Foveal ganglion cell function in the living eye

中央凹是灵长类视网膜的一个特殊区域，负责调节颜色和高敏锐度的视觉感知。 黄斑中心凹视力对疾病高度敏感，是旨在恢复视力的治疗的主要目标 盲人。然而，我们对视网膜神经节细胞(RGC)的理解，即视网膜输出神经元 视网膜图像到大脑，落后于恢复视力的技术，因为我们还不了解 灵长类视网膜节细胞的多样性以及它们在中心凹中的功能。在这些领域取得的进展与常规 视网膜生理学方法一直受到研究脆弱和密集包装的困难的限制 以及在急性制剂中可靠地靶向稀有视网膜节细胞的挑战。这些障碍可能 现在用功能自适应光学钙成像在活眼(Facile)中克服，一种强大的新技术 能够在体内测量数百个中央凹视网膜节细胞的光反应的技术 钙指示剂GCaMP6s。这种非侵入性的、全光学的方法，是在实验室开发的 大卫·威廉姆斯和威廉·梅里根在罗切斯特大学，我计划在那里进行博士后培训 将会发生，提供了前所未有的机会在几个月或几年的时间里记录相同的中心凹RGC， 从而比以往任何时候都能更详细地描述中心凹内的视网膜输出。在《目标1》中，我将 通过开发刺激电池和分析来确定服务于中心凹视觉的视网膜节细胞的功能多样性 高效可靠地对表达GCaMP6的视网膜节细胞的反应特性进行分类。在目标二中，我 将标记六种最罕见的RGC类型，将示踪剂逆行注射到上丘(SC)，然后 想象它们在体内和体外的树枝状形态。这些结果将创建一个详细的地图 上丘中央凹输入的地形图，这是一条进化上的古老通路 潜意识的非成像视觉行为。由此得到的罕见的表达GCaMP6的RGC的图谱将 加快目标1中的分类，因为许多SC投射的RGC从未在功能上被表征 并且可能在侏儒RGC占视网膜输出的90%以上的区域丢失。 这个项目将产生一个人口水平的中心凹侏儒RGC功能的活着的眼睛，将 引导恢复视觉感知的进展。此外，对中心凹视网膜节细胞多样性的洞察 它们传递给大脑的视觉信息最终可能使恢复所有视觉功能成为可能， 包括由罕见的SC投射的视网膜节细胞介导的视觉引导的运动和反射。

The fovea is a specialized region of the primate retina mediating color and high acuity visual perception. Foveal vision is highly susceptible to disease and is the primary target for therapies aiming to restore vision in the blind. However, our understanding of retinal ganglion cells (RGCs), the retinal output neurons that convey the retinal image to the brain, lags behind techniques to restore vision because we do not yet understand the full diversity of primate RGCs nor how they function in the fovea. Progress in these areas with conventional retinal physiology approaches has been limited by the difficulties of studying the fragile and densely packed fovea along with the challenges of reliably targeting rare RGCs in acute preparations. These obstacles can now be overcome with Functional Adaptive-optics Calcium Imaging in the Living Eye (FACILE), a powerful new technique enabling in vivo measurements of the light responses in hundreds of foveal RGCs expressing the calcium indicator GCaMP6s. This non-invasive, all-optical approach, which was developed in the laboratories of David Williams and William Merigan at the University of Rochester where my proposed postdoctoral training will occur, provides the unprecedented opportunity to record from the same foveal RGCs for months or years, allowing a more detailed characterization of the retinal output in the fovea than ever before. In Aim 1, I will determine the functional diversity of RGCs serving foveal vision by developing a stimulus battery and analysis pipeline to effectively and reliably classify the response properties of GCaMP6-expressing RGCs. In Aim Two, I will label six of the rarest RGC types with retrograde tracer injections to the superior colliculus (SC), then image their dendritic morphologies both in vivo and ex vivo. These results will create a detailed map of the topography of the foveal input to the superior colliculus, an evolutionarily ancient pathway mediating subconscious non-image-forming visual behaviors. The resulting map of rare GCaMP6-expressing RGCs will accelerate the classification in Aim 1 as many SC-projecting RGCs have never been characterized functionally and may have otherwise been lost in a region where midget RGCs make up over 90% of the retinal output. This project will produce a population-level account of foveal midget RGC function in the living eye that will guide progress in restoring visual perception. In addition, the insights gained into the diversity of foveal RGCs and the visual information they convey to the brain may ultimately enable the restoration all visual function, including the visually guided movements and reflexes mediated by rare SC-projecting RGCs.