Social interaction revealed by motion: dynamics of neuromagnetic gamma activity.

Perception of dispositions of others revealed by movement is an essential ingredient of adaptive daily-life social behavior. Brain imaging points to several brain regions involved in visual processing of social interaction represented by motion of geometric shapes. However, temporal interrelations among these regions remain unknown. Keeping in mind that successful visual social perception depends on intact communication throughout the brain, we focus here on analysis of the induced gamma neuromagnetic response to social interaction revealed by motion. A peak of induced gamma activity of 62 Hz was found at 1 s from the stimulus onset over the right parieto-temporal junction. Two further enhancements in gamma response of lower frequency of 44 Hz occurred at 1.4 s over the medial prefrontal and posterior temporal cortices in the right hemisphere. Subsequent boosts of 44 Hz were found at 1.6 s over the left temporal and right posterior temporal cortices. For the first time, the findings identify the cortical network engaged in visual processing of social interaction revealed by motion and help to better understand proper functioning of the social brain circuitry.