Synaptic Mechanisms of Hypothalamic Control of Vigilance and Cognitive Function

描述（由申请人提供）：本研究计划的总体目标是更好地了解下丘脑组胺能（HA）投射神经元如何使用电生理，遗传和行为方法在转基因小鼠中控制行为状态转变和认知表现。K99/R00独立之路奖申请人Alexander C. Jackson博士目前是UCSF Roger Nicoll博士实验室的博士后研究员。杰克森博士的长期研究目标是阐明下丘脑神经回路在健康和疾病中调节基本行为状态（如睡眠、清醒、注意力和认知）的细胞、突触和回路水平机制。Jackson博士的长期职业目标是在一个学术研究机构担任终身首席研究员，领导一个基础神经科学研究实验室。大脑中许多与神经精神疾病的病理生理学有关的神经递质通路与那些已知的调节睡眠、觉醒和昼夜节律的神经递质通路不可避免地联系在一起。多种证据表明下丘脑HA系统在调节觉醒、注意力和认知功能方面起着重要作用。此外，选择性增强HA神经元活性的新型药物有望在精神分裂症和痴呆症等疾病中促进清醒和增强认知功能。然而，很大程度上由于下丘脑回路的异质性，我们对ha介导的神经传递的基本机制及其在行为中的作用的理解严重缺乏。作为他研究计划的一部分，Jackson博士将利用尖端的光遗传学策略，在大脑切片和清醒/行为的动物中，以毫秒精度操纵基因靶向HA神经元的兴奋性，从而绕过目前探测下丘脑回路的限制。通过在细胞和突触电生理学方面的训练，他将与他的共同导师Luis de Lecea博士（斯坦福大学）一起在光遗传学、脑电图/肌电图记录和行为分析方面进行额外的训练。利用这些新工具，他将通过三个特定目标以多学科的方式对HA系统进行研究：1)使用新的光遗传学技术，用通道视紫红质（ChR2）特异性靶向HA神经元，然后在脑切片中应用全细胞膜片钳电生理学来确定内源性HA释放（指导）调节目标神经元兴奋性的突触机制。2)通过光遗传学激活体内HA神经元，并通过学习和记忆两种行为模型量化皮质激活、睡眠-觉醒转换和认知功能，阐明HA神经传递在一般唤醒、睡眠-觉醒转换和认知表现中的作用。3)通过评估HA/GABA共释放的可能性、其靶细胞特异性及其在睡眠-觉醒行为和认知（独立）中的功能作用，确定HA/GABA共传递在HA系统中的作用。K99/R00奖提供的培训期将为杰克逊博士的独立职业生涯提供强大的工具箱，以研究健康和疾病中的下丘脑功能。

DESCRIPTION (provided by applicant): The overall goal of this research proposal is to better understand how hypothalamic histaminergic (HA) projec- tion neurons control behavioral state transitions and cognitive performance, using electrophysiological, genetic and behavioral methods in transgenic mice. The applicant for the K99/R00 Pathway to Independence Award, Dr. Alexander C. Jackson, is currently a postdoctoral fellow in Dr. Roger Nicoll's laboratory at UCSF. Dr. Jack- son's long-term research goal is to elucidate the cellular, synaptic and circuit-level mechanisms through which hypothalamic neural circuits regulate fundamental behavioral states, such as sleep, wakefulness, attention and cognition, in health and disease. Dr. Jackson's long-term career goal is to lead a basic neuroscience research laboratory as a tenure-track principal investigator in an academic research institution. Many of the neuro- transmitter pathways in the brain that are implicated in the pathophysiology of neuropsychiatric illnesses are inexorably linked to those known to regulate sleep, wakefulness and circadian rhythms. Multiple lines of evi- dence implicate the hypothalamic HA system in regulating wakefulness, attention and aspects of cognitive function. Moreover, novel drugs that selectively enhance the activity of HA neurons are promising in promoting wakefulness and boosting cognitive function in disorders such as schizophrenia and dementias. However, largely owing to the heterogeneity of hypothalamic circuits, our understanding of the fundamental mechanisms of HA-mediated neurotransmission and its role in behavior is gravely lacking. As part of his research proposal, Dr. Jackson will circumvent current limitations in probing hypothalamic circuits by employing a cutting-edge optogenetic strategy to manipulate the excitability of genetically targeted HA neurons with millisecond preci- sion, in both brain slices and awake/behaving animals. By building on his training in cellular and synaptic elec- trophysiology, he will pursue additional training in optogenetics, EEG/EMG recording and behavioral analysis with his co-mentor Dr. Luis de Lecea (Stanford). Using these new tools, he will interrogate the HA system in a multidisciplinary manner through three Specific Aims: 1) To use novel optogenetic techniques to specifically target HA neurons with channelrhodopsin (ChR2) and then apply whole-cell patch clamp electrophysiology in brain slices to determine the synaptic mechanisms underlying the regulation of target neuron excitability by en- dogenous HA release (mentored). 2) To elucidate the role of HA neurotransmission in general arousal, sleep- wake transitions and cognitive performance, by optogenetically activating HA neurons in vivo, and quantifying cortical activation, sleep-wake transitions and cognitive function through two behavioral models of learning and memory (mentored). 3) To determine the role of co-transmission in the HA system, by assessing the possibil- ity of HA/GABA co-release, its target cell-specificity and its functional role in sleep-wake behavior and cognition (independent). The training period afforded by the K99/R00 Award will provide Dr. Jackson with a powerful toolbox for his independent career investigating hypothalamic function in health and disease. PUBLIC HEALTH RELEVANCE: As the neural circuits in the human brain that regulate the daily cycle of sleep and wakefulness often converge with those that are disrupted in psychiatric and neurological disorders, studying such circuits can potentially reveal targets for the treatment of disease. One such circuit in the brain, which releases the neurotransmitter histamine, is thought to have an important role in mediating wakefulness and enhancing higher brain function but, until recently, has been very difficult to study. This research proposal will use novel technology to decipher the role of the histamine system in sleep, wakefulness and higher brain function with the ultimate goal of identifying targets for treating and improving the quality of lie of patients suffering from psychiatric and neurological disorders.