Photosensitive control of the inner retina

描述(申请人提供)：我们建议将光敏感度直接传递给患病视网膜中正常的非光敏性神经元。虽然遗传性视网膜变性的根源有许多遗传原因，但一个共同的主题是最终光感受器细胞的凋亡性死亡。在大多数情况下，残留的视网膜内神经元在视杆细胞和视锥细胞丢失后存活很长时间。我们目标的核心是使用新的视紫红质，允许精确地光学控制可见光下的神经活动。通道视紫红质-2是一种光敏性阳离子通道，允许神经对蓝光做出反应。功能相反的是卤视紫质，这是一种光敏性氯化物泵，可以用黄色光沉默神经活动。这些视紫红质使用维甲酸作为发色团，直接调节活性，而不需要辅助蛋白级联或外源化学物质。我们推测，如果在适当的细胞亚型中启动，光驱动的兴奋和抑制可能会重新产生正常存在于视网膜上的开中心和偏离中心的视觉信息流。这些并行信息流在很大程度上导致了对比度敏感度和高清晰度。我们建议通过转录靶向和病毒基因转移相结合的方法来实现对期望的中心上或中心外细胞群体的特定传递。膜片钳电生理学结合光栅扫描刺激将是该项目的组成部分，用于评估转基因靶向的特异性和表征由这些神经元网络产生的光电流。最后，我们希望了解，在疾病模型中，光敏的视网膜内部是否可以通过简单的行为工具将功能信息传递到高级视觉中心。利用这些神经工程学和电生理学相结合的方法，我们的目标是确定选择性光刺激和抑制ON和OFF通路的内部神经元是否可以赋予受损的视网膜有用的光敏感性。与公共健康相关：基因疗法是一种非常有希望的方法，可以尝试恢复导致光感受器丧失的疾病的视力，直接向存活的视网膜神经元传授光敏感性可能是一种方法。我们希望了解将非光敏神经元转化为光传感器的潜力，并将这一知识应用于未来视网膜假体的开发。

DESCRIPTION (provided by applicant): We propose to impart light sensitivity directly onto normally non-photosensitive neurons in a diseased retina. While inherited retinal degenerations have many genetic causes at their source, one common theme is the eventual apoptotic death of photoreceptor cells. In most cases, the remaining inner retinal neurons survive long after rods and cones are lost. Central to our goal is the use of novel rhodopsins that allow for precise optical control of neural activity with visible light. Channelrhodopsin-2 is a photosensitive cation channel that allows for neural excitation in response to blue light. A functional converse is Halorhodopsin, a photo- sensitive chloride pump that silences neural activity with yellow light. These rhodopsins use retinoids as their chromophore and directly modulate activity without accessory protein cascades or exogenous chemicals. We hypothesize that if initiated in the appropriate cell subtype, light-driven excitation and inhibition may re- create the ON and OFF-center visual information streams normally present in the retina. These parallel information streams are largely responsible for allowing contrast sensitivity and high acuity. Specific delivery to the desired ON or OFF-center cell population is not trivial, and we propose to approach this by a combination of transcriptional targeting along with viral gene transfer methods. Patch clamp electrophysiology combined with raster scanning stimuli will be integral to the project for both evaluating the specificity of transgene targeting and in characterizing the photocurrents generated from networks of these neurons. Finally, we hope to understand if a photosensitive inner retina can transmit functional information to higher visual centers in a disease model with simple behavioral tools. Using these combined neuroengineering and electrophysiological approaches, we aim to determine if selective photo-excitation and inhibition of ON and OFF pathway inner neurons can confer useful light sensitivity to the injured retina. PUBLIC HEALTH RELEVANCE: Gene therapy is a highly promising method for attempting to restore vision in diseases that cause photoreceptor loss, and imparting light sensitivity directly to surviving retinal neurons may be one approach. We hope to understand the potential for converting non-photosensitive neurons into photosensors and apply this knowledge toward the future development of a retinal prosthetic.