Single Cell Encoding of Cocaine Seeking Behavior in the Nucleus Accumbens

摘要 吸毒成瘾，包括可卡因滥用障碍，是一个重大的公共卫生问题，其特点是： 强迫性药物寻求和戒断后复发倾向增加。可卡因成瘾是 由与药物本身的奖励效应密切相关的环境线索引发。神经元 可卡因相关线索在单细胞水平的编码仍不清楚，限制了我们对可卡因相关线索的理解。 可卡因配对线索触发了药物寻求行为。通过其成分多巴胺D1和D2受体表达 中棘投射神经元（MSNs）中，丘脑核核心（NAcore）在编码中起着关键作用 线索奖励关联和引发可卡因寻求行为的复发。NAcore集成了多个 皮层和异皮层输入。特别是，来自前边缘系统的传入神经元投射的激活 皮质（PL）是必要的线索诱导恢复可卡因寻求。使用化学遗传学和 虽然D1和D2-MSN上的光遗传学操作，但以前的研究表明这些神经元的作用相反， 在啮齿类动物自我给药模型中，所以我 假设背景/线索恢复期间可卡因寻求和消退期间抑制寻求 训练与D1-和D2-MSN的时间和空间上不同的神经元集合相关， 由PL-NAcore投射差异调制。我将通过定量细胞中的Ca 2+活性来解决这一假设。 在可卡因寻找和消退过程中，在有和没有抑制PL-1的情况下，D1-MSNs（目的1）和D2-MSNs（目的2） 向NAcore传出。为了研究D1-和D2-MSN在可卡因寻求过程中的功能作用，我们将 使用头戴式微型显微镜记录D1-和D2-MSN的单细胞Ca 2+动态， 在D1-和D2-cre转基因小鼠中表达Cre依赖性Ca 2+指示剂（GCaMP 6 f），同时接受 可卡因自我给药，消退训练和线索诱导的恢复，我们将进一步抑制PL-NAcore 在药物寻求测试期间（戒断后和线索诱导的恢复期间）使用病毒的预测 表达抑制性Gi-DREADD。将使用高级统计模型分析记录的Ca 2+动态 并聚类以分离与背景/线索诱导的药物寻求和抑制相关的神经元集合 在灭绝中寻找。从这项研究中获得的信息将分离出神经元集合， 编码可卡因寻求，以及PL-NAcore投射影响这些集合的机制 来规范线索诱导的复职这个奖学金将训练我在实验设计，科学写作， 了解药物成瘾背后的大脑回路的尖端技术，包括病毒转染 和显微内窥镜分析的Ca 2+活动的转基因小鼠训练，自我管理和恢复药物， 关联的线索和背景。

ABSTRACT Drug addiction, including cocaine-abuse disorder, represents a major public health issue, characterized by compulsive drug seeking and increased propensity to relapse after abstinence. Relapse to cocaine seeking is triggered by environmental cues strongly associated with the rewarding effects of the drug itself. The neuronal encoding of cocaine-associated cues at a single-cell level remains unclear, limiting our understanding of how cocaine-paired cues trigger drug seeking behavior. Via its constituent dopamine D1- and D2- receptor expressing medium spiny projection neurons (MSNs), the nucleus accumbens core (NAcore) plays a key role in encoding cue-reward associations and triggering relapse to cocaine seeking behavior. The NAcore integrates multiple cortical and allocortical inputs. In particular, the activation of afferent glutamatergic projections from the prelimbic cortex (PL) are necessary for cue-induced reinstatement of cocaine seeking. Using chemogenetic and optogenetic manipulations on D1- and D2-MSNs, previous studies have shown opposite roles of these neuronal subtypes on cue-induced reinstatement of cocaine seeking in rodent models of self-administration. Therefore, I hypothesize that cocaine seeking during context/cue-reinstatement and refraining from seeking during extinction training are associated with temporally and spatially distinct neuronal ensembles of D1- and D2-MSNs that are differentially modulated by PL-NAcore projections. I will address this hypothesis by quantifying Ca2+ activity in D1-MSNs (Aim 1) and D2-MSNs (Aim 2) during cocaine-seeking and extinction, with and without inhibiting PL- efferents to NAcore. To investigate the functional role of D1- and D2-MSNs during cocaine seeking, we will record single-cell Ca2+ dynamics from D1- and D2-MSNs using a head-mounted miniature microscope and virally expressed Cre-dependent Ca2+ indicator (GCaMP6f) in D1- and D2-cre transgenic mice while undergoing cocaine self-administration, extinction training and cue-induced reinstatement, We will further inhibit PL-NAcore projections during drug seeking tests (post abstinence and during cue-induced reinstatement) using virally expressed inhibitory Gi-DREADDs. Recorded Ca2+ dynamics will be analyzed using advanced statistical models and clustered to isolate the neuronal ensembles associated with context/cue-induced drug seeking and refraining from seeking during extinction. The information obtained from this research will isolate neuronal ensembles that encode cocaine-seeking, as well as the mechanism(s) by which PL-NAcore projections affect these ensembles to regulate cue-induced reinstatement. This fellowship will train me in experimental design, scientific writing, and cutting-edge techniques to understand the brain circuits underlying drug addiction, including viral transfection and micro-endoscopic analysis of Ca2+ activity in transgenic mice trained to self-administer and reinstate to drug- associated cues and contexts.