Kim Dai-Youl, Oh Byung-Mo, Paik Nam-Jong
Department of Rehabilitation Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital Seoul, Republic of Korea.
Int J Neurosci. 2005 Feb;115(2):267-83. doi: 10.1080/00207450590519553.
The aim of this study was to confirm the excitability profile of human cortical circuits on the motor evoked potential (MEP) and the silent period (SP) after paired transcranial magnetic stimulation (TMS) with variable interstimulus intervals (ISI), and to compare the time courses of MEP and SP after paired TMS at variable ISIs. MEPs were elicited at the hypothenar muscles at rest, and during tonic muscle contraction by applying paired TMS to the motor cortex. The authors measured the MEP amplitude during rest and the duration of SP during tonic muscle contraction at various ISIs. The response to paired stimuli was inhibited by an ISI of 15 ms and facilitated by an ISI of 1020 ms. The SP at an ISI of 15 ms was shorter than that at the single suprathreshold stimulus, but the SP at an ISI of 1525 ms was longer than this. A significant correlation was observed between the MEP amplitude and the duration of SP at ISIs of 120 ms and for a CS of 80% of threshold. These results may provide useful data for the study of the function of cortical excitability in disease states and suggest that the neural circuits underlying MEP and SP differ partly.
本研究的目的是确定在不同刺激间隔（ISI）的配对经颅磁刺激（TMS）后，人类皮质回路对运动诱发电位（MEP）和静息期（SP）的兴奋性特征，并比较不同ISI的配对TMS后MEP和SP的时间进程。在休息时以及通过对运动皮层施加配对TMS使小鱼际肌进行强直性肌肉收缩时引出MEP。作者测量了不同ISI下休息时的MEP波幅以及强直性肌肉收缩时的SP持续时间。对配对刺激的反应在ISI为15毫秒时受到抑制，在ISI为10 - 20毫秒时得到促进。ISI为15毫秒时的SP比单次阈上刺激时的短，但ISI为15 - 25毫秒时的SP比单次阈上刺激时的长。在ISI为1 - 20毫秒且刺激强度为阈强度的80%时，观察到MEP波幅与SP持续时间之间存在显著相关性。这些结果可能为研究疾病状态下皮质兴奋性的功能提供有用数据，并表明MEP和SP背后的神经回路部分不同。
