REVERSAL OF THE INFLUENCE OF GROUP IB AFFERENTS FROM PLANTARIS ON ACTIVITY IN MEDIAL GASTROCNEMIUS-MUSCLE DURING LOCOMOTOR-ACTIVITY
REVERSAL OF THE INFLUENCE OF GROUP IB AFFERENTS FROM PLANTARIS ON ACTIVITY IN MEDIAL GASTROCNEMIUS-MUSCLE DURING LOCOMOTOR-ACTIVITY
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DOI：
10.1152/jn.1993.70.3.1009
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发表时间：
1993-09-01
影响因子：
2.5
通讯作者：
COLLINS, DF
中科院分区：
文献类型：
--
作者：
PEARSON, KG;COLLINS, DF
1.在可乐定治疗的急性和慢性脊髓猫中诱发节律性运动活动，并检查刺激来自跖肌的I组传入对内侧腓肠肌（MG）运动神经元爆发的时间和幅度的影响.运动节奏夹带时，组I传入的足底神经电刺激与列车的刺激率以上和以下的固有频率的节奏活动。在夹带率高于固有频率，突发的活动在同侧MG运动神经元开始约40毫秒后，每个刺激列车的发病。在较低的夹带率的MG爆发的开始之前的刺激序列的开始，每个刺激序列有一个兴奋效应的MG爆发的潜伏期在30 - 50 ms的范围内。一个类似的兴奋效应时，刺激序列被触发后，在一个预设的延迟MG爆发的内源性产生。跖I组传入的MG运动神经元的兴奋作用，只看到在运动活动期间。在没有节律活动的情况下，相同的刺激序列减少了MG运动神经元中任何正在进行的紧张性活动。振动跖肌优先激活组la传入既不夹带运动节律，也不增加MG爆发的幅度。我们的结论是，在运动活动期间，来自跖肌的Ib组传入神经的输入对产生伸肌爆发的中间神经元系统具有兴奋作用，即，在中央节律发生器的伸肌半中心。这一发现的一个功能含义是，从足底肌肉中的力敏感Ib传入的反馈功能，以加强活动的踝伸肌的产生在步行的站立阶段。
1. Rhythmic locomotor activity was evoked in clonidine-treated acute and chronic spinal cats, and the effect of stimulating group I afferents from the plantaris muscle on the timing and magnitude of bursts in medial gastrocnemius (MG) motoneurons was examined.2. The locomotor rhythm was entrained when group I afferents in the plantaris nerve were electrically stimulated with trains of stimuli presented at rates above and below the intrinsic frequency of the rhythmic activity. During entrainment at rates higher than the intrinsic frequency, a burst of activity in ipsilateral MG motoneurons was initiated approximately 40 ms after the onset of each stimulus train. At lower rates of entrainment the onset of MG bursts preceded the onset of the stimulus trains, and each stimulus train had an excitatory effect on the MG burst with a latency in the range of 30-50 ms. A similar excitatory effect was observed when the stimulus trains were triggered at a preset delay after the endogenous generation of the MG bursts.3. The excitatory action of plantaris group I afferents on the MG motoneurons was only seen during periods of locomotor activity. In the absence of rhythmic activity, the same stimulus trains reduced any ongoing tonic activity in MG motoneurons.4. Vibration of the plantaris muscle to preferentially activate group la afferents neither entrained the locomotor rhythm nor increased the magnitude of the MG bursts.5. We conclude that during locomotor activity, input from group Ib afferents of the plantaris muscle has an excitatory action on the system of interneurons generating the extensor bursts, i.e., on the extensor half-center of the central rhythm generator. One functional implication of this finding is that feedback from the force-sensitive Ib afferents in the plantaris muscle functions to reinforce the generation of activity in the ankle extensor muscles during the stance phase of walking.