Defining the role of a prefrontal-midbrain circuit in exploratory behavior

定义前额叶-中脑回路在探索行为中的作用

• 批准号: 10302269
• 负责人: Victoria L Corbit
• 金额: $ 5.5万
• 依托单位: PRINCETON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-12-01 至 2022-08-05
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10302269
• 关键词: Affect; Amygdaloid structure; Anatomy; Animals; Behavior; Behavioral; Body part; Brain; Cells; Color; Computing Methodologies; Data; Development; Dopamine; Dopaminergic Cell; Electrophysiology (science); Environment; Exploratory Behavior; Genetic; Glutamates; Goals; Grooming; Image; In Vitro; Label; Learning; Locomotion; Maps; Measures; Medial; Mediating; Methods; Midbrain structure; Motor output; Mus; Neurons; Nucleus Accumbens; Physiology; Population; Posture; Prefrontal Cortex; Process; Psychological reinforcement; Research; Resolution; Rewards; Rodent; Role; Running; Stimulus; Supervision; Synapses; Time; Training; Transgenic Mice; Transgenic Organisms; Ventral Tegmental Area; Viral; Virus; Walking; base; behavioral response; cell cortex; cell type; dopaminergic neuron; experimental study; in vivo; machine learning method; neural circuit; novel; optogenetics; programs; relating to nervous system; response; unsupervised learning

ABSTRACT Investigating how neural circuits mediate natural behavior is a critical to our understanding of the brain. Exploratory behaviors are necessary for rodent survival in the natural world and ubiquitous in freely-moving rodent experiments. One neural circuit that may mediate natural exploratory behaviors are the projections from prelimbic cortex (PL, part of rodent prefrontal cortex) to ventral tegmental area (VTA). Stimulation of PL-VTA projections causes increased velocity but is not rewarding, despite the well-known rewarding effect of direct stimulation of VTA-dopamine neurons. Taken together with the fact that VTA has been implicated in exploration, my central hypothesis is that PL-VTA neurons mediate natural exploratory behaviors through downstream effects on a subpopulation of non-dopaminergic VTA neurons. To investigate this hypothesis, I will first develop an unbiased, machine-learning-based method to quantify untrained, freely-moving mouse behaviors (Experiment 1.1). My method will leverage multi-view, high resolution video, supervised body part tracking, and unsupervised machine learning-based postural clustering methods. I will use this method to identify which specific behaviors (rearing, walking, grooming, sniffing, etc.) are affected by optogenetic stimulation or inhibition of PL-VTA cells in the presence and absence of rewards (Experiment 1.2). Preliminary data demonstrates the feasibility of my behavioral quantification method and suggests that PL-VTA stimulation increases exploratory behaviors. Next, to identify the genetically- and target-defined VTA cells that are preferentially synapsed onto by PL projections, I will use a combination of optogenetics, in vitro electrophysiology, transgenic mice, and retrograde tracing. First, I will use transgenic mice to measure the functional strength of PL input specifically onto VTA cells that are dopaminergic, GABAergic, or glutamatergic (Experiment 2.1). In a different set of mice, I will use retrograde tracing to identify if PL synapses preferentially onto VTA cells that project to nucleus accumbens or amygdala (Experiment 2.2). After learning which genetic and target-defined VTA subpopulations receive PL input, I will use retrograde tracing in combination with transgenic labeling to identify specifically which genetically and projection-defined VTA subpopulation receives PL input (Experiment 2.3). Finally, I will use a retrograde cre-dependent virus to selectively infect this VTA subpopulation with ChR2 and use my behavioral quantification pipeline to investigate whether in vivo stimulation of this subpopulation recapitulates the exploratory effects of PL-VTA stimulation (Experiment 2.4). Thus, the project proposed will develop a novel method for quantifying naturalistic behavior and integrate this computational method with diverse experimental methods, including in vivo and in vitro optogenetics, natural behavior, and synaptic physiology. These experiments will contribute novel information on how the PL-VTA circuit mediates naturalistic motor output, independent of the reinforcement effects of VTA-dopamine activity.

摘要 研究神经回路如何调节自然行为对我们理解大脑至关重要。 探索行为是啮齿类动物在自然界生存所必需的，在自由活动的动物中普遍存在 啮齿动物实验一个可能调节自然探索行为的神经回路是来自 前边缘皮层（PL，啮齿动物前额叶皮层的一部分）到腹侧被盖区（VTA）。PL-VTA刺激 预测导致速度增加，但不是奖励，尽管众所周知的直接奖励效应 刺激腹侧被盖区多巴胺神经元。再加上VTA涉嫌 探索，我的中心假设是，PL-VTA神经元介导自然的探索行为，通过 对非多巴胺能腹侧被盖区神经元亚群的下游效应。 为了研究这个假设，我将首先开发一种无偏见的，基于机器学习的方法来量化 未经训练的，自由移动的小鼠行为（实验1.1）。我的方法将利用多视图，高 分辨率视频、有监督的身体部位跟踪和基于无监督机器学习的姿势聚类 方法.我将使用这种方法来识别哪些特定的行为（饲养，行走，梳理，嗅闻等）。 在存在和不存在奖赏的情况下， （实验1.2）。初步数据证明了我的行为量化方法的可行性， 表明PL-VTA刺激增加探索行为。 接下来，为了鉴定PL优先突触的遗传和靶向定义的VTA细胞， 预测，我将使用光遗传学，体外电生理学，转基因小鼠和逆行 追踪首先，我将使用转基因小鼠来测量PL特异性输入到VTA的功能强度 多巴胺能、GABA能或多巴胺能细胞（实验2.1）。在另一组小鼠中，我将使用 逆行追踪，以确定PL突触是否优先投射到投射到延髓核的VTA细胞上， 杏仁核（实验2.2）。在了解哪些遗传和目标定义的VTA亚群接受PL后， 输入，我将使用逆行追踪结合转基因标记，以确定具体 遗传和投影定义的VTA亚群接受PL输入（实验2.3）。最后，我将使用 逆行cre依赖性病毒选择性感染这个VTA亚群与ChR 2和使用我的行为 定量管道，以研究该亚群的体内刺激是否重现了 PL-VTA刺激的探索性效果（实验2.4）。 因此，该项目将开发一种新的方法来量化自然行为，并将其整合到 计算方法与多种实验方法，包括体内和体外光遗传学，自然 行为和突触生理学。这些实验将有助于新的信息，如何PL-VTA 电路介导的自然运动输出，独立的腹侧被盖区-多巴胺活动的强化效果。