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

成体齿状回不断产生颗粒细胞(DGC)，这是特定的 学习和记忆任务，但新神经元对信息处理的准确贡献 海马区的电路仍然未知。在过去，我们已经证明了这一关键 发生在围产期大脑中的发育过程，如兴奋性成熟、传入 突触发生和功能都是在成体神经发生的过程中重现的。我们现在建议 中心假设是，新生的细胞在发育过程中建立功能输出，而 与年轻神经元接触的突触后靶细胞群主要是抑制性的， 因此，不同于成熟颗粒细胞激活的兴奋性/抑制性混合网络。 因此，会有一个时间窗口，在该时间窗口中，年轻的DGC主要激活前馈和/或 不兴奋锥体细胞的反馈抑制电路，对 齿状回输出。在目标1中，我们将构建一张杨激活目标的时空图 成年齿状回发育中的神经元。我们将使用逆转录病毒转导来表达光- 幼年雌性小鼠新生树突状细胞激活的阳离子通道通道视紫红质-2 (C57BL6/J)。我们将在不同的时间处死动物，并准备急性脑片进行 电生理记录。通过用短暂的光脉冲刺激整个海马片，所有的 逆转录病毒转导的神经元会出现尖峰。我们将随机搜索活跃的突触后靶细胞 和CA3区，并通过结合 松散的补丁和全蜂窝录音。在目标2中，我们将研究新的功能成熟 在GABA能和谷氨酸能靶上形成苔藓状纤维突触。我们计划利用全细胞 测试在GABA能中间神经元靶点上形成的突触是否比 我们之前的结构研究表明，这些细胞形成了锥体细胞。我们还将研究 突触前机制的短期和长期可塑性，将形成活动依赖的 突触后回路的竞争和激活。这个项目将解决基本问题 关于新生细胞的连接和激活(尖峰)，这将有助于理解 成体神经发生在已存在的海马网中的精确影响和神经元的规则 成人大脑的连通性。确定神经元整合到现有的 安全和功能相关的网络对于未来的发展也是至关重要的 脑部修复疗法。 将与Gage实验室合作开发新的逆转录病毒工具，以增强 诱导视紫质-2的表达，从而提高新生细胞的光激活能力。在……里面 反过来，这里获得的实验数据将被用来输入正在开发的理论模型 Gage实验室就未成熟神经元在信号处理中的作用进行了研究。建议的成功 该项目依赖于加强位于Leloir的Schinder实验室之间的密切互动 索尔克研究所(布宜诺斯艾利斯)和拉霍亚索尔克研究所的盖奇实验室。委员会成员 迅达实验室将有机会在索尔克接受关于小说的产生和表征的培训 逆转录病毒载体，提高在国外开发先进分子工具的能力 机构。我们预计这一能力建设将导致设计、发电和 Leloir研究所使用新的逆转录病毒工具将对 当地科学界。因此，这种合作努力将成为推动 增加阿根廷调查人员临界人数的部队 研究神经退行性疾病的竞争性技术 研究重点。进行再生的实验室数量的增加- 相关项目一定会提高对这些问题的认识，并与我们的 社区。

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.