Biozentrum, Department of Cell Biology, University of Basel, 4056 Basel, Switzerland.
Nature. 2011 Oct 19;479(7371):61-6. doi: 10.1038/nature10538.
Walking is a key motor behaviour of limbed animals, executed by contraction of functionally antagonistic muscle groups during swing and stance phases. Nevertheless, neuronal circuits regulating the activation of antagonistic extensor-flexor muscles remain poorly understood. Here we use monosynaptically restricted trans-synaptic viruses to elucidate premotor anatomical substrates for extensor-flexor control in mice. We observe a medio-lateral spatial segregation between extensor and flexor premotor interneurons in the dorsal spinal cord. These premotor interneuron populations are derived from common progenitor domains, but segregate by timing of neurogenesis. We find that proprioceptive sensory feedback from the periphery is targeted to medial extensor premotor populations and is required for extensor-specific connectivity profiles during development. Our findings provide evidence for a discriminating anatomical basis of antagonistic circuits at the level of premotor interneurons, and point to synaptic input and developmental ontogeny as key factors in the establishment of circuits regulating motor behavioural dichotomy.
行走是四肢动物的一项重要运动行为，通过在摆动和支撑阶段收缩功能拮抗的肌肉群来实现。然而，调节拮抗伸肌-屈肌肌肉激活的神经元回路仍知之甚少。在这里，我们使用单突触限制的跨突触病毒来阐明小鼠伸肌-屈肌控制的运动前解剖学基质。我们观察到背脊髓中伸肌和屈肌运动前神经元在中侧空间上的分离。这些运动前神经元群体来源于共同的祖细胞区域，但通过神经发生的时间来分离。我们发现来自外周的本体感觉反馈被靶向到内侧伸肌运动前神经元群体，并且在发育过程中对于伸肌特异性连接模式是必需的。我们的发现为拮抗回路在运动前神经元水平上的区分性解剖基础提供了证据，并指出突触输入和发育发生是调节运动行为二分法的电路建立的关键因素。
