CENTRAL CONTROL OF MOTONEURONS

不同行为的运动网络之间发生相互作用 常见于包括人类在内的所有脊椎动物。即使这样 相互作用是脊椎动物运动系统的基础，我们知之甚少 它们是如何在细胞水平上发生的。这份提案概述了 旨在填补我们这一知识空白的实验。这部作品使用了一个 具有网状脊髓之间相互作用的金鱼模型系统 节律性运动的路径和脊髓网络非常相似 对于哺乳动物来说，但在一个特别容易受到 细胞研究。这项工作的重点是了解脊髓的作用 运动之间相互作用中的中间神经元和运动神经元 电路。第一个目标将描述所生产的电机输出的特性 在金鱼的逃逸和游动网络之间的相互作用中， 研究相互作用的细胞基础的基础。这个 启动逃逸的网状脊髓神经元莫特纳轴突将是 在虚构的游泳中被点燃，这是由刺激 中脑。这模仿了游泳时发生的逃生。这个 逃生和游泳之间的互动将通过以下方式进行监测 从运动神经细胞外记录检查L)是否 逃生网络可以覆盖和重置游泳网络，2)是否 相互作用取决于游泳周期的阶段，在这个阶段 开始逃避，以及3)(在大脑、脊髓或两者) 相互作用就会发生。AIM 2将使用细胞内记录来 研究AIM L中相互作用的细胞基础。这一目标将 确定游泳共有哪些脊髓运动神经元和中间神经元 以及逃避网络和研究单细胞水平的事件，这可能 解释在两者相互作用期间产生的马达输出 网络。目标3将使用细胞外和细胞内的组合 记录，以及光学和电子显微镜，以确定 运动神经元的种群被识别出的一类 游泳和逃逸网络共有的中间神经元。AIM 4将使用 用于研究水池功能特性的细胞内记录 游泳和逃跑所共享的中间神经元。这一目标将决定 中间神经元的兴奋性是否与系统相关 它与运动神经元的联系有多强。来自四个国家的数据 AIMS将提供有关汽车网络如何在 脊椎动物之间相互作用。它还将解决几个问题 关于不同类型脊髓中间神经元输出的重要问题 运动神经元类型和中间神经元池的功能组织- 对于任何脊椎动物来说都没有解决的问题。因为 Work研究的是马达组织的典型特征 脊椎动物的运动系统，包括人类，它将产生很好的影响 超越了所研究的特定物种、途径和行为。

Interactions between motor networks for different behaviors occur frequently in all vertebrates including humans. Even though such interactions are fundamental to vertebrate motor systems, little is known about how they occur at a cellular level. This proposal outlines experiments designed to fill this gap in our knowledge. The work uses a goldfish model system that has interactions between a reticulospinal pathway and a spinal network for rhythmic movement that are very similar to those in mammals, but in a system in that is especially amenable to cellular studies. The work focuses on understanding the role of spinal interneurons and motoneurons in the interactions between the motor circuits. The first aim will characterize the motor output produced during interactions between escape and swimming networks in goldfish, as a foundation for studies of the cellular basis of the interactions. The Mauthner axon, a reticulospinal neuron which initiates the escape, will be fired in the midst of fictive swimming produced by stimulation of the midbrain. This mimics an escape that occurs during swimming. The interactions between escape and swimming will be monitored by extracellular recordings from motor nerves to examine l) whether the escape networks can override and reset swimming networks, 2) whether the interactions depend on the phase of the swimming cycle during which an escape is initiated, and 3) where (in the brain, the spinal cord or both) the interactions take place. Aim 2 will use intracellular recording to study the cellular basis of the interactions in aim l. This aim will determine what spinal motoneurons and interneurons are shared by swimming and escape networks and study events at the single cell level that might explain the motor output produced during interactions between the two networks. Aim 3 will use a combination of extracellular and intracellular recording, and light and electron microscopy, to determine what populations of motoneurons are excited by an identified class of interneuron shared by swimming and escape networks. Aim 4 will use intracellular recording to study the functional characteristics of a pool of interneurons shared by swimming and escape. This aim will determine whether the excitability of an interneuron is related in a systematic way to the strength of its connections to motoneurons. The data from the four aims will provide fundamental, new information about how motor networks in vertebrates interact with one another. It will also address several important questions about the output of spinal interneurons to different motoneuron types and the functional organization of interneuron pools - questions that have not been addressed for any vertebrate. Because the work deals with features of motor organization that are typical of all vertebrate motor systems, including humans, it will have implications well beyond the specific species, pathways, and behaviors studied.