Cell types and functional circuitry in the retina

本研究的长期目标是了解内丛状层的视觉加工， 视网膜。更直接的是，这项研究为人类提供了不同无长突细胞类型的遗传途径， 功能表征，并了解它们如何塑造神经节细胞的反应特性。 无长突细胞是视网膜中最多样化的神经元，至少有40-50种形态类型已被发现。 介绍了每种类型的无长突细胞都具有独特的形态， 通过本地电路进行计算。不幸的是，无长突细胞的巨大多样性一直是一个主要的 阻碍了获得用于系统研究的单个细胞类型。因此， 许多无长突细胞仍然是未知的，遗传工具的发展，允许细胞类型特异性 确定目标和操纵将是确定其特征的重要步骤。我们建议使用新的 结合功能成像和电生理记录的小鼠交叉遗传工具， 形态和功能解剖无长突细胞电路在三个独立的目的。在目标1中，我们将创建 通过使用Cre和tTA表达的组合来发现新的无长突细胞类型的交叉策略 并以更高的特异性靶向这些细胞。之后，我们将重点介绍一种新发现的无长突细胞 Ck 2-AC 1类型用于功能分析。我们将通过成像来表征Ck 2-AC 1的光响应 Aim 1神经递质释放部位的Ca ~（2+）反应，并鉴定其突触后神经节 Aim 2中交叉ChR 2激活的细胞。在目标3中，我们将测试关于Ck 2-AC 1的特定假设 并检查它们在化学发生失活的不同回路中的功能作用。我们将使用两者 假设驱动和发现为基础的方法，以获得深入了解Ck 2-AC 1的电路功能， 内层视网膜交叉策略是可扩展的，我们将努力发现更多的新颖性。 无长突细胞和电路，利用建立的Ck 2-AC 1的方法。这项工作将促进我们的 了解视网膜内部的视觉处理，而开发的技术将提供主要的 这是对现有无长突细胞研究方法的进步，也适用于其他脑回路。 此外，该项目将提供深入了解视网膜疾病的病理生理神经机制， 并帮助设计更好的治疗策略。

The long-term goal of this research is to understand the visual processing in the inner plexiform layer of the retina. More immediately, the research serves to provide genetic access to distinct amacrine cell types for functional characterization and to understand how they shape the response properties of ganglion cells. Amacrine cells are the most diverse neurons in the retina, at least 40–50 morphological types have been described. Each type of amacrine cells exhibits a unique morphology and generates specific visual computations through their local circuits. Unfortunately, the great diversity of amacrine cells has been a major obstacle to access individual cell types for systematic studies. As a result, the connectivity and function of many amacrine cells remain unknown, and the development of genetic tools that allow for cell type-specific targeting and manipulation would be an important step towards their characterization. We propose to use new mouse intersectional genetic tools combined with functional imaging and electrophysiology recording to morphologically and functionally dissect amacrine cell circuits in three separate Aims. In Aim 1, we will create intersectional strategies by using a combination of Cre and tTA expression to discover new amacrine cell types and to target these cells with increased specificity. After that, we will focus on a newly discovered amacrine cell type called Ck2-AC1 for functional analysis. We will characterize the light responses of Ck2-AC1s by imaging Ca2+ responses at the sites of neurotransmitter release in Aim 1, and then identify their post-synaptic ganglion cells with intersectional ChR2 activation in Aim 2. In Aim 3, we will test specific hypotheses about Ck2-AC1s and examine their functional roles in different circuits with chemogenetic inactivation. We will use both hypothesis driven and discovery based approaches to gain insights into the circuit functions of Ck2-AC1s in the inner retina. The intersectional strategy is extensible, and we will undoubted discover additional novel amacrine cells and circuits utilizing the methods established for Ck2-AC1s. This work will advance our understanding of visual processing in the inner retina while the technologies developed will provide major advances over existing methods for studying amacrine cells and are also applicable to other brain circuits. Furthermore, this project will provide insight into pathophysiological neuronal mechanisms of retinal diseases, and help design better strategies for therapy.