Background:Interhemispheric asymmetry caused by brain lesions is an adverse factor in the recovery of patients with neurological deficits. Repetitive transcranial magnetic stimulation (rTMS) has been shown to modulate cortical oscillation and proposed as an approach to rebalance the symmetry, whichhas not been documented well. Objective:In this study, we investigated the influence of repetitive transcranial magnetic stimulation (rTMS) on EEG power in patients with unilateral brain lesions by simultaneously stimulating both brain hemispheres and to elucidate asymmetrical changes in rTMS-induced neurophysiological activity. Methods:Fourteen patients with unilateral brain lesions were treated with one active and one sham session of 10 Hz rTMS over the vertex (Cz position). Resting-state EEGs were recorded before and immediately after rTMS. The brain symmetry index (BSI), calculated from a fast Fourier transform, was employed to quantify the power asymmetry in both hemispheres and paired channels over the entire range and five frequency bands (delta, theta, alpha, beta and gamma bands). Results:Comparison between active and sham sessions demonstrated rTMS-induced EEG after-effects. rTMS in the active session significantly reduced the BSI in patients with unilateral brain lesions over the entire frequency range (t = 2.767, P = 0.016). Among the five frequency bands, rTMS only induced a noticeable decrease in the BSI in the delta band (t = 2.254, P = 0.042). Furthermore, analysis of different brain regions showed that significant changes in the BSI of the alpha band were only demonstrated in the posterior parietal lobe. In addition, EEG topographic mapping showed a decreased power of delta oscillations in the ipsilesional hemisphere, whereas distinct cortical oscillations were observed in the alpha band around the parietal-occipital lobe in the contralesional hemisphere. Conclusions:When both brain hemispheres were simultaneously activated, rTMS decreased interhemispheric asymmetry primarily via reducing the delta band in the lesioned hemisphere.

中文翻译：

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在单侧脑损伤患者中通过 rTMS 同时刺激两个大脑半球可减少半球间不对称性

背景：脑损伤引起的大脑半球间不对称是影响神经功能缺损患者康复的不利因素。重复经颅磁刺激 (rTMS) 已被证明可以调节皮质振荡，并被提议作为一种重新平衡对称性的方法，但尚未得到很好的记录。目的：在本研究中，我们通过同时刺激大脑两个半球来研究重复经颅磁刺激 (rTMS) 对单侧脑损伤患者 EEG 功率的影响，并阐明 rTMS 诱导的神经生理活动的不对称变化。方法：14 例单侧脑损伤患者接受了 1 次主动和 1 次顶点 10 Hz rTMS 的假治疗（Cz 位置）。在 rTMS 之前和之后立即记录静息状态脑电图。通过快速傅立叶变换计算得出的大脑对称指数 (BSI) 用于量化整个范围和五个频带（δ、θ、α、β 和 γ 波段）内半球和配对通道的功率不对称性。结果：主动和假会话之间的比较表明 rTMS 诱导的脑电图后效应。活动期间的 rTMS 显着降低了单侧脑损伤患者在整个频率范围内的 BSI（t = 2.767，P = 0.016）。在五个频段中，rTMS 仅导致 delta 频段的 BSI 显着降低（t = 2.254，P = 0.042）。此外，对不同大脑区域的分析表明，α 波段 BSI 的显着变化仅在后顶叶中得到证实。此外，EEG 地形图显示同侧半球 delta 振荡的功率降低，而在对侧半球顶枕叶周围的 alpha 带中观察到明显的皮质振荡。结论：当两个大脑半球同时被激活时，rTMS主要通过减少受损半球的三角带来减少大脑半球间的不对称性。