Influence of retinal ganglion cells on visual neuron identity in superior colliculus

摘要 人脑能够进行令人震惊的复杂计算，这在很大程度上要归功于 专门的神经元被优化来处理离散的信息片段。例如，在视觉系统中， Diff神经元的亚型被调节到视觉场景的不同方面，如Mo8on、颜色或对比度。几十年 的精美工作在许多方面消除了子类，使用了功能、形态和分子标准。 然而，我们对这种多样性是如何在发育中的视觉系统中产生的了解很少， 阻碍制定恢复宏碁因疾病或创伤所致视力丧失的再生策略。至 为了解决这一差距，我们将在本提案中重点关注小鼠上丘(SC)，我们假设这是一个易于处理的模型 开始解决这个复杂的问题。以前的研究已经在SC所需的因子上识别了8个fi转录因子 神经发生和PAKERNING，导致了内在的遗传机制的基础上的命运物种在SC的fiCa8。 然而，与其他视觉区域(例如，re8na或fi)相比，很少有分子被鉴定为具有这种作用 我们以前的和初步的数据挑战了这一点，揭示了大脑神经节的潜在作用。 在宿命种fica8中，细胞(RGC)支配SC。为了测试这种激发的可能性，我们将采取互补的增益-和 丧失功能的方法，利用独特的gen8c工具，允许我们重新安排RGC输入的组织，以 SC和Follow-defiNed神经元群体在不同的ff环境中。此外，通过结合 对单个神经元的形态分析、单核rna测序和活体光基因c细胞的fic序列分析 视觉调谐分析，我们将全面检验我们的假设。在目标1中，我们将直接确定 通过检查神经元的形态(目标1A)和转录水平的fiNed细胞多样性(目标1B)来识别输入 对照组和去核小鼠的SC神经元。在目标2中，我们将利用一个独特的鼠标模型，在该模型中 在SC中，Islet2+和Islet2-RGC的投影子被分离到不同的ff结构域。之前，我们展示了视觉效果 这些区域的功能不同，提示神经元同一性的潜在转换。为了测试这种可能性，我们 将决定基因的视觉调节特性(目标2A)、形态(目标2B)和转录组(目标2C) DefiNed SC神经元分布于SC的Islet2+和Islet2-RGC神经支配区域。这些加在一起， 实验将显著地促进我们对细胞多样性产生机制的理解。fi SC和揭示了外源性synap8c输入在塑造神经元同一性中潜在的范式屏蔽作用。

ABSTRACT The human brain is capable of making astoundingly complex computa8ons thanks in large part to the diversity of specialized neurons that are op8mized to processes discrete bits of informa8on. For example, in the visual system, different subtypes of neurons are tuned to dis8nct aspect of the visual scene, such as mo8on, color or contrast. Decades of elegant work has defined the subclasses in many ways, using func8onal, morphological, and molecular criteria. However, we have a poor understanding of how such diversity arises in the developing visual system, crea8ng a roadblock to the development of regenera8ve strategies to restore vision aCer loss due to disease or trauma8c injury. To address this gap, we will focus on the mouse superior colliculus (SC) in this proposal, which we posit is a tractable model to begin to tackle this complex problem. Previous studies have iden8fied transcrip8on factors required for SC neurogenesis and paKerning, leading to the view that intrinsic gene8c mechanisms underlie fate specifica8on in the SC. However, very few molecules have been iden8fied to have this role in comparison to other visual regions (e.g. re8na or visual cortex); and, our previous and preliminary data challenge this no8on, revealing a poten8al role for re8nal ganglion cells (RGCs) innerva8ng the SC in fate specifica8on. To test this exci8ng possibility, we will take complementary gain- and loss-of-func8on approaches, leveraging unique gene8c tools that allow us to rearrange the organiza8on of RGC inputs to the SC and follow gene8cally-defined neuronal popula8ons in different contexts. Furthermore, by combining morphological analyses of individual neurons, single nucleus RNA sequencing, and cell-specific in vivo optogene8cs with visual tuning analysis, we will comprehensively test our hypothesis. In Aim 1, we will directly determine the role of re8nal input by examining neuronal morphology of (Aim 1A) and the transcrip8onally-defined cellular diversity (Aim 1B) of SC neurons from control and enucleated mice. In Aim 2, we will leverage a unique mouse model in which the projec8ons of Islet2+ and Islet2- RGCs are segregated into different domains in the SC. Previously, we showed that visual func8on was divergent in these regions, sugges8ng poten8al switching of neuronal iden8ty. To test this possibility, we will determine the visual tuning proper8es (Aim 2A), morphology (Aim 2B), and transcriptome (Aim 2C) of gene8cally- defined SC neuron popula8ons in Islet2+- and Islet2--RGC innervated regions of the SC. Taken together, these experiments will significantly advance our understanding of the mechanisms by which cellular diversity is generated in the SC and uncover a poten8ally paradigm-shiCing role for extrinsic synap8c inputs in shaping neuronal iden8ty.