轻度认知障碍老年人脑电的非线性相互依赖脑网络分析

本研究旨在初步探究患轻度认知障碍(MCI)的老年人及正常老年人进行情绪调控时的大脑网络特性。记录了14位MCI患者及18个正常人进行认知重评的情绪调控实验时的头皮脑电信号(EEG),包括中性观看、负性观看和负性重评任务。并采用非线性相互依赖性的方法衡量不同频段的大脑区域间的连接强度,然后根据非线性相互依赖性指数构建两组受试者的大脑功能网络,并运用全局效率和平均局部效率来分析脑区的信息传递效率。研究结果显示,MCI患者脑电theta(F=6.805, P=0.014,η²=0.185)和alpha(负性观看任务:t=2.437,P=0.021, Cohen's d=0.865)活动的非线性相互依赖性指数显著低于正常对照组。在特定阈值下(低gamma频段阈值0.070;theta频段阈值0.075;alpha频段阈值0.115和0.125),MCI患者的网络效率显著低于正常对照组。此外还发现(阈值0.115)正常对照组表现出显著的重评效应(F=5.549,P=0.008,η²=0.246),即负性观看条件下(P=0.018) 的alpha全局效率(0.713±0.042)显著高于负性重评条件下的alpha全局效率(0.699±0.045),MCI组没有发现类似的重评效应。研究表明,MCI患者的情绪调控脑网络异常,表现在大脑信息交换效率低下。未发现非线性相互依赖性、网络效率与行为学、认知分数之间的显著皮尔逊相关性。未来可以对非线性相关性进行深入研究,从而发现更稳定的MCI情绪调控脑网络特征。

Complex Networks Analysis of the Elderly People with Mild Cognitive Impairment by Nonlinear Interdependence of EEG

The aim of this study was to preliminarily investigate brain functional networks of the elderly with mild cognitive impairment (MCI) and the normal elderly during emotion regulation. Fourteen MCI patients and eighteen healthy subjects participated in this experiment. The scalp electroencephalography (EEG) was recorded whenthe subjects performed the cognitive reappraisal task, including neutral/negative viewing task and negative reappraisal task. We applied nonlinear interdependence in different EEG bands to measure the connectivity between brain regions. Then the nonlinear interdependence index was used to construct the brain functional networks of subjects in both groups. The global efficiency and average local efficiency were used to analyze the efficiency of information transmission among brain regions. The result showed that the nonlinear interdependence index of EEG theta activity (F=6.805,P=0.014,η²=0.185) in MCI patients were significantly lower than that in the control group, as well as of alpha band under negative viewing task (t=2.437,P=0.021, Cohen's d=0.865). Under some specific thresholds (threshold was 0.070 in low gamma band, threshold was 0.075 in theta band, threshold were 0.115 and 0.125 in alpha band), the network efficiency of MCI patients was significantly lower than that in the control group. In addition, the reappraisal effect (F=5.549,P=0.008, η²=0.246) was found in the control group (threshold was 0.115), showing that the global efficiency of EEG alpha activity(P=0.018) under the negative viewing condition(0.713±0.042) in controls was higher than that under the condition of negative reappraisal(0.699±0.045). However, similar reappraisal effect was not found in MCI patients. We therefore concluded that MCI patients had the deficit in brain network during emotion regulation, which was manifested in low efficiency of brain information transmission. In addition, no significant Pearson's correlation was found between nonlinear interdependence, network efficiency and behavioral scores, cognitive scores. More research of nonlinear correlation is necessary in order to find more stable brain network features with MCI in emotion regulation.