健康人工作记忆脑电theta网络因果流研究

目的计算健康受试者工作记忆脑电(electroencephalogram,EEG)网络的因果流,为研究工作记忆大脑信息传递机制提供支持。方法实验数据为18名健康受试者在300次视觉工作记忆的32通道EEGs。应用快速傅里叶变换计算工作记忆时EEGs在各个频段的能量密度,选取能量密度最大的频段为工作记忆的特征频段。计算EEGs特征频段分量之间的因果连接强度DTF,构建因果网络,在计算网络每个节点的DTF加权因果流的基础上,计算额叶、顶叶、颞叶和枕叶4个脑区的(节点)平均因果流,研究工作记忆脑区之间的信息传递特征。结果工作记忆EEGs在theta频段的能量密度最大(911±15μV~2/Hz)。额叶、顶叶、颞叶和枕叶脑区的平均因果流:额叶为0.0033±0.0002,顶叶为0.0005±0.0003,枕叶为-0.0022±0.0004,颞叶为-0.0051±0.0003。结论 theta频段是工作记忆EEGs的特征频段。工作记忆EEGs的theta网络因果源在额叶,因果汇在颞叶和枕叶,提示工作记忆各个脑区的信息传递是从额叶流到颞叶和枕叶。

Causal Flow of EEGs Theta Network during Visual Working Memory Task in Healthy Subjects

Objective The study employed multi-channel electroencephalogram (EEG) to measure the causal flow in different brain regions during working memory,thus provide new insight for investigating the information transfer mechanism underlying the working memory.Methods 32-channel EEGs were recorded in 18healthy subjects (300 trials) performing visual working memory tasks.EEGs power density in different frequency bands was calculated by fast Fourier transform and the principal frequency band related to working memory was analyzed.Causal connectivity among EEGs was measured by directed transform function (DTF)via spectral Granger causal analysis.Based on the DTF weighted causal flow,the averaged causal flow in frontal,parietal,temporal and occipital lobe was assessed to analyze the information transfer in different brain regions during working memory.Results The EEGs power density in theta band (911 ± 15 μV2/Hz) was significantly higher than those in other bands.Averaged causal flow in frontal,parietal,temporal and occipital lobe were 0.0033 ± 0.0002,0.0005 ± 0.0003,-0.0022 ± 0.0004 and-0.0051 ± 0.0003,respectively.Conclusion Theta band is the principal frequency band related to working memory.Frontal lobe is the causal source of the EEGs network during working memory while temporal and occipital lobe are causal sinks,implying that the information transfers from frontal to temporal and occipital lobe during working memory.