Dopaminergic modulation of brain circuits that control movement

描述（由申请人提供）： 在人类中，自主运动的控制严重依赖于中脑中含多巴胺的神经元与纹状体中的靶神经元之间的神经元通信。事实上，帕金森病中脑多巴胺神经元的退化导致震颤、运动缓慢和僵硬。相反，过度的多巴胺能刺激诱导多动症，冲动和强迫性药物使用。尽管这些神经元的重要性，它们塑造纹状体中靶神经元活动的机制知之甚少。我的近期目标是阐明中脑多巴胺神经元对运动相关纹状体回路的强大影响。从长远来看，我希望利用这些知识来了解多巴胺神经元信号功能障碍如何导致神经系统疾病。在Bernardo Sabatini博士和Christopher Harvey博士的指导下，并在Mark Andermann博士的支持下，我将获得解决这些长期存在的问题所需的科学和专业培训，并成为一名成功的独立研究人员。哈佛医学院神经生物学系的资源和设施是确保我实现我的研究和职业目标的理想选择。我的研究计划分为三个主要目标：1）解剖多巴胺神经元对纹状体投射神经元的突触和细胞效应，2）确定行为小鼠纹状体神经元的空间和时间活动模式，3）确定多巴胺神经元如何调节体内纹状体活动。我将首先使用电生理学，双光子钙成像和双光子谷氨酸释放来确定多巴胺神经元的光遗传学刺激如何影响纹状体投射神经元的兴奋性以及冲击它们的兴奋性突触的强度（目标1）。与此同时，我将开发一种纹状体窗口准备，使用双光子钙成像来监测在球形跑步机上跑步的小鼠纹状体内的神经活动。然后，我将使用这种技术来揭示在感觉和运动行为过程中识别的纹状体神经元活动的空间和时间模式（目的2）。这些实验不仅将揭示体内纹状体回路动力学的典型特征，而且它们也将作为一个模板， 检测被多巴胺神经元改变的电路元件。在目标3中，我将通过光学监测多巴胺神经元放电的光遗传学或药物遗传学操作前后行为小鼠纹状体神经元的活性来识别这些修饰。通过揭示多巴胺神经元活动的短暂和长期变化如何在突触，细胞和电路水平上影响纹状体神经元，拟议的工作将揭示多巴胺神经元影响自主运动和导致运动障碍的机制帕金森病。重要的是，这些知识将指导这种和其他神经系统疾病的治疗干预措施的发展。

DESCRIPTION (provided by applicant): In humans, the control of voluntary movements is critically dependent on neuronal communication between dopamine-containing neurons in the midbrain and target neurons in the striatum. Indeed, the degeneration of midbrain dopamine neurons in Parkinson's disease results in tremor, slowness of movement and rigidity. Conversely, excessive dopaminergic stimulation induces hyperactivity, impulsiveness and compulsive drug use. Despite the importance of these neurons, the mechanisms by which they shape the activity of target neurons in the striatum are poorly understood. My immediate goal is to shed light on the powerful influence that midbrain dopamine neurons exert on movement-related striatal circuits. In the long run, I wish to use this knowledge to understand how dysfunction of dopamine neuron signaling engenders neurological illnesses. Under the mentorship of Drs. Bernardo Sabatini and Christopher Harvey and with the support of Dr. Mark Andermann, I will acquire the scientific and professional training necessary to address these long-standing questions and to succeed as an independent researcher. The resources and facilities within the Harvard Medical School Department of Neurobiology are ideal to ensure I realize my research and career objectives. My research plan is divided into three main aims: 1) To dissect the synaptic and cellular effects of dopamine neurons on striatal projection neurons, 2) To define the spatial and temporal activity patterns of striatal neurons in behaving mice, and 3) To determine how dopamine neurons modulate striatal activity in vivo. I will first use electrophysiology, two-photon calcium imaging and two-photon glutamate uncaging to determine how optogenetic stimulation of dopamine neurons impacts the excitability of striatal projection neurons and the strength of excitatory synapses that impinge on them (Aim 1). In parallel, I will develop a striatal window preparation to monitor neural activity en masse in the striatum of mice running on a spherical treadmill using two-photon calcium imaging. I will then use this technique to reveal the spatial and temporal patterns of activity of identified striatal neurons during sensory and motor behaviors (Aim 2). These experiments will not only uncover canonical features of striatal circuit dynamics in vivo, but they will also serve as a template for the detection of circuit elements that are modified by dopamine neurons. In Aim 3, I will identify these modifications by optically monitoring the activity of striatal neurons in behaving mice before and after optogenetic or pharmacogenetic manipulation of dopamine neuron discharge. By revealing how brief and prolonged changes in dopamine neuron activity impact striatal neurons at the synaptic, cellular and circuit levels, the proposed work will shed light on the mechanisms employed by dopamine neurons to influence voluntary movements and the disturbances that lead to motor impairments in Parkinson's disease. Importantly, this knowledge will guide the development of therapeutic interventions for this and other neurological diseases.