Familiar-face recognition and comparison: source analysis of scalp-recorded event-related potentials

Objective: We studied the event-related potentials elicited by categorical matching of faces. The purpose was to find cortical sources responsible for face recognition and comparison. Methods: Nineteen healthy volunteers participated in the study. Each trial began with one of the two cues (S1) followed by consecutive pictures (S2 and S3). Each picture was a photograph of a familiar face with a superimposed abstract dot pattern. One cue directed attention to compare faces and another to compare patterns. 128-channel electroencephalogram was recorded. Spatio-temporal multiple dipole source models were generated using Brain Electromagnetic Source Analysis 2000, for the window of 80–600 ms from S3 onset. Results: The obtained model for face recognition and comparison contained 8 dipoles explaining 97% of grand average and about 90% of individual data and showing temporal and spatial separation of sources: in the frontal region, in the occipital cortex, and in the bilateral medial temporal and inferotemporal regions. Different faces elicited larger components than same personʹs faces around 400 ms, mainly explained by frontal dipoles. Conclusions: The sources in our models estimate the activity common for both Face task conditions (the recognition of a familiar person) and also differential activity, related to the match/mismatch item processing