面孔性别信息加工的事件相关电位时空模式研究

Facial sexual feature processing revealed by spatiotemporal pattern of event-related potentials

目的了解面孔认知中性别信息加工的电活动过程。方法2005年3月选择南方医科大学本科大学生40人作为受试者．均右利手．视力正常或矫正视力正常，无精神疾患以及精神病家庭史，自愿参加实验。选取对所有受试者均为陌生的360张真人面孔（男女各半）照片用作刺激，随机顺序依次呈现，每张照片呈现1次。刺激持续时间800ms，间隔1200ms。实验任务要求受试者对所呈现的面孔照片的性别作出按键反应（一半受试者对男性面孔按左键，女性面孔按右键，另一半相反）。采用本实验室开发的通用型19导事件相关电位系统进行脑电记录以及数据处理。记录电极按国际10-20标准导联系统安装，连接的双侧耳垂为参考，接地电极置于前额正中。滤波通频带为[0．1，30]Hz，数字化采样率为1000Hz，头皮与电极之间的阻抗〈5kΩ；记录分析时间为刺激前100ms至刺激后800ms。排除眼动和肌电等伪差。每名受试者同性别面孔刺激每60次为一个叠加单位（除去质量较差的脑电片段，实际叠加45～50次）。每名受试者采集6个波形片段数据（男女刺激面孔各3个），共取得34x6个波形片段。采用本实验室开发的软件将其绘制成刺激后不同时间点的t值统计参数映像。结果（1）刺激后40～100ms双侧额前区域具有显著性差异的趋势但未达到P〈0．05；（2）刺激后140～160ms双侧枕后区域具有显著性差异（P〈0．05）；（3）刺激后200～260ms双侧额前及枕后大部分区域具有显著性差异（P〈0，05）；（4）刺激后280～300ms顶中央较大区域具有显著性差异（P〈0．05）；（5）刺激360ms以后多个区域在不同的时段显示出显著性差异（P〈0．05）或趋势。结论大脑以一种网络方式活动，在不同的时间不同脑区域参与了对面孔性别信息的加工。

Objective To investigate the process of electrical activities when human brain deals with the facial sexual information. Methods Forty healthy college students in March 2005 were selected from Southern Medical University. All subjects participating in the experiment voluntarily were fight-handed with normal or corrected sight and never suffered from family history of mental disorder. 360 pictures of real human face （half females and half males） strange to all participants, were used as the stimulus presented once one by one in randomized order on the screen with a stimulus duration of 800 ms and a stimulus onset asynchrony （SOA） of 1200 ms. Half subjects were asked to press the left button of a game-pad immediately after female face presentation and the fight for male, the other half reversed. Event-related electroencephalogram （EEG） was recorded by 19 channels of international 10-20 system with linked earlobes as reference. EEG epochs from 100 ms before to 800 ms after stimulus were amplified by means of an ERPs system developed in our lab, digitized with sampling frequency of 1000 Hz, bandwidth of [0.1, 30] Hz and a notch of 50 Hz. Electrode impedance was less than 5 kΩ. Trial contaminated with ocular, muscular or any other type of artifacts were inspected visually and rejected. Each 60 stimuli of the same gender faces worked as an overlaying unit （the real overlay number was about 45-50 with bad epochs rejected）. Three female and 3 male subjects were excluded owing to the bad ERP record quality and thus 34 x6 epochs came from the rest ones. Results （1） The possible difference trend （but P〉0.05） between male and female facial stimuli appeared at the frontal area in 40-100 ms after stimuli; （2） The significant difference between male and female appeared at the occipital in 140-160 ms after stimuli （P〈0.05）; （3） The significant difference between male and female appeared at the large frontal and occipital area in 200-260 ms after stimuli （P〈0.05）; （4） The significant difference between male and female appeared at the large central parietal in 280-300 ms after stimuli （P〈0.05）; （5） The significant difference or trend between male and female appeared at several areas in different time after 360 ms. Conclusion In different stage, different brain areas are activated for the facial sexual feaaa＇e processing. Thus, our brain works as a network.