精神疲劳对工作记忆α振荡信息整合的影响

精神疲劳是一定时间内人们进行持续精神注意力的认知活动所体验到的一种生理、心理上的不适。认知活动依赖于大脑多个区域间的信息交流,相位同步作为大脑区域之间信息整合的重要机制,搭起大脑各区域间协同通信的桥梁。α振荡是神经元加工功能抑制的一种主动机制,而主动抑制在工作记忆的注意力分配中起着中心作用。利用自适应N-back实验诱发精神疲劳。采用改进型Sternberg范式作为工作记忆实验,记录精神疲劳前后工作记忆的脑电信号。采用相位同步分析和功率谱分析方法,对精神疲劳前后α振荡工作记忆编码期、保持期和提取期的脑电数据进行分析,研究精神疲劳对大脑信息整合的影响。结果发现, 精神疲劳后,整个工作记忆过程中脑区间的相位同步性显著增大,功率谱值有显著差异。其中,精神疲劳后的3个时期均出现额叶区域间和额枕区域间相位同步性的显著增加,编码期额叶区域间锁相值具有显著性增大的节点对有160个;保持期额叶区域间有222个,额叶、枕顶叶区域之间有65个;提取期额叶区域间有196个,额叶、枕顶叶区域之间有11个。编码期枕顶区出现显著的α振荡事件相关去同步(ERD)(PO8,P=0.048;Oz,P=0.036),额叶区出现α振荡事件相关同步(ERS)的趋势。保持期额叶出现显著的α振荡ERS(Fz,P=0.022),枕顶区有ERS的趋势。提取期额区(Fz,P=0.033)出现α振荡ERS,枕区(Oz,P=0.045)出现α振荡ERD。研究表明,精神疲劳会降低大脑脑区间的信息整合能力,降低大脑内的信息交流,α振荡的相位同步分析对解释精神疲劳对脑区间信息整合的机制有一定的帮助。

Effect of Mental Fatigue on Alpha Oscillation Information Integration of Working Memory

Mental fatigue refers to a kind of physical and psychological discomfort experienced by people when they carry out cognitive activities of continuous mental attention in a certain period. Cognitive activity depends on the exchange of information between multiple regions of the brain. Phase synchronization, as an important mechanism of information integration between brain regions, builds a bridge of cooperative communication between different regions of the brain. Alpha oscillation is considered to be an active mechanism of neuronal processing inhibition that plays a central role in attention allocation in working memory. In this paper,the adaptive N-back experiment was used to induce mental fatigue. The improved Sternberg paradigm was used as a working memory experiment. EEG signals during working memory before and after mental fatigue were recorded. Phase synchronization analysis and power spectrum analysis were used to analyze the EEG data of α oscillatory working memory before and after mental fatigue, and to study the effect of mental fatigue on brain information integration. Results showed that when the mental fatigue occurred, the phase synchronization of the brain region increased significantly in the whole process of working memory, and there was a significant difference in power spectrum. Among them, the phase synchronization between frontal lobe region and fronto-occipital region increased significantly in all three periods after mental fatigue. During coding period, there were 160 node pairs with significant increase in phase lock value between the frontal lobe regions. During the retention period, there were 222 between frontal lobe and 65 between frontal lobe and occipital parietal lobe. During extraction period, 196 between frontal lobe and 11 between frontal lobe and occipital parietal lobe. During the coding period, there was a significant α oscillationevent—related desynchronization (ERD) (PO8, P=0.048; Oz, P=0.036) in the occipital parietal region, and a tendency of α oscillation event—related synchronization(ERS) appeared in the frontal lobe. During the retention period, there was a significant α oscillatoryERS (Fz, P=0.022) in the frontal lobe and a trend of ERS in the occipital parietal region. During the extraction period, α oscillatory ERS, in frontal region (Fz, P=0.033) and α oscillatory ERD in occipital region (Oz, P=0.045). These studies have shown that the mental fatigue could reduce the ability of information integration in brain regions and reduce the information communication in the brain. The phase synchronization analysis of α oscillation is helpful to explain the mechanism of mental fatigue on information integration in brain regions.