Mazzocchio Riccardo, Kitago Tomoko, Liuzzi Gianpiero, Wolpaw Jonathan R, Cohen Leonardo G
Human Cortical Physiology Section, Medical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
Clin Neurophysiol. 2006 Aug;117(8):1682-91. doi: 10.1016/j.clinph.2006.04.019. Epub 2006 Jun 21.
The spinal cord is capable of activity-dependent plasticity, but the extent of its participation in human motor learning is not known. Here, we tested the hypothesis that acquisition of a locomotor-related skill modulates the pathway of the H-reflex, a measure of spinal cord excitability that is susceptible to plastic changes.
Subjects were tested on their ability to establish a constant cycling speed on a recumbent bike despite frequent changes in pedal resistance. The coefficient of variation of speed (CV(speed)) measured their ability to acquire this skill (decreasing CV(speed) with training reflects performance improvements). Soleus H-reflexes were taken at rest before and after cycling.
Ability to establish a target speed increased and H-reflex size decreased more after cycling training involving frequent changes in pedal resistance that required calibrated locomotor compensatory action than with training involving constant pedal resistances and lesser compensation. The degree of performance improvement correlated with the reduction in the amplitude of the H-reflex.
Skillful establishment of a constant cycling speed despite changing pedal resistances is associated with persistent modulation of activity in spinal pathways.
Recalibration of activity in the H-reflex pathway may be part of the control strategy required for locomotor-related skill acquisition.
脊髓具有依赖活动的可塑性，但其参与人类运动学习的程度尚不清楚。在此，我们检验了这样一个假设，即获得与运动相关的技能会调节H反射通路，H反射是脊髓兴奋性的一种测量指标，容易发生可塑性变化。
尽管踏板阻力频繁变化，但仍测试受试者在卧式自行车上建立恒定骑行速度的能力。速度变异系数（CV（速度））衡量了他们获得这项技能的能力（随着训练，CV（速度）降低反映了表现的提高）。在骑行前后静息状态下记录比目鱼肌H反射。
与涉及恒定踏板阻力和较少补偿的训练相比，在涉及频繁踏板阻力变化且需要校准运动补偿动作的骑行训练后，建立目标速度的能力提高得更多，H反射大小降低得更多。表现改善的程度与H反射幅度的降低相关。
尽管踏板阻力变化，但熟练建立恒定骑行速度与脊髓通路活动的持续调节有关。
H反射通路活动的重新校准可能是获得与运动相关技能所需控制策略的一部分。
