MECHANICAL, THERMAL, AND OPTICAL SIGNS OF EXCITATION IN THE NERVOUS SYSTEM

在本财政年度初期，我们开始调查 与脉冲传导有关的热产生过程 有髓神经纤维。因为它的速度和体积都很小 这些快速传导神经释放出的热能 光纤，经典的热探测器，即热电堆电流计 系统，已知不足以确定热的时间进程 这些纤维的生产(见Keynes和Ritchie；J.Physiol，Vol. 210，29P，1970)使用聚偏氟乙烯薄膜，我们有 构造了一个时间分辨率约为 一毫秒。[请注意，经典的时间分辨率 探测器为50-100毫秒。]我们已经成功地确定了 两栖动物坐骨神经在5点产生的热的时间进程 所获得的结果是基于 二价-一价阳离子交换理论是在此之前发展起来的 实验室。 1991年12月，我们开始调查急流的起源。 与大黄鱼嗅觉神经相关的结构变化 激励过程。通过组合我们的设备来检测 具有压电性的非本征染料分子的光学性质 装置，我们已经记录了几种类型的非电表现 嗅神经的兴奋过程。我们发现，在 电刺激的部位，神经的侧向扩张 纤维(即肿胀)与发病同时开始，或在发病之前开始。 在许多光学变化中。这些测量的结果强烈表明 表明海平面表层的含水率上升 神经纤维是观察到的光信号的基础。

During the early part of this fiscal year, we began to investigate the process of heat production associated with impulse conduction in the myelinated nerve fibers. Because of the rapidity and the smallness of the amount of thermal energy liberated by these rapidly conducting nerve fibers, the classical thermal detector, namely, a thermopile-galvanometer system, is known to be inadequate to determine the time-course of heat production in these fibers (see Keynes and Ritchie; J. Physiol., Vol. 210, 29P, 1970) Using thin film of poly(vinylidene fluoride) we have constructed a sensitive thermal detector with a time-resolution of about one millisecond. [Note that the time-resolution achieved by the classical detector was 50-100 milliseconds.] We have succeeded in determining the time-course of the heat generated by the amphibian sciatic nerve at 5 degrees C. The results obtained have been interpreted based on the divalent-univalent cation-exchange theory developed previously in this laboratory. In December of 1991, we started investigating the origin of the rapid structural changes in the garfish olfactory nerve associated with the excitation process. By combining our devices for detecting changes in the optical properties of extrinsic dye molecules with the piezo-electric device, we have recorded several types of non-electrical manifestations of the excitation process in the olfactory nerve. We have found that, at the site of electric stimulation, the lateral expansion of the nerve fibers (i.e. swelling) starts simultaneously with, or precedes, the onset of many optical changes. The results of these measurements strongly suggest that a rise of the water-content in the superficial layer of the nerve fiber is at the base of the observed optical signals.