An MRI study of the corpus callosum and cerebellum in mentally retarded autistic individuals

The areas of seven subregions of the corpus callosum and three subregions o f the cerebellum were examined on midsagittal magnetic resonance imaging sc ans of 27 low-IQ autistic individuals of comparable mental age. Autistic in dividuals had a significantly smaller corpus callosum (most marked in the b ody). No significant between-group differences were found in cerebellum are as. Results demonstrate that abnormalities of the corpus callosum reported in high-functioning autistic individuals are also present in autistic indiv iduals with mental retardation and extend previous reports showing no evide nce for a selective hypoplasia of cerebellar lobules VI-VII.