The Experts below are selected from a list of 16635 Experts worldwide ranked by ideXlab platform
R Morris - One of the best experts on this subject based on the ideXlab platform.
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Fiber system linking the mid dorsolateral frontal cortex with the retrosplenial presubicular region in the rhesus monkey
The Journal of Comparative Neurology, 1999Co-Authors: Deepak N. Pandya, R Morris, Michael PetridesAbstract:The present study investigated the origin, course, and terminations of the Association Fiber system linking the frontal cortex with the hippocampal system by means of the cingulum bundle. Injections of tritiated amino acids were placed within individual cytoarchitectonic areas of the frontal cortex in the rhesus monkey. It was demonstrated that the mid-dorsolateral frontal cortex (areas 46, 9/46, and 9) and its medial extension (medial areas 9 and 9/32) is the origin of a specific Fiber pathway, running posteriorly as part of the cingulum bundle, and terminating mainly in the retrosplenial area 30 and the posterior presubiculum. This Fiber bundle therefore provides the anatomical substrate of a functional interaction between the mid-dorsolateral frontal cortex and the hippocampal memory system for the monitoring of information within working memory. J. Comp. Neurol. 407:183–192, 1999. © 1999 Wiley-Liss, Inc.
Christine Wu Nordahl - One of the best experts on this subject based on the ideXlab platform.
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a diffusion weighted imaging tract based spatial statistics study of autism spectrum disorder in preschool aged children
Journal of Neurodevelopmental Disorders, 2019Co-Authors: Derek S Andrews, Joshua K Lee, Marjorie Solomon, Sally J Rogers, David G Amaral, Christine Wu NordahlAbstract:The core symptoms of autism spectrum disorder (ASD) are widely theorized to result from altered brain connectivity. Diffusion-weighted magnetic resonance imaging (DWI) has been a versatile method for investigating underlying microstructural properties of white matter (WM) in ASD. Despite phenotypic and etiological heterogeneity, DWI studies in majority male samples of older children, adolescents, and adults with ASD have largely reported findings of decreased fractional anisotropy (FA) across several commissural, projection, and Association Fiber tracts. However, studies in preschool-aged children (i.e., < 30–40 months) suggest individuals with ASD have increased measures of WM FA earlier in development. We analyzed 127 individuals with ASD (85♂, 42♀) and 54 typically developing (TD) controls (42♂, 26♀), aged 25.1–49.6 months. Voxel-wise effects of ASD diagnosis, sex, age, and their interaction on DWI measures of FA, mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) were investigated using tract-based spatial statistics (TBSS) while controlling mean absolute and relative motion. Compared to TD controls, males and females with ASD had significantly increased measures of FA in eight clusters (threshold-free cluster enhancement p < 0.05) that incorporated several WM tracts including regions of the genu, body, and splenium of the corpus callosum, inferior frontal-occipital fasciculi, inferior and superior longitudinal fasciculi, middle and superior cerebellar peduncles, and corticospinal tract. A diagnosis by sex interaction was observed in measures of AD across six significant clusters incorporating areas of the body, genu, and splenium of the corpus collosum. In these tracts, females with ASD showed increased AD compared to TD females, while males with ASD showed decreased AD compared to TD males. The current findings support growing evidence that preschool-aged children with ASD have atypical measures of WM microstructure that appear to differ in directionality from alterations observed in older individuals with the condition. To our knowledge, this study represents the largest sample of preschool-aged females with ASD to be evaluated using DWI. Microstructural differences associated with ASD largely overlapped between sexes. However, differential relationships of AD measures indicate that sex likely modulates ASD neuroanatomical phenotypes. Further longitudinal study is needed to confirm and quantify the developmental relationship of WM structure in ASD.
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A diffusion-weighted imaging tract-based spatial statistics study of autism spectrum disorder in preschool-aged children.
eScholarship University of California, 2019Co-Authors: Andrews, Derek Sayre, Lee, Joshua K, Solomon Marjorie, Rogers, Sally J, Amaral, David G, Christine Wu NordahlAbstract:BACKGROUND:The core symptoms of autism spectrum disorder (ASD) are widely theorized to result from altered brain connectivity. Diffusion-weighted magnetic resonance imaging (DWI) has been a versatile method for investigating underlying microstructural properties of white matter (WM) in ASD. Despite phenotypic and etiological heterogeneity, DWI studies in majority male samples of older children, adolescents, and adults with ASD have largely reported findings of decreased fractional anisotropy (FA) across several commissural, projection, and Association Fiber tracts. However, studies in preschool-aged children (i.e., < 30-40 months) suggest individuals with ASD have increased measures of WM FA earlier in development. METHODS:We analyzed 127 individuals with ASD (85♂, 42♀) and 54 typically developing (TD) controls (42♂, 26♀), aged 25.1-49.6 months. Voxel-wise effects of ASD diagnosis, sex, age, and their interaction on DWI measures of FA, mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) were investigated using tract-based spatial statistics (TBSS) while controlling mean absolute and relative motion. RESULTS:Compared to TD controls, males and females with ASD had significantly increased measures of FA in eight clusters (threshold-free cluster enhancement p < 0.05) that incorporated several WM tracts including regions of the genu, body, and splenium of the corpus callosum, inferior frontal-occipital fasciculi, inferior and superior longitudinal fasciculi, middle and superior cerebellar peduncles, and corticospinal tract. A diagnosis by sex interaction was observed in measures of AD across six significant clusters incorporating areas of the body, genu, and splenium of the corpus collosum. In these tracts, females with ASD showed increased AD compared to TD females, while males with ASD showed decreased AD compared to TD males. CONCLUSIONS:The current findings support growing evidence that preschool-aged children with ASD have atypical measures of WM microstructure that appear to differ in directionality from alterations observed in older individuals with the condition. To our knowledge, this study represents the largest sample of preschool-aged females with ASD to be evaluated using DWI. Microstructural differences associated with ASD largely overlapped between sexes. However, differential relationships of AD measures indicate that sex likely modulates ASD neuroanatomical phenotypes. Further longitudinal study is needed to confirm and quantify the developmental relationship of WM structure in ASD
Kazi Akhter - One of the best experts on this subject based on the ideXlab platform.
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mapping of functional areas in the human cortex based on connectivity through Association Fibers
Cerebral Cortex, 2009Co-Authors: Kegang Hua, Kenichi Oishi, Kazi Akhter, Jiangyang Zhang, Setsu Wakana, Takashi Yoshioka, Weihong ZhangAbstract:In the human brain, different regions of the cortex communicate via white matter tracts. Investigation of this connectivity is essential for understanding brain function. It has been shown that trajectories of white matter Fiber bundles can be estimated based on orientational information that is obtained from diffusion tensor imaging (DTI). By extrapolating this information, cortical regions associated with a specific white matter tract can be estimated. In this study, we created population-averaged cortical maps of brain connectivity for 4 major Association Fiber tracts, the corticospinal tract (CST), and commissural Fibers. It is shown that these 4 Association Fibers interconnect all 4 lobes of the hemispheres. Cortical regions that were assigned based on Association with the CST and the superior longitudinal fasciculus (SLF) agreed with locations of their known (CST: motor) or putative (SLF: language) functions. The proposed approach can potentially be used for quantitative assessment of the effect of white matter abnormalities on associated cortical regions.
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human brain white matter atlas identification and assignment of common anatomical structures in superficial white matter
NeuroImage, 2008Co-Authors: Kenichi Oishi, Karl Zilles, Katrin Amunts, Andreia V Faria, Hangyi Jiang, Kazi Akhter, Kegang Hua, Roger P WoodsAbstract:Structural delineation and assignment are the fundamental steps in understanding the anatomy of the human brain. The white matter has been structurally defined in the past only at its core regions (deep white matter). However, the most peripheral white matter areas, which are interleaved between the cortex and the deep white matter, have lacked clear anatomical definitions and parcellations. We used axonal Fiber alignment information from diffusion tensor imaging (DTI) to delineate the peripheral white matter, and investigated its relationship with the cortex and the deep white matter. Using DTI data from 81 healthy subjects, we identified nine common, blade-like anatomical regions, which were further parcellated into 21 subregions based on the cortical anatomy. Four short Association Fiber tracts connecting adjacent gyri (U-Fibers) were also identified reproducibly among the healthy population. We anticipate that this atlas will be useful resource for atlas-based white matter anatomical studies.
Michael Petrides - One of the best experts on this subject based on the ideXlab platform.
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Fiber system linking the mid dorsolateral frontal cortex with the retrosplenial presubicular region in the rhesus monkey
The Journal of Comparative Neurology, 1999Co-Authors: Deepak N. Pandya, R Morris, Michael PetridesAbstract:The present study investigated the origin, course, and terminations of the Association Fiber system linking the frontal cortex with the hippocampal system by means of the cingulum bundle. Injections of tritiated amino acids were placed within individual cytoarchitectonic areas of the frontal cortex in the rhesus monkey. It was demonstrated that the mid-dorsolateral frontal cortex (areas 46, 9/46, and 9) and its medial extension (medial areas 9 and 9/32) is the origin of a specific Fiber pathway, running posteriorly as part of the cingulum bundle, and terminating mainly in the retrosplenial area 30 and the posterior presubiculum. This Fiber bundle therefore provides the anatomical substrate of a functional interaction between the mid-dorsolateral frontal cortex and the hippocampal memory system for the monitoring of information within working memory. J. Comp. Neurol. 407:183–192, 1999. © 1999 Wiley-Liss, Inc.
Deepak N. Pandya - One of the best experts on this subject based on the ideXlab platform.
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The extreme capsule in humans and rethinking of the language circuitry
Brain Structure and Function, 2008Co-Authors: Nikos Makris, Deepak N. PandyaAbstract:Experimental and imaging studies in monkeys have outlined various long Association Fiber pathways within the fronto-temporo-parietal region. In the present study, the trajectory of the extreme capsule (EmC) Fibers has been delineated in five human subjects using DT-MRI tractography. The EmC seems to be a long Association Fiber pathway, which courses between the inferior frontal region and the superior temporal gyrus extending into the inferior parietal lobule. Comparison of EmC Fibers with the adjacent Association Fiber pathway, the middle longitudinal fascicle (MdLF), in the same subjects reveals that EmC is located in a medial and rostral position relative to MdLF flanking in part the medial wall of the insula. The EmC can also be differentiated from other neighboring Fiber pathways such as the external capsule, uncinate fascicle, arcuate fascicle, superior longitudinal fascicles II and III, and the inferior longitudinal fascicle. Given the location of EmC within the language zone, specifically Broca’s area in the frontal lobe, and Wernicke’s area in the temporal lobe and inferior parietal lobule, it is suggested that the extreme capsule could have a role in language function.
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Fiber system linking the mid dorsolateral frontal cortex with the retrosplenial presubicular region in the rhesus monkey
The Journal of Comparative Neurology, 1999Co-Authors: Deepak N. Pandya, R Morris, Michael PetridesAbstract:The present study investigated the origin, course, and terminations of the Association Fiber system linking the frontal cortex with the hippocampal system by means of the cingulum bundle. Injections of tritiated amino acids were placed within individual cytoarchitectonic areas of the frontal cortex in the rhesus monkey. It was demonstrated that the mid-dorsolateral frontal cortex (areas 46, 9/46, and 9) and its medial extension (medial areas 9 and 9/32) is the origin of a specific Fiber pathway, running posteriorly as part of the cingulum bundle, and terminating mainly in the retrosplenial area 30 and the posterior presubiculum. This Fiber bundle therefore provides the anatomical substrate of a functional interaction between the mid-dorsolateral frontal cortex and the hippocampal memory system for the monitoring of information within working memory. J. Comp. Neurol. 407:183–192, 1999. © 1999 Wiley-Liss, Inc.
