任务转换的多脑区作用机制：来自ERP的证据

采用＂任务转换＂实验范式,以数字、汉字的归类为任务,探究预知和未预知条件下任务转换的ERPs.实验中被试先后完成2个连续的任务,任务序列为重复（AA,BB,……）或转换（AB,BA,……）.结果发现,在预知条件下,转换序列的先行任务数/词比重复序列的先行任务数/词、转换序列的后继任务数/词比重复序列的后继任务数/词都产生一个更为负走向的波,在中央区（CZ）差异波为D-N320.而未预知条件下,仅转换序列后继任务数/词比重复序列后继任务数/词产生一个更为负走向的波,中央区差异波为D-N320.对差异波溯源分析发现,内源性准备源于左侧颞区（Left BA20）;外源性调节在预知条件下源于右侧顶区（Right BA19）,而未预知条件下源于左侧额区（Left BA47）和右侧额区（Right BA10）.结果表明,任务转换本质是认知冲突过程,对应的脑电成分为D-N320.在预知条件下任务转换先后单独由颞区和顶区负责,预知准备使得任务转换在低级皮层区完成,而未预知条件下任务转换在更广的高级皮层区完成,同时激活左侧额区和右侧额区,且外源性调节对应的脑区在预知条件和未预知条件下是分离的.

Functional Mechanism of Multiple Cerebral Cortices on Task Switching：an ERP Study

This paper aims to investigate the task switching ERPs under the conditions of foreknowledge and non-foreknowledge,by using ＂task-switching＂ paradigm and taking the classification of Chinese characters or digits as tasks.Participants performed two tasks consecutively which were either task repetition（AA,BB,…） or task switching（AB,BA,…） in the experiment.The results indicated that the predecessor tasks of digit/word and succedent tasks of digit/word all evoked a negative-going wave which was larger for switching trials compared to repeating trials under foreknowledge conditions,and the difference waves in central regions were N-D320.However,under non-foreknowledge conditions,the succedent tasks of digit/word in switching trials evoked a negative-going wave compared to repeating trials only,and the difference waves in central regions were also N-D320.The results of Dipole Source Localization Analysis to difference waves disclosed that the endogenous preparation derived from left temporal region（Left BA20）;the exogenous adjustment derived from right parietal region（Right BA19） under foreknowledge conditions while it derived from left frontal region（Left BA47） and right frontal region（Right BA10） under non-foreknowledge conditions.These results suggested that the nature of task switching was cognitive conflict and the corresponding ERP component was D-N320.Under foreknowledge conditions,task switching was solely in charge of temporal and parietal regions successively.It was the advance preparation that made task switching accomplishment in primary cortex,whereas under non-foreknowledge conditions task switching was accomplished in wilder senior cortex and activates left frontal region and right frontal region at the same time.The cortex for endogenous preparation and exogenous adjustment was dissociative under foreknowledge and non-foreknowledge conditions.