The amygdala theory of autism

Brothers (Brothers L. Concepts in Neuroscience 1990;1:27-51) proposed a net work of neural regions that comprise the "social brain", which includes the amygdala. Since the childhood psychiatric condition of autism involves def icits in "social intelligence", it is plausible that autism may be caused b y an amygdala abnormality. In this paper we review the evidence for a socia l function of the amygdala. This includes reference to the Kluver-Bucy synd rome (which Hetzler and Griffin suggested may serve as an animal model of a utism). We then review evidence for an amygdala deficit in people with auti sm, who are well known to have deficits in social behaviour. This includes a detailed summary of our recent functional magnetic resonance imaging (fMR I) study involving judging from the expressions of another person's eyes wh at that other person might be thinking or feeling. In this study, patients with autism or AS did not activate the amygdala when making mentalistic inf erences from the eyes, whilst people without autism did show amygdala activ ity. The amygdala is therefore proposed to be one of several neural regions that are abnormal in autism. We conclude that the amygdala theory of autis m contains promise and suggest some new lines of research. (C) 2000 Elsevie r Science Ltd. All rights reserved.