Brooke J D, McIlroy W E, Collins D F, Misiaszek J E
Interdepartmental Biophysics Group, University of Guelph, Ont., Canada.
Brain Res. 1995 May 15;679(2):255-60. doi: 10.1016/0006-8993(95)00239-m.
Passive locomotor-like movement induces depression of the gain of a fast conducting spinal sensorimotor path in humans. It was hypothesized that this gain control is mediated through a spinal circuit. In the first experiment, passive pedalling motion was rapidly initiated in eight able bodied subjects. Soleus H-reflexes (used to reveal the gain of the short latency stretch reflex) were recorded over the first 250 ms after the movement started. Significant depression in H-reflex magnitude was observed by 50 ms after the onset of movement. On the basis of the timing, this gain attenuation was likely mediated through a spinal circuit. In a second experiment we tested chronic quadriplegics with clinically complete lesions of the spinal cord. Of five subjects tested, three expressed the reflex and all three showed significant inhibition with passive pedalling movement (mean depression was to 39% of controls). Both the rapid onset of the gain change (Expt. 1) and the presence of movement-induced inhibition in individuals with spinal lesions (Expt. 2) provide evidence that this component of human locomotor control is located in the spinal cord. The initiating source is probably somatosensory receptor discharge due to the movement.
被动的类似运动的动作会导致人类快速传导的脊髓感觉运动通路的增益降低。据推测，这种增益控制是通过脊髓回路介导的。在第一个实验中，对八名身体健全的受试者快速启动被动蹬踏动作。在动作开始后的前250毫秒内记录比目鱼肌H反射（用于揭示短潜伏期牵张反射的增益）。运动开始后50毫秒时观察到H反射幅度显著降低。基于时间，这种增益衰减可能是通过脊髓回路介导的。在第二个实验中，我们测试了患有脊髓临床完全损伤的慢性四肢瘫痪患者。在测试的五名受试者中，三名表现出该反射，并且所有三名受试者在被动蹬踏运动时均表现出显著抑制（平均抑制程度为对照组的39%）。增益变化的快速发生（实验1）以及脊髓损伤个体中存在运动诱导的抑制（实验2）均提供了证据，表明人类运动控制的这一组成部分位于脊髓中。起始来源可能是由于运动引起的躯体感觉受体放电。
