Event-related oscillations in structural and semantic encoding of faces

Objective: The ability to perceive faces is acquired through an interaction between species-specific biological mechanisms and social experience. To elucidate the mechanisms of the cognitive system underlying face recognition, we investigated cerebral oscillations related to encoding in 'person identity nodes'.

Methods: EEG was measured in nine healthy adults during perception of their own face, familiar face and unfamiliar face images.

Results: Event-related synchronization (ERS) in theta, alpha and beta bands was initially induced in occipito-temporal areas within 0-200 ms of the presentation of facial stimuli. In addition, delta ERS over parietal and left temporal areas was greater in response to familiar faces around 0-800 ms compared with unfamiliar faces. Beta ERS over the right prefrontal area was significantly greater in response to a participant's own face compared with a familiar face at 400-800 ms post-stimulus.

Conclusions: ERS within 0-200 ms reflects structural encoding of faces (i.e., N170 of the event related potential). Delta ERS within 0-800 ms suggests an association with memory retrieval. Beta ERS within 400-800 ms is consistent with the cortical areas reported to be strongly related to self-face perception in previous fMRI studies.

Significance: The delta and beta bands ERS might provide an index of familiarity and self-recognition, respectively.