The development of sensorimotor networks in mammals

运动系统在哺乳动物中达到了最高的复杂性，这从它们复杂的运动行为和控制它们的一系列神经结构中得到了证明。运动是由脊髓中引起肌肉收缩的运动神经元产生的，并由神经元间网络协调。位于脊髓颈膨大和腰膨大的中央模式发生器(CPG)分别调节前肢和后肢运动。为了使运动适应外部环境以及动物的内部状态和动机，CPG受到来自外周的感觉输入以及来自其他脊椎水平和大脑的输入的调节。所有这些系统在开发期间是如何到位的，这是我的研究项目的目标。研究哺乳动物运动系统发育的一个主要困难是它们主要是在产前形成的。我们使用了一个原始的哺乳动物模型，负鼠Monodelphis home tica，它在出生时相当于出生前大约一周的啮齿动物胚胎。我们已经开发了他们的神经轴和四肢的体外准备，我们使用解剖学、生理学、药理学和行为学的方法来解决运动发育问题。最近，我们发现三叉神经介导的面部机械感觉输入影响前肢运动。在这里，我们建议研究面部温度感觉和前庭输入对运动发育的影响，并确定它们如何与已知的影响CPG的下行中枢系统整合，如网状结构和一些中脑区域。最后，对于参与机械感觉的嘌呤能受体，我们将详细研究其不同亚型在发育中负鼠头部和神经轴中的表达，并确定每个亚型在运动行为控制中的作用。这一基础研究计划(以前、现在和将来的条款)将使我们彻底了解电机系统在开发过程中是如何到位的，并将为旨在调查再生的研究服务。

Motor systems attain the highest complexity in mammals, as evidenced by the sophistication of their motor behaviors and the array of nervous structures controlling them. Locomotion is produced by motoneurons in the spinal cord that cause muscle contractions and are coordinated by interneuronal networks. The central pattern generators (CPGs) located in the cervical and lumbar enlargements of the spinal cord regulate forelimb and hindlimb movements, respectively. For locomotion to be adapted to the external environment and to the animal’s internal state and motivation, the CPGs are modulated by sensory inputs from the periphery, and inputs from other spinal levels and from the brain. How all these systems are put in place during development is the object of my research program. A major difficulty of investigating motor systems development in mammals is that they form largely prenatally. We use an original mammalian model, the opossum Monodelphis domestica, which at birth corresponds to a rodent embryo of about one week before birth. We have developed in vitro preparations of their neuraxis with the limbs attached on which we use anatomical, physiological, pharmacological and behavioral approaches to address motor development. Recently we have shown that facial mechanosensory inputs mediated by the trigeminal nerve influence forelimb movements. Herein we propose to investigate the influence of facial thermosensation and of vestibular inputs on motor development and to determine how they integrate with descending central systems known to affect the CPGs, such as the reticular formation and some midbrain areas. Finally, purinergic receptors being involved in mechanosensation, we will study in detail the expression of their different subtypes in the head and neuraxis of developing opossums and determine the involvement of each subtype in the control of motor behaviors. This fundamental research program (previous, present and future terms) will give us a thorough understanding of how motor systems are put in place during development and will serve research aimed at investigating regeneration.