Mapping the optic lobes for color vision

描述（由申请人提供）：色觉依赖于大脑中对不同波长光敏感的光感受器输入的比较。在果蝇视网膜中，每个小眼内的颜色检测是由不同的光感受器介导的，这些光感受器具有不同的专门化，并且随机分布在视网膜中；小眼虫似乎对短波长有区别，而小眼虫对短波长有区别。内PR投射到视叶的髓质部分，在那里R7和R8（可能还有p和y PR）之间发生比较。我们提出研究髓质中的色觉回路：R7和R8与哪些类型的神经元接触；p和y目标神经元有区别吗？中间神经元如何连接pr和目标神经元？这三个特定的目标将帮助我们理解果蝇视觉系统中的颜色视觉处理。1. 绘制髓质神经元。我们描述了参与处理色觉的15种髓质神经元的形态和投射模式。我们将识别这些神经元的分子标记，建立它们之间的连通性和信息流的方向。我们将研究PR靶和调节神经元使用的神经递质类型。我们还将尝试揭示不同的地图是否独立处理来自p和y的信息，以及是否有一个特殊的地图处理p和y光感受器之间的比较。2. 我们将重建髓质细胞的谱系，并建立髓质发育的逻辑：它是否基于柱状组织，即一个神经母细胞在每个PR端附近产生不同的神经元？调节性非柱状神经元是否存在广泛的迁移？髓质的发育需要多少神经母细胞？3. 光感受器的神经支配或活动如何影响色觉网络的建立？我们将通过基因切除或电沉默每个特定的PR亚型，并研究髓质神经元在其发育和投射模式中如何受到影响，从而揭示从视网膜到视叶的可能诱导事件。为了解决在各类髓质神经元中特异性表达的基因的功能，我们将使用功能损失和增益实验来确定它们在细胞命运决定中所起的作用。我们希望能够对髓质进行精确的解剖描述，以补充Cajal和Fischbach的经典工作。在未来，这项工作将通过我们开发的行为测试以及活动成像和电生理学进行功能分析。这将为果蝇处理颜色信息的机制提供精确的信息。

DESCRIPTION (provided by applicant): Color vision relies on the comparison in the brain of inputs from photoreceptors sensitive to different wavelengths of light. In the Drosophila retina, color detection is mediated within each ommatidium by different sets of photoreceptors that have different specializations and are distributed stochastically in the retina; p ommatidia appear to discriminate among short wavelengths while y ommatidia discriminate among longer wavelengths. The inner PR's project to the medulla part of the optic lobe where comparison between R7 and R8 (and perhaps between p and y PRs) occurs. We offer to investigate the color vision circuitry in the medulla: What types of neurons are contacted by R7 and R8; is there a difference between p and y target neurons? How do interneurons interconnect PRs and target neurons? The three specific aims will help us understand color vision processing in the Drosophila visual system. 1. Map medulla neurons. We have characterized the morphology and projection patterns of 15 types of medulla neurons involved in processing color vision. We will identify molecular markers for these neurons, establish their connectivity and the direction of information flow between them. We will investigate the type of neurotransmitters used by the PR target and by modulatory neurons. We will also attempt to uncover whether distinct maps independently process information from p and from y ommatidia, and whether a special map deals with comparison between p and y photoreceptors. 2. We will reconstruct the lineage of medulla cells and establish the logic of medulla development: Is it based on a columnar organization whereby one neuroblast gives rise to distinct neurons near each PR termination? Is there extensive migration of modulatory, non-columnar neurons? How many neuroblasts are required for the development of the medulla? 3. How does photoreceptor innervation or activity affect the establishment of the color vision network? We will genetically ablate or electrically silence each of the specific PR subtypes and study how medulla neurons are affected in their development and projection patterns, thus revealing possible inductive events from the retina to the optic lobes. To address the function of the genes that are specifically expressed in the various classes of medulla neurons, we will use loss- and gain of function experiments to define the role they play in cell fate determination. We hope to be able to build a precise anatomical description of the medulla that will complement classical work performed by Cajal and by Fischbach. In the future, this work will be followed by a functional analysis using behavior tests that we have developed, and through activity imaging and electrophysiology. This will provide precise information on the mechanisms by which Drosophila processes color information.