AGING AND THE NERVOUS SYSTEM

该计划项目的总体目标是检查行为， 神经正常老化过程中发生的解剖和生化变化 哺乳动物的系统，以及老化的神经系统的补偿潜力 为这些变化。为了实现这些目标，一些系统正在进行 检查过了。在听觉系统中，年龄对大鼠听力的影响 获得和保持听觉辨别力的研究正在进行中，而这种能力 与耳蜗骨的形态年龄变化有关 核团和螺旋神经节。形态变化包括检查 受体细胞的丧失，神经元之间突触的变化，以及 色素的积累。更重要的是，听觉神经元的能力 对不同年龄的皮层对去传入的反应进行了检查 确定遗失的膝盖骨是否会导致代偿性生长 从丘脑进入皮质的传入神经。在嗅觉系统中 受体细胞、神经元形态及其突触的变化 随着老鼠年龄的增长，投入正在被研究。这些研究还将表明， 老化的神经系统仍然表现出可塑性，侧枝萌发 目前正在对齿状回内的轴突进行进一步研究。 神经元老化的一个可能的重要因素是 微血管网络，这一点正在进行生化和 从解剖学上讲。更多的生物化学研究正在进行中 染色质，用它来评估年龄的影响，通过测定 染色质对细菌核酸酶切割的敏感性。

The general objective of this program project is to examine behavioral, anatomical and biochemical changes that occur during normal aging of the nervous system of mammals, and the potential of the aging nervous system to compensate for these changes. To accomplish these goals, a number of systems are being examined. In the auditory system the effect of age on the ability of rats to acquire and maintain auditory discrimination are being studied, and this ability is being correlated with morphological age changes in the cochleas, cochlear nuclei and spiral ganglion. The morphological changes include examination of the loss of receptor cells, changes in synapses between neurons, and accumulation of pigment. More centrally, the ability of neurons in the auditory cortex to respond to deafferentation at varying ages are being examined to determine if loss of the callosal input results in compensatory growth of afferents entering the cortex from the thalamus. In the olfactory system changes in the receptor cells, the morphology of neurons and their synaptic input are being studied as rats age. These studies will also indicate if the aging nervous system still exhibits plasticity, and collateral sprouting of axons is being further studied in the dentate gyrus. A possible important factor in the aging of neurons is the state of the microvascular network, and this is being examined both biochemically and anatomically. Additional biochemical studies are being carried out on nuclear chromatin, with which the effects of age are being assessed by determining the susceptibility of chromatin to cleavage by bacterial nuclease.