DEVELOPMENT AND REGENERATION SENSORY-MOTOR SYNAPSES

随着神经系统的发育，神经细胞之间的突触连接 最初是以一种高度特定的方式建立的。 这些初始 然后可以在有限的范围内修改接触， 更进一步的特殊性。 对功能和形态的知识 在中枢神经系统中，突触发育的相关性是基本的 了解神经细胞最初是如何制造和提炼的， 保持良好的联系。 脊髓内肌肉感觉传入神经之间的突触联系 纤维和运动神经元，形成神经元基础的连接， 牵张反射为研究这一现象提供了一个很好实验系统 在单个功能鉴定细胞水平上的问题。 在 青蛙的脊髓，这些连接的形成与高度的 特异性，此后仅进行有限的修饰。 前庭 对这些运动神经元的输入在成年青蛙中也是特定的，但是 这种特异性以未知的方式发展。 其主要目的是 建议是比较这两种感觉输入的发展，以获得 了解特定突触是如何形成的 青蛙的感觉纤维在被切断后也可以再生。 背根，他们重新神经支配运动神经元的高度， 的特异性 对影响数量的因素的继续研究 这种再生的特异性可以帮助我们 脊髓意外损伤后的再生。 今后五年，我的目标是：（一）研究 肌肉感觉轴突之间的单突触连接的正常发育 和运动神经元在单个功能鉴定细胞的水平上。 2)将这些研究扩展到前庭脊髓输入的发展， 前肢运动神经元 3)检查病变类型对 感觉背根轴突再生到脊髓中的程度。

As the nervous system develops, synaptic connections between nerve cells are initially established in a highly specific manner. These initial contacts can then be modified to a limited extent, increasing their specificity still further. A knowledge of the functional and morphological correlates of synaptic development in the central nervous system is basic to an understanding of how nerve cells originally make and then refine and maintain their proper connections. Synaptic connections in the spinal cord between muscle sensory afferent fibers and motoneurons, connections which form the neuronal basis of the stretch reflex, provide an excellent experimental system for studying this problem at the level of single, functionally identified cells. In the frog's spinal cord, these connections form with a high degree of specificity and undergo only limited modifications thereafter. Vestibular inputs to these same motoneurons are also specific in adult frogs, but the manner in which this specificity develops in unknown. A major aim of this proposal is to compare the development of these two sensory inputs to gain insights into how specific synapses are formed. Sensory fibers in the frog can also regenerate after they are cut in the dorsal root, and they re-innervate motoneurons with a high degree of specificity. A continued study of the factors that influence the amount and specificity of this regeneration could help in achieving specific regeneration in human spinal cord after accidental injury. My objectives during the next five years are as follows: 1) Study the normal development of monosynaptic connections between muscle sensory axons and motoneurons at the level of individual functionally identified cells. 2) Extend these studies to the development of the vestibulospinal input to forelimb motoneurons. 3) Examine the effects of types of lesions on the extent of regeneration of sensory dorsal root axons into the spinal cord.