Perrier J F, Lamotte D'Incamps B, Kouchtir-Devanne N, Jami L, Zytnicki D
Centre National de la Recherche Scientifique EP 1848, Université René Descartes, Unité de Formation et de Recherche Biomédicale, 75270 Paris 06, France.
J Neurophysiol. 2000 Jun;83(6):3201-8. doi: 10.1152/jn.2000.83.6.3201.
Peroneal motoneurons were recorded intracellularly in anesthetized cats during sustained submaximal contractions of peroneus brevis muscle (PB) elicited by repetitive electrical stimulation of motor axons in the distal portion of cut ventral root filaments. Mechanical stimulation of the territory innervated by the superficial peroneal nerve (SP) was applied during contraction to assess the influence of afferents from this territory on the contraction-induced excitation of motoneurons. In 21 peroneal motoneurons in which PB contraction evoked excitatory potentials, a stimulation engaging mechanoreceptors located in the skin around toes was found to either enhance (in 12 motoneurons) or reduce (in 9 motoneurons) the contraction-induced excitatory potentials. Among positive effects, six showed simple summation of the responses to each individual stimulus, suggesting a convergence of afferent pathways on motoneurons. In six other motoneurons, complex interactions were observed, as may result from convergence at a premotoneuronal level. Among negative effects, a single instance was observed of inhibitory facilitation, as may result from convergence of cutaneous and muscular, possibly Ib, afferents on inhibitory interneurons. Several pathways, mediating either facilitory or inhibitory influences, are available for cooperation of muscle and cutaneous input, allowing flexibility of motoneuron activation in different tasks.
在麻醉猫身上，通过对切断的腹根细丝远端的运动轴突进行重复性电刺激，诱发腓骨短肌（PB）持续的次最大收缩，在此期间细胞内记录腓骨运动神经元。在收缩过程中，对腓浅神经（SP）支配区域进行机械刺激，以评估该区域传入神经对运动神经元收缩诱导兴奋的影响。在21个PB收缩诱发兴奋性电位的腓骨运动神经元中，发现刺激位于脚趾周围皮肤的机械感受器，要么增强（12个运动神经元），要么降低（9个运动神经元）收缩诱导的兴奋性电位。在产生积极作用的情况中，6个表现出对每个单独刺激的反应简单叠加，表明传入通路在运动神经元上汇聚。在另外6个运动神经元中，观察到复杂的相互作用，这可能是运动神经元前水平汇聚的结果。在产生消极作用的情况中，观察到一个抑制易化的例子，这可能是皮肤和肌肉（可能是Ib类）传入神经在抑制性中间神经元上汇聚的结果。有几种介导促进或抑制影响的通路，可用于肌肉和皮肤输入的协同作用，从而在不同任务中实现运动神经元激活的灵活性。
