EPP: An ERP Late Positive Component Related to Facial Expression Processing / 航天医学与医学工程

ABSTRACT

Objective To examine ERP components related to different processings of emotional expression of fury, neutral and smile during face-map recognition. Method Twelve undergraduate students (7 male, 5 female), 19～24 years old, were served as subjects in the experiment. The visual stimuli consisted of six kinds of pictures three kinds of facial pictures (neutral, smile, fury) and three kinds of non-facial ones. The subjects were asked to complete two tasks, i. e., face recognition (FR) and facial expression classification (FEC). During FR task, two runs of 210 stimuli (duration 50 ms) with each (3 facial and 3 non-facial pictures) were randomly presented with equal probability (ISI from 1 500 ms to 2 000 ms randomly), and subjects were asked to react to facial stimuli and non-facial stimuli by pressing the left button and right button respectively as quickly as possible. During FEC task, 210 stimuli (3 facial stimuli and 3 non-facial stimuli) were randomly presented with equal probability (duration 50 ms, ISI from 1 500 ms to 2 000 ms), and subjects were asked to react to different facial expressions by pressing 3 different buttons respectively as quickly as possible. Electroencephalogram (EEG) was recorded with NeuroScan-32 cap (10/20 system), in reference to bilateral mastoids. Result: 1) Compared with the ERP elicited by facial stimuli during FR task, the responses during FEC task evoked a P580 component clearly. 2) A positive-potential difference after 450 ms post-stimulation between ERP during FEC task and during FR task was observed, which was significant at central and parietal sites. According to the difference of task demand between two tasks, this wave was termed the expression processing positivity (EPP) to reflect the expression processing during face recognition. 3) The peak latency of furyEPP was the shortest and smile-EPP the longest. Conclusion The mode and site of the EPP are likeIv to represent brain function in late processinq of the expression.