The Influence of the Pretectum on the Visual Thalamus

项目摘要/摘要 顶盖前(PT)是哺乳动物中一个相对未被探索的大脑区域，目前尚不清楚。 PT如何影响复杂整合下丘脑神经元的视觉特性 有远见和行动。在这里，一组调查人员提出了一种多方面的方法-来自 行为突触-回答有关PT电路的基本问题(目标1)，视觉 和/或已识别的PT神经元的运动反应特性(目标2)，PT输入对 丘脑神经元的反应特性(目标3)，以及PT对视觉行为的影响 (目标4)。每个目标将利用新颖的交叉电路标记技术的组合， 神经元激活和记录策略以探测两条已识别的PT通路：GABA能 外侧膝状核(LGN)和丘脑网状结构视区的通路 核团(VTRN)和从PT神经元到枕核的非GABA能通路(PUL) 含有小白蛋白的。目标1将使用依赖cre的单突触狂犬病跟踪来诱导 钙指示剂GCaMP的表达在2P成像中对感受区的分类 支配PT-LGN/TRN和PT-Pul的视网膜神经节细胞的特性和形态 神经元。单突触狂犬病追踪也将被用来表征皮质和皮质下 脑对PT-LGN/TRN和PT-PUL细胞的输入；已确定的PT输入将在随后进行研究 使用电子显微镜和体外全细胞记录配合光遗传激活 鉴定它们的超微结构和突触特性。AIM 2将在体内使用细胞外 在清醒的动物中进行配对的记录和“光标记”以确定反应特性 PT-LGN/TRN和PT-Pul神经元。AIM 3将使用清醒时的活体细胞外录音 与PT输入的光遗传激活配对的动物以确定PT输入的影响 关于LGN、vTRN和PUL响应特性。最后，目标4将使用依赖于cre和flp的 PT-LGN/TRN或PT-PUL神经元的化学激活以确定这些细胞是否影响 立体视和/或视动反应。总而言之，这4条调查路线将提供关键 关于PT在主动视力中的作用的信息。

PROJECT SUMMARY / ABSTRACT The pretectum (PT) is a relatively unexplored brain area in mammals, and it is currently unknown how the PT affects the visual properties of thalamic neurons that underly the complex integration of vision and movement. Here, a team of investigators propose a multifaceted approach - from synapse to behavior – to answer fundamental questions regarding PT circuits (Aim 1), the visual and/or motor response properties of identified PT neurons (Aim 2), the effects of PT input on the response properties of thalamic neurons (Aim 3), and the effects of the PT on visual behavior (Aim 4). Each aim will utilize a combination of novel intersectional circuit labeling techniques, neuronal activation, and recording strategies to probe two identified PT pathways: a GABAergic pathway to the lateral geniculate nucleus (LGN) and the visual sector of the thalamic reticular nucleus (vTRN), and a nonGABAergic pathway to the pulvinar nucleus (PUL) from PT neurons that contain parvalbumin. Aim 1 will use cre-dependent monosynaptic rabies tracing to induce the expression of the calcium indicator GCaMP to classify, using 2P imaging, the receptive field properties and morphology of retinal ganglion cells that innervate PT-LGN/TRN and PT-PUL neurons. Monosynaptic rabies tracing will also be used to characterize cortical and subcortical brain inputs to PT-LGN/TRN and PT-PUL cells; identified PT inputs will subsequently be studied using electron microscopy and in vitro whole cell recordings paired with optogenetic activation to characterize their ultrastructure and synaptic properties. Aim 2 will use in vivo extracellular recordings in awake animals paired with “opto-tagging” to determine the response properties of PT-LGN/TRN and PT-PUL neurons. Aim 3 will use in vivo extracellular recordings from awake animals paired with optogenetic activation of PT inputs to determine the effects of the PT inputs on LGN, vTRN and PUL response properties. Finally, Aim 4 will use cre- and flp-dependent chemogenetic activation of PT-LGN/TRN or PT-PUL neurons to determine if these cells affect stereopsis and/or optokinetic responses. Collectively, these 4 lines of inquiry will provide key information regarding the role of the PT in active vision.