Mechanisms controlling the expression of a rhythmic behavior

有节奏的行为产生对于运动和呼吸等活动是必不可少的。这些系统的中断可能会导致即使是简单任务的执行也会出现困难。因此，人们对节律行为背后的机制进行了广泛的研究。行为启动和振荡产生等领域在几个物种中都得到了很好的理解。然而，关于节律行为持续时间控制的信息很少。神经系统如何能够保持产生持续行为所必需的高水平兴奋？这项建议通过测试新的游泳维持模型来检查药用水蚤中有节奏的游泳的维持。这个模型基于初步的和已发表的数据，提出了多个级别的控制协同工作以维持游泳。在尾侧中体神经节中发现了一种新的细胞“OM”，其持续兴奋可无限期地延长游泳时间。在尾侧脑中，已经鉴定出几个细胞，它们的抑制似乎是长时间游泳所必需的，它们的兴奋有助于游泳的终止。尖电极电生理学将被用来对这些新型游泳控制神经元的功能、细胞和电路特性进行分类。我们对水蚤游泳网络中细胞间连接的详细了解使其成为计算机建模的极佳系统。通过实验获得的数据将被输入到NeuroDynamix II程序中，以测试游泳维护模型是否确实能够解释游泳维护。这项拟议研究的完成将增加我们对神经系统如何维持有节奏的行为的理解，为更复杂物种的行为维持研究奠定基础。此外，这项提议将填补原本特征良好的水蛭游泳系统的一个重要空白，该系统可用于研究其他领域，如脉冲编码、学习和记忆、行为选择和设计神经假体设备。

Rhythmic behavior production is essential for activities such as locomotion and breathing. A disruption to these systems can cause difficulties in executing even simple tasks. For this reason, extensive research has focused on the mechanisms behind rhythmic behaviors. Areas such as behavior-initiation and oscillation production are well understood in several species. However, there is a paucity of information regarding control of rhythmic behavior duration. How are nervous systems able to maintain the high level of excitation necessary to generate a sustained behavior? This proposal examines the maintenance of rhythmic swimming in the medicinal leech by testing the novel Swim-Maintenance Model. This model, based on preliminary and published data, proposes that multiple levels of control work in concert to sustain swimming. A novel cell, "OM", has been identified in a caudal midbody ganglion whose sustained excitation prolongs swimming indefinitely. In the caudal brain, several cells have been identified whose inhibition appears to be necessary for prolonged swimming, and whose excitation contributes to swim-termination. Sharp-electrode electrophysiology will be employed to classify the functional, cellular and circuit properties of these novel swim-control neurons. Our detailed knowledge of the cell-to-cell connections in leech swim-networks makes it an excellent system for computer modeling. Experimentally obtained data will be entered into the Neurodynamix II program to test if the Swim- Maintenance Model can, indeed, account for swim-maintenance. Completion of the proposed research will increase our understanding of how nervous systems sustain rhythmic behavior, forming a foundation for research on behavior maintenance in more complex species. Additionally, this proposal will fill an important gap in an otherwise well-characterized leech swim-system that can be used to study other areas such as spike coding, learning and memory, behavioral choice and in designing neuro-prosthetic devices.