Mechanisms of Dopamine Action in Learning: Implications for Addiction

项目摘要 中脑边缘多巴胺，沿着其腹侧纹状体靶点，在 巴甫洛夫奖励学习。巴甫洛夫奖励学习过程的基础是许多方面 在药物复吸中起着关键作用。工具性学习 过程也形成了药物寻求行为的基本要素，并且可能取决于 对黑质纹状体背侧纹状体多巴胺神经支配的影响。在这里我们试图理解 纹状体靶点内中脑边缘和黑质纹状体多巴胺作用如何介导选择 奖励寻求行为的组成部分，并测试这些之间的相互作用 系统有助于正常和病态的寻求奖励的行为。我们专注于 多巴胺，因为自然和药物奖励都能激活多巴胺神经元， 在我们最近的发现中证实，多巴胺神经元激活，当取代 奖励，驱动特定形式的联想学习，涉及成瘾行为。 在这里，使用Th：Cre转基因大鼠限制通道视紫红质表达多巴胺， 神经元，我们利用选择性激活中脑边缘多巴胺的能力， 神经元，以更好地了解其对行为，神经活动和整合的影响， 腹侧和背侧纹状体系统。我们测试中脑边缘多巴胺神经元 奖励相关的激活在特定形式的兴奋过程中招募更多的背侧纹状体回路。 学习一个突出的假设假定，随着时间的推移，奖励寻求取决于更多的 背侧纹状体回路作为行为控制成为习惯。因此，我们还要求 激活中脑边缘多巴胺系统是否可以加速习惯性 对自然或药物的奖励作出反应。此外，我们将确定神经信号 介导由中脑边缘多巴胺激活调节的行为，以揭示 下游神经元群体的神经变化，介导的性能， 这些多巴胺介导的习得行为。这些研究将提供新的信息 关于腹侧和背侧纹状体回路的单独和交互作用， 寻求奖励的行为，可以由多巴胺启动，并与我们的 对涉及暴饮暴食和物质使用障碍的行为障碍的理解。

Project summary Mesolimbic dopamine, along with its ventral striatal targets, plays a major role in Pavlovian reward learning. Pavlovian reward learning processes underlie many aspects of drug seeking behavior and play a critical role in drug relapse. Instrumental learning processes also form a fundamental element of drug seeking behavior, and may depend on nigrostriatal dopamine innervation of dorsal striatum. Here we seek to understand how mesolimbic and nigrostriatal dopamine action within striatal targets mediates select components of reward-seeking behavior, and to test whether interactions between these systems contribute to normal and pathological reward-seeking behavior. We focus on dopamine because both natural and drug rewards activate dopamine neurons, and, as confirmed in our recent findings, dopamine neuron activation, when substituted for reward, drives specific forms of associative learning implicated in addictive behavior. Here, using the Th:Cre transgenic rat to limit channelrhodopsin expression to dopamine neurons, we take advantage of the ability to selectively activate mesolimbic dopamine neurons to better understand their impact on behavior, neural activity, and integration of ventral and dorsal striatal systems. We test whether mesolimbic dopamine neuron reward-related activation recruits more dorsal striatal circuits during specific forms of learning. A prominent hypothesis posits that reward seeking depends over time on more dorsal striatal circuits as behavioral control becomes habitual. Thus, we also ask whether activating mesolimbic dopamine systems can hasten development of habitual responding for natural or drug reward. In addition, we will determine neural signals mediating behaviors conditioned by mesolimbic dopamine activation in order to reveal neural changes in downstream neuronal populations that mediate the performance of these dopamine-mediated learned behaviors. These studies will provide new information on the separate and interactive contributions of ventral and dorsal striatal circuits to reward seeking behavior that can be initiated by dopamine, and are relevant for our understanding of behavioral disorders involving overeating and substance use disorders.