Synaptic Mechanisms of Hypothalamic Control of Vigilance and Cognitive Function

描述(申请人提供)：本研究方案的总体目标是更好地了解在转基因小鼠中，下丘脑组胺能(HA)投射神经元如何利用电生理、遗传和行为方法控制行为状态转换和认知表现。K99/R00独立之路奖的申请人亚历山大·C·杰克逊博士目前是加州大学旧金山分校罗杰·尼科尔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睡眠、清醒、注意力和认知等基本行为状态的细胞、突触和电路水平的机制。杰克逊博士的长期职业目标是领导一家基础神经科学研究实验室，在一家学术研究机构担任终身教职首席研究员。与神经精神疾病的病理生理学有关的大脑中的许多神经递质通路，都与那些已知的调节睡眠、清醒和昼夜节律的通路有着不可阻挡的联系。多条线索表明，下丘脑HA系统调节觉醒、注意力和认知功能的各个方面。此外，选择性增强HA神经元活性的新型药物在促进觉醒和提高精神分裂症和痴呆症等障碍的认知功能方面很有希望。然而，很大程度上由于下丘脑环路的异质性，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缺乏了解。作为他的研究计划的一部分，杰克逊博士将绕过目前在探测下丘脑回路方面的限制，采用尖端的光遗传学策略，在大脑切片和清醒/行为的动物中，操纵具有毫秒精度的遗传靶向HA神经元的兴奋性。在细胞和突触电生理学培训的基础上，他将与他的合作导师Luis de Lecea博士(斯坦福大学)继续进行光遗传学、脑电/肌电记录和行为分析方面的额外培训。使用这些新工具，他将通过三个具体目标以多学科的方式询问HA系统：1)使用新颖的光遗传学技术以通道视紫红质(ChR2)特异性靶向HA神经元，然后在脑片中应用全细胞膜片钳电生理学，以确定内源性HA释放调节目标神经元兴奋性的突触机制(Mentored)。2)通过在体内光遗传学激活透明质酸神经元，并通过学习和记忆两种行为模型对皮质激活、睡眠-觉醒转换和认知功能进行量化，阐明透明质酸神经传递在一般觉醒、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-觉醒行为和认知中的功能作用(独立)，确定共传导在HA系统中的作用。K99/R00奖提供的训练期将为杰克逊博士的独立职业生涯提供一个强大的工具箱，他研究健康和疾病中的下丘脑功能。 与公共健康相关：由于人类大脑中调节睡眠和清醒日常周期的神经回路经常与精神和神经疾病中被破坏的神经回路汇合，研究这种回路可能会揭示治疗的靶点。 疾病的威胁。大脑中有一个这样的回路，它释放神经递质组胺，被认为在调节清醒和增强高级大脑功能方面发挥着重要作用，但直到最近，研究一直非常困难。这项研究计划将使用新技术来破译组胺系统在睡眠、清醒和更高大脑功能中的作用，最终目标是确定治疗和改善患有精神和神经疾病患者的谎言质量的目标。

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.