis on implementing running units in the latter. The lack of affine parametrization for timelike worldlines and the cosmological constant problem in the Einstein frame are clarified, and a paradox in the literature about cosmological singularities appearing only in one frame is solved. While, classically, the two conformal frames are physically equivalent, they seem to be inequivalent at the quantum level.

  15. Non linear evolution: revisiting the solution in the saturation region

    NASA Astrophysics Data System (ADS)

    Contreras, Carlos; Levin, Eugene; Meneses, Rodrigo

    2014-10-01

    In this paper we revisit the problem of the solution to Balitsky-Kovchegov equation deeply in the saturation domain. We find that solution has the form given in ref. [23] but it depends on variable and the value of Const is calculated in this paper. We propose the solution for full BFKL kernel at large in the entire kinematic region that satisfies the McLerran-Venugopalan-type [3-7] initial condition.

  16. Discussion of "Computational Electrocardiography: Revisiting Holter ECG Monitoring".

    PubMed

    Baumgartner, Christian; Caiani, Enrico G; Dickhaus, Hartmut; Kulikowski, Casimir A; Schiecke, Karin; van Bemmel, Jan H; Witte, Herbert

    2016-08-01

    This article is part of a For-Discussion-Section of Methods of Information in Medicine about the paper "Computational Electrocardiography: Revisiting Holter ECG Monitoring" written by Thomas M. Deserno and Nikolaus Marx. It is introduced by an editorial. This article contains the combined commentaries invited to independently comment on the paper of Deserno and Marx. In subsequent issues the discussion can continue through letters to the editor. PMID:27406570

  17. The Transverse Momentum Dependent Statistical Parton Distributions Revisited

    NASA Astrophysics Data System (ADS)

    Bourrely, Claude; Buccella, Franco; Soffer, Jacques

    2013-04-01

    The extension of the statistical parton distributions to include their transverse momentum dependence (TMD) is revisited by considering that the proton target has a finite longitudinal momentum. The TMD will be generated by means of a transverse energy sum rule. The new results are mainly relevant for electron-proton inelastic collisions in the low Q2 region. We take into account the effects of the Melosh-Wigner rotation for the helicity distributions.

  18. Indoor air and human health revisited: A recent IAQ symposium

    SciTech Connect

    Gammage, R.B.

    1994-12-31

    Indoor Air and Human Health Revisited was a speciality symposium examining the scientific underpinnings of sensory and sensitivity effects, allergy and respiratory disease, neurotoxicity and cancer. An organizing committee selected four persons to chain the sessions and invite experts to give state-of-the-art presentations that will be published as a book. A summary of the presentations is made and some critical issues identified.

  19. Asymmetrical white matter networks for attending to global versus local features

    PubMed Central

    Chechlacz, Magdalena; Mantini, Dante; Gillebert, Celine R.; Humphreys, Glyn W.

    2015-01-01

    The ability to draw objects is a complex process depending on an array of cognitive mechanisms including routines for spatial coding, attention and the processing of both local and global features. Previous studies using both neuropsychological and neuroimaging data have reported hemispheric asymmetries in attending to local versus global features linked to a variety of cortical loci. However, it has not been examined to date whether such asymmetries exist at the level of white matter pathways sub-serving global/local attention. The current study provides a comprehensive analysis of brain-behaviour relationships in the processing of local versus global features based on data from a large cohort of sub-acute stroke patients (n = 248) and behavioural measures from a complex figure copy task. The data analysis used newly developed methods for automated delineation of stroke lesions combined with track-wise lesion deficits procedures. We found (i) that reproduction of local features in figure copying was supported by a neural network confined to the left hemisphere, consisting of cortical loci within parietal, occipital and insular lobes and interconnected by the inferior-fronto-occipital fasciculus (IFOF), and (ii) that global feature processing was associated with a right hemisphere network interconnected by the third branch of the superior longitudinal fasciculus and the long segment of the perisylvian network. The data support the argument that asymmetrical white matter disconnections within long–range association pathways predict poor complex figure drawing resulting from deficits in hierarchical representation. We conclude that hemispheric asymmetries in attending to local versus global features exist on the level of both cortical loci and the supporting white matter pathways. PMID:25727548

  20. Connectivity-based whole brain dual parcellation by group ICA reveals tract structures and decreased connectivity in schizophrenia.

    PubMed

    Wu, Lei; Calhoun, Vince D; Jung, Rex E; Caprihan, Arvind

    2015-11-01

    Mapping brain connectivity based on neuroimaging data is a promising new tool for understanding brain structure and function. In this methods paper, we demonstrate that group independent component analysis (GICA) can be used to perform a dual parcellation of the brain based on its connectivity matrix (cmICA). This dual parcellation consists of a set of spatially independent source maps, and a corresponding set of paired dual maps that define the connectivity of each source map to the brain. These dual maps are called the connectivity profiles of the source maps. Traditional analysis of connectivity matrices has been used previously for brain parcellation, but the present method provides additional information on the connectivity of these segmented regions. In this paper, the whole brain structural connectivity matrices were calculated on a 5 mm(3) voxel scale from diffusion imaging data based on the probabilistic tractography method. The effect of the choice of the number of components (30 and 100) and their stability were examined. This method generated a set of spatially independent components that are consistent with the canonical brain tracts provided by previous anatomic descriptions, with the high order model yielding finer segmentations. The corpus-callosum example shows how this method leads to a robust parcellation of a brain structure based on its connectivity properties. We applied cmICA to study structural connectivity differences between a group of schizophrenia subjects and healthy controls. The connectivity profiles at both model orders showed similar regions with reduced connectivity in schizophrenia patients. These regions included forceps major, right inferior fronto-occipital fasciculus, uncinate fasciculus, thalamic radiation, and corticospinal tract. This paper provides a novel unsupervised data-driven framework that summarizes the information in a large global connectivity matrix and tests for brain connectivity differences. It has the

  1. Structural Variability within Frontoparietal Networks and Individual Differences in Attentional Functions: An Approach Using the Theory of Visual Attention

    PubMed Central

    Gillebert, Celine R.; Vangkilde, Signe A.; Petersen, Anders; Humphreys, Glyn W.

    2015-01-01

    Visuospatial attention allows us to select and act upon a subset of behaviorally relevant visual stimuli while ignoring distraction. Bundesen's theory of visual attention (TVA) (Bundesen, 1990) offers a quantitative analysis of the different facets of attention within a unitary model and provides a powerful analytic framework for understanding individual differences in attentional functions. Visuospatial attention is contingent upon large networks, distributed across both hemispheres, consisting of several cortical areas interconnected by long-association frontoparietal pathways, including three branches of the superior longitudinal fasciculus (SLF I-III) and the inferior fronto-occipital fasciculus (IFOF). Here we examine whether structural variability within human frontoparietal networks mediates differences in attention abilities as assessed by the TVA. Structural measures were based on spherical deconvolution and tractography-derived indices of tract volume and hindrance-modulated orientational anisotropy (HMOA). Individual differences in visual short-term memory (VSTM) were linked to variability in the microstructure (HMOA) of SLF II, SLF III, and IFOF within the right hemisphere. Moreover, VSTM and speed of information processing were linked to hemispheric lateralization within the IFOF. Differences in spatial bias were mediated by both variability in microstructure and volume of the right SLF II. Our data indicate that the microstructural and macrostrucutral organization of white matter pathways differentially contributes to both the anatomical lateralization of frontoparietal attentional networks and to individual differences in attentional functions. We conclude that individual differences in VSTM capacity, processing speed, and spatial bias, as assessed by TVA, link to variability in structural organization within frontoparietal pathways. PMID:26224851

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

    PubMed

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

    2015-12-01

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

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

    PubMed

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

    2014-01-01

    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

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

    PubMed Central

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

    2009-01-01

    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. PMID:20046827

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

    PubMed Central

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

    2014-01-01

    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

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

    PubMed

    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

    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

  7. Age and Sex Effects on White Matter Tracts in Psychosis from Adolescence through Middle Adulthood.

    PubMed

    Schwehm, Andrew; Robinson, Delbert G; Gallego, Juan A; Karlsgodt, Katherine H; Ikuta, Toshikazu; Peters, Bart D; Malhotra, Anil K; Szeszko, Philip R

    2016-09-01

    There is controversy regarding specificity of white matter abnormalities in psychosis, their deviation from healthy aging, and the influence of sex on these measures. We used diffusion tensor imaging to characterize putative white matter microstructure in 224 patients with psychosis and healthy volunteers across the age range of 15-64 years. Sixty-five younger (age <30 years; 47M/18F) patients with psychosis (all experiencing a first episode of illness) and 48 older (age ⩾30 years; 30M/18F) patients were age-matched to younger and older healthy volunteer groups (N=63 (40M/23F) and N=48 (29M/19F), respectively). The trajectories of two inter-hemispheric (splenium and genu), two projection (cortico-pontine and anterior thalamic), and five bilateral association (inferior fronto-occipital, inferior longitudinal, superior longitudinal, cingulum, and uncinate) tracts were quantified using tractography to derive measures of fractional anisotropy and mean, axial, and radial diffusivity. Fractional anisotropy was significantly lower in the inferior longitudinal fasciculus and superior longitudinal fasciculus in all patients compared with all healthy volunteers, with comparable effect sizes observed in both the younger and older patients compared with their respective healthy volunteer groups. Moreover, age-associated differences in fractional anisotropy within these tracts were comparable between groups across the age span. In addition, female patients had significantly lower fractional anisotropy across all tracts compared with female controls regardless of age. Our findings demonstrate comparable putative white matter abnormalities in two independent samples of patients with psychosis and argue against their progression in patients. These data further highlight the novel and potentially underappreciated role of sex in understanding white matter dysfunction in the neurobiology of psychosis. PMID:27067129

  8. Alterations of functional and structural connectivity of freezing of gait in Parkinson's disease.

    PubMed

    Wang, Min; Jiang, Siming; Yuan, Yongsheng; Zhang, Li; Ding, Jian; Wang, Jianwei; Zhang, Jiejin; Zhang, Kezhong; Wang, Jie

    2016-08-01

    This study assessed the patterns of functional and structural connectivity abnormalities in patients with Parkinson's disease with freezing of gait (PD FOG+) compared with those without freezing (PD FOG-) and healthy controls (HCs). Resting state functional MRI (rs-fMRI) and diffusion tensor imaging (DTI) scans were obtained from 14 PD FOG+, 16 PD FOG- and 16HCs. Between-group difference in pedunculopontine nucleus (PPN) functional connectivity (FC) was performed to assess FC dysfunction. Tract-based spatial statistics (TBSS) was applied to compare white matter (WM) impairment across the whole brain between groups. PD FOG+ patients exhibited abnormal PPN FC, compared with HCs and with PD FOG-, mainly in the corticopontine-cerebellar pathways (in the bilateral cerebellum and in the pons), as well as the visual temporal areas (in the right middle temporal gyrus and in the right inferior temporal gyrus). Moreover, PD FOG+ patients, showed more pronounced WM abnormalities, relative to controls, including the interhemispheric connections of corpus callosum, the cortico-cortical WM tracts of the cingulum, the superior longitudinal fasciculus and inferior fronto-occipital fasciculus, the corticofugal tract (cerebral peduncles, internal capsule, corona radiata), as well as tracts connecting the thalamus (thalamic radiation). This study suggests that FOG in PD is associated with abnormal PPN FC network, mainly affecting the corticopontine-cerebellar pathways as well as visual temporal areas involved in visual processing, and with diffuse WM deficits extending to motor, sensory and cognitive regions. Combining rs-fMRI and DTI method, our study should advance the understanding of neural mechanisms underlying FOG in PD. PMID:27230857

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

    PubMed

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

    2016-04-01

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

  10. A Longitudinal Diffusion Tensor Imaging Study Assessing White Matter Fiber Tracts after Sports-Related Concussion

    PubMed Central

    Murugavel, Murali; Cubon, Valerie; Putukian, Margot; Echemendia, Ruben; Cabrera, Javier; Osherson, Daniel

    2014-01-01

    Abstract The extent of structural injury in sports-related concussion (SRC) is central to the course of recovery, long-term effects, and the decision to return to play. In the present longitudinal study, we used diffusion tensor imaging (DTI) to assess white matter (WM) fiber tract integrity within 2 days, 2 weeks, and 2 months of concussive injury. Participants were right-handed male varsity contact-sport athletes (20.2±1.0 years of age) with a medically diagnosed SRC (no loss of consciousness). They were compared to right-handed male varsity non-contact-sport athletes serving as controls (19.9±1.7 years). We found significantly increased radial diffusivity (RD) in concussed athletes (n=12; paired t-test, tract-based spatial statistics; p<0.025) at 2 days, when compared to the 2-week postinjury time point. The increase was found in a cluster of right hemisphere voxels, spanning the posterior limb of the internal capsule (IC), the retrolenticular part of the IC, the inferior longitudinal fasciculus, the inferior fronto-occipital fasciculus (sagittal stratum), and the anterior thalamic radiation. Post-hoc, univariate, between-group (controls vs. concussed), mixed-effects analysis of the cluster showed significantly higher RD at 2 days (p=0.002), as compared to the controls, with a trend in the same direction at 2 months (p=0.11). Results for fractional anisotropy (FA) in the same cluster showed a similar, but inverted, pattern; FA was decreased at 2 days and at 2 months postinjury, when compared to healthy controls. At 2 weeks postinjury, no statistical differences between concussed and control athletes were found with regard to either RD or FA. These results support the hypothesis of increased RD and reduced FA within 72 h postinjury, followed by recovery that may extend beyond 2 weeks. RD appears to be a sensitive measure of concussive injury. PMID:24786666