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 最初是以非常具体的方式建立的。这些首字母 然后，可以在有限的范围内修改联系人，从而增加其 更进一步的专一性。功能和形态方面的知识 中枢神经系统中突触发育的相关性是基本的 为了理解神经细胞最初是如何制造和提炼的 保持他们之间的适当联系。 脊髓内肌肉感觉神经传入的突触联系 纤维和运动神经元，这些连接构成了 伸展反射，为研究这一现象提供了一个很好的实验系统 在单个功能识别单元的级别上存在问题。在 青蛙的脊髓，这些连接形成的高度 并在此之后只进行有限的修改。前庭 这些运动神经元的输入也是成年青蛙特有的，但 这种专一性在未知中发展的方式。这样做的一个主要目的是 建议将这两种感觉输入的发展进行比较以获得 对特定突触是如何形成的洞察。 青蛙体内的感觉纤维在被切断后也可以再生 背根，它们以高度的 专一性。对影响数量的因素的继续研究 而这种再生的特殊性可以帮助实现特定的 人脊髓意外损伤后的再生。 我今后五年的目标是：1)研究 肌肉感觉轴突间单突触联系的正常发育 以及单个功能识别细胞水平上的运动神经元。 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 感觉神经后根轴突进入脊髓的再生程度。

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.