Department of Neuroscience Imaging and Clinical Science, ITAB, Institute for Advanced Biomedical Technologies, University "G. D'Annunzio", Chieti, Italy.
Department of Neuroscience Imaging and Clinical Science, ITAB, Institute for Advanced Biomedical Technologies, University "G. D'Annunzio", Chieti, Italy.
Cortex. 2021 May;138:302-310. doi: 10.1016/j.cortex.2021.02.014. Epub 2021 Mar 4.
Electrophysiological (EEG) correlates both at time (i.e., event-related potentials, ERP) and frequency (i.e., event-related desynchronization, ERD) domains have been shown to be modulated by external magnetic interference. Parallel studies reported a similar interference also for the EEG microstate at rest and in the period that anticipates a task. Here we investigated whether such interference was prolonged during the evoked activity in the framework of the semantic decision task. To this aim, rTMS was delivered over a core region of both the Default mode network and the language network (i.e., left angular gyrus, AG), previously associated to the current task, and as active control we stimulated the left IPS. When subjects received a non-active stimulation (i.e., Sham), in the period that follows the target onset (i.e., 2 sec after the rTMS) we found an interesting alternation of two dominant microstates (MS1, MS3), previously associated to the phonological network and the Cingulo-Opercular Network (CON), respectively. This dynamic was not altered when TMS was delivered over the left IPS. On the contrary, rTMS over left AG selectively suppressed the phonological-related microstate. These findings provide the first causal evidence of region specificity of the EEG microstates topography during the evoked activity corroborating the idea of a crucial role of AG in the semantic memory. Moreover, the present results might provide insight for understanding the neurophysiological correlates of language disorders e.g., aphasia as well as for planning non-invasive brain stimulation protocols for the rehabilitation.
电生理（EEG）相关性，无论是在时间（即事件相关电位，ERP）还是在频率（即事件相关去同步化，ERD）领域，都已被证明受到外部磁场干扰的调节。平行研究报告称，在休息和任务前期间，静息态和微状态也存在类似的干扰。在这里，我们研究了在语义决策任务框架内，这种干扰是否会在诱发活动期间延长。为此，我们在与当前任务相关的默认模式网络和语言网络（即左角回，AG）的核心区域施加 rTMS，并将左侧 IPS 作为主动控制进行刺激。当受试者接受非活跃刺激（即假刺激）时，我们发现了一个有趣的现象，即在目标出现后 2 秒（即 rTMS 后 2 秒）的时期内，两个主要微状态（MS1、MS3）交替出现，它们分别与语音网络和扣带-脑岛网络（CON）有关。当 TMS 施加于左侧 IPS 时，这种动态没有改变。相反，rTMS 施加于左侧 AG 选择性地抑制了与语音相关的微状态。这些发现为 EEG 微状态拓扑在诱发活动期间的区域特异性提供了第一个因果证据，支持了 AG 在语义记忆中的关键作用的观点。此外，目前的结果可能为理解语言障碍（如失语症）的神经生理相关性提供见解，并为康复计划非侵入性脑刺激方案提供参考。
