Magnetic resonance imaging study of the brain in autism

Autism is a neuropsychiatric disorder of social, cognitive, and language de velopment. Cerebellar abnormality in autism has been shown consistently fro m autopsy and magnetic resonance image (MRI) studies. A new MRI study with careful methodologic designs identified two subgroups of autistic patients: hypoplasia and hyperplasia of cerebellar vermian lobules VI-VII. The exist ence of these two subtypes was also supported via the meta-analysis of data from separate research groups. In addition to die cerebellar abnormality, recent MRI studies in autism demonstrated abnormalities in the parietal lob e and the posterior subregions of the corpus callosum where parietal cortic al fibers are concentrated Furthermore, neurobehavioral correlates of cereb ellar and parietal abnormalities have also been investigated. In contrast, there is a lack of significant difference in the cross-sectional size of th e posterior hippocampal formation between autistic and normal subjects, whi ch is discrepant with predictions based on some autopsy studies.