and an important hypothesis is that the autistic brain shows underconnectivity between regions, plausibly associated with white matter abnormalities Uust, Cherkassky, Keller, Kana & Minshew, 2007; Just, Cherkassky, Keller, & Minshew, 2004). Structural brain abnormalities include findings of increased neuronal cell size and increased cell packing density in regions of the limbic system that subserve emotional and social behavior, and in the cerebellum (Bailey, Phillips, & Rutter, 1996).