Basal Forebrain Corticopetal GABAergic Neurons and Cortical Arousal

项目摘要/摘要 基底前脑(BF)的结构和功能的完整性是维持大脑功能的绝对要求 行为和脑电(EEG)觉醒。脑脊液调节脑电的机制和底物 然而，神经行为唤醒仍然鲜为人知。对相关文献的回顾表明 大多数关于BF回路的研究都集中在大脑皮质顶叶胆碱能BF系统上。 生理(脑电和行为唤醒)和病理生理(神经退行性疾病)调节， 尽管事实是1)胆碱能BF系统的损伤在脑电或行为上产生有限的变化 2)BF还包含一群皮质投射的GABA能神经元，大致 与胆碱能神经元混合在一起。虽然一段时间以来人们一直认为其他皮质顶叶 BF神经递质系统可能与胆碱能神经元相互作用或并行工作，调节大脑皮质 回路，GABA能BF神经元，特别是那些投射到大脑皮层的神经元，对此的贡献 这一过程在很大程度上仍未得到探索。在这项建议中，我们试图确定体外(细胞)和体内 BF GABA能神经元参与脑电和行为反应的(系统)机制和底物 唤醒，包括睡眠-觉醒周期。我们假设BF GABA能种群严重地参与了 维持脑电和行为觉醒，这种影响主要是通过皮质投射来调节的 GABA能BF神经元，而不是由BF GABA能中间神经元或BF GABA能神经元投射到 大脑区域，如外侧下丘脑。BF-GABA能作用的实验解剖 然而，神经元，特别是大脑皮质顶叶BF-GABA能神经元，在脑电和行为觉醒中 事实证明，考虑到GABA的多个发射器系统和子种群，这是一个相当大的挑战 BF内的神经元。因此，我们寻求开发和验证新的基于病毒的药物遗传学 和条件性启动子特异的转基因表达系统通过选择性地 BF-GABA能神经元的分离和操纵。具体来说，我们将使用所谓的DREADD(Designer 受体仅由特制药物激活)系统可可逆地激活或沉默BF-GABA能 神经元，包括选择性操作皮质投射的BF-GABA能神经元，在体外和 在活体内。这项实验工作的结果将提供关于底物的重要信息 是产生和维持觉醒所必需的，并强调BF GABA能的关键贡献 在行为自由、无拘无束的动物身上，神经元对这些过程起作用。

Project Summary/Abstract The structural and functional integrity of the basal forebrain (BF) is an absolute requirement for maintaining behavioral and electrographic (EEG) wake. The mechanisms and substrates by which the BF regulates EEG and neurobehavioral arousal remains however poorly understood. A review of the relevant literature reveals that the vast majority of studies on BF circuitry have focused on the corticopetal cholinergic BF system in physiological (EEG and behavioral arousal) and pathophysiological (neurodegenerative disorders) regulation, despite the facts that 1) lesions of the cholinergic BF system produce limited changes in EEG or behavioral wake; and 2) the BF also contains a population of cortically projecting GABAergic neurons that roughly intermingle with the cholinergic neurons. While it has been appreciated for some time that other corticopetal BF neurotransmitter systems may interact or work in parallel with cholinergic neurons in modulating cortical circuitry, the contribution of GABAergic BF neurons, and in particular those projecting to the cortex, to this process remains largely unexplored. In this proposal we seek to determine the in vitro (cellular) and in vivo (system) mechanisms and substrates by which the BF GABAergic neurons contribute to EEG and behavioral arousal, including sleep-wake cycles. We hypothesize that the BF GABAergic population is critically involved in maintaining EEG and behavioral wake and that this influence is mediated primarily by cortically-projecting GABAergic BF neurons and not by BF GABAergic interneurons or BF GABAergic neurons that project to other brain regions, such as the lateral hypothalamus. The experimental dissection of the role of BF GABAergic neurons, and in particular the corticopetal BF GABAergic neurons in EEG and behavioral arousal, has however proven a considerable challenge given the multiple transmitter systems and sub-populations of GABAergic neurons within the BF. We have therefore sought to develop and validate novel viral-based pharmacogenetic and conditional promoter-specific transgene expression systems to test our hypothesis through the selective isolation and manipulation of BF GABAergic neurons. Specifically we will use the so-called DREADD (designer receptors exclusively activated by designer drugs) system to reversibly activate or silence BF GABAergic neurons, including the selective manipulation of cortically-projecting BF GABAergic neurons, both in vitro and in vivo. The results from this experimental work will provide important information regarding the substrates that are necessary to produce and maintain arousal and emphasize the critical contribution of BF GABAergic neurons to these processes in freely behaving, unrestrained animals.