DISTINCTIVE SPATIOTEMPORAL MAP OF TARGET ACTIVATION BY YOUNG NEURONS OF THE ADULT

成人年轻神经元目标激活的独特时空图

• 批准号: 8017606
• 负责人: FRED H GAGE
• 金额: $ 5.24万
• 依托单位: FUNDACION INSTITUTO LELOIR
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-01-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8017606
• 关键词: Acute; Address; Adult; Animals; Area; Astrocytes; Awareness; Axon; Behavior; Biological; Brain; Cations; Cells; Characteristics; Collaborations; Communities; Data; Defect; Development; Developmental Process; Disease; Distal; Dyes; Feedback; Female; Frequencies; Future; Generations; Glutamates; Goals; Grant; Growth; Hilar; Hippocampus (Brain); In Vitro; Infection; Institutes; Institution; Instruction; International; Interneurons; Joints; Knowledge; Laboratories; Learning; Light; Long-Term Potentiation; Maps; Mediating; Memory; Mental Depression; Molecular; Morphology; Mus; Natural regeneration; Nerve Degeneration; Neurodegenerative Disorders; Neuronal Differentiation; Neurons; Newborn Infant; Outcome; Output; Perinatal; Physiologic pulse; Population; Presynaptic Terminals; Process; Property; Protein Family; Pyramidal Cells; Research; Research Personnel; Retroviral Vector; Role; Shapes; Signal Pathway; Signal Transduction; Slice; Societies; Solid; Source; Staging; Stimulus; Synapses; Technology; Testing; Theoretical model; Time; Training; Trauma; United States National Institutes of Health; Whole-Cell Recordings; adult neurogenesis; brain repair; computerized data processing; dentate gyrus; design; driving force; expectation; feeding; gamma-Aminobutyric Acid; granule cell; hippocampal pyramidal neuron; improved; in vivo; information processing; loss of function; member; mossy fiber; nerve stem cell; neurogenesis; neuron development; newborn neuron; novel; parent grant; postsynaptic; presynaptic; reconstruction; regenerative therapy; response; retroviral transduction; spatiotemporal; success; synaptogenesis; tool; transmission process; young adult

DESCRIPTION (provided by applicant): The adult dentate gyrus continuously generates granule cells (DGCs) that are needed for specific learning and memory tasks, but the precise contribution of new neurons to information processing in the hippocampal circuitry remains unknown. In the past, we have demonstrated that key developmental processes occurring in the perinatal brain such as maturation of excitability, afferent synaptogenesis and function are all recapitulated during adult neurogenesis. We now propose the central hypothesis that newly born cells establish functional outputs as they develop, and the population of postsynaptic target cells contacted by young neurons is predominantly inhibitory, therefore different from the mixed excitatory/inhibitory network activated by mature granule cells. Thus, there would be a time window in which young DGCs primarily activate feedforward and/or feedback inhibitory circuits without exciting pyramidal cells, exerting a tight inhibitory control over the dentate gyrus output. In Aim 1 we will build a spatio-temporal map of target activation by young developing neurons of the adult dentate gyrus. We will use retroviral transduction to express the light- activated cation channel Channelrhodopsin-2 in newborn DGCs of young-adult female mice (C57Bl6/J). We will sacrifice the animals at different times and prepare acute brain slices to carry out electrophysiological recordings. By stimulating the whole hippocampal slice with brief light pulses, all retrovirally transduced neurons will spike. We will search randomly for active postsynaptic target cells throughout the hilus and CA3 regions, and identify and characterize responsive neurons by combining loose patch and whole-cell recordings. In Aim 2 we will investigate the functional maturation of new mossy fiber synapses made onto GABAergic and glutamatergic targets. We plan to utilize whole-cell recordings to test whether synapses forming onto GABAergic interneuron targets mature faster than those made onto pyramidal cells, as suggested by our previous structural studies. We will also study presynaptic mechanisms of short- and long-term plasticity that will shape both activity-dependent competition and activation of postsynaptic circuits. This project will address fundamental questions about connectivity and activation (spiking) of newborn cells that will contribute to understanding the precise impact of adult neurogenesis in the preexisting hippocampal network and the rules of neuronal connectivity in the adult brain. Identifying the rules by which neurons integrate in the existing network in a manner that is both safe and functionally relevant is also crucial for developing future brain repair therapies. Novel retroviral tools will be developed in collaboration with the Gage lab to enhance Channelrhodopsin-2 expression, thus improving the capability of light activation of newborn cells. In turn, experimental data obtained here will be used to feed into the theoretical model being developed by the Gage lab on the role of immature neurons in signal processing. The success of the proposed project relies on strengthening the close interaction between the Schinder laboratory at the Leloir Institute (Buenos Aires) and the Gage laboratory at the Salk Institute of La Jolla. Members of the Schinder lab will have the opportunity to train at Salk on the generation and characterization of novel retroviral vectors, improving the capabilities to develop advanced molecular tools at the foreign institution. We anticipate that capacity building leading to the design, generation and use of novel retroviral tools at the Leloir Institute will have an enormous impact on the local scientific community. This collaborative effort will therefore serve as a driving force to increase the critical mass of Argentine investigators that incorporate competitive technologies for the study of neurodegenerative disorders within their research focus. An increase in the number of laboratories carrying out regeneration- related projects will certainly enhance awareness to these and related problems to our community. PUBLIC HEALTH RELEVANCE: There is a lot of expectation in our society on the potential of neural progenitor cells as powerful tools for brain repair, and we will need to understand how adult-born neurons establish their connectivity in the adult healthy brain before attempts can be made in case of neurodegeneration or trauma. Solid research on functional integration of newborn neurons of the adult hippocampus will certainly contribute to the development of regenerative therapies for the treatment of disorders occurring in non-neurogenic areas. In particular, it is critical to identify the rules by which neurons integrate in the adult brain circuits in a manner that is both safe and functionally relevant. This will be a major outcome of the proposed project.

描述（由申请人提供）：成年齿状回持续产生特定学习和记忆任务所需的颗粒细胞（DGC），但新神经元对海马回路中信息处理的精确贡献仍不清楚。在过去，我们已经证明，关键的发育过程中发生在围产期的大脑，如兴奋性，传入突触和功能的成熟都在成年神经发生重演。我们现在提出一个中心假设，即新生细胞在发育过程中建立功能输出，年轻神经元接触的突触后靶细胞群体主要是抑制性的，因此不同于成熟颗粒细胞激活的混合兴奋/抑制网络。因此，将有一个时间窗口，其中年轻的DGC主要激活前馈和/或反馈抑制回路，而不兴奋锥体细胞，对齿状回输出施加严格的抑制控制。在目标1中，我们将建立一个时空地图的成年齿状回的年轻发育中的神经元的目标激活。我们将使用逆转录病毒转导来在未成年雌性小鼠（C57 B16/J）的新生DGC中表达光激活阳离子通道视紫红质-2。我们将在不同的时间处死动物，并制备急性脑切片进行电生理记录。通过用短暂的光脉冲刺激整个海马切片，所有逆转录病毒转导的神经元都会出现尖峰。我们将随机搜索整个门和CA 3区域的活跃突触后靶细胞，并通过结合松散的补丁和全细胞记录来识别和表征反应神经元。在目标2中，我们将研究新的苔藓纤维突触的功能成熟的GABA能和谷氨酸能的目标。我们计划利用全细胞记录来测试形成在GABA能中间神经元靶上的突触是否比形成在锥体细胞上的突触成熟得更快，正如我们以前的结构研究所建议的那样。我们还将研究短期和长期可塑性的突触前机制，这些机制将塑造活动依赖性竞争和突触后回路的激活。该项目将解决有关新生细胞的连接和激活（尖峰）的基本问题，这将有助于理解成人神经发生在预先存在的海马网络中的确切影响以及成人大脑中神经元连接的规则。确定神经元以安全和功能相关的方式整合到现有网络中的规则对于开发未来的大脑修复疗法也至关重要。将与Gage实验室合作开发新的逆转录病毒工具，以增强视紫红质-2的表达，从而提高新生细胞的光激活能力。反过来，这里获得的实验数据将被用于Gage实验室正在开发的关于未成熟神经元在信号处理中的作用的理论模型。拟议项目的成功取决于加强Leloir研究所（布宜诺斯艾利斯）Schinder实验室与拉霍亚Salk研究所Gage实验室之间的密切互动。Schinder实验室的成员将有机会在Salk接受关于新型逆转录病毒载体的生成和表征的培训，提高在外国机构开发先进分子工具的能力。我们预计，Leloir研究所设计、生产和使用新型逆转录病毒工具的能力建设将对当地科学界产生巨大影响。因此，这种合作努力将成为一种推动力，以增加阿根廷研究人员的临界质量，将有竞争力的技术纳入其研究重点的神经退行性疾病的研究。增加进行再生相关项目的实验室数量，肯定会提高我们社会对这些问题和相关问题的认识。 公共卫生相关性：我们的社会对神经祖细胞作为大脑修复的强大工具的潜力有很大的期望，我们需要了解成年出生的神经元如何在成年健康的大脑中建立连接，然后才能在神经变性或创伤的情况下进行尝试。对成年海马新生神经元功能整合的扎实研究肯定会有助于开发用于治疗非神经源性区域疾病的再生疗法。特别是，确定神经元以安全和功能相关的方式整合到成人大脑回路中的规则至关重要。这将是拟议项目的主要成果。