Corticospinal contributions to lower limb muscle activity during cycling in humans.
Corticospinal contributions to lower limb muscle activity during cycling in humans.
复制标题
皮质脊髓对人类骑行期间下肢肌肉活动的贡献。
DOI：
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复制
发表时间：
2012
影响因子：
2.5
通讯作者：
T. Carroll
中科院分区：
文献类型：
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作者：
S. Sidhu;B. Hoffman;A. Cresswell;T. Carroll
本研究的目的是探讨皮质脊髓对自行车运动中腿部肌肉运动驱动的作用。我们研究了1）通过阈下经颅磁刺激（TMS）激活皮层中的抑制性中间神经元是否会导致EMG抑制，以及2）如何在运动周期中调节对通过TMS和颈髓刺激（CMS）刺激运动皮层的反应。TMS在强度阈下激活皮质脊髓束引起抑制肌电图约一半的主题和肌肉在骑自行车，并在匹配的静态收缩股外侧肌。在运动周期中，TMS引起的运动诱发电位（MEP）的大小也有显著的调制（P < 0.001），这与所有肌肉中背景EMG的变化密切相关（r > 0.86; P < 0.05）。当MEP和CMEP振幅归一化为背景EMG时，它们在主EMG爆发之前相对较大，而在背景EMG最大时较小。由于正常化MEP和CMEP反应的调制模式相似，数据表明，人类骑自行车期间皮质脊髓反应的相位依赖性调制主要由脊髓机制驱动。然而，在EMG爆发前促进正常化MEP和CMEP反应的程度存在细微差异，这可能反映了最大肌肉激活前皮质兴奋性的小幅增加。这些数据表明，运动皮层积极促进运动驱动，脊髓因素主导的相位依赖性调制皮质脊髓兴奋性在人类骑自行车。
The purpose of the current study was to investigate corticospinal contributions to locomotor drive to leg muscles involved in cycling. We studied 1) if activation of inhibitory interneurons in the cortex via subthreshold transcranial magnetic stimulation (TMS) caused a suppression of EMG and 2) how the responses to stimulation of the motor cortex via TMS and cervicomedullary stimulation (CMS) were modulated across the locomotor cycle. TMS at intensities subthreshold for activation of the corticospinal tract elicited suppression of EMG for approximately one-half of the subjects and muscles during cycling, and in matched static contractions in vastus lateralis. There was also significant modulation in the size of motor-evoked potentials (MEPs) elicited by TMS across the locomotor cycle (P < 0.001) that was strongly related to variation in background EMG in all muscles (r > 0.86; P < 0.05). When MEP and CMEP amplitudes were normalized to background EMG, they were relatively larger prior to the main EMG burst and smaller when background EMG was maximum. Since the pattern of modulation of normalized MEP and CMEP responses was similar, the data suggest that phase-dependent modulation of corticospinal responses during cycling in humans is driven mainly by spinal mechanisms. However, there were subtle differences in the degree to which normalized MEP and CMEP responses were facilitated prior to EMG burst, which might reflect small increases in cortical excitability prior to maximum muscle activation. The data demonstrate that the motor cortex contributes actively to locomotor drive, and that spinal factors dominate phase-dependent modulation of corticospinal excitability during cycling in humans.
影响因子：
14.5
作者：
CALANCIE, B;NEEDHAMSHROPSHIRE, B;GREEN, BA
通讯作者：
GREEN, BA