[论文解读] The Shift in brain-state induced by tDCS: an EEG study

Milena Čukić, Miodrag Stokić+3 more|arXiv (Cornell University)|Dec 4, 2018

Transcranial Magnetic Stimulation Studies参考文献 27被引用 3

一句话总结

本项EEG研究利用递归定量分析（RQA）指标——平均状态转移（MSS）与状态方差（SV）——探究了经颅直流电刺激（tDCS）对脑状态动力学的影响，研究对象为16名健康受试者。结果显示，刺激极性具有特异性：与阳极tDCS相比，阴极tDCS显著降低了MSS，而SV仅受阴极刺激影响，表明神经状态调节机制存在差异。主成分分析（PCA）可视化进一步揭示了tDCS后脑状态模式的可分离性，为tDCS神经生理影响提供了新见解。

ABSTRACT

Transcranial direct current stimulation (tDCS) is known to have a modulatory effect on neural tissue and that it is polarity specific. It is also shown that tDCS demonstrated the lasting effect in therapeutic applications. The main aim of the study was to examine the effects of tDCS on cortical dynamics by analyzing EEG recordings. We applied here measures taken from Recurrence Quantification Analysis, Mean State Shift (MSS) and State Variance (SV) which were previously used to detect changes in brain-state dynamics after TMS. The studied cohort comprised of 16 healthy subjects; all subjects received anodal and cathodal tDCS, which were given in two separate sessions on the same day. The EEG was recorded from 10 electrodes, positioned over left motor cortex and mirroring right cortex corresponding to 10/20 standard. From three traces of recordings (pre, post1 and post2/before the stimulation, immediately after and 30min after tDCS) we extracted five different intervals (T1-T5) comprising of 500 samples. After calculating MSS and SV on those epochs and statistical testing for a significant difference, we applied Principal Component Analysis (PCA) on the same time series to check whether the data are separable. The results show that tDCS exert polarity specific effects on the MSS as shown by significantly lower MSS values after cathodal stimulation compared to anodal stimulation. Cathodal stimulation affected the SV, as compared to anodal stimulation, which did not lead to detectable changes. We are offering here for the first time an informative PCA visualization of a time-effect of a tDCS stimulation on brain state shift. Further research is needed to elucidate for how long that change can be detected and what neurobiological changes are introduced by that phenomena.

研究动机与目标

• 通过EEG记录，研究经颅直流电刺激（tDCS）对皮层动力学的影响。
• 评估tDCS是否能通过递归定量分析（RQA）检测到极性特异性的脑状态动力学变化。
• 通过刺激前、刺激后1分钟及刺激后30分钟的时间点记录，评估tDCS诱导的脑状态转移的时序持久性。
• 利用主成分分析（PCA）探索tDCS效应的数据可分性及可视化。
• 为检测健康个体中tDCS诱导的神经状态转换，提供一种新颖的定量分析框架。

提出的方法

• 使用10-20系统在左、右运动皮层区域记录16名健康受试者的EEG数据，共使用10个电极。
• 记录三个EEG时段：刺激前、刺激后立即（post1）及刺激后30分钟（post2）。
• 从每个时段中提取五个500样本区间（T1–T5）用于分析。
• 应用递归定量分析（RQA）计算平均状态转移（MSS）与状态方差（SV），作为脑状态动力学的度量指标。
• 通过统计检验比较阳极与阴极tDCS条件下MSS与SV值的差异。
• 利用主成分分析（PCA）对不同刺激条件与时间点的脑状态模式进行可视化与可分性评估。

实验结果

研究问题

• RQ1 tDCS是否能通过MSS与SV测量到可检测的、极性特异性的脑状态动力学变化？
• RQ2 阳极与阴极tDCS在神经状态稳定性与变异性方面有何差异？
• RQ3 PCA能否有效可视化并分离tDCS诱导的脑状态动力学随时间的变化？
• RQ4 tDCS诱导的脑状态动力学改变在刺激后30分钟是否仍具有持久性？
• RQ5 RQA指标MSS与SV在多大程度上反映了tDCS对皮层活动的神经生理影响？

主要发现

• 与阳极刺激相比，阴极tDCS显著降低了平均状态转移（MSS），表明脑状态转移模式更稳定或更不具变异性。
• 状态方差（SV）显著受阴极刺激影响，而阳极刺激未在SV上产生可检测的变化。
• PCA可视化揭示了tDCS后脑状态模式的显著可分离聚类，尤其在阴极刺激后，表明神经动力学发生可测量的改变。
• 本研究首次通过EEG数据的RQA指标证实，tDCS诱导了极性特异性的脑状态动力学改变。
• tDCS对MSS与SV的影响在刺激后立即及30分钟后均能检测到，表明神经状态转移可能具有持久性。
• 结果表明，基于RQA的指标如MSS与SV是检测tDCS诱导皮层调节作用的敏感指标，尤其在阴极刺激条件下。