Crone C, Hultborn H, Mazières L, Morin C, Nielsen J, Pierrot-Deseilligny E
Department of Neurophysiology, Panum Institute, University of Copenhagen, Denmark.
Exp Brain Res. 1990;81(1):35-45. doi: 10.1007/BF00230098.
In parallel experiments on humans and in the cat it was investigated how the sensitivity of monosynaptic test reflexes to facilitation and inhibition varies as a function of the size of the control test reflex itself. In man the monosynaptic reflex (the Hoffmann reflex) was evoked in either the soleus muscle (by stimulation of the tibial nerve) or the quadriceps muscle (by stimulation of the femoral nerve). In the decerebrate cat monosynaptic reflexes were recorded from the nerves to soleus and medial gastrocnemius muscles; they were evoked by stimulation of the proximal ends of the sectioned L7 and S1 dorsal roots. Various excitatory and inhibitory spinal reflex pathways were used for conditioning the test reflexes (e.g. monosynaptic Ia excitation, disynaptic reciprocal inhibition, cutaneous inhibition, recurrent inhibition, presynaptic inhibition of the Ia fibres mediating the test reflex). It was shown that the additional number of motoneurones recruited in a monosynaptic test reflex by a constant excitatory conditioning stimulus was very much dependent on the size of the test reflex itself. This dependency had the same characteristic pattern whatever the conditioning stimulus. With increasing size of the test reflex the number of additionally recruited motoneurones first increased, then reached a peak (or plateau) and finally decreased. A similar relation was also seen with inhibitory conditioning stimuli. The basic physiological factors responsible for these findings are discussed. Finally, the implications for the interpretation of experiments in man with the H-reflex technique are considered.
在针对人类和猫的平行实验中，研究了单突触测试反射对易化和抑制的敏感性如何随对照测试反射本身的大小而变化。在人类中，通过刺激胫神经在比目鱼肌中诱发单突触反射（霍夫曼反射），或通过刺激股神经在股四头肌中诱发。在去大脑的猫中，从比目鱼肌和内侧腓肠肌的神经记录单突触反射；通过刺激切断的L7和S1背根的近端来诱发。使用各种兴奋性和抑制性脊髓反射通路来对测试反射进行条件化（例如单突触Ia兴奋、双突触交互抑制、皮肤抑制、回返抑制、介导测试反射的Ia纤维的突触前抑制）。结果表明，由恒定的兴奋性条件刺激在单突触测试反射中额外募集的运动神经元数量非常依赖于测试反射本身的大小。无论条件刺激如何，这种依赖性都具有相同的特征模式。随着测试反射大小的增加，额外募集的运动神经元数量首先增加，然后达到峰值（或平台期），最后减少。在抑制性条件刺激下也观察到类似的关系。讨论了导致这些发现的基本生理因素。最后，考虑了对用H反射技术进行人体实验解释的影响。
