FUNCTIONAL ORGANIZATION OF VISUAL SYSTEM

在这个项目接下来的五年里，我们将专注于旨在阐明多巴胺在视网膜内的作用的实验。特别是，我们将开展旨在揭示多巴胺在斑马鱼内丛状层介导杆状信号传递中的作用的实验。我们还将开发更复杂的电生理测试，基于视网膜电图（ERG）记录，分析斑马鱼视网膜突变。通过行为测试，我们已经确定了影响斑马鱼视网膜功能的显性和隐性突变。许多突变类似于人类的遗传性视网膜疾病，包括显性遗传性视网膜色素变性（我们的nba突变体）、色盲（我们的pob突变体）和先天性静止性夜盲症（我们的noa突变体）。此外，这些突变体的电生理测试将有助于确定视网膜中特定缺陷的位置，并更多地了解缺陷的性质。未来五年计划开展的具体子课题包括：1)眼内注射6-羟多巴胺对正常斑马鱼和多巴胺剥夺斑马鱼神经节细胞反应的分析。在神经丛状层内注入K+后，神经节细胞会被片夹住，并在细胞内诱发突触电流。2)斑马鱼视网膜电图（ERG）将通过选择性阻断光感受器细胞向所有二级细胞的传递、杆状光感受器细胞向ON-bipolar细胞的传递、杆状和锥状光感受器细胞向OFF-bipolar细胞的传递的药物进行药理学解剖。作为子项目的一部分，这些药理学操作对斑马鱼视觉表现的影响将进行行为学测试。3)选择的斑马鱼突变体的ERG反应将使用上述(2)中描述的药理学操作进一步研究。特别地，突变对光感受器（ERG - a波）功能的影响将被检查。

For the next five years of this project, we shall focus on experiments designed to elucidate the role of dopamine in the inner retina. In particular, we shall carry out experiments designed to uncover to role of dopamine in mediating rod signal transmission through the inner plexiform layer of the zebrafish. We shall also develop more sophisticated electrophysiological tests, based on electroretinographic (ERG) recordings, to analyze zebrafish retinal mutations. With behavioral tests, we have identified both recessive and dominant mutations that affect retinal function in zebrafish. A number of the mutations resemble inherited retinal diseases in man including dominantly- inherited retinitis pigmentosa (our nba mutant) protanopia (our pob mutant) and congenital stationary night blindness (our noa mutant). Further, electrophysiological testing of these mutants will help identify where in the retina a specific defect resides and more about the nature of the defect. Specific sub-projects planned for the next five years include: 1) An analysis of ganglion cell responses in normal zebrafish and zebrafish deprived of dopamine by the intraocular injection of 6- hydroxydopamine. Ganglion cells will be patch-clamped and synaptic currents evoked in the cells by puffs of K+ applied in the inner plexiform layer. 2) The electroretinogram (ERG) of the zebrafish will be dissected pharmacologically by drugs that selectively block transmission from photoreceptor cells to all second-order cells, transmission from rod photoreceptor cells to ON-bipolar cells, and transmission from rod and cone photoreceptor cells to OFF-bipolar cells. As part of this sub- project, the effects of these pharmacological manipulations on the visual performance of zebrafish will be tested behaviorally. 3) The ERG responses of selected zebrafish mutants will be further studied using the pharmacological manipulations described in (2) above. In particular, the effects of the mutations on photoreceptor (ERG a-wave) function will be examined.