首页> 外文期刊>The Journal of Physiology >Effects of volitional contraction on intracortical inhibition and facilitation in the human motor cortex.
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Effects of volitional contraction on intracortical inhibition and facilitation in the human motor cortex.

机译:自愿收缩对人类运动皮层皮质内抑制和促进的影响。

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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.
机译:在16位健康受试者的第一背骨间壁肌肉(FDI)的皮质运动区,评估了短间隔皮质内抑制(SICI),皮质内促进(ICF)和短间隔内皮质促进(SICF)。配对脉冲TMS以以下刺激间隔(ISI)传送到左半球:SICI为2和3毫秒,ICF为10和15毫秒,SICF为1-5毫秒。从静止和活跃的右FDI记录了电机诱发的电位。通过调节刺激(S1)的四种强度(主动运动阈值的60-90%,AMT)和三种水平的肌肉收缩(最大自愿收缩的10%,25%,50%)对SICI和ICF产生影响, MVC)进行了评估。用两种强度(A2的90%和70%)和相同的肌肉收缩水平评估对SICF的作用。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量与10%MVC时静止时相同,但在更高的收缩水平下下降; (iii)仅在S1 = 90%AMT的静止状态下观察到ICF; (iv)以10%和25%的MVC促进SICF,但是以50%的MVC促进。我们得出结论,在肌肉激活过程中,皮层内兴奋性反映了SICI和SICF系统激活之间的平衡。收缩期间SICI减少的部分原因是因为SICF的征聘重叠。低强度(70%AMT)调节刺激可以测试SICI,而与低收缩水平下对SICF的影响无关。

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