Examining the effects of retinal cell loss on downstream visual brain areas

由于人类在很大程度上依赖于视觉来体验世界，因此眼部疾病尤其令人衰弱 因为它们对患者的健康和生活质量具有显著的不利影响。很多人都知道 青光眼等眼部疾病中视网膜细胞丢失的潜在机制。然而，我们所知的要少得多。 关于视网膜细胞缺失如何影响视网膜下游的视觉大脑区域。视觉脑区立即 视网膜下游，特别是丘脑的外侧膝状体核（LGN）及其主要皮质 目标，初级视皮层（V1），可能经历实质性结构和功能重组 在从视网膜移除它们的主要输入源之后。因此，完全恢复视觉 患有眼病的患者的感知将需要“大脑水平”的视力恢复，除了修复 视网膜受损这项新研究计划的目标是通过检查影响来填补一个明显的知识空白 视网膜细胞丢失对LGN神经元结构和功能的影响。我们开发了一种视网膜 通过玻璃体内注射红藻氨酸（KA），雪貂的神经节细胞（RGC）损失。雪貂有很多 视觉特化与灵长类动物同源，包括人类，这使他们成为一个很好的模型， 以研究资助局损失对下游的影响。重要的是，雪貂的早期视觉通路被组织成 并行处理流，能够检查RGC损失在功能不同的 LGN中的神经元类别。作为具体目标1的一部分，我们将描述范围，模式和可能的 我们的雪貂模型中细胞丢失的RGC类型特异性，并将雪貂中RGC丢失的模式与 在人类眼病中观察到的表型相似性。在具体目标1中，我们还将描述 RGC缺失对LGN神经元结构和生理的影响。在具体目标2中，我们将描述 KA诱导的RGC丢失后不同存活时间后LGN神经元结构和生理学的变化。 我们将采用创新的方法，如高分辨率光学相干层析成像，全场 视网膜电图记录和视网膜组织学，以量化RGC损失并指导多电极阵列 将LGN中的记录与暗点位置进行比较。我们将同时记录来自多个单独神经元的数据， 完整眼睛和注射眼睛下游的双侧LGN，以量化生理反应特性， 功能性连接。最后，我们将利用脑组织组织学分析来表征轴突， 在LGN的变性和神经元形态，以量化下游的结构变化。 将每只动物的量化结构和生理数据进行关联，以控制注射引起的变异性 尺寸然后将在具有以下特征的动物队列中检查结构和生理变化的模式： 注射后不同的存活时间以评估变化率。该项目的长期目标是建立 RGC损失对视网膜下游神经元和回路的影响的机械理解， 以便为潜在的治疗提供信息，并制定一种大脑水平的方法来恢复视力。

Because humans rely heavily on vision to experience the world, diseases of the eye are particularly debilitating in that they have significant adverse effects on patient health and quality of life. Much is known about the mechanisms underlying retinal cell loss in eye diseases like glaucoma. However, significantly less is known about how retinal cell loss impacts visual brain areas downstream of the retina. Visual brain areas immediately downstream of the retina, especially the lateral geniculate nucleus (LGN) of the thalamus and its main cortical target, primary visual cortex (V1), are likely to undergo substantial structural and functional reorganization following the removal of their major source of input from the retina. Accordingly, full restoration of visual perception in patients with eye disease will require “brain-level” vision restoration in addition to repair of the damaged retina. The goal of this new research program is to fill a glaring knowledge gap by examining the effects of retinal cell loss on the structure and function of neurons in the LGN. We have developed a model of retinal ganglion cell (RGC) loss in the ferret through intravitreal injection of kainic acid (KA). Ferrets have a number of visual specializations homologous to primates, including humans, that make them an excellent model in which to study the downstream effects of RGC loss. Importantly, the early visual pathways in ferrets are organized into parallel processing streams enabling examination of differential effects of RGC loss across functionally distinct neuronal classes in the LGN. As a part of Specific Aim 1, we will characterize the extent, pattern, and possible RGC-type specificity of cell loss in our ferret model and compare patterns of RGC loss in the ferret with those observed in human eye disease for phenotypic similarities. Also in Specific Aim 1, we will characterize the impact of RGC loss on the structure and physiology of LGN neurons. In Specific Aim 2, we will describe the rate of changes in LGN neuronal structure and physiology after different survival times following KA-induced RGC loss. We will employ innovative methods such as high-resolution optical coherence tomography imaging, full-field electroretinogram recording, and retinal histology to quantify RGC loss and to guide multi-electrode array recordings in the LGN to scotoma locations. We will record simultaneously from multiple individual neurons in bilateral LGNs downstream of intact and injected eyes in order to quantify physiological response properties and functional connectivity. Finally, we will utilize brain tissue histological analyses to characterize axonal degeneration and neuronal morphology in the LGN in order to quantify downstream structural changes. Quantified structural and physiological data will be correlated per animal to control for variability due to injection size. Patterns of structural and physiological changes will then be examined across cohorts of animals with different survival times post-injection to assess rates of change. The long-term goal of this project is to establish a mechanistic understanding of the impact of RGC loss on the neurons and circuits downstream of the retina in order to inform potential therapeutic treatments and enact a brain-level approach toward vision restoration.