Nielsen J, Crone C, Sinkjaer T, Toft E, Hultborn H
Department of Medical Informatics and Image Analysis, Aalborg University, Denmark.
Exp Brain Res. 1995;104(1):99-106. doi: 10.1007/BF00229859.
The size of the soleus Hoffmann reflex (H-reflex) was measured in six healthy human subjects before and after transmission in the common peroneal nerve (CPN) was blocked reversibly by local injection of lidocaine. It was found that the H-reflex at rest increased after the block. When the subjects attempted to perform a dorsiflexion while the CPN was blocked ("fictive dorsi flexion"), the soleus H-reflex was strongly depressed. Stimulation of the CPN proximal to the block elicited a short-latency inhibition of the soleus H-reflex, which was probably mediated by reciprocal Ia interneurones. This inhibition never increased during dorsiflexion relative to rest prior to the CPN block, but after the block a significant increase in inhibition was seen during fictive dorsiflexion in three subjects. Stimulation of the femoral nerve (FN) elicited a short-latency monosynaptic Ia facilitation of the soleus H-reflex. This facilitation was found to decrease during dorsiflexion relative to rest before the block as well as during fictive dorsiflexion after the block. The decrease in the H-reflex during fictive dorsiflexion demonstrates that although an increased Ia-afferent feedback via the gamma-loop may contribute to reciprocal inhibition when transmission in the CPN is intact, a noticeable, centrally mediated inhibition may occur in the absence of this feedback. It is suggested that this inhibition is caused by central facilitation of interneurones mediating disynaptic Ia inhibition as well as interneurones mediating presynaptic inhibition of Ia afferents.
在六名健康人体受试者中，通过局部注射利多卡因可逆性阻断腓总神经（CPN）传导前后，测量了比目鱼肌霍夫曼反射（H反射）的大小。结果发现，阻断后静息时的H反射增强。当受试者在CPN阻断时试图进行背屈（“假想背屈”）时，比目鱼肌H反射强烈抑制。在阻断部位近端刺激CPN可引起比目鱼肌H反射的短潜伏期抑制，这可能是由Ia类交互神经元介导的。相对于CPN阻断前的静息状态，这种抑制在背屈过程中从未增强，但在阻断后，三名受试者在假想背屈过程中抑制作用显著增强。刺激股神经（FN）可引起比目鱼肌H反射的短潜伏期单突触Ia类易化。发现这种易化在阻断前相对于静息状态的背屈过程中以及阻断后假想背屈过程中均降低。假想背屈过程中H反射的降低表明，尽管在CPN传导完整时，通过γ-环路增加的Ia传入反馈可能有助于交互抑制，但在没有这种反馈的情况下，可能会出现明显的中枢介导抑制。提示这种抑制是由介导双突触Ia抑制的中间神经元以及介导Ia传入突触前抑制的中间神经元的中枢易化引起的。
