STRUCTURE AND PHYSIOLOGY OF PREMOTOR LOCAL INTERNEURONS

目标是了解神经元如何在模式生成电路中 功能和有助于有序的运动。 局部中间神经元是 大脑中最丰富的神经元，但因为它们很小， 为了记录，人们对它们的生理特征知之甚少。 一 已经发现了一小部分无轴突、无尖峰的局部中间神经元， 小龙虾是神经回路的一部分， 游泳运动 这些中间神经元是可识别的， 允许实验探索它们的生理特性， 突触相互作用 我们提出了三个项目，将描述如何 这些非尖峰的局部中间神经元有助于游泳节律。 为了测试这些中间神经元在产生swimmeret中的作用， 运动时，单个中间神经元将受到干扰或消融， 神经系统正在产生游泳节律。 的膜 中间神经元将被钳位到不同的电位， 单电极电压钳控制其释放变送器。 将通过光灭活消融单个中间神经元。 比较 在电压箝位之前和期间产生的电机模式，或者 在消融之前和之后，将揭示这些 在他们自己的电路和整个运动模式的中间神经元 动物 为了检验假设，非尖峰局部中间神经元是运动前， 生理上远离感觉输入，成对的识别出的 运动神经元、感觉神经元和中间神经元将被注射 荧光黄和HRP，然后研究，以描述和计数其点 接触。 对于EM，将对表观接触区域进行薄切片， 找到任何突触 为了分析这些中间神经元如何整合突触电流，我们将 在详细的分区中描述它们的无源电气结构 通过结合它们的脉冲响应和阶跃响应的测量来建立模型 仔细测量它们的解剖结构 的预测 将使用单电极电压钳对该型号的 测量已知来源的突触电流和突触电位。 这 分析将检验突触整合的“亚单位” 存在于这些树枝状结构中。

The goal is to understand how neurons in pattern-generating circuits function and contribute to orderly movements. Local interneurons are the most abundant neurons in brains, but because they are small and difficult to record, little is known about their physiological characteristics. A small set of axonless, nonspiking local interneurons has been discovered in the crayfish that is part of the neural circuits that generate rhythmic swimming movements. These interneurons are identifiable, and large enough to permit experiments that explore their physiological properties and synaptic interactions. We propose three projects that will describe how these nonspiking local interneurons contribute to the swimmeret rhythm. To test the role of these interneurons in generating the swimmeret movements, individual interneurons will be perturbed or ablated while the nervous system is generating the swimmeret rhythm. The membranes of interneurons will be clamped to different potentials with a single-electrode voltage clamp to control their release of transmitter. Individual interneurons will be ablated by photoinactivation. Comparisons of the motor patterns generated before and during the voltage clamp or before and after ablation will reveal the contribution of these interneurons to the motor pattern in their own circuit and in the whole animal. To test the hypothesis that nonspiking local interneurons are premotor, and physiologically remote from sensory input, pairs of identified motorneurons, sensory neurons and interneurons will be injected with Lucifer yellow and HRP and then studied to describe and count their points of contact. Regions of apparent contact will be thin-sectioned for EM to locate any synapses. To analyze how these interneurons integrate synaptic currents, we will describe their passive electrical structure in a detailed compartmental model by combining measurements of their pulse-responses and step-responses with careful measurements of their anatomical structure. The predictions of this model will be tested with a single-electrode voltage clamp to measure synaptic currents and synaptic potentials from known sources. This analysis will test the hypothesis that "subunits" of synaptic integration exist in these dendritic structures.