Brain dynamics in young infants' recognition of faces: EEG oscillatory activity in response to mother and stranger.

The brain electrical responses of 3-month-old infants were compared between images of familiar and unfamiliar faces. Infants were shown images of their mothers and of appearance-matched female strangers for 500 ms per trial while their electroencephalography was recorded. Electroencephalographic signals were segmented from stimulus onset through 1200 ms, and segments were analyzed in the time-frequency domain with a continuous wavelet transform. Differentiated responses were apparent in three time windows: 370-480, 610-690, and 830-960 ms. Across response windows, event-related synchronization or desynchronization was observed in beta or gamma frequency bands at the left frontal, midline central, bilateral temporal, and right parietal sites. In conclusion, these findings provide the first evidence of organized brain activity underlying familiar face recognition in very young infants and are discussed in relation to comparable patterns that have been observed in adults.