Recent research has shown that CNTNAP2 is an autism risk gene, and creating a mutation of this gene in mice causes multiple autism-like behavioral phenotypes including abnormal social behavior. In these mice, a lowered level of brain oxytocin has been found, and supplementing the hormone remarkably improves their social behavior. It remains unknown how a mutation in this gene leads to lowered brain oxytocin, and also how this interferes with social behavior. I propose to investigate the brain circuit abnormalities involving oxytocin neurons in the Cntnap2 knockout mice, with aims to discover how gene disruptions can interfere with proper development of brain circuits, which may underlie abnormal social behavior observed in autism.