Synaptic Function: Effects of the Nerve Injury, Repair, and Altered Activity

描述（由申请人提供）：本项目的目标是了解神经活动的损伤、再生和改变如何影响突触和网络功能，并探索促进或阻碍恢复的机制。我们的动机是特别的知识，自愿运动仍然受损后，周围神经损伤，即使在成功的神经再生。五个项目，每个项目都由NIH资助的研究者领导，他们为该项目带来了独特的实验专业知识和概念见解，将促进我们对周围神经损伤后脊髓运动回路中突触和细胞发生的变化的基本理解，无论是否有肌肉再神经支配。项目1将应用电生理方法在体内检测脊髓中可能阻止神经再生后感觉运动功能恢复的细胞和网络机制。项目2将研究损伤/再生神经元上抑制性突触的改造在多大程度上改变了它们的特性。用共聚焦显微镜和电子显微镜观察周围神经损伤后运动神经元抑制突触的结构、分子和神经化学组织。可能的改变将在兴奋性突触平行损伤诱发的可塑性和周围再生和肌肉神经再生的进展的背景下进行分析。由此产生的功能特性将通过体内电生理学研究，使用循环和互抑回路作为测试突触。项目3将建立控制神经系统损伤后突触前和突触后活动慢性不匹配导致的突触强度变化的规则。这个目标将使用电压钳技术应用于活动控制的神经肌肉禁令。项目4将研究递质释放的分子机制，以更好地理解损伤如何通过增加突触前量子的大小导致突触强度的增加。用膜片钳法记录正常小鼠和RabSA突变小鼠的简单突触模型（神经肌肉连接）和简单神经元回路模型（培养海马神经元）。项目5将阐明周围神经损伤改变运动神经元亚细胞分布和膜离子通道聚集的机制，并将研究改变的通道定位和特性对神经元固有兴奋性和整合的功能影响。这一目标将把计算模型与共聚焦成像和体内电生理结合起来。这五个项目相互作用，相互增加重要价值，以解决这些复杂的问题，它们通过共享的成像核心进行协调，以一种独立研究项目无法完成的方式取得进展。该项目将产生关于突触和电路适应的新信息，并以这种方式加速发现促进神经创伤恢复的有效方法。

DESCRIPTION (provided by applicant): The goal of this Program Project is to understand how injury, regeneration, and alterations in neural activity affect synaptic and network function and to explore the mechanisms that either promote or impede recovery. We are motivated in particular by knowledge that voluntary movement remains impaired following peripheral nerve injury, even after successful nerve regeneration. Five projects, each led by an NIH funded investigator who brings unique experimental expertise and conceptual insight to the program, will advance our fundamental understanding of the changes that occur in synapses and cells in spinal locomotor circuits following peripheral nerve injury with or without reinnervation of muscle. Project 1 will apply electrophysiological methods in vivo to examine cellular and network mechanisms in the spinal cord suspected of preventing recovery of sensorimotor function following nerve regeneration. Project 2 will examine the extent to which reformation of inhibitory synapses on injured/regenerating neurons alters their properties. The structure, molecular and neurochemical organization of inhibitory synapses on motoneurons axotomized after peripheral nerve injuries will be analyzed with confocal and electron microscopy. Possible alterations will be analyzed in the context of parallel injury-evoked plasticity at excitatory synapses and the progression of peripheral regeneration and muscle reinnervation. The resultant functional properties will be investigated with in vivo electrophysiology using the recurrent and reciprocal inhibitory circuits as test synapses. Project 3 will establish the rules that govern changes in synaptic strength that result from chronic mismatches of pre- and postsynaptic activity following injury to the nervous system. This aim will use voltage-clamp techniques applied to the activity-manipulated neuromuscular injunction. Project 4 will study molecular mechanisms of transmitter release to better understanding of how injury can lead to an increase in synaptic strength via increased size of the presynaptic quantum. A simple model synapse (neuromuscular junction) and a simple model of neuronal circuits (hippocampal neurons in culture) in normal and RabSA mutant mice will be examined using patch-clamp recording. Project 5 will elucidate mechanisms by which peripheral nerve injury alters the sub-cellular distribution and clustering of membrane ion channels on motoneurons, and will examine the functional effects of altered channel localization and properties on intrinsic neuronal excitability and integration. This aim will combine computational modeling with confocal imaging and electrophysiology in vivo. The five projects interact and add significant value to each other to attack these complex problems, and they are coordinated together with a shared Imaging Core to progress in ways that cannot be accomplished by a collection of independent research projects. The Program Project will yield new information about synaptic and circuit adaptations and in this way accelerate discovery of effective means of promoting recovery from neurotrauma.