Circuit Assembly in the Vertebrate Retina

描述（由申请人提供）：视觉需要从光感受器到视网膜神经节细胞（RGC）（视网膜的输出神经元）的适当信息传递。这些信息由视网膜双极细胞（BC）沿沿着许多解剖学上和功能上不同的通道分布。由于BC通道携带不同的色彩和时间信息，因此RGC的光响应由其接收的BC输入的独特组合来塑造。到目前为止，只有少数功能定义的RGC类型的电路是已知的，主要是因为通过连续电子显微镜重建技术上具有挑战性和耗时。使用最先进的成像方法和分子工具来可视化突触和连接，我们能够通过光学显微镜轻松重建这些电路。我们将建立并比较小鼠视网膜中三种功能不同的BC-RGC回路的连接模式，以学习新的原理或揭示BC输入可以塑造RGC输出的不同策略（目标1）。我们将研究神经传递的丧失（目标2）或视网膜神经元的死亡（目标3）如何改变内层视网膜的电路。由于活动阻断的影响可以根据神经传递在发育或疾病中的扰动方式而变化，因此我们将确定BC的输入和/或输出的中断如何影响它们与RGC的连接。我们将使用新的转基因小鼠，其中传输以不同的方式受到干扰，以及在少数或整个BC群体中活动发生改变的小鼠。在目标3中，我们将确定当来自一个或另一个群体的细胞被消融时，成熟BC和RGC重新连接的潜力。我们将通过使用转基因小鼠来做到这一点，在这些小鼠中，细胞死亡的幅度和时间可以控制。这些发现对于设计基于细胞的疗法来恢复视力特别重要。总而言之，该项目的发现将显着增加我们对调节视网膜通道功能、组装和修复的细胞机制的了解，这些通道是将信息从光感受器传递到RGC所必需的。 公共卫生相关性：正常视力需要视网膜中神经元回路的正确组装和维护。 视网膜疾病的视网膜回路被破坏。因此，这个项目的广泛目标是了解视网膜回路组装、拆卸和重组的细胞机制。

DESCRIPTION (provided by applicant): Vision requires proper information transfer from photoreceptors to retinal ganglion cells (RGCs), the output neurons of the retina. This information is distributed by retinal bipolar cells (BCs) along many anatomically and functionally distinct channels. Because BC channels carry different chromatic and temporal information, the light response of a RGC is shaped by the unique combination of BC input it receives. To date, the circuitry of only a few functionally defined RGC types is known, largely because reconstructions by serial electron microscopy are technically challenging and time consuming. Using state-of-the art imaging approaches and molecular tools to visualize synapses and connectivity, we are able to readily reconstruct these circuits by light microcopy. We will establish, and compare, the connectivity patterns of three functionally distinct BC-RGC circuits in the mouse retina, in order to learn new principles or uncover distinct strategies by which BC input can shape RGC output (Aim 1). We will investigate how loss of neurotransmission (Aim 2), or death of retinal neurons (Aim 3) alters circuitry in the inner retina. Because the effects of activity blockade can vary according to how neurotransmission is perturbed in development or in disease, we will determine how disruption of input and/or output of BCs influence their connectivity with RGCs. We will use novel transgenic mice in which transmission is perturbed in distinct ways, and also mice in which activity is altered in either a few or entire populations of BCs. In Aim 3, we will determine the potential of mature BCs and RGCs to re-connect when cells from one or the other population are ablated. We will do this by using transgenic mice in which the magnitude and timing of cell death can be controlled. These findings will be particularly significant for designing cell-based therapies to restore vision. Together, the discoveries of this project will significantly increase our understanding of the cellular mechanisms that regulate the function, assembly and repair of retinal channels necessary for conveying information from photoreceptors to RGCs. PUBLIC HEALTH RELEVANCE: Normal vision requires proper assembly and maintenance of neuronal circuits in the retina. Retinal circuitry is disrupted in retinal diseases. The broad goal of this project is thus to understand the cellular mechanisms that underlie the assembly, disassembly and reassembly of retinal circuits.