GABAergic circuit interactions within the behaving mouse dLGN

摘要 视觉信息从视网膜通过背外侧膝状体核的流动 （dLGN）的皮质，是由行为调节。然而，发生在 清醒动物的dLGN及其行为的调节还有待揭示。目的 这项建议的目的是开发工具来确定dLGN的抑制回路（利用 神经递质γ-氨基丁酸（GABA）在体内相互作用，以及它们如何共同形成 行为背景下的视觉。这项研究的前提是基于两个关键信息： 1)我们以前的超微结构分析和体外光遗传学实验表明，两个 外源性GABA能输入dLGN，起源于丘脑网状核（TRN）， 前顶盖（PT）分别起抑制或增强视网膜膝状体传递的作用。2)先前 研究表明，TRN和PT在不同的行为状态下是活跃的。因此我们 假设这两种抑制源用于抑制或增强视觉信号， dLGN在不同的行为状态。我们建议通过记录dLGN视觉来测试这一假设。 在选择性和独立地操纵TRN和/或PT的同时， dLGN内的终端。在头部固定的警觉小鼠中，我们将记录dLGN的视觉反应， 神经元到计算机生成的视觉显示，同时记录运行速度，眼睛 运动和瞳孔直径。目标1实验将检验PT功能的假设 在眼球运动后立即增强视网膜膝状体传递， 视觉目标获取后激活。为此，将记录膝状体反应 在PT末端的光遗传学沉默或激活，TRN末端的化学遗传学沉默， 或PT和TRN末端的组合光遗传学/化学遗传学操作。目标2 实验将检验TRN抑制视网膜神经传递的假设， 静止状态为此目的，将在光遗传学沉默期间记录膝状体反应， TRN末端的激活，PT末端的化学遗传沉默，或组合 TRN和PT末端的光遗传学/化学遗传学操作。技术的发展， 在体内操纵回路，除了我们现有的解剖和体外实验策略， 将提供一个强有力的多管齐下的方法来破译大脑的各个组成部分是如何 电路是集成的。一旦这些体内方法完善，我们的方法学整合 这种方法可以用来回答各种各样的悬而未决的问题，关于丘脑功能。

Abstract The flow of visual information from the retina, through the dorsal lateral geniculate nucleus (dLGN) to the cortex, is regulated by behavior. However, the dynamic circuit interactions that occur in the dLGN of awake animals, and their modulation by behavior, have yet to be revealed. The purpose of this proposal is to develop tools to determine how inhibitory circuits of the dLGN (which utilize the neurotransmitter gamma amino butyric acid, GABA) interact in vivo, and how they collectively shape vision in the context of behavior. The premise of this study is based on two key pieces of information: 1) Our previous ultrastructural analyses and in vitro optogenetic experiments suggest that two extrinsic GABAergic inputs to the dLGN, originating from the thalamic reticular nucleus (TRN) and pretectum (PT), serve to suppress or enhance retinogeniculate transmission respectively. 2) Previous studies suggest that the TRN and PT are active during different behavioral states. Thus, we hypothesize that these two sources of inhibition serve to suppress or enhance visual signals in the dLGN during different behavioral states. We propose to test this hypothesis by recording dLGN visual responses in behaving mice while selectively and independently manipulating TRN and/or PT terminals within the dLGN. In head-fixed alert mice, we will record the visual responses of dLGN neurons to computer-generated visual displays while simultaneously recording running speed, eye movements, and pupil diameter. The Aim 1 experiments will test the hypothesis that the PT functions to enhance retinogeniculate transmission immediately following eye movements, to boost cortical activation following visual target acquisition. For this aim, geniculate responses will be recorded during optogenetic silencing or activation of PT terminals, chemogenetic silencing of TRN terminals, or the combined optogenetic/chemogenetic manipulation of PT and TRN terminals. The Aim 2 experiments will test the hypothesis that the TRN dampens retinogeniculate transmission during quiescent states. For this aim, geniculate responses will be recorded during optogenetic silencing or activation of TRN terminals, chemogenetic silencing of PT terminals, or the combined optogenetic/chemogenetic manipulation of TRN and PT terminals. The development of techniques to manipulate circuits in vivo, in addition to our existing anatomical and in vitro experiment strategies, will provide a powerful multipronged approach to deciphering how the individual components of brain circuits are integrated. Once these in vivo methods are perfected, our methodologically-integrated approach can be used to answer a wide variety of outstanding questions regarding thalamic function.