title: Left-hemispheric microstructural abnormalities in children with high-functioning autism spectrum disorder.
abstract: Current theories of the neurobiological basis of autism spectrum disorder (ASD) posit an altered pattern of connectivity in large-scale brain networks. Here we used diffusion tensor imaging to investigate the microstructural properties of the white matter (WM) that mediates interregional connectivity in 36 high-functioning children with ASD (HF-ASD) as compared with 37 controls. By employing an atlas-based analysis using large deformation diffeometric morphic mapping registration, a widespread but left-lateralized pattern of abnormalities was revealed. The mean diffusivity (MD) of water in the WM of HF-ASD children was significantly elevated throughout the left hemisphere, particularly in the outer-zone cortical WM. Across diagnostic groups, there was a significant effect of age on left-hemisphere MD, with a similar reduction in MD during childhood in both typically developing and HF-ASD children. The increased MD in children with HF-ASD suggests hypomyelination and may reflect increased short-range cortico-cortical connections subsequent to early WM overgrowth. These findings also highlight left-hemispheric connectivity as relevant to the pathophysiology of ASD and indicate that the spatial distribution of microstructural abnormalities in HF-ASD is widespread and left-lateralized. This altered left-hemispheric connectivity may contribute to deficits in communication and praxis observed in ASD.
authors.affiliation: Center for Neurodevelopment and Imaging Research (CNIR), Kennedy Krieger Institute, Baltimore, Maryland.
authors.forename: Daniel
authors.initials: D
authors.lastname: Peterson
authors.forename: Rajneesh
authors.initials: R
authors.lastname: Mahajan
authors.forename: Deana
authors.initials: D
authors.lastname: Crocetti
authors.forename: Amanda
authors.initials: A
authors.lastname: Mejia
authors.forename: Stewart
authors.initials: S
authors.lastname: Mostofsky
mesh_terms: D000067877:Autism Spectrum Disorder / Q000503:physiopathology*; D001931:Brain Mapping / Q000379:methods; D002648:Child; D056324:Diffusion Tensor Imaging / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000473:pathology; D009434:Neural Pathways / Q000503:physiopathology; D012720:Severity of Illness Index; D066127:White Matter / Q000503:physiopathology*
keywords: diffusion tensor imaging (DTI); laterality; neuroimaging; white matter