老年人轻度认知障碍部分定向相干脑网络分析

Cortical Networks of the Elderly with Mild Cognitive Impairment by Partial Directed Coherence Analysis of EEG

近年的研究表明,轻度认知障碍(MCI)患者的认知加工呈现脑连通性缺失特征,但各脑区间如何影响,因果特性不明。本研究的目的在于分析MCI患者在认知任务下的有向脑网络特征。采集了30位老人在信息冲突颜色认知作业下的头皮脑电,包括21位正常人和9位MCI患者。选取刺激呈现后的脑电计算其部分定向相干值,依此构建脑网络,并着重分析了不同脑区的入度差异。研究发现:在beta段,MCI患者右前额区信息流入缺失,左中央区的信息流入异常增强;在患者组和正常组中前脑区的入度要远高于后脑区;正常人在匹配和不匹配刺激下右脑区的入度要高于左脑区;但是在患者组中左右脑区的入度却没有明显差别。在特定阈值下:正常人在匹配刺激下左脑区(阈值0.14)的入度要低于MCI患者(F=3.780,P=0.040);正常人在不匹配刺激下左脑区(阈值0.26)的入度要低于MCI患者(F=3.280,P=0.040);正常人在匹配刺激下右脑区(阈值0.18)的入度要高于MCI患者(F=3.941,P=0.021)。文章从入度为脑网络特征验证了MCI患者在颜色认知任务下右脑的功能缺损。

The deficiency of brain connectivity has been discovered in cognitive processing of MCI in recent research. It is still unclear that how different brain regions influence each other and what causality is in the brain regions. The aim of this study was to analyze electroencephalography （EEG） directed cortical networks under cognitive task. Thirty elders, including 9 patients with MCI and 21 normal controls, participated in the experiment. We recorded their scalp EEG when they were judging whether the color of two graphics was matched or not. The first 1 seconds EEG data after the stimulus onset were extracted to calculate Partial Directed Coherence. Results showed that the deficiency information flow of right prefrontal cortex and abnormal enhance information flow of left central area were observed in MCI; The input degrees of the front hemisphere were higher than the back hemisphere in both controls and patients. The input degrees of right hemisphere were higher than left hemisphere in controls, but there were not significant differences in patients. Under specific threshold： the input degrees of left hemisphere in controls were lower than MCI under match task （threshold was 0. 14, F = 3. 780,P = 0. 040） ; the input degrees of left hemisphere in controls were lower than MCI under no match task （ threshold was 0.26, F = 3. 280,P = 0. 040） ; the input degrees of right hemisphere in controls were lower than MCI under no match task （threshold was 0. 18, F = 3. 941 ,P = 0. 021 ）. We used the input degree to prove that the MCI had the deficit in right hemisphere under color cognitive task.