Zhang Chong, Yu Xiaolin, Yang Yong, Xu Lei
Department of Information Engineering, Officers College of CAPF, Chengdu, China
Department of Information Engineering, Officers College of CAPF, Chengdu, China.
Clin EEG Neurosci. 2014 Oct;45(4):249-256. doi: 10.1177/1550059413503961. Epub 2014 Mar 3.
In this article, 2 synchronization measures, phase locking value (PLV) and spectral coherence value (SCV), are used to characterize the changes of the phase synchronization and functional coupling of electroencephalogram (EEG) waves at different brain cortical areas for mental fatigue caused by a long-term cognitive task. The long-term cognitive task induces a significant decrease in the interhemispheric SCVs and PLVs of beta in central and parietal regions, a significant decrease in the intrahemispheric SCVs and PLVs of beta frequency band at the frontal-parietal and central-parietal, and frontal-central middle electrode pairs, suggesting EEG decreases in cooperative processing, strength of functional coupling, and flux of mutual information exchange in the corresponding inter- and intrahemispheres. However, when the mental fatigue level increases, the interhemispheric PLVs of theta are enhanced in the frontal region and C3-Cz electrode pair, and the intrahemispheric PLVs of theta are heightened at frontal-central middle electrode pairs. PLV and SCV measures could reflect the changes of the phase synchronization and functional coupling of EEG waves from time and frequency domains, which are sensitive to mental fatigue. Therefore, PLVs and SCVs can provide an effective and reliable way to quantify brain response to mental fatigue.
在本文中，采用两种同步测量方法，即锁相值（PLV）和频谱相干值（SCV），来表征长期认知任务导致的精神疲劳状态下不同脑皮层区域脑电图（EEG）波的相位同步和功能耦合变化。长期认知任务导致中央和顶叶区域β波的半球间SCV和PLV显著降低，额顶叶、中央顶叶以及额中央中间电极对处β频段的半球内SCV和PLV显著降低，这表明相应半球间和半球内的EEG协同处理、功能耦合强度以及互信息交换通量降低。然而，当精神疲劳程度增加时，额叶区域以及C3-Cz电极对处θ波的半球间PLV增强，额中央中间电极对处θ波的半球内PLV升高。PLV和SCV测量方法能够从时域和频域反映EEG波的相位同步和功能耦合变化，对精神疲劳敏感。因此，PLV和SCV能够提供一种有效且可靠的方法来量化大脑对精神疲劳的反应。
