ANALYSIS OF GRADED VISUAL SIGNALS

我们将研究突触整合，区域膜特性，以及 大鼠食道上神经节神经元内钙离子的调控 巨型藤壶。我们是特别的，但不是 只对视觉神经元的这些特性感兴趣 信息通过分级势进行处理和传递的途径 而不是动作电位。藤壶神经节有几个优点 为研究这些特性提供了形态和生理特征。 这些事件大多发生在丘脑的树突或突触前终末。 细胞，因此不容易使用微电极进行检测。我们会 采用光学方法，使用电压敏感染料同时记录 从单个细胞上的许多位置，包括精细过程。使用 这项技术我们将在许多情况下确定被动膜的性质 细胞上的位置，离子电导机制的区域差异， 突触位置和突触电位在脑内的传播 手机。对于一些选定的神经元，我们将尝试将所有这些组合在一起 将属性整合到统一的电气模型中。此外，我们还将审查 正中神经突触前终末内钙离子的调控 光感受器。这是一个不疲劳的分级突触的例子。 使用用于膜电位测量的相同仪器，我们 将测量染料偶氮砷III的吸收变化，以表明 不同体位及不同运动方式下体内钙的变化 感光器中的生理状态。

We will study synaptic integration, regional membrane properties, and control of internal calcium in neurons of the supraesophageal ganglion of the giant barnacle Balanus nubilus. We are particularly, but not exclusively, interested in these properties in neurons in the visual pathway where information is processed and transmitted by graded potentials and not action potentials. The barnacle ganglion has several advantageous morphological and physiological features for studying these properties. Most of these events occur on the dendrites or presynaptic terminals of cells and hence cannot be easily examined using microelectrodes. We will employ optical methods using voltage-senstive dyes to record simultaneously from many positions on individual cells, including fine processes. With this technique we will determine passive membrane properties at many positions on the cell, regional variations in ionic conductance mechanisms, synapse locations and the propagation of synaptic potentials within a cell. For some selected neurons, we will attempt to combine all of these properties into a unified electrical model. In addition, we will examine the control of internal calcium in the presynaptic terminal of the median photoreceptor. This is an example of a non-fatiguing, graded synapse. With the same apparatus used for the membrane potential measurements we will measure changes in absorption in the dye Arsenazo III to indicate changes in internal calcium at different positions and under a variety of physiological conditions in the photoreceptor.