Functional Roles of Retinal Gap Junctions in Visual Processing

视网膜间隙连接在视觉处理中的功能作用

• 批准号: 10018868
• 负责人: Stewart Allen Bloomfield
• 金额: $ 40.5万
• 依托单位: STATE COLLEGE OF OPTOMETRY
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-03-01 至 2022-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10018868
• 关键词: Affect; Amacrine Cells; Back; Biological Models; Brain; Cell Communication; Cells; Chemical Synapse; Chemicals; Communication; Complex; Conflict (Psychology); Connexins; Coupled; Coupling; Data; Dyes; Electrical Synapse; Electrophysiology (science); Feedback; Functional disorder; Ganglion Cell Layer; Gap Junctions; Glaucoma; Goals; Human; Knockout Mice; Label; Lateral; Light; Mediating; Modality; Modeling; Motion; Mus; Neurons; Neuropathy; Neurophysiology - biologic function; Pathway interactions; Pattern; Pharmacology; Physiological; Play; Regulation; Reporting; Retina; Retinal Diseases; Retinal Ganglion Cells; Retinitis Pigmentosa; Role; Signal Transduction; Stimulus; Structure; Synapses; Synaptic Transmission; Techniques; Testing; Transgenic Mice; Transgenic Organisms; Vision; Visual; Visual impairment; Work; base; cell type; experimental study; ganglion cell; genetic approach; human disease; interdisciplinary approach; multi-electrode arrays; neglect; nervous system disorder; neural circuit; novel; optogenetics; preservation; programs; recruit; response; retinal neuron; visual processing; visual stimulus

Electrical synaptic transmission via gap junctions (GJs) is an important mode of neuronal communication in the CNS. An elegant example is the retina in which each of the five main neuronal types is electrically coupled via GJs. The broad distribution, diverse connexin subunit structure, and regulation of retinal GJs suggest a diversity of functional roles in visual processing; elucidating these roles forms the long-term goal of our experimental program. Here we propose to study the GJs in the inner mouse retina, which subserve a rich and complex variety of electrical circuits. The first aim of this proposal is to determine the role of cell-to-cell vs. neuron ensemble interactions in creating the robust, correlated activity displayed by retinal ganglion cells (RGCs). Correlated RGC activity is believed to have a number of functions, including enhancement of signal saliency and encoding of specific information about visual stimuli such as intensity, size, and motion. While it is now clear that GJs are critical to the creation of the robust concerted activity between RGC neighbors, the exact mechanism remains unclear. While it has been posited that reciprocal drive between coupled RGC neighbors can produce concerted firing, our preliminary data suggest that this does not occur. Rather, it appears that coherent activity within neuronal ensembles is necessary to recruit additional RGCs and produce their coherent activity. We propose a multidisciplinary approach combining electrophysiological, pharmacological, and optogenetic techniques applied to transgenic and knockout mouse lines to differentiate the circuits responsible for correlated RGC activity. The second aim will focus on the coupling between RGCs and amacrine cells (ACs). This type of electrical coupling occurs extensively across the retina, but how this affects neuronal activity has not been studied comprehensively due to a lack of an experimental platform to visualize and target coupled RGC-AC pairs for recording. We will target coupled RGC-AC pairs using two techniques: (1) labeling cells with the GJ-permenat dye Po-Pro-1; and (2) using the transgenic Grik4 mouse line in which ON α-RGCs and coupled ACs express fluorescent markers. For both, we will record from coupled pairs of RGCs and ACs to determine the role that this electrical interaction has on the response activity of inner retinal neurons. In the third aim we will study the novel idea that RGCs can alter intraretinal activity by signaling back to AC through interconnecting GJs. We posit that RGCs can alter the activity of coupled ACs, which, in turn, inhibit other ganglion cells via conventional chemical synapses. This form of intraretinal signaling thereby creates a circuit providing a novel form of lateral inhibition. Deficits in GJ communication have been implicated in a number of brain neuropathies, including visual impairments associated with retinitis pigmentosa, glaucoma and ischemic retinopathy. The experimental program proposed here will extend our understanding of the distribution and physiological roles of GJs, which forms an important prerequisite for determining how GJ dysfunction affects neural function so as to indicate novel targets for the treatment of human diseases.

通过间隙连接（GJ）的电突触传递是神经元通讯的重要模式 中枢神经系统。一个很好的例子是视网膜，其中五种主要神经元类型中的每一种都通过 GJ。视网膜 GJ 的广泛分布、不同的连接蛋白亚基结构和调节表明 视觉处理中功能角色的多样性；阐明这些角色构成了我们的长期目标 实验计划。在这里，我们建议研究小鼠视网膜内的 GJ，它有助于丰富和 各种复杂的电路。该提案的首要目标是确定细胞间与细胞间的作用。 神经元群体相互作用，创造视网膜神经节细胞显示的稳健、相关的活动 （RGC）。相关的 RGC 活动被认为具有多种功能，包括增强信号 有关视觉刺激的特定信息（例如强度、大小和运动）的显着性和编码。虽然它是 现在很清楚，GJ 对于 RGC 邻国之间建立强有力的协调活动至关重要， 确切的机制仍不清楚。虽然已经假设耦合 RGC 之间存在相互驱动 邻居可以产生协同射击，但我们的初步数据表明这种情况不会发生。相反，它 看来神经元群内的连贯活动对于招募额外的 RGC 并产生 他们的连贯活动。我们提出了一种结合电生理学、 药理学和光遗传学技术应用于转基因和基因敲除小鼠系以区分 负责相关 RGC 活动的电路。第二个目标将重点关注 RGC 之间的耦合 和无长突细胞（AC）。这种类型的电耦合广泛发生在视网膜上，但是这种电耦合是如何发生的？ 由于缺乏实验平台，尚未全面研究对神经元活动的影响 可视化和目标耦合的 RGC-AC 对进行记录。我们将使用两个目标耦合 RGC-AC 对 技术：（1）用GJ-permenat染料Po-Pro-1标记细胞； (2) 使用转基因 Grik4 小鼠 ON α-RGC 和偶联的 AC 表达荧光标记的线。对于两者，我们将从耦合记录 RGC 和 AC 成对，以确定这种电相互作用对内部响应活动的作用 视网膜神经元。在第三个目标中，我们将研究 RGC 可以通过信号传导改变视网膜内活动的新想法 通过互连的 GJ 返回到 AC。我们假设 RGC 可以改变耦合 AC 的活动，这在 反过来，通过传统的化学突触抑制其他神经节细胞。这种形式的视网膜内信号传导因此 创建一个提供新型侧抑制形式的电路。 GJ 沟通缺陷受到牵连 多种脑神经病变，包括与色素性视网膜炎、青光眼相关的视力障碍 和缺血性视网膜病变。这里提出的实验计划将扩展我们对 GJ的分布和生理作用是确定GJ如何发挥作用的重要前提 功能障碍影响神经功能，从而为治疗人类疾病提供新的靶点。