Functional integration of adult-born neurons into the mammalian brain

描述（由申请人提供）：神经干细胞之所以令人兴奋，很大程度上是因为人们希望利用它们来修复患病的大脑。然而，对于这些新的神经元如何通过适当的连接整合到现有的大脑回路中，我们所知甚少——这个过程可以比作在汽车行驶时更换车轮。此外，关于成年神经发生和功能整合如何受到局部因素和动物经验的调节的主要问题在很大程度上仍未得到解答。在这个提议中，我们将进行创新的实验来研究新的神经元如何整合到小鼠嗅球的突触回路中。啮齿类动物嗅球具有神经发生率高、可及性强、组织模块化和行为相关性强等特点，是一个很好的模型系统。我们将通过使用多光子激光扫描显微镜在活小鼠的完整大脑中以高分辨率成像其形态和功能来描述成年出生的神经元在其天然环境中的自然历史。我们还将开始揭示利用遗传扰动将新神经元功能整合到现有电路中的细胞和分子过程。为了实现我们的目标，我们将使用立体定向病毒注射，遗传编码钙指示剂和慢性多光子显微镜来实时检查新生颗粒细胞如何发展其形态和功能特性。通过在体内使用延时成像跟踪已识别的神经元数周，我们将能够发现结构和功能变化，这些变化对于在每个动物中获得单个快照的传统方法是不可见的。我们将在一个“关键”时期改变老鼠的气味体验，在这个时期，标记的新生细胞被整合到灯泡中，并研究这是如何改变它们的功能特性和生存的。本项目的实验将以三个目标为指导。目的1：利用多光子显微镜确定已鉴定的成年神经元在发育过程中感觉反应的时间演变。目的2：确定感官体验如何影响成年出生的神经元细胞的功能特性及其存活。目的3：确定成熟神经元功能特性完善的细胞和分子机制。这里提出的研究将对新生细胞如何找到合适的突触伙伴并融入成人大脑提供更深入的了解。从这项研究中获得的见解将为使用神经元替代疗法治疗人类大脑疾病的努力提供信息。

DESCRIPTION (provided by applicant): The excitement about neural stem cells arises in large part from the hope that they can be harnessed therapeutically to repair diseased brains. Very little is known, however, about how these new neurons integrate into existing brain circuits by making appropriate connections - this process can be compared to changing the wheels of a car while it is running. In addition, major questions of how adult neurogenesis and functional integration are regulated by local factors as well as by an animal's experience remain largely unanswered. In this proposal, we will conduct innovative experiments to investigate how new neurons are integrated into synaptic circuits in the mouse olfactory bulb. The rodent olfactory bulb is an excellent model system because of the high rate of neurogenesis, its accessibility, modular organization and behavioral relevance. We will describe the natural history of adult-born neurons in their native environment by imaging their morphology and function at high resolution in the intact brains of living mice using multiphoton laser scanning microscopy. We will also begin to uncover the cellular and molecular processes involved in the functional integration of new neurons into existing circuits using genetic perturbations. To achieve our goals, we will use stereotaxic viral injections, genetically-encoded calcium indicators and chronic multiphoton microscopy to examine in real time how newborn granule cells develop their morphological and functional properties. By tracking identified neurons over several weeks using time-lapse imaging in vivo, we will be able to uncover structural and functional changes that are not visible to conventional methods that obtain single snapshots in each animal. We will alter the odor experience of mice in a "critical" period during which labeled newborn cells are integrated into the bulb and investigate how this alters their functional properties and their survival. Experiments in this project will be guided by three Aims. Aim 1: To determine the time evolution of sensory responses of identified adult-born neurons over their development using multiphoton microscopy. Aim 2: To determine how sensory experience affects the functional properties of adult-born neurons cells and their survival. Aim 3: To determine the cellular and molecular mechanisms in the refinement of functional properties of adult-born neurons. The research proposed here will provide a deeper understanding about how newborn cells find appropriate synaptic partners and integrate into the adult brain. Insights gained from this study will inform efforts to treat human brain disorders using neuron replacement therapies.