Modelling spinal circuitry involved in locomotor pattern generation: insights from deletions during fictive locomotion
Modelling spinal circuitry involved in locomotor pattern generation: insights from deletions during fictive locomotion
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DOI：
10.1113/jphysiol.2006.118703
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发表时间：
2006-12-01
影响因子：
5.5
通讯作者：
McCrea, David A.
中科院分区：
文献类型：
--
作者：
Rybak, Ilya A.;Shevtsova, Natalia A.;McCrea, David A.
哺乳动物的脊髓含有一个运动中枢模式发生器（CPG），它可以在缺乏节律输入和本体感受反馈的情况下产生屈肌和伸肌运动神经元的交替节律活动。在这种虚构的自发活动在去大脑猫，自发遗漏的活动同时发生在多个激动剂运动神经元池的一些周期。在这些“删除”，拮抗剂运动神经元池通常成为紧张性活动，但也可能继续有节奏。缺失后重新出现的节律活动通常不会发生相移。这表明当运动神经元活动丧失时，某些神经元机制可以维持运动期。为了解释这些观察结果，一个简化的计算模型的脊髓电路已被开发，其中的运动CPG由两个级别：一个半中心的节奏发生器（RG）和模式形成（PF）的网络，在每个级别的拮抗剂神经种群之间的相互抑制的相互作用。该模型代表了一个网络的相互作用的神经种群与单个interneurones和运动神经元描述的霍奇金-赫胥黎风格。该模型再现的范围内的运动周期和相位持续时间观察到在成年猫的真实的运动，并允许独立控制的运动神经元的活动水平和步骤周期定时。通过改变PF网络内神经群体的兴奋性，该模型可以再现运动神经元活动失败但运动振荡的相位保持的缺失。该模型还提出了参与哺乳动物运动模式生成的脊髓间神经元的功能鉴定标准。
The mammalian spinal cord contains a locomotor central pattern generator (CPG) that can produce alternating rhythmic activity of flexor and extensor motoneurones in the absence of rhythmic input and proprioceptive feedback. During such fictive locomotor activity in decerebrate cats, spontaneous omissions of activity occur simultaneously in multiple agonist motoneurone pools for a number of cycles. During these 'deletions', antagonist motoneurone pools usually become tonically active but may also continue to be rhythmic. The rhythmic activity that re-emerges following a deletion is often not phase shifted. This suggests that some neuronal mechanism can maintain the locomotor period when motoneurone activity fails. To account for these observations, a simplified computational model of the spinal circuitry has been developed in which the locomotor CPG consists of two levels: a half-centre rhythm generator (RG) and a pattern formation (PF) network, with reciprocal inhibitory interactions between antagonist neural populations at each level. The model represents a network of interacting neural populations with single interneurones and motoneurones described in the Hodgkin-Huxley style. The model reproduces the range of locomotor periods and phase durations observed during real locomotion in adult cats and permits independent control of the level of motoneurone activity and of step cycle timing. By altering the excitability of neural populations within the PF network, the model can reproduce deletions in which motoneurone activity fails but the phase of locomotor oscillations is maintained. The model also suggests criteria for the functional identification of spinal interneurones involved in the mammalian locomotor pattern generation.