人脑对外源性和内源性信息冲突处理机制的探讨

Serial Processing of Exogenous and Endogenous Information Conflicts in Human Brain

目的采用事件相关电位技术研究人脑对外源性刺激相关的信息冲突和内源性心理相关的信息冲突的处理机制。方法15名健康志愿者参与试验。视觉刺激为白色的两位数字,先后呈现的两个数字(S1和S2)组成一个刺激对。任务1要求受试者比较S1和S2的数值是否相同,并做出相应的按键反应。刺激对包含S1与S2的数值相同(S-)和S1与S2数值不同(S+)两种类型。任务2要求受试者心算S1与S2的差,并把计算结果与数字"3"做比较,对差等于"3"(M-)和不等于"3"(M+)的情况做出相应的按键反应。刺激对包含3种类型:S1与S2数值相同,差值不等于"3"(S-M+);数值不同但差等于"3"(S+M-);数值不同且差不等于"3"(S+M+)。结果S2呈现后,S+、S+M-和S-M+类型的刺激对均引出N270,S+M+则依次引出N270和N400两个成分。N270的最大波幅出现在后头部,N400的最大波幅则位于中央区。结论N270和N400的出现提示人脑对外源性和内源性信息冲突的处理采用的是串行处理模式。该处理活动可能是由冲突处理系统中不同的神经结构来完成的。

Objective To investigate the cortical activities for processing exogenous stimulus-related information conflict and endogenous mental-related information conflict. Methods Event-related potentials （ERPs） were recorded while 15 healthy subjects performed a digit matching task. Each trial consisted of two sequentially presented digits （S1-S2）, where S2 was either the same as S1 （S-） or different from S1 （S＋） in digital value. Subjects pressed a button of a push-pad when S2 was the same as S1 and pressed the other button when S2 was different from S1 in the first session. Furtherly, they were required to calculate the difference between S1 and S2, and compare their calculation result with digit ＂3＂ in the second session. They pressed a button when the calculation result was equal to ＂3＂ （M-） and pressed the other button when it was not （M＋）. Three trial types were included： same numbers but their difference was not equal to ＂3＂ （S-M＋）, different numbers but their difference was ＂3＂ （S＋ M-） and different numbers but their difference was not ＂3＂ （S＋M＋）. Results Following S2 onset, a component N270 was broadly elicited at all the scalps by S＋, S＋M - and S-M＋. N270 and N400 were elicited in series by S＋M＋. The maximal amplitude of N270 was at the posterior scalp while the maximal amplitude of the N400 was at the central areas. Conclusion The different spatio-temporal distributions of the two nega rive potentials suggested that exogenous and endogenous information conflicts were serially processed in the human brain by the conflict processing system of multiple neural substrates.