Altered White Matter Fiber Tracts and Regional White Matter Volume related to Motor Function in Individuals with Autism Spectrum Disorder
Date Issued
2016
Date
2016
Author(s)
Lin, Chia-Wei
Abstract
Background: Motor impairment is frequently observed in individuals with autism spectrum disorder (ASD). However, there has been no research investigating the motor function related white matter fiber tracts integrity and regional white matter (WM) and grey (GM) matter structure alterations in individuals with ASD. Objective: To investigate the motor function related WM fiber tracts integrity and regional WM and GM volumes in individuals with ASD. Method: We recruited 55 boys with ASD and 68 age-matched typically developing control boys (TD), aged 6-18 years old. They received intelligence test, and three subsets of the Cambridge Neuropsychological Test Automated Battery (CANTAB): reaction time (RT), Stockings of Cambridge (SOC), intra-dimensional/extra-dimensional (ID/ED) to assess the motor performance. White matter (WM) fiber tracts integrity was analyzed by using diffusion spectrum imaging (DSI) controlling the age and FIQ, and the generalized fractional anisotropy (GFA) of the following tracts was computed: cortico-spinal tracts, cortico-ponto-cerebellar tracts, and dento-rubro-thalamo-cortical tracts. Voxel-based morphometry (VBM) was utilized to investigate the WM and GM volume in primary motor area, supplementary motor area, somatosensory area, and cerebellum controlling the age and FIQ. We then analyzed the correlation between the CANTAB score and GFA value of those WM tracts, and regional WM and GM volume in brain regions involving these tracts. Result: The final sample of analysis consisted of 55 ASD (13.39±2.48 years old) and 68 TD (12.71±2.59 years old) male subjects. The CANTAB score disclosed (1) the ASD group had shorter movement time (5-choices) in the RT subtest, (2) in the SOC subtest, the ASD group had shorter initial thinking time, required more moves to complete the task while solving the 5 movement problems, and solved fewer problems in minimal moves, (3) in the ID/ED set-shifting performance, the ASD group required more trials to reach criterion and made more errors. The ASD group had decreased GFA value in the left parieto-ponto-cerebellar tract, crossed tract (ASD vs TD, 0.348±0.010 vs 0.350±0.009, p=0.01) and uncrossed tract (ASD vs TD, 0.343±0.012 vs 0.344±0.011, p=0.02), but increased GFA value in the left parieto-ponto tract (ASD vs TD, 0.342±0.013 vs 0.342±0.012, p=0.02) through DSI study. The VBM analysis revealed that the ASD group had increased local white matter volume in the left somatosensory area (ASD vs TD, 7.149±0.883 vs 6.936±0.594, p=0.01). For ASD group, significant correlations were found between motor score and the GFA value of the left parieto-ponto-cerebellar tract (r=0.302, p=0.027). Conclusion: Individuals with ASD had altered WM volume in the left somatosensory area and altered GFA value in the left parieto-ponto-cerebellar tract. The altered integrity of the left parieto-ponto-cerebellar tract may predict the motor performance in individuals with ASD.
Subjects
autism spectrum disorder
motor
diffusion spectrum imaging
voxel based morphometry
Type
thesis
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