Patterns of locomotor drive to motoneurons and last-order interneurons: Clues to the structure of the CPG
Patterns of locomotor drive to motoneurons and last-order interneurons: Clues to the structure of the CPG
复制标题
DOI：
10.1152/jn.2001.86.1.447
复制
发表时间：
2001-07-01
影响因子：
2.5
通讯作者：
Simon, ES
中科院分区：
文献类型：
--
作者：
Burke, RE;Degtyarenko, AM;Simon, ES
我们研究了几个后肢运动池的活动模式与未麻醉的失智猫在有效运动期间的少突触皮肤反射通路的调节之间的联系，以评估这种联系可以揭示运动中枢模式发生器（CPG）的结构。我们将注意力集中在投射到指长屈肌运动池的皮肤反射通路上，因为该肌肉在猫的正常和有效运动中具有独特的可变行为。从腓浅皮传入神经和足底内侧传入神经到FDL运动神经元的低阈值通路中，末级兴奋性中间神经元的差异运动控制首次得到了充分的证明。差异控制的定性模式显示，无论FDL肌肉在通常发现的早期屈曲阶段活跃，还是在有效运动的伸展阶段活跃，这在有效行走期间不太常见，都保持不变。运动池活动和反射通路调节的模式表明，有效运动屈曲阶段有明显的早期和晚期成分。在“正常”和“不寻常”模式下的观察表明，运动模式形成的某些方面可以与节奏产生分离，这意味着这两种CPG功能可能至少部分地体现在不同的神经组织中。结果讨论了与一个临时电路图，可以解释实验结果。
We have examined the linkage between patterns of activity in several hindlimb motor pools and the modulation of oligosynaptic cutaneous reflex pathways during fictive locomotion in decerebrate unanesthetized cats to assess the notion that such linkages can shed light on the structure of the central pattern generator (CPG) for locomotion. We have concentrated attention on the cutaneous reflex pathways that project to the flexor digitorum longus (FDL) motor pool because of that muscle's unique variable behavior during normal and fictive locomotion in the cat. Differential locomotor control of last-order excitatory interneurons in pathways from low-threshold cutaneous afferents in the superficial peroneal and medial plantar afferents to FDL motoneurons is fully documented for the first time. The qualitative patterns of differential control are shown to remain the same whether the FDL muscle is active in early flexion, as usually found, or during the extension phase of fictive locomotion, which is less common during fictive stepping. The patterns of motor pool activity and of reflex pathway modulation indicate that the flexion phase of fictive locomotion has distinct early versus late components. Observations during "normal" and unusual patterns of fictive stepping suggest that some aspects of locomotor pattern formation can be separated from rhythm generation, implying that these two CPG functions may be embodied, at least in part, in distinct neural organizations. The results are discussed in relation to a provisional circuit diagram that could explain the experimental findings.