VISUAL SYSTEM DEVELOPMENT AND SYNAPTOGENESIS

视觉系统中突触发生的定量方面将是 从光感受器突触的数量和分布来研究 家蝇的第一个视神经丛 研究将集中在 这说明了两个主要问题：1）什么是发展 突触数量和间距的决定因素; 2）视觉的影响 这些决定因素的影响？ 突触数量的测定将 在神经支配比率的自然发生的差异中进行检查 突触前和突触后神经元之间的关系，并使用定量EM 抽样技术 突触间距将在不同的时间点进行分析。 发育年龄，无论是从冷冻断裂的突触前膜， 突触后树突的连续EM，以测试一个突触的影响， 附近的突触发生，因此，检查 突触发生与树突形态发生的关系。 使用 类似的分析，视觉体验对突触群的影响 将在暴露于光和/或 无论是在发育期还是在成年期，都是黑暗的。 突触发生的定性方面将检查可能的改变 突触类形成后，激光诱导删除的 在发育过程中或在果蝇的各种突变体中的突触后神经元 或者缺乏感光功能，或者怀疑缺乏 一类反馈突触或怀疑存在额外的 突触后神经元 这些都将进行定量分析， 串行EM技术的目的是了解规则， 神经元通常以多接触突触（二联体、三联体等）结合联合收割机。 来自于扰动后形成的新组合。 预计这些研究将为我们提供有关 视神经元突触群大小、组成和分布 在发育过程中，在细胞数量变化的影响下， 视觉体验的差异。

Quantitative aspects of synaptogenesis in the visual system will be investigated from the number and distribution of photoreceptor synapses in the first optic neuropile of Musca. Studies will concentrate upon elucidating two major questions: 1) What are the developmental determinants of synapse number and spacing; 2) What influence has visual experience upon these determinants? Determination of synapse number will be examined amongst naturally occurring differences in innervation ratios between pre- and postsynaptic neurons and analyzed using quantitative EM sampling techniques. Synapse spacing will be analyzed at different developmental ages either from freeze-fractured presynaptic membrane or serial-EM of postsynaptic dendrites, to test the influence of one synaptic site upon synaptogenesis nearby and, consequently, to examine the relationship between synaptogenesis and dendritic morphogenesis. Using similar analyses, the effects of visual experience on synaptic population size and distribution will be examined following exposure to light and/or dark, either during development or in the adult. Qualitative aspects of synaptogenesis will examine possible altered synaptic classes formed either following laser-induced deletions of the postsynaptic neurons during development or in various mutants of Drosophila either lacking photoreceptor function or with the suspected absence of a class of feedback synapses or the suspected presence of an additional postsynaptic neuron. These will all be analyzed with quantitative- and serial-EM techniques with the aim of understanding the rules with which neurons normally combine at multiple-contact synapses (dyads, triads, etc.) from the novel combinations formed following perturbations. It is anticipated these studies will inform us about the regulation of synaptic population size, composition and distribution in visual neurons during development under eithr the influence of changes in cell number of differences in visual experience.