Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL, USA.
J Clin Neurophysiol. 2012 Jun;29(3):271-7. doi: 10.1097/WNP.0b013e318257c2b7.
The aim of this study was to investigate the function of group Ib inhibition exerted between ankle synergists during assisted stepping in people with chronic motor incomplete spinal cord injury (SCI). During stepping, the soleus (SOL) H-reflex was conditioned by percutaneous stimulation of the medialis gastrocnemius (MG) nerve by a bipolar electrode placed distal and medial to the cathode electrode for the tibial nerve. Stimulation was delivered at 0.95 times MG M-wave motor threshold with a pulse train at short conditioning-test intervals. To counteract movement of recording and stimulating electrodes, a supramaximal stimulus at 80 to 100 milliseconds after the test H-reflex was delivered. Stimuli were randomly dispersed across the step cycle, which was divided into 16 equal bins. The conditioned SOL H-reflex was significantly facilitated throughout the stance phase, while it was depressed during the swing phase when compared with the unconditioned SOL H-reflex. Ankle clonus during the stance phase may have affected the excitability state of spinal motoneuronal and interneuronal circuits, but the presence of group Ib inhibition in the swing phase suggests that in the absence of loading this spinal circuit is modulated in a physiologic manner in human incomplete SCI. Repetitive body loading and unloading promotes functional integration of sensory signals mediating load in human SCI.
本研究旨在探讨慢性运动性不完全性脊髓损伤（SCI）患者辅助步行时踝关节协同肌之间群 Ib 抑制的作用。在步行过程中，通过将双极电极放置在阴极电极的远端和内侧，对腓肠肌内侧（MG）神经进行经皮刺激，从而对比目鱼肌（SOL）H 反射进行条件反射。用短的刺激-测试间隔的脉冲串，以 MG M 波运动阈值的 0.95 倍刺激。为了抵消记录和刺激电极的运动，在测试 H 反射后 80 到 100 毫秒时，会施加一个最大刺激。刺激随机分布在整个步周期中，步周期被分为 16 个相等的区间。与未条件反射的 SOL H 反射相比，在整个站立阶段，条件反射的 SOL H 反射明显得到增强，而在摆动阶段则受到抑制。站立阶段的踝阵挛可能会影响脊髓运动神经元和中间神经元回路的兴奋性状态，但摆动阶段存在群 Ib 抑制表明，在没有负荷的情况下，该脊髓回路以生理方式在人类不完全性 SCI 中被调节。反复的身体加载和卸载促进了人类 SCI 中介导负荷的感觉信号的功能整合。
