Assessing direction selectivity map development in the retina

项目摘要 视觉信息通过一组神经回路进行处理，这些神经回路组织成功能 地图分布在丘脑、中脑和大脑皮层。然而，人们对此知之甚少 关于视网膜中的回路是如何发展和组织的，这一信息处理是从那里开始的。这个 这项建议的目标是确定电路发展的潜在机制， 视网膜的中介方向选择性(DS)。经典研究表明，偏爱的分布 方向，称为DS图，与主轴--上、下、前--对齐。 后方。然而，最近的特征表明，DS映射遵循由定义的轴 光流。结果，整个成人视网膜的DS图随着位置的变化而变化，其中 这些簇彼此垂直，离视神经更近，并随着距离的增加而倾斜 来自视神经的增加。这张地图让人大开眼界。这家复杂的组织如何 在睁开眼睛之前发生的情况尚不清楚。这促使人们对发育因素进行调查。 这有助于DS地图的形成。 方向选择性神经节细胞(DSGCs)对首选方向的运动反应强烈 并微弱地朝相反或零的方向运动。为了实现这一计算，DSGCs 星爆无长突细胞在零向运动时受到更大的突触抑制 通过精确的布线模式。有趣的是，在DSGCs连接的发育期 在有囊的情况下，视网膜自发活跃。这一活动表现为波的传播 穿过视网膜表面--称为视网膜波。 在这个提案中，我将探索视网膜波的作用，特别是由胆碱能驱动的波 信令，在DS地图的开发中。此外，我建议研究突触的基础 在视网膜表面形成这种独特的组织的基础上。作为第一步 为了了解视网膜波是否影响DS图的形成，我将使用双光子 人群钙成像、遗传工具和药理学评估DS图谱如何在 在整个发展过程中存在和不存在模式化的自发活动。要做到这一点，我 将使用一种小鼠模型，其中胆碱能波通过敲除β2而被严重扰乱 烟碱型乙酰胆碱受体的亚基(目标1)。此外，考虑到 不对称抑制对于定向调谐是必要的，我认为抑制输入的调谐 DSGCs在视网膜的不同位置会发生变化，以解释首选的偏斜 方向。为了测试这一点，我将使用双光子目标电压钳记录来揭开 这个组织的突触基础(目标2)。这些发现将为我们提供对 在开发过程中作为这种精确组织的基础的机制。

Project Summary Visual information is processed through a set of neural circuits that organize into functional maps distributed throughout the thalamus, midbrain, and cerebral cortex. However, little is known about how circuits develop and organize in the retina, where this information processing begins. The goal of this proposal is to determine the mechanisms underlying the development of the circuits that mediate direction selectivity (DS) in the retina. Classic studies show that the distribution of preferred directions, referred to as the DS map, align with the cardinal axes–– superior-inferior and anterior- posterior. However, recent characterization has shown that the DS map follows the axes defined by optic flow. As a result, the DS map across the adult retina changes as a function of location, where the clusters are orthogonal to one another closer to the optic nerve and become skewed as distance from the optic nerve increases. This map is present at eye opening. How this complex organization arises prior to eye opening is not known. This prompts an investigation of the developmental factors that contribute to the formation of DS maps. Direction-selective ganglion cells (DSGCs) respond robustly to motion in a preferred direction and weakly to motion in the opposite, or null, direction. In order to achieve this computation, DSGCs receive greater synaptic inhibition during null direction motion from starburst amacrine cells (SACs) via precise wiring patterns. Interestingly, during the developmental period where DSGCs are wiring up with SACs, the retina is spontaneously active. This activity presents itself as waves propagating across the surface of the retina––termed retinal waves. In this proposal, I will explore the role of retinal waves, specifically waves driven by cholinergic signaling, in the development of DS maps. Additionally, I propose to investigate the synaptic basis underlying the formation of this distinct organization across the retinal surface. As a first step towards understanding whether retinal waves influence DS map formation, I will use two-photon population calcium imaging, genetic tools, and pharmacology to assess how the DS map develops in the presence and absence of patterned spontaneous activity across development. To achieve this, I will use a mouse model where cholinergic waves are severely disrupted by knocking out the β2 subunit of the nicotinic acetylcholine receptor (Aim 1). Moreover, given the extent to which asymmetric inhibition is necessary for directional tuning, I propose that the tuning of inhibitory inputs onto DSGCs will change at varied locations in the retina, to account for the skewing of preferred directions. To test this, I will use two-photon-targeted voltage clamp recordings to unmask the synaptic basis of this organization (Aim 2). These findings will provide key insights into the mechanisms that underlie this precise organization during development.