从Ia抑制性通路的运动轴突侧支到运动神经元的反复抑制。

Recurrent inhibition from motor axon collaterals of transmission in the Ia inhibitory pathway to motoneurones.

Hultborn H, Jankowska E, Lindström S

J Physiol. 1971 Jul;215(3):591-612. doi: 10.1113/jphysiol.1971.sp009487.

Abstract

The effects of impulses in recurrent motor axon collaterals on reflex transmission from different types of primary afferents to motoneurones were investigated in the cat by conditioning of PSPs evoked in motoneurones.2. IPSPs evoked by volleys in large muscle spindle (Ia) afferents were effectively decreased when preceded by an antidromic stimulation of ventral roots. Some IPSPs from group II muscle afferents and low threshold cutaneous afferents were also slightly depressed, while other PSPs were unaffected.3. The depression of the IPSPs could be evoked by antidromic volleys, which produced neither conductance changes in the motoneurones nor depolarization of Ia afferent terminals.4. The effect on the Ia IPSPs is most likely due to post-synaptic inhibition of the Ia inhibitory interneurones, evoked through alpha-motor axon collaterals and Renshaw cells. The depression of some IPSPs from flexor reflex afferents is explained by a convergence of excitatory effects from these afferents on the Ia inhibitory interneurones.5. The results indicate a selective recurrent control from motor axon collaterals of the interneurones in the reciprocal Ia inhibitory pathway to motoneurones.

摘要

通过对运动神经元中诱发的突触后电位（PSP）进行条件刺激，在猫身上研究了回返性运动轴突侧支冲动对不同类型初级传入纤维至运动神经元的反射传递的影响。
当在腹根进行逆向刺激之前，由大肌梭（Ia）传入纤维的群放电诱发的抑制性突触后电位（IPSP）会有效降低。来自II类肌肉传入纤维和低阈值皮肤传入纤维的一些IPSP也略有降低，而其他PSP则不受影响。
IPSP的抑制可由逆向群放电诱发，这种逆向群放电在运动神经元中既不产生电导变化，也不会使Ia传入纤维终末发生去极化。
对Ia IPSP的影响很可能是由于通过α运动轴突侧支和闰绍细胞诱发的Ia抑制性中间神经元的突触后抑制。来自屈肌反射传入纤维的一些IPSP的降低是由于这些传入纤维对Ia抑制性中间神经元的兴奋作用的汇聚所致。
结果表明，在相互抑制的Ia抑制通路中，运动轴突侧支对中间神经元至运动神经元存在选择性的回返控制。