CENTRAL CONTROL OF MOTONEURONS

不同行为的运动网络之间会发生相互作用 常见于包括人类在内的所有脊椎动物。即使这种 相互作用是脊椎动物运动系统的基础， 它们是如何在细胞水平上发生的。该提案概述了 旨在填补我们知识空白的实验。作品使用了A 金鱼模型系统，具有网状脊髓之间的相互作用， 有节奏运动的神经通路和脊髓网络 但在一个特别适合于 细胞研究这项工作的重点是了解脊髓的作用， 中间神经元和运动神经元之间的相互作用， 电路. 第一个目标将描述所产生的电机输出 在金鱼的逃避和游泳网络之间的相互作用中， 这是研究相互作用的细胞基础的基础。的 Mauthner轴突，一个启动逃逸的网状脊髓神经元， 在刺激产生的虚构的游泳中发射， 中脑这模仿了游泳时发生的逃跑。的 逃生和游泳之间的相互作用将被监测， 运动神经的细胞外记录，以检查l）是否 逃逸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， 逃避开始，3）在哪里（在大脑，脊髓或两者） 互动发生了。Aim 2将使用细胞内记录， 研究目标l中相互作用的细胞基础。这一目标将 确定哪些脊髓运动神经元和中间神经元是游泳共享的 和逃逸网络，并在单细胞水平上研究可能 解释两者之间相互作用时产生的运动输出 网络.目标3将使用细胞外和细胞内的组合 记录，光学和电子显微镜，以确定 运动神经元的群体被一类确定的 游泳和逃逸网络共享的interneuron。目标4将使用 细胞内记录以研究池的功能特性 游泳和逃跑共享的中间神经元。这一目标将决定 中间神经元的兴奋性是否以系统的方式相关 与运动神经元连接的强度有关。四个数据 aims将提供关于运动网络如何在 脊椎动物之间相互影响。它还将解决几个 关于脊髓中间神经元输出到不同的 运动神经元类型和中间神经元池的功能组织- 这些问题还没有在任何脊椎动物身上得到解决。因为 工作涉及运动组织的特征，这些特征是所有运动组织的典型特征。 包括人类在内的脊椎动物运动系统， 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.