Post-activation depression of Soleus stretch reflexes in healthy and spastic humans
Post-activation depression of Soleus stretch reflexes in healthy and spastic humans
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DOI：
10.1007/s00221-007-1142-6
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发表时间：
2008-02-01
影响因子：
2
通讯作者：
Nielsen, Jens B.
中科院分区：
文献类型：
--
作者：
Grey, Michael J.;Klinge, Klaus;Nielsen, Jens B.
先前激活后Ia传入神经递质释放的抑制减少（激活后抑制）被认为与痉挛的病理生理有关。然而，这种机制对肌张力反射的影响及其对痉挛参与者反射兴奋性增加的可能贡献尚未得到测试。为了研究这些影响，我们研究了激活后抑郁症的比目鱼肌H反射反应和机械诱发的比目鱼肌牵张反射反应。牵张反射反应与连续背屈扰动在不同的时间间隔提供。牵张反射和踝关节扭矩反应的幅度作为扰动之间的时间的函数进行评估。比目鱼肌牵张反射以恒定速度（175度/）和振幅（6度）跖屈扰动诱发。比目鱼肌H反射是通过电刺激腘窝中的胫神经而诱发的。30名痉挛参与者（多发性硬化症或脊髓损伤）的牵张反射和H反射反应与15名健康参与者进行了比较。在健康的参与者中，比目鱼肌牵张反射和H反射的幅度随着刺激/扰动之间的间隔减小而减小。同样地，牵张诱发的扭矩降低。在痉挛参与者中，反射和牵张诱发扭矩的激活后抑制显著小于健康参与者。这些研究结果表明，激活后抑郁症是一个重要的因素，在评估牵张反射的兴奋性和肌肉僵硬痉挛，他们加强的假设，减少激活后抑郁症在痉挛的病理生理学中发挥作用。
Reduced depression of transmitter release from Ia afferents following previous activation (post-activation depression) has been suggested to be involved in the pathophysiology of spasticity. However, the effect of this mechanism on the myotatic reflex and its possible contribution to increased reflex excitability in spastic participants has not been tested. To investigate these effects, we examined post-activation depression in Soleus H-reflex responses and in mechanically evoked Soleus stretch reflex responses. Stretch reflex responses were evoked with consecutive dorsiflexion perturbations delivered at different intervals. The magnitude of the stretch reflex and ankle torque response was assessed as a function of the time between perturbations. Soleus stretch reflexes were evoked with constant velocity (175 degrees/) and amplitude (6 degrees) plantar flexion perturbations. Soleus H-reflexes were evoked by electrical stimulation of the tibial nerve in the popliteal fossa. The stretch reflex and H-reflex responses of 30 spastic participants (with multiple sclerosis or spinal cord injury) were compared with those of 15 healthy participants. In the healthy participants, the magnitude of the soleus stretch reflex and H-reflex decreased as the interval between the stimulus/perturbation was decreased. Similarly, the stretch-evoked torque decreased. In the spastic participants, the post-activation depression of both reflexes and the stretch-evoked torque was significantly smaller than in healthy participants. These findings demonstrate that post-activation depression is an important factor in the evaluation of stretch reflex excitability and muscle stiffness in spasticity, and they strengthen the hypothesis that reduced post-activation depression plays a role in the pathophysiology of spasticity.