Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive brain stimulation technique that can influence cortical excitability. Low-frequency rTMS (stimulation frequency ≤1Hz) can induce inhibitory effects on cortical excitability. In order to investigate dynamic changes in neuronal activity after low-frequency rTMS, 20 healthy subjects received 1-Hz rTMS over the right motor area, and electroencephalography (EEG) in resting condition with eyes open was recorded before rTMS and at 0 min, 20 min, 40 min, and 60 min after rTMS. Power values, functional connectivity based on a weighted phase lag index (wPLI), and network characteristics were assessed and compared to study the aftereffects of rTMS. Our results show that low-frequency rTMS produced a delayed long-lasting increase in alpha-band power values in frontoparietal brain areas and an immediate long-lasting increase in theta-band power values in the ipsilateral frontal and contralateral centroparietal areas. In the alpha band, functional connectivity decreased immediately after rTMS but significantly increased at 20 min after rTMS. Moreover, an analysis of undirected graphs revealed that the number of connections significantly changed in the anterior and posterior regions in the alpha band. In addition, there were significant decreases in clustering coefficients of the channels near the site of stimulation in the alpha and theta bands after rTMS. In conclusion, low-frequency rTMS produces widespread and long-lasting alterations in neural oscillation and functional connectivity. This work implies that low-frequency rTMS can induce inhibitory effects on motor cortical excitability ipsilateral to the stimulation site.

中文翻译：

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低频重复经颅磁刺激对健康受试者静息状态脑电图的持久影响

重复经颅磁刺激（rTMS）是一种非侵入性脑刺激技术，可以影响皮层兴奋性。低频rTMS（刺激频率≤1Hz）可以诱导对皮层兴奋性的抑制作用。为了研究低频rTMS后神经元活动的动态变化，共有20名健康受试者在右运动区接受1-Hz rTMS，并在rTMS之前和0分钟，20分钟时记录了睁眼时处于静止状态的脑电图（EEG）在rTMS之后的分钟，40分钟和60分钟。评估并比较了功率值，基于加权相位滞后指数（wPLI）的功能连接性和网络特性，以研究rTMS的后效应。我们的研究结果表明，低频rTMS在额顶大脑区域产生了一个长期持久的α带能量值增加延迟，并且在同侧额叶和对侧向心区产生了theta带能量值的立即持续持久增加。在alpha波段中，rTMS后功能连接立即下降，但在rTMS后20分钟时功能连接显着增加。此外，对无向图的分析显示，连接的数量在alpha波段的前后区域显着变化。另外，在rTMS后，α和θ带中刺激部位附近的通道的聚集系数显着降低。总之，低频rTMS在神经振荡和功能连接性方面产生广泛而持久的变化。