One of the core symptoms of autism is impaired interpretation of social cues and abnormal emotional responses to social cues. The amygdala is a brain region that plays a fundamental role in social functioning. Human imaging studies have demonstrated abnormal amygdala activity in people with autism, which is likely to contribute to the socio-emotional symptoms. However, the amygdala comprises several interconnected regions, and the neural basis for these behaviors is not clear.
The medial amygdala facilitates social behaviors, whereas the basolateral amygdala contributes to emotional affect. The link between these two regions is likely to play a critical role in socio-affective behavior, but little is known about this particular neural connection.
Amiel Rosenkranz and his colleagues at Rosalind Franklin University of Medicine and Science in Chicago performed behavioral and electrophysiological studies in a rodent genetic model of autism (neurexin-1 knockout rats) to determine whether the circuit connecting the medial and basolateral amygdala underlies socio-emotional behaviors. Socio-emotional behavior, as assessed by a social learning paradigm that involves an emotion component, was found to be impaired in neurexin-1 knockout rats. The researchers also observed decreased activity and excitability of the medial amygdala, and a disruption of the circuit between the medial and basolateral amygdala. Increasing the activity of the medial amygdala restored normal socio-emotional behavior.
These experiments are the first to demonstrate the role of intra-amygdala circuits in social learning, and demonstrate a specific abnormality of this circuit in a genetic model of autism. The findings provide a novel circuit that can be targeted to alleviate socio-emotional symptoms.