MAPPING RETINOTECTAL CIRCUITS FOR VISUAL-EVOKED INNATE BEHAVIORS

项目总结 神经回路的精确组装确保了准确的神经功能和行为。为 例如，为了向大脑传达视觉世界的特定方面，视网膜神经节细胞(RGC)找到并 与不同神经元群体中的特定突触后伙伴形成突触联系 大脑中的视黄醇受体区域。一个这样的区域是上丘(SC)，它接受直接的视网膜 输入和发送命令，以进行直接的先天行为，如逃跑或捕获猎物。分子是什么？ 选择性RGC至SC神经元连接的决定因素？平行的视网膜顶盖回路如何被分类到不同的 SC板层和神经元中继器？不同的视网膜顶盖回路是如何与明确的视觉诱发行为联系起来的？ 这项拟议的研究旨在回答小鼠视觉系统中的这些问题。 为了实现这一目标，首先，我们将绘制平行的视网膜顶盖回路。我们已经建立了一个 综合顺行追踪和测序平台，Trans-Seq，定义了一种从基因上- 已定义RGC子类型。我们将跨序列应用于全局、α-RGC和开关方向的所有RGC子类型- 选择性神经节细胞及其分化输出重建至上丘浅层(SSC) 神经元亚型。我们建议将Trans-Seq应用于代表不同视觉的其他主要RGC亚型 功能。拟议的研究将确定视网膜顶盖回路在神经元亚型上的汇聚和发散。 决议。其次，我们的目标是了解调节特定视网膜顶盖的细胞和分子机制。 电路布线。我们分析了α-RGC的特异性输出，揭示了一种选择性的SSc神经元亚型。 肾连蛋白阳性广域神经元(NPWF)。α-RGC-to-NPWF电路的遗传学验证使用 成像、电生理学和逆行追踪。我们建议研究Nephronectin是如何调节α-RGC的 在深SSc层的选择性轴突分层以及Nephronectin是否决定随后的 α-RGC对NPWF的突触特异性。我们还将研究是什么分子机制在 Nephronectin结合并导致哺乳动物视网膜顶盖回路的选择性组装。第三，我们将具体链接 视网膜顶盖回路来定义视觉诱发行为。我们建议将遗传和光遗传工具结合起来 以确定α-RGC-to-NPWF回路是否参与视觉诱发的先天 行为，如隐约可见，触发了防御反应。我们还将研究分子决定因素 对于连接性，如Nephronectin，通过这些视网膜顶盖回路调节这种行为输出。 我们的电路映射平台以神经元亚型分辨率构建了精确的连接图。此外， 这项工作将使精确的神经元接线图与与生俱来的视觉诱发行为保持一致，从而预示未来 功能和行为分析。在这里获得的新知识可能包括潜在的分子原理 哺乳动物的电路连接与视觉系统以外的系统有关。

PROJECT SUMMARY The precise assembly of neural circuits ensures accurate neurological function and behavior. For example, to communicate specific aspects of the visual world to the brain, retinal ganglion cells (RGCs) find and form synaptic contacts with specific postsynaptic partners out of the heterogeneous neuronal population of retino-recipient areas in the brain. One such area is the superior colliculus (SC), which receives direct retinal inputs and sends commands for direct innate behaviors such as escape or prey capture. What are the molecular determinants for selective RGC to SC neuron wiring? How are parallel retinotectal circuits sorted onto different SC laminae and neuronal relays? How are distinct retinotectal circuits linked to defined visual evoked behaviors? This proposed study aims to answer these questions in the mouse visual system. To accomplish this goal, first, we will map out parallel retinotectal circuits. We have established an integrated anterograde-tracing and sequencing platform, Trans-Seq, that defines the outputome of a genetically- defined RGC subtype. We applied Trans-Seq to all RGC subtypes globally, α-RGCs, and On-Off direction- selective-ganglion-cells and reconstructed their differential outputomes onto superficial superior-collicular (sSC) neuron subtypes. We propose to apply Trans-Seq to other major RGC subtypes representing different visual features. The proposed studies will determine retinotectal circuit convergence and divergence at neuron subtype resolution. Second, we aim to understand cellular and molecular mechanisms regulating specific retinotectal circuit wiring. We have analyzed α-RGC specific outputomes and revealed a selective sSC neuron subtype, Nephronectin-positive-wide-field neurons (NPWFs). The α-RGC-to-NPWF circuit was genetically validated using imaging, electrophysiology, and retrograde tracing. We propose to study how Nephronectin mediates α-RGC selective axonal lamination onto the deep sSC layer and whether Nephronectin determines the subsequent synaptic specificity from α-RGCs to NPWFs. We will also investigate what molecular mechanisms mediate Nephronectin binding and lead to a selective mammalian retinotectal circuit assembly. Third, we will link specific retinotectal circuits to defined visual evoked behaviors. We propose to combine genetic and optogenetic tools established above to determine whether the α-RGC-to-NPWF circuit contributes to visual evoked innate behaviors, such as looming triggered defense responses. We will also examine whether molecular determinants for connectivity, such as Nephronectin, regulate this behavioral output via these retinotectal circuits. Our circuit mapping platform builds a precise connectivity map at neuronal subtype resolution. Further, this work will align the precise neuronal wiring diagram to innate visual evoked behaviors, informing future functional and behavioral analysis. The new knowledge gained here may include molecular principles underlying mammalian circuit wiring relevant beyond the visual system.