It has been proposed that general abnormalities in structural and functional neuronal connectivity may underlie many of the triad of deficits observed in autism. Oscillatory neural activity in the gamma frequency range (>30Hz), as measured using electroencephalography (EEG) and magnetoencephalography (MEG), has been shown to accompany a wide variety of cognitive processes, including intrinsic GABAergic activity (gamma-aminobutyric acid neurotransmitter) in animal and computational models of the neocortex. Data have been published demonstrating that gamma activity is abnormal in people with autism, possibly reflecting a cortical GABA dysfunction. Using a whole-head MEG system, this project will assess patterns of auditory cortical synchronization. Parents of forty affected individuals as well as probands will be studied, as preliminary evidence indicates that a gamma- synchronization deficit may be familial. Their data will be compared to matched adults with no personal or family history of autism spectrum disorders in their children. Follow-up studies will associate such deficits with GABAergic dysfunction and GABA receptor candidate genes and evaluate pharmacological interventions that directly target GABA function.