Convergent neuroanatomical and behavioural evidence of an amygdala hypothesis of autism

In this study we report a convergence of behavioural and neuroanatomical ev idence in support of an amygdala hypothesis of autism. We find that people with high-functioning autism (HFA) show neuropsychological profiles charact eristic of the effects of amygdala damage, in particular selective impairme nt in the recognition of facial expressions of fear, perception of eye-gaze direction, and recognition memory for faces. Using quantitative magnetic r esonance (MR) image analysis techniques, we find that the same individuals also show abnormalities of medial temporal lobe (MTL) brain structure, nota bly bilaterally enlarged amygdala volumes. These results combine to suggest that developmental malformation of the amygdala may underlie the social-co gnitive impairments characteristic of HFA. This malformation may reflect in complete neuronal pruning in early development. NeuroReport 11:2931-2935 (C ) 2000 Lippincott Williams & Wilkins.