面孔表情加工的结构编码和特征编码ERP特点研究

Studies on Characteristics of ERP Underlying Structure Encoding and Feature Encoding of Facial Expressions

利用事件相关电位（ERP）技术,分析面孔表情的早期和晚期加工特点,探讨面孔表情的结构编码和特征编码机制.随机呈现3种卡通面孔表情图片（中性、愉快、愤怒）及3种非面孔图片,要求14名被试者执行面孔及表情识别任务.利用Neuroscan 64导电极帽记录脑电,对面孔和非面孔、不同面孔表情诱发的早期成分N170及晚期正成分（LPC）进行分析.结果显示：面孔与非面孔图片的N170存在明显差异,在P7电极处,面孔与非面孔诱发的N170幅值分别为（-9.15±1.47）μV和（-6.91±1.21）μV;而不同面孔表情的N170差异不明显,N170不受面孔表情内容的调制.不同面孔表情在刺激后350 ～550 ms诱发了明显的LPC,其幅值存在明显差异,呈现显著的表情效应,在CZ电极处,中性、愉快及愤怒面孔诱发的LPC幅值分别为（6.11±1.79）μV、（7.49±1.31） μV和（9.89±1.77） μV）.以上结果表明,面孔识别的早期与晚期加工机制不同,早期成分N170反映了面孔结构编码的加工,即对整个面孔轮廓的表征;而面孔的情绪加工主要体现在晚期成分,LPC反映面孔的特征编码加工.

The event-related potentials （ERP） technique was used to analyze the early and late characteristics of facial expressions processing,to investigate the mechanisms underlying structure encoding and feature encoding.Three kinds of cartoon facial expressions （neutral,happy,angry） and three kinds of non-facial cartoons were presented randomly,14 volunteers were instructed to implement face and facial expression recognition tasks.Electroencephalography （EEG） was record with Neuroscan-64 cap.We analyzed the early component N170 and the late positive component （LPC） evoked by faces,non-faces,and different emotional faces.Results indicated that there were significant differences between N170 evoked by facial cartoons and that evoked by non-facial cartoons.The amplitudes of N170 at P7 evoked by facial cartoons and non-facial cartoons were （-9.15 ± 1.47） μV and （-6.91 ± 1.21） μV.There were not significant differences among N170 evoked by different emotional faces,N170 was not regulated by facial emotion content.Expressional effects appeared at 350 ～ 550 ms after stimulus,there were significant differences among LPC evoked by different emotional faces.The amplitudes of LPC at CZ evoked by neutral,happy and angry facial expressions were （6.11 ± 1.79） μV,（7.49 ± 1.31） μV and （9.89 ± 1.77） μV,respectively.These results suggest that early and late processing mechanisms of face recognition are different,the early component N170 reflects the processing of face structure encoding,so called the characterization of the whole face contour;while face emotional processing is mainly reflected in the late component,LPC reflects mechanism of face feature encoding.