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Structural Neural Phenotype of Autism: Preliminary Evidence from a Diffusion Tensor Imaging Study Using Tract-Based Spatial Statistics

Structural Neural Phenotype of Autism: Preliminary Evidence from a Diffusion Tensor Imaging Study... BACKGROUND AND PURPOSE: There is mounting evidence suggesting widespread aberrations in neural connectivity as the underlying neurobiology of autism. Using DTI to assess white matter abnormalities, this study implemented a voxelwise analysis and tract-labeling strategy to test for a structural neural phenotype in autism. MATERIALS AND METHODS: Subjects included 15 boys with autism and 8 controls, group-matched on age, cognitive functioning, sex, and handedness. DTI data were obtained by using a 3T scanner. FSL, including TBSS, was used to process and analyze DTI data where FA was chosen as the primary measure of fiber tract integrity. Affected voxels were labeled by using an integrated white matter tractography atlas. Post hoc correlation analyses were performed between FA of each affected fiber tract and scores on the Social Responsiveness Scale. RESULTS: The autism group exhibited bilateral reductions in FA involving numerous association, commissural, and projection tracts, with the most severely affected being the forceps minor. The most affected association tracts were the inferior fronto-occipital fasciculus and superior longitudinal fasciculus. There were no areas of increased FA in the autism group. All post hoc correlation analyses became nonsignificant after controlling for multiple comparisons. CONCLUSIONS: This study provides preliminary evidence of reduced FA along many long-range fiber tracts in autism, suggesting aberrant long-range corticocortical connectivity. Although the spatial distribution of these findings suggests widespread abnormalities, there are major differences in the degree to which different tracts are affected, suggesting a more specific neural phenotype in autism. Abbreviations AMY amygdala ASD autism spectrum disorders ATR anterior thalamic radiation BCC body of corpus callosum CNG cingulum CST corticospinal tract DAS Differential Abilities Scale DTI diffusion tensor imaging FA fractional anisotropy FDT FMRIB Diffusion Toolbox FFA fusiform face area FMAJ forceps major FMIN forceps minor fMRI functional MR imaging FMRIB Oxford Centre for Functional Magnetic Resonance Imaging of the Brain FSL FMRIB Software Library GRAPPA generalized autocalibrating partially parallel acquisition IFOF inferior fronto-occipital fasciculus ILF inferior longitudinal fasciculus JHU Johns Hopkins University MNI Montreal Neurologic Institute SLF superior longitudinal fasciculus SRS Social Responsiveness Scale SSC somatosensory cortex STS superior temporal sulcus TBSS Tract-Based Spatial Statistics TDC typically developing control TPJ temporal parietal junction UNF uncinate fasciculus VMPC ventromedial prefrontal cortex http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png American Journal of Neuroradiology American Journal of Neuroradiology

Structural Neural Phenotype of Autism: Preliminary Evidence from a Diffusion Tensor Imaging Study Using Tract-Based Spatial Statistics

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Publisher
American Journal of Neuroradiology
Copyright
Copyright © 2011 by the American Society of Neuroradiology.
ISSN
0195-6108
eISSN
1936-959X
DOI
10.3174/ajnr.A2558
pmid
21799040
Publisher site
See Article on Publisher Site

Abstract

BACKGROUND AND PURPOSE: There is mounting evidence suggesting widespread aberrations in neural connectivity as the underlying neurobiology of autism. Using DTI to assess white matter abnormalities, this study implemented a voxelwise analysis and tract-labeling strategy to test for a structural neural phenotype in autism. MATERIALS AND METHODS: Subjects included 15 boys with autism and 8 controls, group-matched on age, cognitive functioning, sex, and handedness. DTI data were obtained by using a 3T scanner. FSL, including TBSS, was used to process and analyze DTI data where FA was chosen as the primary measure of fiber tract integrity. Affected voxels were labeled by using an integrated white matter tractography atlas. Post hoc correlation analyses were performed between FA of each affected fiber tract and scores on the Social Responsiveness Scale. RESULTS: The autism group exhibited bilateral reductions in FA involving numerous association, commissural, and projection tracts, with the most severely affected being the forceps minor. The most affected association tracts were the inferior fronto-occipital fasciculus and superior longitudinal fasciculus. There were no areas of increased FA in the autism group. All post hoc correlation analyses became nonsignificant after controlling for multiple comparisons. CONCLUSIONS: This study provides preliminary evidence of reduced FA along many long-range fiber tracts in autism, suggesting aberrant long-range corticocortical connectivity. Although the spatial distribution of these findings suggests widespread abnormalities, there are major differences in the degree to which different tracts are affected, suggesting a more specific neural phenotype in autism. Abbreviations AMY amygdala ASD autism spectrum disorders ATR anterior thalamic radiation BCC body of corpus callosum CNG cingulum CST corticospinal tract DAS Differential Abilities Scale DTI diffusion tensor imaging FA fractional anisotropy FDT FMRIB Diffusion Toolbox FFA fusiform face area FMAJ forceps major FMIN forceps minor fMRI functional MR imaging FMRIB Oxford Centre for Functional Magnetic Resonance Imaging of the Brain FSL FMRIB Software Library GRAPPA generalized autocalibrating partially parallel acquisition IFOF inferior fronto-occipital fasciculus ILF inferior longitudinal fasciculus JHU Johns Hopkins University MNI Montreal Neurologic Institute SLF superior longitudinal fasciculus SRS Social Responsiveness Scale SSC somatosensory cortex STS superior temporal sulcus TBSS Tract-Based Spatial Statistics TDC typically developing control TPJ temporal parietal junction UNF uncinate fasciculus VMPC ventromedial prefrontal cortex

Journal

American Journal of NeuroradiologyAmerican Journal of Neuroradiology

Published: Oct 1, 2011

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