Synaptic Integration and Propagation in CA1 Dendrites

描述(申请人提供)：海马CA1区锥体神经元接受兴奋性突触输入到不同的树突域：基树突、顶斜树突和顶丛树突。要了解CA1神经元如何执行其在空间导航、学习和记忆中的拟议功能，关键是了解这些神经元如何整合这些不同树突域中的突触输入。在完整动物身上的实验已经确定了突触输入到不同树突结构域的功能关联，但这些输入如何整合的生物物理学仍不清楚。在这里，我们提出了一系列研究，旨在更好地了解CA1锥体神经元兴奋性突触输入整合的细胞和分子过程。主要的方法是使用谷氨酸的双光子去功能化来激活海马片神经元不同树突域中的树突棘。连续切片电子显微镜也将被用来研究不同树突域中树突棘和突触的结构。用免疫金标记法结合连续切片电子显微镜观察突触谷氨酸受体(AMPA和NMDA受体)、代谢性谷氨酸受体(MGluR)和乙酰胆碱受体(MAChRs)在不同树突室的密度。这些突触和调制受体的功能将通过全细胞膜片钳记录和双光子去势来探索。树突状整合的调节可能受mGluR和mAChR的控制，这可能解释了不同行为状态下海马区不同的功能状态。这一结果将在前所未有的结构和分子细节水平上为突触输入的树突整合提供洞察力。这样的见解将有助于更好地了解海马体功能，这对于了解影响海马体的疾病，如阿尔茨海默病、精神分裂症和癫痫是必要的。

DESCRIPTION (provided by applicant): CA1 pyramidal neurons of the hippocampus receive excitatory synaptic input onto different dendritic domains: basal dendrites, apical oblique, and apical tuft dendrites. To understand how CA1 neurons carry out their proposed functions in spatial navigation, learning, and memory, it is critical to understand how these neurons integrate synaptic input in these different dendritic domains. Experiments in intact animals have identified functional correlates for synaptic inputs to different dendritic domains, but the biophysics of how these inputs are integrated remains unclear. Here we propose a series of studies designed to better understand the cellular and molecular processes underlying the integration excitatory synaptic inputs in CA1 pyramidal neurons. The primary approach will be to use two-photon uncaging of glutamate to activate dendritic spines in different dendritic domains of neurons in hippocampal slices. Serial-section electron microscopy will also be used to study the structure of dendritic spines and synapses in different dendritic domains. Immunogold labeling combined with serial section electron microscopy will be used to study the densities of synaptic glutamate receptors (AMPA and NMDA receptors) and metabotropic glutamate receptors (mGluR) and acetylcholine receptors (mAChRs) in different dendritic compartments. The function of these synapses and modulatory receptors will be explored using whole-cell patch-clamp recording and two-photon uncaging. Modulation of dendritic integration is likely to be under the control of mGluR and mAChR, which may account for different functional states of the hippocampus during different behavioral states. The results will offer insight into dendritic integration of synaptic inputs at an unprecedented level of structural and molecular detail. Such insights will lead to a better understanding of hippocampal function, which is necessary to understand diseases affecting the hippocampus, such as Alzheimer's disease, schizophrenia, and epilepsy.