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

项目总结/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。内 近十年来，研究表明腹侧被盖区由释放神经调质的神经元组成 多巴胺、释放抑制性神经递质GABA的神经元和释放兴奋性神经递质GABA的神经元。 神经递质谷氨酸。基于使用光遗传学技术来操纵多巴胺、GABA或 谷氨酸神经元，目前的模型VTA功能假设，奖励和厌恶为基础的动机是 VTA神经元及其离散神经元网络的异质类型介导的。但我们 最近在腹侧被盖区发现了一种意料之外的神经元，它们同时释放谷氨酸和GABA。 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 多种遗传特征的VTA细胞类型：释放谷氨酸而不释放GABA（仅谷氨酸神经元）， 释放GABA而不释放谷氨酸（仅GABA神经元），或释放两者（谷氨酸-GABA神经元）。而 光遗传学研究表明，谷氨酸释放或GABA释放神经元的作用， 行为，腹侧被盖区谷氨酸和GABA释放神经元的重新定义为三种亚型表明， 对腹侧被盖区细胞类型在动机性行为中的特定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，以确定神经网络和作用，在奖励或 VTA谷氨酸-GABA、仅谷氨酸和仅GABA神经元和回路的厌恶介导行为。在 目的1，我们将全面绘制VTA谷氨酸-GABA，谷氨酸- 用细胞类型特异性的顺行追踪和单突触逆行追踪， 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GCaMP 6，我们将鉴定 腹侧被盖区谷氨酸-GABA、仅谷氨酸和仅GABA神经元的神经元活动模式，以及 主要传入神经的神经元活动模式，靶向每种遗传上分离的VTA细胞类型， 奖励和厌恶刺激及其预测因子。最后，我们将光遗传学刺激或抑制VTA 谷氨酸-GABA、仅谷氨酸和仅GABA神经元和回路，以确定其因果贡献 有动机的行为。初步数据支持这一假设，腹侧被盖区谷氨酸-GABA，谷氨酸- 仅GABA神经元和仅GABA神经元具有不同的神经元网络和动机功能。所有这些 研究将全面重新定义腹侧被盖区神经元及其各自回路的动机功能。 研究结果将为缓解成瘾等基于奖赏和厌恶的疾病提供新的方向。

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.