Transgenic strategy to map structure and function of neural circuits in retina

描述（由申请人提供）：本申请涉及广泛的挑战领域06，使能技术，特定的挑战主题06-NS- 106：“验证研究大脑连接的新方法。“这项研究的长期目标是从根本上了解眼睛如何与大脑沟通。更直接的是，这项研究有助于验证和改进一套用于神经回路研究的遗传工具。视网膜是眼睛后部的神经元的复杂网络，其将视觉图像转换成动作电位流，所述动作电位流通过视神经的纤维行进到大脑。视网膜的回路开始于感受光的感光细胞，穿过双极细胞和其他中间神经元，并结束于形成视神经的神经节细胞。总的来说，视网膜使用超过50种不同类型的神经元;仅神经节细胞就包括大约20种不同类型。这些神经节细胞类型中的每一种都提取并报告视觉场景的不同方面。视觉神经科学的一个长期目标是了解在这些流中发生了什么样的视觉处理，以及这些过程是如何通过视网膜的精细神经回路实现的。新的遗传学方法开始加速我们对神经系统的理解。特别是，人们对发现区分大脑许多不同神经元类型的遗传标记非常感兴趣。经验表明，这种标记物的可用性与新的分子和生理方法相结合，可以大大加快相应神经回路结构和功能的科学进展。在这里，我们建议应用这些方法来组装一个完整的目录的神经节细胞类型在小鼠视网膜和分析其视觉功能。具体的研究目标是：（1）找到在一种类型的视网膜神经节细胞中特异表达的基因;（2）构建基于这些基因的转基因小鼠，其中给定类型的所有神经元都被标记;（3）利用这些品系对视网膜通路的结构和功能进行靶向研究。对于每种类型的视网膜神经节细胞，我们将确定神经元在视网膜上的分布，它们的树突区域如何覆盖视觉空间，以及它们的轴突在大脑中的投影位置。在单细胞水平上，我们将检查视网膜内神经节细胞树突树的形状和位置，以推断视网膜中间神经元之间可能的突触伙伴。为了分析视觉功能，我们将确定每种神经节细胞类型从视觉场景中提取的图像特征。此外，我们将评估其参与生态重要的计算，如图像运动的处理，适应视觉环境。这项研究将导致对视网膜功能的质的新理解。它将告知我们对高级视觉区域的理解，这些区域从视网膜获取所有输入。此外，这项工作将验证和收集一套遗传工具的经验，这些工具可以推广到所有的大脑回路。 公共卫生相关性：该项目涉及对大脑回路功能的基础研究。它将开发和测试用于可视化神经细胞类型的新遗传方法，并利用这些标记来了解电路如何处理信息。从长远来看，这将增强我们对大脑如何工作的理解，以及它如何在某些疾病中失败。

DESCRIPTION (provided by applicant): This application addresses broad Challenge Area 06, Enabling technologies, specific Challenge Topic 06-NS- 106: "Validating new methods to study brain connectivity." The long-term goal of this research is a fundamental understanding of how the eye communicates with the brain. More immediately, the research serves to validate and improve a set of genetic tools for the study of neural circuits. The retina is a complex network of neurons in the back of the eye that converts a visual image into streams of action potentials that travel through the fibers of the optic nerve to the brain. The circuits of the retina begin with the photoreceptor cells that sense the light, pass through bipolar cells and other interneurons, and end with the ganglion cells that form the optic nerve. In all, the retina uses over 50 different types of neurons; the ganglion cells alone comprise about 20 different types. Each of these ganglion cell types extracts and reports a different aspect of the visual scene. A long-term goal of visual neuroscience is to understand what kind of visual processing occurs in each of these streams, and how those processes are implemented by the elaborate neural circuitry of the retina. New genetic methods are beginning to accelerate our understanding of neural systems. In particular, there has been great interest in finding genetic markers that distinguish the brain's many different neuron types. Experience has shown that availability of such a marker, in combination with new molecular and physiological approaches, can dramatically accelerate scientific progress on the structure and function of the corresponding neural circuits. Here we propose to apply these methods to assemble a complete catalog of the ganglion cell types in the mouse retina and to analyze their visual functions. The specific research goals are: (1) to find genes that are expressed specifically in one type of retinal ganglion cell; (2) to construct transgenic mice based on these genes in which all neurons of a given type are marked; (3) to exploit these lines for targeted studies of the structure and function of retinal pathways. For each type of retinal ganglion cell, we will determine the distribution of the neurons across the retina, how their dendritic fields cover visual space, and where in the brain their axons project. At the single-cell level we will examine the shape and location of the ganglion cell's dendritic tree within the retina to deduce its likely synaptic partners among retinal interneurons. To analyze visual function, we will determine what image features each ganglion cell type extracts from the visual scene. In addition, we will assess its involvement in ecologically important computations, such as the processing of image movement, and adaptation to the visual environment. This research will lead to a qualitatively new understanding of retinal function. It will inform our understanding of higher visual areas that draw all their input from the retina. Furthermore, the work will validate and gather experience with a set of genetic tools that can generalize to all brain circuits. PUBLIC HEALTH RELEVANCE: This project concerns basic research into the function of brain circuits. It will develop and test new genetic methods for visualizing types of nerve cells, and exploit these markers to understand how the circuits process information. In the long run, this will enhance our understanding of how the brain works, and how it fails in certain disorders.