Effects of volitional contraction on intracortical inhibition and facilitation in the human motor cortex
Effects of volitional contraction on intracortical inhibition and facilitation in the human motor cortex
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DOI：
10.1113/jphysiol.2008.158956
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发表时间：
2008-11-01
影响因子：
5.5
通讯作者：
Rothwell, John C.
中科院分区：
文献类型：
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作者：
Ortu, Enzo;Deriu, Franca;Rothwell, John C.
对 16 名健康受试者的第一背侧骨间肌 (FDI) 的皮质运动区进行短间隔皮质内抑制 (SICI)、皮质内促进 (ICF) 和短间隔皮质内促进 (SICF) 评估。成对脉冲 TMS 按以下刺激间隔 (ISI) 传递到左半球：SICI 为 2 和 3 ms，ICF 为 10 和 15 ms，SICF 为 1-5 ms。运动诱发电位是从静息和活动右 FDI 中记录的。评估了调节刺激 (S1) 的四种强度（主动运动阈值的 60-90%，AMT）和三个水平的肌肉收缩（最大自主收缩的 10%、25%、50%，MVC）对 SICI 和 ICF 的影响。使用两种强度（AMT 的 90% 和 70%）的测试刺激 (S2) 和相同水平的肌肉收缩来评估对 SICF 的影响。结果表明： (i) 在 10% MVC 期间，在 S1 = 70% AMT 时观察到最大 SICI； (ii) S1 = 70% AMT 时获得的 SICI 量在静息时与 10% MVC 期间相同，但在较高收缩水平时下降； (iii) 仅在 S1 = 90% AMT 的静息状态下观察到 ICF； (iv) SICF 在 10% 和 25% MVC 下得到促进，但在 50% MVC 下则不然。我们的结论是，在肌肉激活过程中，皮质内兴奋性反映了 SICI 和 SICF 系统激活之间的平衡。收缩期间 SICI 减少的部分原因是 SICF 的叠加募集。低强度（70% AMT）条件刺激可以独立于低收缩水平下对 SICF 的影响来测试 SICI。
Short-interval intracortical inhibition (SICI), intracortical facilitation (ICF) and short-interval intracortical facilitation (SICF) were assessed in the cortical motor area of the first dorsal interosseous muscle (FDI) of 16 healthy subjects. Paired-pulse TMS was delivered to the left hemisphere at the following interstimulus intervals (ISIs): 2 and 3 ms for SICI, 10 and 15 ms for ICF and 1-5 ms for SICF. Motor-evoked potentials were recorded from the resting and active right FDI. The effects exerted on SICI and ICF by four intensities (60-90% of active motor threshold, AMT) of the conditioning stimulus (S1) and by three levels of muscle contraction (10%, 25%, 50% of maximal voluntary contraction, MVC) were evaluated. The effects exerted on SICF were evaluated with two intensities (90% and 70% of AMT) of the test stimulus (S2) and with the same levels of muscle contraction. Results showed that: (i) during 10% MVC, maximum SICI was observed with S1 = 70% AMT; (ii) the amount of SICI obtained with S1 = 70% AMT was the same at rest as during 10% MVC, but decreased at higher contraction levels; (iii) ICF was observed only at rest with S1 = 90% AMT; (iv) SICF was facilitated at 10% and 25% MVC, but not at 50% MVC. We conclude that during muscle activation, intracortical excitability reflects a balance between activation of SICI and SICF systems. Part of the reduction in SICI during contraction is due to superimposed recruitment of SICF. Low intensity (70% AMT) conditioning stimuli can test SICI independently of effects on SICF at low contraction levels.