Induced gamma-band brain responses to direct eye contact in the frontal and parietal cortices.

We used simultaneous recordings of the neuromagnetic (MEG) and electrooculogram (EOG) recordings on a pair of directly facing subjects, i.e., the sender and the observer of the eye gaze, to measure changes in the spontaneous brain activities while the observer perceives changes in eye gaze direction of the sender. The MEG signals were analyzed in the time-frequency domain to evaluate event-related changes in the spontaneous brain activities induced by the onset of eye movements. Significant increase in the gamma-band power was observed in the eye-contact condition compared to the averting condition in the right superior parietal, bilateral posterior superior-temporal, and the frontal areas of the observer. Together with the preliminary results from the frequency-domain Granger-Geweke causality analysis, the current results indicate that the connectivity between (a) the bilateral frontal areas, and (b) the right frontal and parietal areas might be crucial for the perception of eye gaze of the directly facing person. The increase in gamma-band activities in these regions might reflect the integration of information processed individually in these regions for eye gaze perception.