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，正如其运动行为的复杂性和控制它们的神经结构阵列所证明的那样。运动是由脊髓中的运动神经元产生的，运动神经元引起肌肉收缩，并由神经元间网络协调。位于脊髓颈段和腰段扩大区的中央模式发生器（CPG）分别调节前肢和后肢的运动。为了使运动适应外部环境和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髓水平和大脑的输入的调节。如何在开发过程中将所有这些系统放在适当的位置是我的研究计划的目标。研究哺乳动物运动系统发育的一个主要困难是它们主要在产前形成。我们使用原始的哺乳动物模型，负鼠Monodelphis南极洲，在出生时对应于出生前一周左右的啮齿动物胚胎。我们已经开发了体外制备的神经轴与四肢连接，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。最近，我们已经表明，面部mechanosensory输入介导的三叉神经影响前肢运动。在这里，我们建议调查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影响CPGs的下行中枢系统整合，如网状结构和一些中脑区域。最后，嘌呤能受体参与机械感觉，我们将详细研究其不同亚型在发育中的负鼠的头部和轴突中的表达，并确定每个亚型参与运动行为的控制。这个基础研究计划（以前，现在和未来的条款）将使我们深入了解运动系统是如何在发展过程中到位，并将服务于旨在调查再生的研究。

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.