ULTRASTRUCT PROPERTIES OF SYNAPSES OF IDENTIFIED NEURON IN PRIMATE VISUAL CORTEX

我们的目标是了解视觉皮层的各个组成部分 电路有助于产生视觉的计算 perception. 为此，我们做了详细的解剖和 初级视觉皮层局部连接的生理学研究。 这些研究表明，兴奋性连接可以 被归类为两种类型之一：那些强壮或驾驶， 那些是弱的或调节性的。 这些属性似乎是 与提供突触的锥体神经元类型相关 9输入。 (We以前已经确定了大约10种类型的神经元， 灵长类初级视皮层深层细胞内标记 光学显微镜分析）。其他实验室的研究表明 突触输入的功能性影响 与突触的超微结构特性相关，例如 突触前和突触后密度的大小，以及对接的数量 突触囊泡 因此，我们建议测量这些参数 对于由已知类型的细胞提供的突触。 个人 神经元将在活脑切片中进行细胞内标记， 在解剖学上在光水平下表征以用于分类。 突触前标记的突触将被重建 用高压EM法鉴别 不同细胞类型的突触。 我们已经开始工作， 该项目旨在确定标记神经元的最佳方法， 包括二氨基联苯胺的固定、渗透和强度 标签。 我们进行了一次连续切片重建， 预计不久将进行断层重建。

We aim to understand how the various components of visual cortical circuits contribute to the computations that give rise to visual perception. To this end, we have done detailed anatomical and physiological studies of local connectivity in primary visual cortex. These studes have recealed that excitatory connections can be classified as one of two types: those that are strong or driving and those that are weak or modulatory. These properties appear to be correlated with the type of pyramidal neuron providing the synaptic 9input. (We have previously identified approx 10 types of neurons in deep layers of primate primary visual cortex by intracellular labeling and light microscopic analysis.) Studies in other labs have indicated that the functional influence of a synaptic input is strongly correlated with ultrastructural properties of the synapse, such as the sizes of pre- and postsynaptic densities, and the numbers of docked synaptic vesicles. We therefore propose to mea sure these parameters for synapses that are provided by cells of known type. Individual neurons will be intracellularly labeled in living brain slices and characterized anatomically at the light level for classification. Synapses that are labeled presynaptically will then be reconstructed with the high-voltage EM to identify morphological characteristics of synapses arising from the different cell types. We have begun work on this project to determine the optimal method for labeling neurons, including fixation, permeablization and intensity of diaminobenzidine labeling. We have performed one serial section reconstruction and anticipate performing tomographic reconstructions shortly.