老年轻度认知障碍患者的脑电熵分析

Entropy Analysis of EEG for Elderly Patients with Mild Cognitive Impairment

选取8名轻度认知障碍(mild cognitive impairment,MCI)老年人和17名正常老年人参与图片颜色的认知任务,并同步记录他们的脑电信号,然后采用相对能量、样本熵和累积残余熵分析方法,研究这两组被试在执行任务时的不同脑区脑电活动的差异.研究发现:1)两组被试alpha相对能量无差异,但MCI患者额中央区和顶枕中央区的脑电熵高于正常人;2)两组被试额区脑电的熵值都高于其他区域,中线区域的脑电熵值低于左右半球;3)刺激类型对两组被试的脑电活动有影响,在完成匹配任务时,两组被试大脑前侧区域的脑电活动更为复杂,并且正常人大脑右侧中央区域的脑电活动复杂性较高;4)与样本熵相比,累积残余熵能更细致地刻画出MCI患者脑电的非线性特征.结果表明,MCI患者认知过程中的脑电活动存在异常,信号更为复杂.与样本熵相比,累积残余熵更适合于分析脑电的非线性特征.

In this study, eight elderly patients with mild cognitive impairment （MCI） and 17 normal controls participated in a cognition task. The subjects were asked to judge whether the color of two graphics is matched or not, and their scalp electroencephalographs （EEG） were recorded. We calculated the relative power, sample entropy （SEn） and cumulative residual entropy （CI=LEn） of the event-related EEG signals to explore differ- ences between the MCI patients and normal controls. The following results were obtained. 1） There was no difference in alpha relative power, while the MCI patients had higher complexity at medial-frontal and medial- posterior regions than the normal controls. 2） The frontal region showed significantly higher complexity than other regions and the center hemisphere had lower complexity than left and right hemisphere in both groups throughout the task. 3） Complexity in anterior brain in match task was higher than that in mismatch task in both groups. Normal controls had more complex EEG activity during the match task in the right-center region. 4） Relative to SEn, the analysis of CREn found more specific nonlinear characteristic in the EEG of MCI patients. All these results show the MCI patients have abnormal EEG activity in brain, and CREn is more suitable for describing the nonlinear characteristic of EEG than SEn.