INPUT-OUTPUT BEHAVIOR OF REAL AND MODEL MOTONEURONS

描述：（摘自申请人摘要） 神经系统的输入输出特性是基于 它的各个神经元 虽然有一些 神经元输入输出行为的经验和分析模型，无 具有普遍的预测价值。 拟议研究的目标 是测试和完善一个神经元的计算机模型， 生物物理特性，是计算上易处理的， 在很宽的范围内精确地再现神经元的输入输出行为 的条件。 拟议的工作将主要涉及实验性 测量突触和注入电流对神经元的影响， 完整猫脊髓α运动神经元的重复放电 结合计算机模拟观察到的行为。 研究设计是基于这样的假设，即一个人的反应 神经元对突触输入的重复放电由三个因素决定 过程：（1）传递突触电流到索马（和 体细胞膜电位的后续变化）;（2）峰间电位 体细胞膜电位的运动轨迹;（3）锋电位间期 电压阈值的轨迹。 项目1旨在研究 注入电流瞬变提前或延迟尖峰的能力 重复放电运动神经元，以量化 尖峰起始的电压阈值。 在项目2中， 尖峰放电的注入电流瞬变将与 这些突触后电位来自三组识别的 突触前神经元 在项目3中，一种新颖的频率匹配范例 将用于比较真实的和模型运动神经元对 缓慢变化的注入电流。 这种方法将在 项目4：大鼠舌下神经运动神经元的体外制备 这种长时间、稳定的细胞内记录和更精确的控制， 细胞外环境是可能的。 在项目5中， 将研究神经调节对神经元输入输出行为的影响 通过比较运动神经元对四种不同输入的反应， 制备：完整巴比妥酸盐麻醉猫;未麻醉 去脑猫;去脑猫在刺激的 中脑运动区;和去脑脊髓猫i. v. 注射肾上腺素能和去甲肾上腺素能前体。 的结果 这些研究将提高我们对 潜在的神经元输入输出行为，也将有助于 人类和慢性动物电生理学解释 从运动神经元的变化推断突触事件的研究 放电

DESCRIPTION: (Taken from applicant's abstract) The integrative function of the nervous system is predicated on the input-output properties of its individual neural elements. Although there are a number of empirical and analytical models of neuronal input-output behavior, none of them has general predictive value. The goal of the proposed research is to test and refine a computer model of a neuron that is based on the biophysical properties, is computationally tractable, and that accurately recreates neuronal input-output behavior over a wide range of conditions. The proposed work will primarily involve experimental measurement of the effects of synaptic and injected currents on the repetitive discharge of alpha motoneurons from the intact cat spinal cord in combination with computer simulation of the observed behaviors. The research design is based on the hypothesis that the response of a repetitively discharging neuron to synaptic input is determined by three processes: (1) the delivery of synaptic current to the soma (and the subsequent change in somatic membrane potential); (2) the interspike trajectory of somatic membrane potential; and (3) the interspike trajectory of voltage threshold. Project 1 is designed to examine the capacity of injected current transients to advance or delay spikes in repetitively discharging motoneurons in order to quantify variation in the voltage threshold for spike initiation. In Project 2, the effects of injected current transients on spike discharge will be compared to those of postsynaptic potentials from three identified sets of presynaptic neurons. In Project 3, a novel frequency matching paradigm will be used to compare the responses of real and model motoneurons to slowly-varying injected currents. This approach will be extended in Project 4 to an in vitro preparation of rat hypoglossal motoneurons in which long, stable intracellular recordings and more precise control of the extracellular environment are possible. In Project 5, neuromodulatory effects on neuronal input-output behavior will be studied by comparing motoneuron responses to selected inputs in four distinct preparations: intact barbiturate-anesthetized cats; unanesthetized decerebrate cats; decerebrate cats during stimulation of the mesencephalic locomotor region; and decerebrate-spinal cats with i.v. injection of serotonergic and noradrenergic precursors. The results of these studies will improve our understanding of the mechanisms underlying neuronal input-output behavior, and will also aid the interpretation of both human and chronic animal electrophysiological studies in which synaptic events are inferred from changes in motoneuron discharge.