Viala D, Viala G, Jordan M
Institut des Neurosciences-CNRS-URA 9, Faculté des Sciences Mirande, Dijon, France.
Exp Brain Res. 1991;84(1):177-86. doi: 10.1007/BF00231773.
In decorticate, unanaesthetized and curarized rabbit preparations displaying spontaneous fictive locomotor sequences, the firing pattern of neurones was recorded extracellularly in the L6-S1 spinal cord. These neurones, located in the intermediate part of the cord, were not invaded by antidromic stimulation of the hindlimb muscle nerves and thus were considered as interneurones (or propriospinal or tract cells ascending to the brain). When compared to the output from the ipsilateral muscle nerves, these neurones were classified as flexor (F INs) or extensor (E INs) according to the phase of the locomotor cycle when they displayed their maximal firing rate. Among 69 F INs, 33 maintained tonic firing during the periods between episodes of locomotor activity. Their maximal firing rate was in phase with the flexor efferent bursts of the locomotor sequence; during the extensor phase, they maintained an instantaneous frequency (i.f.) that was clearly above the resting i.f. Of these neurones, six became completely silent during the initial flexorextensor coactivation that opened the sequence (F1 neurones) whereas the 27 others increased their firing rate at that time (F2 neurones). The other neurones (36 F3) were silent between the locomotor episodes. Although most of them had a rhythmic activity limited to the flexor bursts, some fired throughout locomotor sequence with a maximal rate during flexor bursts. All the 123 E neurones completely stopped firing during the flexor phase. As was the case for F3 neurone firing, E3 neurone firing (34 neurones) occurred only during periods of locomotor activity. Among the neurones that displayed tonic activity between locomotor episodes, the E2 neurones (24 from 123) remained at this resting value during the extensor phase whereas the E1 neurones (65 neurones) showed an increased i.f. for all or part of this phase. These data, which suggest an asymmetrical genesis of the flexor and extensor activities in locomotion, need to be supported by further analysis.
在呈现自发虚构运动序列的去皮质、未麻醉且箭毒化的兔实验准备中，在L6 - S1脊髓中细胞外记录神经元的放电模式。这些位于脊髓中间部分的神经元，未被后肢肌肉神经的逆向刺激所激活，因此被视为中间神经元（或上升至脑的脊髓固有神经元或传导束细胞）。与同侧肌肉神经的输出相比，根据这些神经元在运动周期中显示最大放电率的阶段，将它们分类为屈肌（F INs）或伸肌（E INs）。在69个F INs中，33个在运动活动发作之间的时间段保持强直性放电。它们的最大放电率与运动序列的屈肌传出爆发同步；在伸肌阶段，它们保持的即时频率（i.f.）明显高于静息i.f.。在这些神经元中，六个在开启序列的初始屈肌 - 伸肌共同激活期间完全沉默（F1神经元），而其他27个在此时增加了放电率（F2神经元）。其他神经元（36个F3）在运动发作之间是沉默的。尽管它们中的大多数具有仅限于屈肌爆发的节律性活动，但一些在整个运动序列中放电，在屈肌爆发期间具有最大放电率。所有123个E神经元在屈肌阶段完全停止放电。与F3神经元放电情况相同，E3神经元放电（34个神经元）仅在运动活动期间发生。在运动发作之间显示强直性活动的神经元中，E2神经元（123个中的24个）在伸肌阶段保持此静息值，而E1神经元（65个神经元）在该阶段的全部或部分时间显示i.f.增加。这些数据表明运动中屈肌和伸肌活动的不对称起源，需要进一步分析来支持。
