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。这是 使用轴突终扣或树突的解剖分析在新皮层中有充分的记录 固定组织和体内的脊柱，使用纵向成像。然而， 在不了解它们如何存在的情况下推断这些突触变化的后果 在小区类型特定联系人的定义网络内，需要识别 突触的突触后伙伴。在这里，我们将使用在体内成像和成像技术， 荧光标记的分子定义的前和突触后神经元，以监测输入- 在小鼠须依赖性任务中感觉学习期间特定突触增加和丢失。 突触接触将使用事后扩增显微镜进行验证， 免疫组织化学用于纳米级分辨率。分析将侧重于学习依赖 来自高级丘脑核、后内侧核的丘脑输入的重组 核（POm）的树突上的第5层（L5）锥体神经元，已被特异性 与依赖经验的可塑性有关。定量，可重复，体内成像， 不同的学习阶段将提供对皮层回路如何编码和改变的深入了解 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.