Midbrain cellular and circuit dynamics of cocaine seeking

项目摘要 成瘾是一种主要的公共卫生问题，其特征是强迫性渴望，寻求毒品， 以及很高的复发概率，这通常是由药物相关线索的存在所刺激的。药物性 中脑回路的变化，包括腹侧被盖区（VTA）和黑质（SN），被认为是 这些行为的基础，但神经元亚型和投射的异质混合物， 中脑的研究阻碍了对特定神经元和回路在行为中的作用的清晰理解。在 以前的研究利用光遗传学方法特异性地操纵中脑多巴胺神经元， 发现投射到延髓核的神经元与投射到延髓核的神经元的贡献存在功能分离， 背侧纹状体的条件线索的动机效应，这表明奖励过程是 分布在中脑的各个解剖分区。在这里，我扩展了这些发现，以确定和 比较VTA和SN中多巴胺和GABA神经元在可卡因诱发行为中的作用， 可卡因相关线索诱发的可卡因寻求复发。我会用最先进的病毒式 可视化和操纵神经元活动的方法。 在K99目标中，我首先提出采用体内深部脑成像来可视化脑组织中的钙动力学。 大量的多巴胺和GABA神经元在中脑可卡因暴露。接下来，我提议 使用化学遗传学方法，该方法依赖于将设计受体插入靶神经元， 沉默多巴胺和GABA神经元的活性，以评估它们在对 可卡因这些研究将确定可卡因诱导的生理反应的遗传定义的腹侧被盖区， SN神经元及其在可卡因诱发行为中的作用。 基于新的训练和对可卡因神经生理学影响的见解，我在 K99时期，我将利用体内钙成像和光遗传学来确定活性模式， 选择性中脑投射在可卡因寻找和线索触发复吸中的时间作用 R 00周期。首先，我将想象投射到纹状体或丘脑的多巴胺和GABA神经元的活动， 动物寻找可卡因并对可卡因相关的线索做出反应。接下来，我将利用时间精确度 光遗传学在离散的时间点分阶段地操纵这些投射，以确定它们的必要性。 和/或可卡因自我给药和线索触发复发测试的充足性。拟议的研究将 提供了一个新颖的和全面的表征电路机制，中脑神经元 协调可卡因和可卡因线索相关的行为。

Project Summary Addiction is a disorder of major public health concern, characterized by compulsive craving, drug seeking, and a high probability of relapse that is often spurred by the presence of drug-associated cues. Drug-induced changes in midbrain circuits, including the ventral tegmental area (VTA) and substantia nigra (SN), are thought to underlie these behaviors, but the heterogeneous mixture of neuronal subtypes and projections of the midbrain has prevented a clear understanding of the role of specific neurons and circuits in behavior. In previous studies, which utilized optogenetics methods to specifically manipulate midbrain dopamine neurons, I found a functional dissociation in the contribution of neurons projecting to the nucleus accumbens versus dorsal striatum in the motivational effects of conditioned cues, suggesting that reward processes are parcellated across anatomical divisions in the midbrain. Here, I expand on these findings to identify and compare the role of dopamine and GABA neurons in the VTA and SN in cocaine-evoked behaviors and relapse of cocaine seeking evoked by cocaine-associated cues. I will do so using state-of-the-art viral-based methods to visualize and manipulate neuronal activity. In the K99 Aims, I first propose to employ in vivo deep brain imaging to visualize the calcium dynamics of large numbers of dopamine and GABA neurons in the midbrain during cocaine exposure. Next, I propose to use chemogenetic methods, which rely on the insertion of designer receptors into target neurons, to tonically silence the activity of dopamine and GABA neurons to assess their functional role in behavioral sensitization to cocaine. These studies will define the cocaine-induced physiological responses of genetically defined VTA and SN neurons, and their role in cocaine-evoked behavior. Building on the new training and insights into the neurophysiological effects of cocaine I gain during the K99 period, I will utilize in vivo calcium imaging and optogenetics to determine to the activity patterns and temporal role of select midbrain projections in operant cocaine seeking and cue-triggered relapse during the R00 period. First, I will image activity of dopamine and GABA neurons projecting to the striatum or thalamus as animals seek cocaine and respond to cocaine-associated cues. Next, I will harness the temporal precision optogenetics to phasically manipulate these projections at discrete time points to determine their necessity and/or sufficiency for cocaine self-administration and cue-triggered relapse test. The proposed studies will provide a novel and comprehensive characterization of the circuit mechanisms by which midbrain neurons orchestrate cocaine and cocaine-cue related behaviors.