FACES AND EMOTIONS - BRAIN ELECTRIC-FIELD SOURCES DURING COVERT EMOTIONAL PROCESSING

Covert brain activity related to task-free, spontaneous (i.e. unreques ted), emotional evaluation of human face images was analysed in 27-cha nnel averaged event-related potential (ERP) map series recorded from 1 8 healthy subjects while observing random sequences of face images wit hout further instructions. After recording, subjects self-rated each f ace image on a scale from ''liked'' to ''disliked''. These ratings wer e used to dichotomize the face images into the affective evaluation ca tegories of ''liked'' and ''disliked'' for each subject and the subjec ts into the affective attitudes of ''philanthropists'' and ''misanthro pists'' (depending on their mean rating across images). Event-related map series were averaged for ''liked'' and ''disliked'' face images an d for ''philanthropists'' and ''misanthropists''. The spatial configur ation (landscape) of the electric field maps was assessed numerically by the electric gravity center, a conservative estimate of the mean lo cation of all intracerebral, active, electric sources. Differences in electric gravity center location indicate activity of different neuron al populations. The electric gravity center locations of all event-rel ated maps were averaged over the entire stimulus-on time (450 ms). The mean electric gravity center for disliked faces was located (signific ant across subjects) more to the right and somewhat more posterior tha n for liked faces. Similar differences were found between the mean ele ctric gravity centers of misanthropists (more right and posterior) and philanthropists. Our neurophysiological findings are in line with neu ropsychological findings, revealing visual emotional processing to dep end on affective evaluation category and affective attitude, and exten ding the conclusions to a paradigm without directed task. (C) 1998 Els evier Science Ltd. All rights reserved.