经颅直流电刺激对基于偏定向相干因效脑网络特征的影响

利用脑网络研究经颅直流电刺激(tDCS)对脑功能机制和脑皮层状态的影响具有重要意义。本研究基于偏定向相干因果分析方法,构建被试在不同tDCS刺激实验范式下进行运动想象的因效性脑网络。以因效性脑网络的功能脑区通道信息流入、流出率为局部特征,平均聚类系数、全局效率为全局特征,分析研究tDCS对运动想象脑网络特征的影响。16名健康被试均为右利手。结果显示,被试执行左手运动想象下,伪刺激和阳极刺激C4后的C4通道信息流出率、流入率、平均聚类系数和全局效率分别为0.142±0.014、0.193±0.013、0.585±0.046、0.347±0.031和0.223±0.025、0.258±0.023、0.817±0.021、0.491±0.091,均存在显著性差异(P<0.05);tDCS阴极刺激C4后的C4通道信息流出率、平均聚类系数和全局效率分别为0.109±0.009、0.356±0.037和0.252±0.024,与伪刺激相比差异显著(P<0.05),C4通道信息流入率为0.184±0.008,与伪刺激相比无显著差异(P>0.05)。研究表明,阳极tDCS有效激活该脑区皮层的活跃性,使脑区信息交流更加频繁,增加脑网络的聚集程度,提高脑网络的连通性;阴极tDCS刺激则会抑制脑区皮层的活跃性,降低了脑区信息的流出,减少脑网络的聚集程度,降低脑网络的连通性。

The Influence of tDCS on the Effective Brain Networks Based on Biased Partial DirectedCoherence

Using brain network to study the effects of tDCS on brain function mechanisms and cerebral cortex state is of vital significance. In this study, we constructed effective brain networks of motor imagery in the different tDCS paradigms based on partial directional coherence. Taking the inflow and outflow rate of functional brain channel information of the effective brain networks as local features, and the average clustering coefficient and global efficiency as global features, we analyzed the influence of tDCS on the brain network characteristics of motor imagery. We found out that when the subjects performed left-hand motor imagery, the information outflow rate, inflow rate, average clustering coefficient and global efficiency of C4 channels after sham and tDCS anodal C4 stimulation was 0.142±0.014, 0.193±0.013, 0.585±0.046, 0.347±0.031 and 0.223±0.025, 0.258±0.023, 0.817±0.021 and 0.491±0.091, respectively, with significant differences (P<0.05). The information outflow rate, average clustering coefficient and global efficiency of C4 channel after tDCS cathodalC4 stimulation was 0.109±0.009, 0.356±0.037 and 0.252±0.024, respectively, which were significantly different from those of sham stimulation (P<0.05). The information inflow rate of C4 channel was 0.184±0.008, which was not significantly different from that of sham stimulation (P>0.05). The results indicated that the anodal tDCS effectively activated the activity of the cerebral cortex, made the brain area information exchange more frequently, increased the aggregation degree of the brain network, and improved the connectivity of the brain network. Cathodal tDCS would inhibit the activity of the cerebral cortex, reduce the outflow of brain information, reduce the aggregation degree of the brain network, and reduce the connectivity of the brain network.