Suppression of EMG activity by transcranial magnetic stimulation in human subjects during walking
Suppression of EMG activity by transcranial magnetic stimulation in human subjects during walking
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DOI：
10.1111/j.1469-7793.2001.00651.x
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发表时间：
2001-12-01
影响因子：
5.5
通讯作者：
Nielsen, JB
中科院分区：
文献类型：
--
作者：
Petersen, NT;Butler, JE;Nielsen, JB
1.在人类行走过程中的运动皮层的参与进行了评估，使用经颅磁刺激（TMS）的运动皮层在各种强度。对行走过程中胫前肌和比目鱼肌的肌电图记录进行校正和平均.低强度的TMS（低于运动诱发电位（MEP）的阈值）抑制了行走过程中持续的EMG活动。这种抑制的平均潜伏期为40.0 +/- 1.0 ms。在稍高强度的刺激下，EMG活动有一个平均潜伏期为29.5 +/- 1.0 ms的易化。随着刺激强度的增加，易化的大小增加，最终在单个扫描中MEP是清晰的。在三名受试者中，TMS被运动皮层上的电刺激所取代。在短潜伏期（类似于28 ms）时，MEP阈值以下有明显的易化。随着电刺激强度的降低，促进作用的大小逐渐减小，直到最终消失。我们在任何受试者身上都没有观察到类似于TMS产生的EMG活动抑制。本研究表明，运动神经元活动在步行过程中可以抑制激活皮层内抑制回路。这第一次说明了运动皮层的活动直接参与了人类行走过程中肌肉的控制。
1. The involvement of the motor cortex during human walking was evaluated using transcranial magnetic stimulation (TMS) of the motor cortex at a variety of intensities. Recordings of EMG activity in tibialis anterior (TA) and soleus muscles during walking were rectified and averaged.2. TMS of low intensity (below threshold for a motor-evoked potential, MEP) produced a suppression of ongoing EMG activity during walking. The average latency for this suppression was 40.0 +/- 1.0 ms. At slightly higher intensities of stimulation there was a facilitation of the EMG activity with an average latency of 29.5 +/- 1.0 ms. As the intensity of the stimulation was increased the facilitation increased in size and eventually a MEP was clear in individual sweeps.3. In three subjects TMS was replaced by electrical stimulation over the motor cortex. Just below MEP threshold there was a clear facilitation at short latency (similar to 28 ms). As the intensity of the electrical stimulation was reduced the size of the facilitation decreased until it eventually disappeared. We did not observe a suppression of the EMG activity similar to that produced by TMS in any of the subjects.4. The present study demonstrates that motoneuronal activity during walking can be suppressed by activation of intracortical inhibitory circuits. This illustrates for the first time that activity in the motor cortex is directly involved in the control of the muscles during human walking.