Heterotopias were found in the brains of four autistic subjects and no control subjects. The topography of the lesions was different in each case. Subcortical heterotopias were detected in the white matter of the anterior cingulate gyrus of a 5-year-old (Fig. 2a, b) and in the inferior frontal gyrus in an 11-year-old subject. Periventricular heterotopias were detected near the wall of lateral ventricle in 7-year old subject (Fig. 2c, d). A single heterotopia was noted in the stratum oriens of the hippocampus. In the cerebellum of the 11-year-old subject, heterotopias were detected in the vermis and the cerebellar white matter close to the dentate nucleus (Fig. 2f–h). These defects of migration were observed in two brains as a single aggregate of gray matter, in one brain as two aggregates and in one brain as three lesions measuring from 1 to 3 mm in diameter. Subcortical and periventricular heterotopias comprised poorly differentiated oval or multipolar neurons without spatial orientation (Fig. 2a) or had a distorted laminar organization (Fig. 2e). Cerebellar heterotopias had a distorted morphology of the granule and molecular layers with a few dispersed Purkinje cells (Fig. 2g, h).
