Dissecting the Synaptic and Cellular Actions of Dopamine in Vivo

项目摘要 神经调节剂多巴胺对激励、执行和加强目标导向行为至关重要，而且 多巴胺信号的缺陷在抑郁症、强迫症等神经精神障碍中很常见 精神障碍、成瘾和帕金森氏症。我们理解多巴胺功能的核心是这样一个概念 纹状体细胞外多巴胺水平的时相增加和减少调制纹状体输出以 修改短时间尺度和长时间尺度上的行为。例如，纹状体多巴胺的相位性升高由 显著刺激和奖励预测线索被提出用来促进觉醒，促进行动的启动和 增加从几秒到几分钟的工作动机，同时也要修改未来的行动和行为 对更长时间尺度的决定可以延长到几天。这就提出了一个基本问题：多巴胺是如何 调节纹状体神经元的活动，从而对行为产生影响？体外实验已经有了 揭示了无数对多巴胺调制敏感的分子靶点。然而，这些因素的净影响 体内纹状体输出的变化尚不清楚。原因之一是很少有方法能够解剖 多巴胺对突触强度、躯体兴奋性和网络的细胞类型特异性神经调制作用 清醒的、行为的大脑的动态。这项提议旨在利用活体全细胞来填补这一知识空白 电生理学和双光子显微镜，最初侧重于发生在 从秒到分钟的时间刻度。根据我们发布的和这些技术的初步数据，我们 将检验这样一种假设，即时相的多巴胺瞬变反应积极和消极的奖励 预测误差促进纹状体投射神经元表达D1型和D2型 多巴胺受体(D_1-SPN和D_2-SPN)分别通过内源性和突触结合 短期塑性机制。要做到这一点，我们将利用我们的能力来记录亚阈值薄膜 体内电位动力学揭示行为和光遗传诱发的多巴胺瞬变如何改变 D_1和D_2-SPN的内在兴奋性(Aim 1)和兴奋性突触撞击它们的效力(Aim 2)。在目标3中，我们将使用钙成像来揭示相变的多巴胺的短期影响。 纹状体的输出量。总之，我们的实验将为调节作用提供至关重要的机械性见解。 多巴胺在体内的变化，揭示了多巴胺释放和行为改变之间的关键联系，以及 为旨在治疗神经精神障碍的新型治疗干预措施铺平道路。

Project Summary The neuromodulator dopamine is critical for motivating, performing, and reinforcing goal-directed behaviors, and deficits in dopamine signaling are common in neuropsychiatric disorders like depression, obsessive-compulsive disorder, addiction and Parkinson’s disease. Central to our understanding of dopamine function is the notion that phasic increases and decreases in extracellular dopamine levels in the striatum modulate striatal output to modify behavior on short and long timescales. For instance, phasic elevations in striatal dopamine elicited by salient stimuli and reward-predicting cues have been proposed to promote arousal, facilitate action initiation and increase motivation to work on timescales of seconds to minutes, but also to modify future actions and behavioral decisions on longer timescales extending to days. This raises a fundamental question: How does dopamine modulate the activity of striatal neurons to exert its influence on behavior? Experiments in vitro have revealed a myriad of molecular targets sensitive to modulation by dopamine. However, the net effects of these changes on striatal output in vivo remain unknown. One reason is that few methods are capable of dissecting dopamine’s cell type-specific neuromodulatory effects on synaptic strength, somatic excitability and network dynamics in the awake, behaving brain. This proposal aims to fill this gap in knowledge using in vivo whole-cell electrophysiology and two-photon microscopy, focusing initially on the neuromodulatory effects occurring on timescales of seconds to minutes. Informed by our published and preliminary data with these techniques, we will test the hypothesis that phasic dopamine transients reflecting positive and negative reward prediction errors promote the activation of striatal projection neurons expressing D1- and D2-type dopamine receptors (D1-SPNs and D2-SPNs), respectively, via a combination of intrinsic and synaptic short-term plasticity mechanisms. To do so, we will harness our ability to record sub-threshold membrane potential dynamics in vivo to reveal how behaviorally- and optogenetically-evoked dopamine transients alter the intrinsic excitability of D1- and D2-SPNs (Aim 1) and the potency of excitatory synapses impinging on them (Aim 2). In Aim 3, we will employ calcium imaging to uncover the short-term influence of phasic dopamine transients on striatal output. Together, our experiments will provide crucial mechanistic insights into the modulatory actions of dopamine in vivo, shedding light on a key link between dopamine release and behavioral modifications, and paving the way for novel therapeutic interventions aimed at treating neuropsychiatric disorders.