Department of Neurosurgery, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
TUM-Neuroimaging Center, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
J Clin Neurophysiol. 2020 Mar;37(2):131-139. doi: 10.1097/WNP.0000000000000528.
Although transcranial magnetic stimulation (TMS) is routinely applied in neuroscience and clinical settings, not much is known about its effects on brain networks. Therefore, this pilot study was set up using repetitive navigated transcranial magnetic stimulation (rTMS) combined with resting-state functional MRI (rs-fMRI) to explore frequency-dependent stimulation effects on an intranetwork and internetwork level.
Six healthy subjects (median age: 23.5 years) underwent two rTMS sessions (1 and 10 Hz), 7 days apart, and prestimulation and poststimulation rs-fMRI. Repetitive navigated transcranial magnetic stimulation was delivered to the left dorsolateral prefrontal cortex, with the exact stimulation target being determined by independent component analysis. Alterations of functional connectivity strength were evaluated using seed-based correlation analyses within and between the salience network, central executive network, and posterior and anterior default mode network.
Low-frequency rTMS resulted in significant intranetwork alterations only for the anterior default mode network and primarily within the left hemisphere. In contrast, high-frequency rTMS led to changes within all four networks of interest. Moreover, the posterior and anterior default mode network largely showed opposite effects to rTMS, and the anterior default mode network was rather isolated from the other networks, which was especially true for low-frequency rTMS. Changes in functional connectivity strength because of low-frequency rTMS were even detectable 7 days after stimulation.
This is one of the first studies using neuronavigated TMS with independent component analysis-based target selection to explore frequency-dependent stimulation effects in a combined rTMS-fMRI approach. Future studies including higher subject numbers may define the underlying mechanisms for the different responses to low- and high-frequency rTMS.
尽管经颅磁刺激（TMS）在神经科学和临床环境中得到了常规应用，但人们对其对大脑网络的影响知之甚少。因此，本研究使用重复经颅磁刺激（rTMS）联合静息态功能磁共振成像（rs-fMRI）来探索频率依赖性刺激对内联网和互联网水平的影响，这是一项初步研究。
6 名健康受试者（中位年龄：23.5 岁）接受了两次 rTMS 治疗（1Hz 和 10Hz），间隔 7 天，并在刺激前和刺激后进行 rs-fMRI。rTMS 施加于左侧背外侧前额叶皮层，通过独立成分分析确定精确的刺激靶点。使用基于种子的相关分析，在突显网络、中央执行网络以及后默认模式网络和前默认模式网络内和之间评估功能连接强度的变化。
低频 rTMS 仅导致前默认模式网络的内联网发生显著变化，主要发生在左半球。相比之下，高频 rTMS 导致四个感兴趣的网络都发生了变化。此外，后默认模式网络和前默认模式网络的反应在很大程度上与 rTMS 相反，而且前默认模式网络与其他网络的联系相对孤立，这在低频 rTMS 中尤其明显。低频 rTMS 引起的功能连接强度变化甚至在刺激后 7 天仍可检测到。
这是使用基于独立成分分析的神经导航 TMS 探索 rTMS-fMRI 联合方法中频率依赖性刺激效应的首批研究之一。未来包括更多受试者数量的研究可能会确定对低频和高频 rTMS 产生不同反应的潜在机制。
