恐惧情绪面孔和身体姿势加工的比较:事件相关电位研究

Comparison of Facial Expressions and Body Expressions: An Event-related Potential Study

面孔和身体姿势均为日常交往中情绪性信息的重要载体,然而目前对后者的研究却很少。本文采用事件相关电位(ERP)技术,考察了成年被试对恐惧和中性身体姿势的加工时程,并将此与同类表情的面孔加工ERP结果进行比较。结果发现,与情绪性面孔加工类似,大脑对情绪性身体姿势的加工也是快速的,早在P1阶段即可将恐惧和中性的身体姿势区分开来,同时身体姿势图片比面孔图片诱发了更大的枕区P1成分。与情绪性面孔相比,情绪性身体姿势诱发出的N170和VPP幅度较小,潜伏期较短,这两个ERP成分能区分恐惧和中性的面孔,但不能区分恐惧和中性的身体姿势,说明在情绪性信息加工的中期阶段,大脑在身体姿势加工方面的优势不如在面孔加工方面的优势大。最后,在加工的晚期阶段,P3可区分情绪载体和情绪类别,且在两个主效应上均产生了较大的效应量,体现了大脑在此阶段对情绪性信息的更深入的加工。本研究提示,情绪性身体姿势和面孔的加工具有相似性,但与情绪性面孔相比,大脑似乎对情绪性身体姿势的加工在早期阶段(P1时间窗)更有优势。本文对情绪性面孔和身体姿势的结合研究将有助于深入了解情绪脑的工作机制,同时找到更多的情绪相关的生物标记物以帮助临床诊断具有情绪认知障碍的精神病患者的脑功能缺损。

Facial expressions and body expressions are both important emotion carriers in everyday communication and interaction. However, cognitive neuroscience in the field of emotion focuses mainly on the brain mechanism of facial expression processing and leave many problems of the body expression processing largely unsolved. The current study employed the event-related potentials（ERPs） to examine the time course of fearful and neutral body/face processing in 40 healthy adults. A total of 40 pictures of faces and 40 pictures of bodies were selected from Chinese facial and body picture systems. The experimental participants were required to discriminate the emotion（fear or neutral） of each picture（presented for 300 ms） as fast as possible. The task consisted of two blocks（face and body） of 120 trials each. Blocks were separated by self-terminated breaks. The order of the two blocks was counterbalanced across subjects. Stimulus display and behavioral data acquisition were conducted using E-Prime software. Brain electrical activity was recorded referentially against left mastoid and off-line re-referenced to average reference, by a 64-channel amplifier using a standard 10-20 system（Brain Products）.The results of this study help to answer three question on the processing of fearful face and body expressions. First, the emotional carrier does influence the processing of fearful information. It is found that compared with facial expressions, the occipital P1 was larger in response to body expressions. Another finding in the early processing stage is that, similar with facial emotion processing, the brain could discriminate fearful and neutral bodies as early as approximately 100 ms post stimulus, reflected by a larger P1 in the fearful body condition. Second, the ERP components of N170 and VPP showed similar results in response to fearful facial and body expressions. The two components discriminated fearful and neutral faces but not bodies. In addition, compared with facial expressions, body expressions evoked smaller and slower N170/VPP, indicating that the brain in this processing stage allocated less cognitive resources to body expressions. Finally, the P3 component differed not only between body and face conditions, but also fearful and neutral conditions, suggesting a comprehensive processing of emotional information. The current result indicated that facial and body expressions had similar processing dynamics in the form of ERP data. Compared with facial expressions, it is seemed that the brain prefers body expressions at the early processing stage（the P1 time window）. It is hoped that the current results regarding the emotional processing of facial and body expressions will be helpful for our understanding of the mechanisms of the emotional brain. The investigated ERP components in this study are potential biomarkers for the diagnosis of emotional disorders.