The Functional Significance of Hippocampal Sprouting

描述（由申请人提供）：在患有阿尔茨海默病的患者的海马结构中观察到死后神经元发芽。海马电路的重组可能存在以下可能性：1）导致与疾病相关的行为症状;或2）补偿投射到海马的内嗅神经元的损失。遗憾的是，目前对中枢神经系统（CNS）中发芽的行为意义知之甚少。本研究旨在探讨内嗅皮层单侧损伤后海马齿状回出芽的功能意义。这项研究将集中在增殖的同源输入的突触功效（即，在一个阶段或进行性EC损伤后的交叉颞齿状突投影- CTD）。已知进行性EC病变可加速分隔齿状回、连合/联合和CTD发芽至齿状回，然而，进行性病变对CTD支持长时程增强（一种可能与学习和记忆相关的突触功效测量）能力的影响尚不清楚。发芽CTD途径是特别感兴趣的，因为：1）它出现在同一个细胞层在对侧同源作为正常同侧内嗅输入到齿状回;和2）它已经牵连在单侧内嗅损伤后的空间记忆的恢复。特别值得注意的是，进行性病变的内嗅区已被证明是备用的赤字通常与内嗅损伤的空间记忆。这种电生理分析将为今后的工作奠定基础，评估中枢神经系统发芽的功能意义。

DESCRIPTION (provided by applicant): Neuronal sprouting has been observed post-mortem in the hippocampal formation of patients suffering from Alzheimer's disease. The possibility exists that the reorganization of hippocampal circuitry may: 1) contribute to the behavioral symptoms associated with the disease; or 2) compensate for the loss of entorhinal neurons projecting to the hippocampus. Unfortunately, little is presently known about the behavioral significance of sprouting in the central nervous system (CNS). The purpose of this small-scale investigation is to evaluate the functional significance of sprouting in the dentate gyrus of the hippocampal formation after unilateral lesions of the entorhinal cortex in rats. This study will focus on the synaptic efficacy of a proliferated homologous input (i.e., the crossed temporodentate projection -- CTD) after a one-stage or progressive EC lesion. Progressive EC lesions are known to accelerate septodentate, commissural/associational, and CTD sprouting to the dentate gyrus, however, the effects of progressive lesions on the ability of the CTD to support long-term potentiation, a measure of synaptic efficacy that may have relevance to learning and memory, are unknown. The sprouted CTD pathway is of special interest because: 1) it emerges from the same cell layer in the contralateral homologue as the normal ipsilateral entorhinal input to the dentate gyrus; and 2) it has been implicated in the recovery of spatial memory after unilateral entorhinal injury. Particularly noteworthy, progressive lesions of the entorhinal area have been shown to spare spatial memory from the deficits typically associated with entorhinal injury. This electrophysiological analysis will lay the foundation for future work assessing the functional significance of CNS sprouting.