中文摘要：

通过前额皮质脑电θ波段（4～8 Hz）特征信息的分析,揭示大脑前额皮质在字母工作记忆过程中“信息保持与回忆”阶段作用的地位与机制.采集15名被试在3字母、5字母、7字母的不同记忆负荷下,工作记忆实验中头皮脑电图信号（EEG）,并使用Morlet小波分解方法提取出各电极上的θ波段信号.在能量分析方面,采用Welch功率谱密度计算平均功率,采用短时傅里叶变化（STFT）进行时频分析;在相关性分析方面,采用基于电极间功率谱的相关系数进行相关性分析,采用电极间同步锁相值（PLV）进行相位同步性分析.分析比较不同记忆负荷下,前额皮质与顶叶、中叶等脑区θ波段脑电信号的特征信息,并对结果进行配对t检验和单因素方差分析F值检验.结果表明,随着记忆负荷的增加,前额皮质（电极：Fp1、Fp2、F3、Fz、F4）θ波能量相对于中央叶（电极：C7、C3、Cz、C4、C8）和顶叶（电极：P7、P3、Pz、P4、P8）有显著上升（P＜0.05）.在低字母记忆负荷下,左右脑同侧脑区前额叶-中央叶（F3-C3、F4-C4）、前额叶-顶叶（F3-P3、F4-P4）的相关系数相似.但随着记忆负荷的增加,右脑的脑区相关系数相对于左脑有明显上升.相位同步性方面,随着记忆负荷的增加,右脑前额叶-中央叶（F4-C4）和前额叶-顶叶（F4-P4）相对于左脑的相位同步性明显增强,锁相比值（PLV）显著上升（P＜0.05）.在工作记忆的“信息保持与回忆”阶段,大脑前额皮质的活跃程度和信息交流明显高于中叶和顶叶皮质,可能起到兼有自身记忆信息储存与保持、执行调用其他皮质信息的多功能重要作用.随着记忆负荷的增加,大脑将自主调用更多右脑皮质参与工作记忆,并从理性逻辑记忆模式,转化为感性形象记忆模式以提高工作效率.

英文摘要：

The analysis of feature information for the prefrontal cortex EEG （electroencephalograph） theta bands （4 ～ 8 Hz） signal can reveal the function status and mechanism of the prefrontal cortex in the process of ＂information maintain and recall＂ phase within the working memory.Fifteen participants＇ scalp EEG signals were collected during the experiment,in which participants did the working memory task with different memory loads,including 3 letters,5 letters and 7 letters.The theta band signal of each electrode was extracted using morlet wavelet decomposition method.In terms of energy analysis,the Welch power spectral density was used to calculate the average power and the short time Fourier transform （STFT） was used for the time-frequency analysis.In terms of correlation analysis,the correlation coefficient based on the power spectrum between different electrodes was used for the correlation analysis and the phase locking value （PLV） between the different electrodes was used for the phase synchronization analysis.It is concluded that brain has the comparative function of the feature information of the theta band signal from the prefrontal cortex,central cortex and parietal cortex within different memory loads.The results are analysed by the paired t test and the F test of single factor analysis of variance.With the increase of the memory load,the power of the theta bands in the prefrontal cortex （electrode：Fp1,Fz,ofFp2,F3,F4） has more increased dramatically than that in the central lobe （electrode：C7,C3,Cz,C4,C8） and parietal lobe （electrode：P7,P3,Pz,P4,P8）.The result has the statistical significance （P ＜ 0.05,of which the Fz：P ＜ 0.01）.In terms of correlation analysis,with the lower letters memory load,the correlation coefficient of the ipsilateral regions,such as prefrontal lobe-the central lobe （F3-C3,F4-C4）,frontal lobe-parietal lobe （F3-P3,F4-p4） is similar between the left region and right region in the brain.But with the increase of the memory load,re