多通道EEG信号小波相干分析的测谎研究

Lie detection study based on wavelet coherence analysis on multi-channel EEG signals

为区分说谎与讲真两种思维状态下不同脑区之间的功能连接,并且研究这种功能连接在时域与频域的变化,征选了40名平均年龄21岁、健康右利手受试者作为实验对象,随机分为说谎和讲真两个被试组(各20名),采用标准三刺激模式测谎协议记录了在两种思维状态下12导联的脑电信号(electroencephalogram,EEG),然后利用小波相干分析方法,对刺激后250~1300 ms时段(P300典型发生时段)上的θ(0.5~4 Hz)、δ(4~8 Hz)、α(8~13 Hz)、β(13~30 Hz)、γ(30~100 Hz)五个频带的66个导联对的小波相干系数分别进行计算,分析不同导联对在不同时频域的功能连接.最后,利用秩和检验对两类受试者的相同时-频域的相干系数分别对比分析,实验结果表明,在θ及δ频带对应的时频域上,两类受试者在OZ-P4、OZ-P3及P3-P4三个导联对的相干值均存在统计学差异,推测人在面对物证说谎时进行功利和非功利的道德判断时导致视觉联合皮层(P3和OZ)和顶下小叶(P4)相应区域被激活,故而产生不同脑区间功能连接的显著统计性差异.

In order to distinguish the functional connectivity on different brain areas between two mental states of lying and telling-truth and to research this functional connectivity change in time-frequency domains,forty healthy right-handed subjects with an average age of 21 were randomly divided into two groups(20 each):Lying and telling-truth.Through standard three stimuli paradigm,we recorded the 12 channels electroencephalogram(EEG)signalsin two states.Then,used wavelet coherence method to calculate the coherence coefficient on66 pairs of channelsof the following time-frequency bands:θ(0.5~4 Hz)、δ(4~8 Hz)、α(8~13 Hz)、β(13~30 Hz)、γ(30~100 Hz)and the time range of 250~1300 ms after the stimuli(typical occurrence time of P300).Analyzed the functional connectivity on different channels pairs in different time-frequency areas.Finally,Wilcoxon test was used to compare the difference of wavelet coherence on the same time-frequency domain between the two groups of the subjects.The experimental resultshows that in the time-frequency domain corresponding to frequency bandsθandδ,there were statistical differences in the coherence values of OZ-P4,OZ-P3 and P3-P4 of the two groups of subjects.The finding indicates that when lying with physicalevidence,the associative visual cortex(P3 and OZ)and inferiorparietallobule(P4)may be activated during utilitarian and nonutilitarian moral judgments,yielding significant statistical differences in the functional connectivity between different brain regions.