PLASTICITY OF SYNAPTIC MEMBRANE SPECIALIZATIONS

神经元的可塑性对神经元回路的补偿很重要 损伤后，老化过程中的神经元磨损，环境影响 成人期和连通性的发展组织。虽然 萌芽以恢复突触接触的数量被认为是 神经系统中常见的可塑性形式，大小变化 突触部位现在似乎也是几乎 浦肯野细胞去传入后的即刻反应。本研究 解决了其他神经元是否也有这种潜力的问题 作为一个产物，剩余突触位置的大小迅速改变 每个靶神经元上突触后接触总面积的恒定。 这项研究旨在通过以下方式来检验这一守恒原则 对大脑的另外两个区域进行定量分析，即 颈上神经节优势神经元和颗粒细胞 海马体的。在主要传入神经减少到 这两个靶神经元的传入数量之间的关系 靶神经元上的输入部位和个体的平均大小 将对突触后膜的特化进行量化。值来自 一系列不同的削减水平将被用来定义 每个神经元上的总接触面积保持不变，无论 每个目标神经元上的传入接触量。结果是 将确定：(1)其他神经元(除浦肯野细胞外)是否可能 能够通过快速重新分配 剩余受体膜部位的大分子，(2)是否有 支持一种假设，即快速可塑性的机制是基于 对靶部位的内在控制以及(3)突触后部位是否 反过来，诱导传入产生更多的突触小泡和更大的 突触前接触总面积。

Plasticity of neurons is important for compensation in neuronal circuitry following lesions, neuronal attrition in aging, environmental influences in adulthood and developmental organization of connectivity. Although sprouting to restore the number of synaptic contacts is considered the common form of plasticity in the nervous system, changes in the size of synaptic sites now also appear to be an important mechanism for almost immediate response following Purkinje cell deafferentation. This study addresses the question of whether other neurons also have this potential for rapid alteration in the size of remaining synaptic sites as a product of a constancy in total postsynaptic contact area on each target neuron. The study is designed to test for this conservation principle by quantitative analysis of two other regions of the brain, namely the predominent neurons of the superior cervical ganglion and the granule cells of the hippocampus. Following reductions in the principal afferents to these two target neurons, the relationship between the number of afferent input sites on target neurons and the average size of individual postsynaptic membrane specializations will be quantitated. The values from a series of different reduction levels will be used to define whether the total area of contact on each neuron remains constant regardless of the amount of afferent contacts on each of the target neurons. The results will establish: (1) whether other neurons (besides Purkinje cells) may be able to re-organize connectivity through rapid redistribution of macromolecules for remaining receptor membrane sites, (2) whether there is support for a hypothesis that a mechanism of rapid plasticity is based on intrinsic control over target sites and (3) whether the post-synaptic sites in turn induce the afferents to produce more synaptic vesicles and a larger total presynaptic contact area.