Changes in motoneuron excitability during voluntary muscle activity in humans with spinal cord injury.
Changes in motoneuron excitability during voluntary muscle activity in humans with spinal cord injury.
复制标题
脊髓损伤患者随意肌肉活动期间运动神经元兴奋性的变化。
DOI：
10.1152/jn.00367.2019
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发表时间：
2020
影响因子：
2.5
通讯作者：
Perez,MonicaA
中科院分区：
文献类型：
--
作者：
Vastano,Roberta;Perez,MonicaA
脊髓损伤（SCI）后静息运动神经元的兴奋性增加。然而，对于SCI患者自主肌肉活动期间运动神经元兴奋性变化的程度仍然知之甚少。为了解决这个问题，我们在慢性颈不完全性脊髓损伤和老年人中，通过在腕部使用尺神经的超大电流电刺激测量F波，并通过在第一骨间背侧肌的颈髓交界处使用高电流电刺激测量颈髓运动诱发电位（CMEP）。对照组参与者。我们发现，与对照组相比，SCI患者休息时F波的持续性（每组中存在的F波数量）和振幅更高。随着自主收缩水平的增加，两组的F波振幅增加，但持续性没有增加，但SCI组与对照组相比增加的程度较小。同样，CMEP振幅增加，在两组中，但在SCI的程度较低，与对照组相比。这些结果也被发现在匹配的绝对水平的肌电图活动，表明这些变化是不相关的减少自愿运动输出后SCI。在两组中，F波和CMEP振幅在不同条件下呈正相关。这些结果支持了这一假设，运动神经元池在自愿活动减少后SCI，这可能会改变自愿肌肉contractions.New和强度值得注意的运动神经元的兴奋性如何变化在人类脊髓损伤（SCI）的自愿肌肉活动仍然知之甚少。我们发现，F-波和颈髓运动诱发电位振幅，结果反映运动神经元的兴奋性，增加自愿活动与休息相比，在SCI参与者，但在较小程度上，在控制。这些结果提示脊髓损伤后运动神经元在自主活动中的反应性降低，可能影响损伤后功能相关的可塑性。
The excitability of resting motoneurons increases following spinal cord injury (SCI). The extent to which motoneuron excitability changes during voluntary muscle activity in humans with SCI, however, remains poorly understood. To address this question, we measured F waves by using supramaximal electrical stimulation of the ulnar nerve at the wrist and cervicomedullary motor-evoked potentials (CMEPs) by using high-current electrical stimulation over the cervicomedullary junction in the first dorsal interosseous muscle at rest and during 5 and 30% of maximal voluntary contraction into index finger abduction in individuals with chronic cervical incomplete SCI and aged-matched control participants. We found higher persistence (number of F waves present in each set) and amplitude of F waves at rest in SCI compared with control participants. With increasing levels of voluntary contraction, the amplitude, but not the persistence, of F waves increased in both groups but to a lesser extent in SCI compared with control participants. Similarly, the CMEP amplitude increased in both groups but to a lesser extent in SCI compared with controls. These results were also found at matched absolutely levels of electromyographic activity, suggesting that these changes were not related to decreases in voluntary motor output after SCI. F-wave and CMEP amplitudes were positively correlated across conditions in both groups. These results support the hypothesis that the responsiveness of the motoneuron pool during voluntary activity decreases following SCI, which could alter the generation and strength of voluntary muscle contractions.NEW & NOTEWORTHYHow the excitability of motoneurons changes during voluntary muscle activity in humans with spinal cord injury (SCI) remains poorly understood. We found that F-wave and cervicomedullary motor-evoked potential amplitude, outcomes reflecting motoneuronal excitability, increased during voluntary activity compared with rest in SCI participants but to a lesser extent that in controls. These results suggest that the responsiveness of motoneurons during voluntary activity decreases following SCI, which might affect functionally relevant plasticity after the injury.