title: White matter and visuospatial processing in autism: a constrained spherical deconvolution tractography study.
abstract: Autism spectrum disorders (ASDs) are associated with a marked disturbance of neural functional connectivity, which may arise from disrupted organization of white matter. The aim of this study was to use constrained spherical deconvolution (CSD)-based tractography to isolate and characterize major intrahemispheric white matter tracts that are important in visuospatial processing. CSD-based tractography avoids a number of critical confounds that are associated with diffusion tensor tractography, and to our knowledge, this is the first time that this advanced diffusion tractography method has been used in autism research. Twenty-five participants with ASD and aged 25, intelligence quotient-matched controls completed a high angular resolution diffusion imaging scan. The inferior fronto-occipital fasciculus (IFOF) and arcuate fasciculus were isolated using CSD-based tractography. Quantitative diffusion measures of white matter microstructural organization were compared between groups and associated with visuospatial processing performance. Significant alteration of white matter organization was present in the right IFOF in individuals with ASD. In addition, poorer visuospatial processing was associated in individuals with ASD with disrupted white matter in the right IFOF. Using a novel, advanced tractography method to isolate major intrahemispheric white matter tracts in autism, this research has demonstrated that there are significant alterations in the microstructural organization of white matter in the right IFOF in ASD. This alteration was associated with poorer visuospatial processing performance in the ASD group. This study provides an insight into structural brain abnormalities that may influence atypical visuospatial processing in autism.
authors.affiliation: Department of Psychiatry, Trinity Centre for Health Sciences, St James's Hospital, Dublin, Ireland.
authors.forename: Jane
authors.initials: J
authors.lastname: McGrath
authors.forename: Katherine
authors.initials: K
authors.lastname: Johnson
authors.forename: Erik
authors.initials: E
authors.lastname: O'Hanlon
authors.forename: Hugh
authors.initials: H
authors.lastname: Garavan
authors.forename: Louise
authors.initials: L
authors.lastname: Gallagher
authors.forename: Alexander
authors.initials: A
authors.lastname: Leemans
mesh_terms: D000293:Adolescent; D001111:Arcuate Nucleus of Hypothalamus / Q000503:physiopathology; D001931:Brain Mapping; D002659:Child Development Disorders, Pervasive / Q000175:diagnosis* / Q000503:physiopathology*; D056324:Diffusion Tensor Imaging; D004292:Dominance, Cerebral / Q000502:physiology; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D009778:Occipital Lobe / Q000503:physiopathology; D010468:Perceptual Disorders / Q000175:diagnosis* / Q000503:physiopathology*; D012016:Reference Values; D013028:Space Perception; D014795:Visual Pathways / Q000503:physiopathology; D014796:Visual Perception / Q000502:physiology; D055815:Young Adult
keywords: autism; constrained spherical deconvolution; diffusion MRI; inferior fronto-occipital fasciculus; tractography; visuospatial processing