In Vivo Synaptic Imaging in Neocortex

摘要 突触的增加和丢失与整个大脑的学习有关。这已经是 通过对轴突或树突的解剖分析，很好地记录了新皮质中的情况 使用纵向成像，在固定组织和活体组织中都有脊椎。然而，这一过程一直很艰难 在不了解这些突触变化的原理的情况下推断它们的后果 在定义的单元类型特定触点网络中，需要识别前置和 突触的突触后伙伴。在这里，我们将使用活体成像和多色 分子定义的突触前和突触后神经元的荧光标记以监测输入- 在小鼠的胡须依赖任务中感觉学习过程中特定突触的增加和丢失。 突触接触将使用后扩展显微镜和 纳米级分辨率的免疫组织化学。分析将集中在依赖学习的问题上 丘脑高阶核--丘脑后内侧核--的输入重组 核(POM)到第5层(L5)锥体神经元的树突上，这些神经元 牵涉到经验依赖的可塑性。定量、多色、活体成像 学习的不同阶段将提供对大脑皮层回路如何编码和改变的洞察 通过显著的感官信息。

ABSTRACT Synapse addition and loss have been linked to learning throughout the brain. This has been well-documented in the neocortex using anatomical analysis of axonal boutons or dendritic spines in both fixed tissue and in vivo, using longitudinal imaging. However, it has been difficult to extrapolate the consequences of these synaptic changes without understanding how they lie within a defined network of cell-type specific contacts, requiring identification of the pre- and postsynaptic partners of the synapse. Here we will use in vivo imaging and multicolor fluorescence labeling of molecularly-defined pre- and postsynaptic neurons to monitor input- specific synapse addition and loss during sensory learning in a whisker-dependent task in mice. Synaptic contacts will be validated using post-hoc expansion microscopy and immunohistochemistry for nanoscale resolution. Analysis will be focused on learning-dependent reorganization of thalamic inputs from a higher-order thalamic nucleus, the posterior medial nucleus (POm) onto the dendrites of layer 5 (L5) pyramidal neurons that have been specifically implicated in experience-dependent plasticity. Quantitative, multicolor, in vivo imaging across different stages of learning will provide insight into how cortical circuits encode and are changed by salient sensory information.