Molecular-genetic dissection of basal forebrain circuitry regulating arousal

 描述（由申请人提供）：大细胞基底前脑（BFmc）包括胆碱能和非胆碱能细胞群，这些细胞群参与广泛的高级神经生物学过程，最根本的是支持与认知相关的唤醒和皮质节律。BFmc电路的损伤与许多神经精神和神经退行性疾病（例如，阿尔茨海默氏病）的条件，以及认知障碍的正常老化。然而，在理解BFmc支持觉醒和与认知相关的快速皮质节律的细胞和突触电路基础方面存在根本性的差距。长期目标是了解BFmc支持皮层唤醒的功能电路基础。我们在先前的研究期间的工作揭示了GABA能BFmc神经元在促进唤醒和快速皮质节律中的意想不到的和特别关键的作用。本申请的目的是扩展这些发现 通过定义BFmc GABA能神经元促进唤醒和与认知相关的快速皮质节律的功能性突触“神经回路”基础。中心假设是，BFmc GABA能神经元促进觉醒，间接通过下丘脑后部的局部GABA能神经元的去抑制和/或直接通过基底皮质投射，而且，这些神经元在体内的活动是严重依赖于来自脑桥臂旁核的兴奋性输入。拟议研究的基本原理是，确定电路基础，包括输入和输出关系，BFmc GABA能神经元支持觉醒/皮层觉醒，这是操纵它们并减少觉醒障碍个体所经历的功能障碍的关键第一步。在强有力的初步数据的指导下，我们的假设将通过追求三个特定的目标来检验：1）确定BFmc GABA能神经元是否通过局部GABA能中间神经元解除对促进唤醒的、皮质投射的后外侧下丘脑（pLH）神经元的抑制来促进唤醒; 2）确定BFmc GABA能神经元是否通过直接抑制前额叶皮质神经元来促进唤醒;和3）确定BFmc GABA能神经元支持觉醒的能力是否严重依赖于来自脑桥臂旁核的兴奋性输入。该方法在智力和技术上是创新的，因为它代表了一个新的和实质性的偏离当代模型的BFmc功能-这强调胆碱能BFmc神经元在这些过程中-因为它采用了一种新的组合，新开发的和验证的方法，包括免费的体内和体外化学和光遗传学为基础的实验。拟议的研究是重要的，因为它有望纵向推进和扩大对BFmc GABA能调节唤醒的细胞和回路（突触）机制的理解。最终，这些知识有可能为许多神经精神，神经退行性和觉醒性疾病（包括昏迷）的治疗和干预策略的发展提供信息。

 DESCRIPTION (provided by applicant): The magnocellular basal forebrain (BFmc) comprises cholinergic and non-cholinergic cell populations that are implicated in a wide range of higher-level neurobiological processes, most fundamentally the support of wake and cortical rhythms associated with cognition. Impairment of BFmc circuitry is linked with a host of neuropsychiatric and neurodegenerative (e.g., Alzheimer's disease) conditions as well as the cognitive impairments of normal aging. There is a fundamental gap however in understanding the cellular and synaptic circuit basis by which the BFmc support wakefulness and fast cortical rhythms associated with cognition. The long-term goal is to understand the functional circuit basis by which the BFmc supports cortical arousal. Our work during the prior grant period has revealed an unexpected and especially critical role for GABAergic BFmc neurons in promoting arousal and fast cortical rhythms. The objective in this particular application is to extend these findings by defining the functional, synaptic "neurocircuit" basis by which BFmc GABAergic neurons promote arousal and fast cortical rhythms associated with cognition. The central hypothesis is that BFmc GABAergic neurons promote arousal either indirectly through disinhibition of local GABAergic neurons in the posterior hypothalamus and/or directly via basocortical projections and, moreover, that the activity of these neurons in vivo is critically dependent upon excitatory inputs from the pontine parabrachial nucleus. The rationale for the proposed research is that identifying the circuit basis, including input and output relationships, by which BFmc GABAergic neurons support wakefulness/cortical arousal represents a critical first step towards manipulating them and reducing the dysfunction experienced by individuals with arousal-based disorders. Guided by strong preliminary data, our hypotheses will be tested by pursuing three specific aims: 1) Determine if BFmc GABAergic neurons promote arousal by disinhibiting wake-promoting, cortically-projecting posterior lateral hypothalamic (pLH) neurons through local GABAergic interneurons; 2) Determine if BFmc GABAergic neurons promote arousal by directly inhibiting prefrontal cortex neurons; and 3) Determine if the ability of BFmc GABAergic neurons to support wake is critically dependent upon excitatory inputs from the pontine parabrachial nucleus. The approach is intellectually and technically innovative because it represents a new and substantive departure from contemporary models of BFmc function - which have emphasized cholinergic BFmc neurons in these processes - and because it employs a novel combination of newly developed and validated approaches, including complimentary in vivo and in vitro chemico- and opto-genetic based experiments. The proposed research is significant because it is expected to vertically advance and expand understanding of the cellular and circuit (synaptic) mechanisms underlying BFmc GABAergic regulation of arousal. Ultimately, such knowledge has the potential to inform the development therapeutic and interventional strategies for a host of neuropsychiatric, neurodegenerative and arousal-based disorders, including coma.