Genetic dissection of ventral tegmental area glutamate and GABA neurons in reward and aversion

项目摘要/摘要 腹侧被盖区(VTA)控制着追求奖励和避免有害刺激的动机。在 最近十年的研究表明，室旁核由释放神经调节剂的神经元组成。 多巴胺，释放抑制性神经递质GABA的神经元，以及释放兴奋性的神经元 神经递质谷氨酸。基于使用光遗传技术来操控多巴胺、GABA或 谷氨酸神经元，目前的VTA功能模型假设，基于奖励和厌恶的动机是 由不同类型的VTA神经元及其离散的神经元网络介导。然而，我们有 最近在VTA中发现了一种意想不到的神经元，即释放谷氨酸和GABA的神经元。 VTA谷氨酸-GABA神经元的发现重新定义了GABA释放和谷氨酸释放 VTA细胞类型由多种遗传特征决定：释放谷氨酸而不释放GABA(仅谷氨酸神经元)， 释放不含谷氨酸的GABA(仅含GABA的神经元)，或同时释放两者(谷氨酸-GABA神经元)。而当 光遗传学研究表明，谷氨酸释放或GABA释放的神经元在动力障碍中的作用 行为，VTA谷氨酸和GABA释放神经元分为三个亚型的重新定义表明，我们的 对VTA细胞类型在动机行为中的具体作用的理解是不完整的。我们将使用小说 交叉和减法遗传和病毒工具，以确定神经元网络和在奖励中的角色-或 VTA谷氨酸-GABA、仅谷氨酸和仅GABA神经元和回路的厌恶中介行为。在……里面 目标1，我们将全面映射VTA谷氨酸-GABA，谷氨酸-谷氨酸-的全脑输入和输出 仅用细胞类型特异性顺行追踪和单突触逆行追踪的仅有GABA神经元 携带一种改良的狂犬病病毒。在目标2中，使用遗传编码的钙指示剂GCaMP6，我们将识别 VTA谷氨酸-GABA、仅谷氨酸和仅GABA神经元的活动模式，以及 针对每个遗传分离的VTA细胞类型的主要传入神经元的活动模式，以响应 奖赏和厌恶刺激及其预测因素。最后，我们将从光基因上刺激或抑制VTA 谷氨酸-GABA、仅谷氨酸和仅GABA神经元和回路以确定它们的因果贡献 有动机的行为。初步数据支持VTA谷氨酸-GABA、谷氨酸- 只有和只有GABA的神经元有不同的神经元网络和动机功能。加在一起，这些 研究将全面重新定义VTA神经元及其个别回路的动力功能。 研究结果将为减轻成瘾等基于奖励和厌恶的障碍提供新的方向。

Project Summary / Abstract The ventral tegmental area (VTA) controls the motivation to pursue rewards and avoid harmful stimuli. Within the last decade it has been shown that the VTA is populated by neurons that release the neuromodulator dopamine, neurons that release the inhibitory neurotransmitter GABA, and neurons that release the excitatory neurotransmitter glutamate. Based on the use of optogenetic techniques to manipulate dopamine, GABA, or glutamate neurons, current models of VTA function postulate that reward and aversion-based motivation is mediated by heterogeneous types of VTA neurons and their discrete neuronal networks. However, we have recently discovered an unanticipated type of neuron in the VTA, those that release both glutamate and GABA. The discovery of the VTA glutamate-GABA neurons redefines the GABA-releasing and glutamate-releasing VTA cell-types by multiple genetic features: release of glutamate without GABA (glutamate-only neurons), release of GABA without glutamate (GABA-only neurons), or release of both (glutamate-GABA neurons). While optogenetic studies have shown roles of glutamate-releasing or GABA-releasing neurons in motivated behavior, the redefinition of VTA glutamate and GABA-releasing neurons into three subtypes indicates that our understanding of the VTA cell-type specific roles in motivated behavior is incomplete. We will use novel intersectional and subtractive genetic and viral tools to identify the neuronal networks and roles in reward- or aversion-mediated behavior of VTA glutamate-GABA, glutamate-only, and GABA-only neurons and circuits. In Aim 1, we will comprehensively map the brain-wide inputs and outputs of VTA glutamate-GABA, glutamate- only, and GABA-only neurons using cell-type specific anterograde tracing and monosynaptic retrograde tracing with a modified rabies virus. In Aim 2, using the genetically encoded calcium indicator GCaMP6 we will identify the neuronal activity patterns of VTA glutamate-GABA, glutamate-only, and GABA-only neurons, as well as the neuronal activity patterns of major afferents that target each genetically separate VTA cell-type, in response to rewarding and aversive stimuli and their predictors. Finally, we will optogenetically stimulate or inhibit VTA glutamate-GABA, glutamate-only, and GABA-only neurons and circuits to define their causal contributions towards motivated behavior. Preliminary data support the hypothesis that VTA glutamate-GABA, glutamate- only, and GABA-only neurons have distinct neuronal networks and motivational functions. Together, these studies will comprehensively redefine the motivational functions of VTA neurons and their individual circuits. Results will provide new directions to alleviate reward and aversion based disorders such as addiction.