COMPETITION BETWEEN AXONS AT THE NEUROMUSCULAR JUNCTION

几条证据表明，病毒的数量和分布 突触后细胞上的轴突接触受竞争性调节 发育过程中轴突之间的相互作用。的目的是为了更好地 了解规范这一竞争的发展战略。 这些研究将利用几种新开发的技术来 光照下活体标本中突触终末的可视化 显微镜。 正常情况下发生的轴突数量的竞争性减少 在给突触后细胞神经支配之后，将观察到 通过活动依赖示踪剂以一种新的方式显示不同的轴突 领悟。在下列任何一种情况下短暂激活运动轴突 几种不同颜色的荧光分子选择性地填充 带有示踪剂的轴突的突触终末。通过刺激不同的 轴突在不同颜色的探针存在下，精确分布 可以描述不同轴突的突触终末。这很简单 和强大的技术将被用来描述正常发生的 支配肌肉纤维的轴突数量的竞争性减少 在蛇和哺乳动物中都有。 第二个目标是从解剖学和电生理学的角度研究 随着时间的推移，随着突触重构的发生，相同的神经末梢也在发生。 之前未使用过的荧光探针选择性染色的发现 哺乳动物运动神经末梢几乎没有毒性， 低背景首次允许同一图像的多个视图 哺乳动物在不同时间点的交界处。这种荧光分子 将用于监测突触连接的重组 活体小鼠在肌肉期间的单个哺乳动物神经肌肉连接 神经再支配。研究生活终端的突触竞争将 提供有关突触动态方面的直接信息 重塑--这是一个人们知之甚少的话题，大概是 一些最重要的长期神经变化的基础 系统(例如，学习和记忆)。

Several lines of evidence indicate that the number and distribution of axonal contacts on postsynaptic cells are regulated by competitive interactions between axons duuring development. The aim of is to better understand the developmental strategies that regulate this competition. The studies will utilize several newly developed techniques for the visualization of synaptic terminals in living preparations under the light microscope. The normally occurring competitive reduction in the number of axons that innervate a postsynaptic cell will be followed by viewing the terminals of different axons made visible in a novel way by activity dependent tracer uptake. Brief activation of a motor axon in the presence of any one of several differently colored fluorescent molecules selectively fills the synaptic terminals of that axon with the tracer. By stimulating different axons in the presence of different colored probes, the precise distribution of the synaptic terminals of different axons can be described. This simple and powerful technique will be used to characterize the normally occurring competitive reduction in the number of axons that innervate a muscle fiber in both snakes and mammals. The second goal is to study anatomically and electrophysiologically the same nerve terminals over time as synaptic remodelling is taking place. The finding that a previously unused fluorescent probe selectively stains mammalian motor nerve terminals with virtually no toxicity and extremely low background has for the first time permitted multiple views of the same mammalian junctions at different time points. This fluorescent molecule will be used to monitor the reorganization of synaptic connections at individual mammalian neuromuscular junctions in living mice during muscle reinnervation. Studying synaptic competition at living terminals will provide direct information about the dynamic aspects of synaptic remodelling -- a subject which is very poorly understood and presumably is the basis of some of the most important long-term changes in the nervous system (e.g., learning and memory).