Background Neural oscillations reflect rapidly changing brain excitability states. We have demonstrated previously with EEG-triggered transcranial magnetic stimulation (TMS) of human motor cortex that the positive vs. negative peak of the sensorimotor μ-oscillation reflect corticospinal low-vs. high-excitability states. In vitro experiments showed that induction of long-term depression (LTD) by low-frequency stimulation depends on the postsynaptic excitability state. Objective/Hypothesis: We tested the hypothesis that induction of LTD-like corticospinal plasticity in humans by 1 Hz repetitive TMS (rTMS) is enhanced when rTMS is synchronized with the low-excitability state, but decreased or even shifted towards long-term (LTP)-like plasticity when synchronized with the high-excitability state. Methods We applied real-time EEG-triggered 1-Hz-rTMS (900 pulses) to the hand area of motor cortex in healthy subjects. In a randomized double-blind three-condition crossover design, pulses were synchronized to either the positive or negative peak of the sensorimotor μ-oscillation, or were applied at random phase (control). The amplitude of motor evoked potentials was recorded as an index of corticospinal excitability before and after 1-Hz-rTMS. Results 1-Hz-rTMS at random phase resulted in a trend towards LTD-like corticospinal plasticity. RTMS in the positive peak condition (i.e., the low-excitability state) induced significant LTD-like plasticity. RTMS in the negative peak condition (i.e., the high-excitability state) showed a trend towards LTP-like plasticity, which was significantly different from the other two conditions. Conclusion The level of corticospinal depolarization reflected by phase of the μ-oscillation determines the degree of corticospinal plasticity induced by low-frequency rTMS, a finding that may guide future personalized therapeutic stimulation.

中文翻译：

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低频 rTMS 诱导 LTD 样皮质脊髓可塑性取决于感觉运动 μ 节律的预刺激阶段

背景神经振荡反映快速变化的大脑兴奋状态。我们之前已经通过 EEG 触发的人类运动皮层的经颅磁刺激 (TMS) 证明，感觉运动 μ 振荡的正峰值与负峰值反映了皮质脊髓低与。高兴奋状态。体外实验表明，低频刺激对长期抑郁（LTD）的诱导取决于突触后兴奋状态。目的/假设：我们检验了以下假设：当 rTMS 与低兴奋性状态同步时，1 Hz 重复 TMS (rTMS) 对人类 LTD 样皮质脊髓可塑性的诱导增强，但降低甚至转向长期 (LTP ) 样可塑性，当与高兴奋性状态同步时。方法我们将实时 EEG 触发的 1-Hz-rTMS（900 脉冲）应用于健康受试者运动皮层的手部区域。在随机双盲三条件交叉设计中，脉冲与感觉运动 μ 振荡的正峰值或负峰值同步，或以随机相位应用（对照）。运动诱发电位的幅度被记录为 1-Hz-rTMS 前后皮质脊髓兴奋性的指标。结果 随机相位的 1-Hz-rTMS 导致了类似 LTD 的皮质脊髓可塑性的趋势。RTMS 在正峰值条件下（即低兴奋性状态）诱导显着的 LTD 样可塑性。RTMS 在负峰条件下（即高兴奋性状态）显示出类似 LTP 的可塑性趋势，这与其他两种条件有显着差异。