The interference effects of transcranial magnetic stimulation (TMS) on several electroencephalographic (EEG) measures in both temporal and frequency domains have been reported. We tested the hypothesis whether the offline external inhibitory interference, although focal, could result in a global reorganization of the functional brain state, as assessed by EEG microstates. In 16 healthy subjects, we inhibited five parietal areas and used a pseudo stimulation (Sham) at rest. The EEG microstates were extracted before and after each stimulation. The canonical A, B, C and D templates were found before and after all stimulation conditions. The Sham, as well as the stimulation of a ventral site did not modify any resting EEG microstates' topography. On the contrary, interfering with parietal key-nodes of both dorsal attention (DAN) and default mode networks (DMN), we observed that the microstate C clearly changes, whereas the other three topographies are not affected. These results provide the first causal evidence of a microstates modification following magnetic interference. Since the microstate C has been associated to the activity in regions belonging to the cingulo-opercular network (CON), the regional specificity of such inhibition seems to support the theory of a link between CON and both DAN and DMN at rest.

中文翻译：

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人顶叶皮层的离线刺激不同地影响静息的脑电微状态。

据报道，经颅磁刺激（TMS）在时域和频域均对几种脑电图（EEG）措施产生干扰作用。我们测试了这一假设，即离线的外部抑制干扰（尽管是局灶性的）是否会导致功能性大脑状态的整体重组（如EEG微观状态所评估）。在16名健康受试者中，我们抑制了五个顶叶区域，并在休息时使用了假刺激（假手术）。在每次刺激之前和之后提取脑电图微状态。在所有刺激条件之前和之后都发现了规范的A，B，C和D模板。假手术以及腹侧部位的刺激均未改变静息性脑电图微区的形貌。相反，干扰背部注意（DAN）和默认模式网络（DMN）的顶叶关键节点，我们观察到微状态C明显改变，而其他三个拓扑不受影响。这些结果提供了磁干扰后微状态改变的第一个因果证据。由于微状态C已与属于扣带-神经网络（CON）的区域中的活性相关联，因此这种抑制作用的区域特异性似乎支持了CON与DAN和DMN处于静止状态之间的联系的理论。