Flocculonodular dysplasia (Fig. 4a, b), usually affecting the entire nodule, was found in the cerebellum in six autistic subjects (46%). In the dysplastic areas, a thin granule layer formed the labyrinth, which was mixed with irregular islands of the molecular layer. Clusters of granule cells and a few Purkinje cells were dispersed within the distorted molecular layer. The only developmental abnormality detected in the control group was flocculonodular dysplasia in the cerebellum of the 51-year-old control subject (not shown). Local cortical dysplasia was also detected within the vermis of the 13-year-old autistic male. In the affected area, the cytoarchitecture of the molecular and granule layers and the Purkinje cells was completely disorganized (Fig. 4c, d).
