Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation approach in which low level currents are administered over the scalp to influence underlying brain function. Prevailing theories of tDCS focus on modulation of excitation-inhibition balance at the local stimulation location. However, network level effects are reported as well, and appear to depend upon differential underlying mechanisms. Here, we evaluated potential network-level effects of tDCS during the Serial Reaction Time Task (SRTT) using convergent EEG- and fMRI-based connectivity approaches. Motor learning manifested as a significant (p <.0001) shift from slow to fast responses and corresponded to a significant increase in beta-coherence (p <.0001) and fMRI connectivity (p <.01) particularly within the visual-motor pathway. Differential patterns of tDCS effect were observed within different parametric task versions, consistent with network models. Overall, these findings demonstrate objective physiological effects of tDCS at the network level that result in effective behavioral modulation when tDCS parameters are matched to network-level requirements of the underlying task.

中文翻译：

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经颅直流电刺激 (tDCS) 对视觉运动学习的潜在影响的网络级机制

经颅直流电刺激 (tDCS) 是一种非侵入性脑刺激方法，其中在头皮上施加低水平电流以影响潜在的脑功能。tDCS 的流行理论侧重于在局部刺激位置调节兴奋-抑制平衡。然而，也报告了网络级别的影响，并且似乎取决于不同的潜在机制。在这里，我们使用基于 EEG 和 fMRI 的收敛连接方法评估了 tDCS 在串行反应时间任务 (SRTT) 期间的潜在网络级影响。运动学习表现为从缓慢到快速反应的显着 (p <.0001) 转变，并且对应于 β 相干性 (p <.0001) 和 fMRI 连接性 (p <.01) 的显着增加，尤其是在视觉运动通路中. 在不同的参数任务版本中观察到 tDCS 效应的不同模式，与网络模型一致。总体而言，这些发现证明了 tDCS 在网络级别的客观生理效应，当 tDCS 参数与基础任务的网络级别要求匹配时，会导致有效的行为调节。