Face-specific evoked brain potentials

Abstract

ABSTRACT The present study's aim was to investigate face specific evoked brain potentials during face and other kinds of visual stimuli. It was hypothesized that a specific electrophysiological wave form occurs during exposure to a face-like stimulus as an indicator of the discrimination of a face-like stimulus from other visual stimuli. Two paradigms were applied. In the first paradigm schematic drawings of a face, a non-face and a clock were used since it was easy to keep the parts of the pattrens constant. In the second paradigm, photographs of a face, a tree, and an irrelevant figure were used since they were close to a real stiuation. EEG was recorded from Oz, Cz, T3 and T4. Vertex (Cz) was chosen since it was close to the association areas of the brain and face specific responses were recorded mostly from that location by the previous researchers. Left (T3) and right (T4) temporal locations were measured for checking the hemispheric differences. Finally, EEG was recorded from occipital region (Oz) for checking the possible variation of EEG due to the physical properties of the stimuli. The 15 subjects were unpaid medical students (18 to 27 years of age) of both sexes (7 female, 8 male) who are right-handed. Computer controlled recording and stimulating devices were utlilized. The significant variation at Cz in both paradigms and additional variation found at T3 and T4 provided evidence for the hypothesis. Results of the present study were congruent with the previous studies. The present data provided physiological evidence for the universal character of the facial expressions and face recognition.