Haridas Carlos, Zehr E Paul
Centre for Neuroscience, University of Alberta, Edmonton, Alberta T6G 2S2, Canada.
J Neurophysiol. 2003 Nov;90(5):2850-61. doi: 10.1152/jn.00531.2003. Epub 2003 Jul 9.
It has been shown that stimulation of cutaneous nerves innervating the hand (superficial radial, SR) and foot (superficial peroneal, SP) elicit widespread reflex responses in many muscles across the body. These interlimb reflex responses were suggested to be functionally relevant to assist in motor coordination between the arms and legs during motor tasks such as walking. The experiments described in this paper were conducted to test the hypothesis that interlimb reflexes were phase-dependently modulated and produced functional kinematic changes during locomotion. Subjects walked on a treadmill while electromyographic (EMG) activity was collected continuously from all four limbs, and kinematic recordings were made of angular changes across the ankle, knee, elbow, and shoulder joints. Cutaneous reflexes were evoked by delivering trains of electrical stimulation pseudorandomly to the SP nerve or SR nerves in separate trials. Reflexes were phase-averaged according to the time of occurrence in the step cycle, and phasic amplitudes and latencies were calculated. For both nerves, significant phase-dependent modulation (including reflex reversals) of interlimb cutaneous reflex responses was seen in most muscles studied. Both SR and SP nerve stimulation resulted in significant alteration in ankle joint kinematics. The results suggest coordinated and functionally relevant reflex pathways from the SP and SR nerves onto motoneurons innervating muscles in nonstimulated limbs during walking, thus extending observations from the cat to that of the bipedal human.
研究表明，刺激支配手部（桡浅神经，SR）和足部（腓浅神经，SP）的皮神经会在全身许多肌肉中引发广泛的反射反应。这些肢体间反射反应被认为在功能上与行走等运动任务中协助手臂和腿部之间的运动协调相关。本文所述的实验旨在检验以下假设：肢体间反射在运动过程中受到相位依赖性调节，并产生功能性运动学变化。受试者在跑步机上行走，同时从四肢连续采集肌电图（EMG）活动，并记录踝关节、膝关节、肘关节和肩关节的角度变化。在单独的试验中，通过向SP神经或SR神经伪随机施加一系列电刺激来诱发皮肤反射。根据步周期中的发生时间对反射进行相位平均，并计算相位幅度和潜伏期。对于这两条神经，在大多数研究的肌肉中都观察到了肢体间皮肤反射反应的显著相位依赖性调节（包括反射反转）。SR和SP神经刺激均导致踝关节运动学的显著改变。结果表明，在行走过程中，从SP和SR神经到支配未受刺激肢体肌肉的运动神经元存在协调且功能相关的反射通路，从而将猫的观察结果扩展到两足人类。
