Neural correlates of dyadic interaction during infancy.

This study examines the electrophysiological correlates of dyadic interaction in 14-month-old infants. Infants were presented with three conditions of live stimuli. A baseline condition involved the observation of moving geometric shapes. In a second condition the infant observed an adult performing movements that were not in reference to the infant and were not within the infant's proficient motor repertoire, such as dancing or hopping. A third condition involved face to face dyadic interactions in the context of an imitative game, where the infant and adult engaged in copying each other's hand and facial actions. Motor activity by the infant was controlled between conditions by synchronizing EEG with video frames of action. Infant EEG data was then edited offline to match in motor intensity across conditions. We expected mu rhythm (6-9 Hz) suppression during dyadic interactions relative to the amount of mu present in the baseline condition. This prediction was confirmed. We also observed suppressed mu in the interaction condition relative to the observation condition. The mu rhythm results suggest that infants at 14 months may well utilize a functioning mirroring system during dyadic interactions.