Arai Noritoshi, Furubayashi Toshiaki, Inomata-Terada Satomi, Okabe Shingo, Kobayashi-Iwata Nobue, Hanajima Ritsuko, Terao Yasuo, Ugawa Yoshikazu
Department of Neurology, Division of Neuroscience, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
Neurosci Lett. 2009 Oct 25;462(3):188-92. doi: 10.1016/j.neulet.2009.06.062. Epub 2009 Jun 24.
Intracortical circuit excitability of the human motor cortex has been studied by measuring effects of some conditioning TMS stimulus on the succeeding test TMS stimulus in the motor cortex, such as short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF). A single-pulse TMS was used as a conditioning stimulus (CS) in these techniques, but a train of several TMS pulses might induce some intracortical changes in the motor cortex more effectively. For nine healthy volunteers, we compared the SICI and ICF induced by a single conditioning biphasic TMS pulse with those induced by a train of 10 biphasic TMS pulses of the same intensity. As a conditioning stimulus, we delivered a subthreshold single biphasic pulse (CS1) or 10, 10-Hz biphasic pulses (CS10) before a suprathreshold monophasic test stimulus at several interstimulus intervals (ISIs) of 3-40 ms over the hand motor area. The CS intensity was 50-100% of the active motor threshold (AMT). We compared the motor cortical excitability after the conditioning stimulus (single pulse or a train of ten pulses) at the intervals for SICI and ICF. A train of ten 10-Hz pulses elicited greater inhibition at short ISIs than a single conditioning pulse did. The facilitation at ISIs around 10 ms corresponding to the ICF was evoked by CS1 only at an intensity of 80% AMT; CS10 evoked no ICF. Furthermore, CS10 evoked MEP inhibition at longer intervals. Results show that a train of high-frequency, low-intensity, biphasic TMS pulses can have a strong inhibitory effect on the motor cortex.
通过测量某些条件性经颅磁刺激（TMS）刺激对运动皮层中后续测试TMS刺激的影响，如短间隔皮层内抑制（SICI）和皮层内易化（ICF），对人类运动皮层的皮层内回路兴奋性进行了研究。在这些技术中，单脉冲TMS被用作条件刺激（CS），但一串几个TMS脉冲可能会更有效地在运动皮层中诱导一些皮层内变化。对于九名健康志愿者，我们比较了单个条件性双相TMS脉冲与一串10个相同强度的双相TMS脉冲所诱导的SICI和ICF。作为条件刺激，我们在手部运动区以3 - 40毫秒的几个刺激间隔（ISI）在阈上单相测试刺激之前施加一个阈下单个双相脉冲（CS1）或10个10赫兹双相脉冲（CS10）。CS强度为主动运动阈值（AMT）的50 - 100%。我们在SICI和ICF的间隔时间比较了条件刺激（单个脉冲或一串十个脉冲）后的运动皮层兴奋性。一串十个10赫兹脉冲在短ISI时比单个条件脉冲引起更大的抑制。仅在80%AMT强度下，CS1在对应于ICF的约10毫秒ISI时诱发易化；CS10未诱发ICF。此外，CS10在较长间隔时诱发运动诱发电位（MEP）抑制。结果表明，一串高频、低强度的双相TMS脉冲可对运动皮层产生强烈的抑制作用。
