Differences in after-effect between monophasic and biphasic high-frequency rTMS of the human motor cortex
Differences in after-effect between monophasic and biphasic high-frequency rTMS of the human motor cortex
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DOI：
10.1016/j.clinph.2007.07.006
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发表时间：
2007-10-01
影响因子：
4.7
通讯作者：
Ugawa, Yoshikazu
中科院分区：
文献类型：
--
作者：
Arai, Noritoshi;Okabe, Shingo;Ugawa, Yoshikazu
目的：目的：研究高频、单相和双相重复经颅磁刺激（rTMS）的远期效应差异。方法：10 Hz rTMS经左侧初级运动皮层，记录右侧第一骨间背侧肌运动诱发电位（MEP）。为了探测运动皮层的兴奋性，我们记录了MEP在几个时间之前，期间和之后的几种类型的条件性rTMS。我们还记录了F波，以探测脊髓兴奋性的变化。总共给出了一千个脉冲，其中10 Hz的脉冲串，每分钟传递100个脉冲（10分钟10个脉冲串）。对于单相和双相rTMS，强度固定在90%主动运动阈值（AMT）或90%静息运动阈值（RMT）。此外，我们使用固定强度为90%的RMT进行了单相rTMS实验，用于双相脉冲。结果：在90%AMT下，单相和双相rTMS后几分钟内MEP均增强。另一方面，在90%RMT时，单相rTMS后诱发的MEP增强比双相rTMS后更大、更长。将强度调整为双相90%RMT的单相rTMS引起了与单相90%RMT的单相rTMS后类似的极大增强。90%RMT双相rTMS对F波振幅和出现率均无显著影响。结论：这些结果表明，rTMS后的增强发生在运动皮层。单相rTMS对运动皮层兴奋性的后效比双相rTMS强。这可能是因为双相脉冲优先激活一个相对均匀的人口在同一方向上的神经元和他们的效果更容易比双相rTMS激活不同方向的神经元在稍微不同的timing.Significance：目前的结果表明，当使用rTMS作为一种治疗工具或在研究领域，磁脉冲的波形可能会影响结果深刻。(C)2007年国际临床神经生理学联合会。由Elsevier爱尔兰有限公司出版。保留所有权利。
Objective: To study differences in the long-term after-effect between high-frequency, monophasic and biphasic repetitive transcranial magnetic stimulation (rTMS).Methods: Ten hertz rTMS was delivered over the left primary motor cortex and motor evoked potentials (MEPs) were recorded from the right first dorsal interosseous muscle. To probe motor cortex excitability we recorded MEPs at several timings before, during and after several types of conditioning rTMSs. We also recorded F-waves to probe spinal excitability changes. Thousand pulses were given in total, with a train of 10 Hz, 100 pulses delivered every minute (ten trains for 10 min). The intensity was fixed at 90% active motor threshold (AMT) or 90% resting motor threshold (RMT) for both monophasic and biphasic rTMS. In addition, we performed a monophasic rTMS experiment using a fixed intensity of 90%, RMT for biphasic pulses.Results: At 90% AMT, MEPs were enhanced for a few minutes after both monophasic and biphasic rTMS. On the other hand, at 90% RMT, a larger and longer enhancement of MEPs was evoked after monophasic rTMS than after biphasic rTMS. Monophasic rTMS at an intensity adjusted to biphasic 90% RMT elicited a great enhancement similar to that after monophasic rTMS at monophasic 90% RMT. Neither F-wave amplitude nor its occurrence rate was significantly altered by 90% RMT monophasic rTMS.Conclusions: These results suggest that enhancement after rTMS occurs at the motor cortex. Monophasic rTMS has a stronger aftereffect on motor cortical excitability than biphasic rTMS. This is probably because monophasic pulses preferentially activate a relatively uniform population of neurons oriented in the same direction and their effects summate more readily than biphasic rTMS activating differently oriented neurons at slight different timings altogether.Significance: The present results suggest that when using rTMS as a therapeutic tool or in research fields, the waveforms of magnetic pulses may affect the results profoundly. (C) 2007 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.