FUNCTIONAL ORGANIZATION OF VISUAL SYSTEM

在接下来的五年里，我们将专注于旨在阐明多巴胺在视网膜内层中的作用的实验。 特别是，我们将进行实验，旨在揭示多巴胺在介导杆信号传输通过内丛状层的斑马鱼的作用。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，以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隐性和显性突变。 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）、原盲（我们的pob突变体）和先天性静止性夜盲（我们的noa突变体）。 此外，对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所在的位置以及更多关于缺陷性质的信息。 未来五年计划的具体子项目包括：1）分析正常斑马鱼和通过眼内注射6-羟基多巴胺剥夺多巴胺的斑马鱼的神经节细胞反应。 神经节细胞将被膜片钳，并且通过在内部丛状层中施加的K+的喷流在细胞中诱发突触电流。 2)斑马鱼的视网膜电图（ERG）将被药物解剖，这些药物选择性地阻断从感光细胞到所有二级细胞的传输，从视杆感光细胞到ON-双极细胞的传输，以及从视杆和视锥感光细胞到OFF-双极细胞的传输。 作为该子项目的一部分，将从行为上测试这些药理学操作对斑马鱼视觉表现的影响。3)所选斑马鱼突变体的ERG反应将使用上述（2）中描述的药理学操作进一步研究。 特别是，将检查突变对光感受器（ERG a波）功能的影响。

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.