OPTOGENETIC MAPPING OF CELL SPECIFIC CONNECTIONS IN THE MOUSE BRAIN AFTER STROKE

项目摘要/摘要 目前这项提议的目标是确定分子和系统水平的大脑修复机制 相互作用影响小鼠局灶性脑缺血后的行为恢复。中风会直接造成结构性损害 本地电路和对全球网络的间接功能损害，可导致跨 多个域。卒中后的神经可塑性涉及周围组织中的分子变化，这种变化可能是 受偏远地区影响，幸免于难。在系统层面上，功能磁共振成像 揭示了中风的康复与大脑功能的重组有关 形成新的或替代的电路。直接受影响的脑区重新映射到邻近组织 行为康复。在全球范围内，静息状态功能连接的模式在 康复情况良好的患者。虽然在人类和动物模型中进行的功能神经成像研究 始终如一地显示中风后局部和整体脑组织功能的变化，这是未知的 这些过程如何相互关联以支持行为恢复。了解如何(或是否)重新映射大脑 地区重新融入全球网络以支持中风后的康复需要更直接的检查 不断演变的本地和全球互联互通结构。在分子水平上，有限的数据表明新的轴突 卒中后出现在梗死灶周围皮质和远端同位对侧皮质。增加了对 在皮损周围组织中发现了与可塑性相关的基因，包括那些参与轴突萌发的基因。生长 相关蛋白43(GAP-43)是一种完整的膜蛋白，存在于轴突生长锥体、突触和 局灶性脑缺血后广泛诱导。这种蛋白质可能驱动脑梗塞周围的解剖连接， 支持中风后的功能恢复。然而，轴突萌发在功能神经可塑性中的作用 局灶性脑缺血后尚未进行检查。我们假设依赖于GAP-43的轴突萌发是 本地电路修复和重新融入全球网络所需的，这一不断发展的过程推动了 中风后的行为恢复。我们进一步假设轴突的萌发可以由神经调节。 兴奋性结节的活动与损伤部位有关，而这些活动依赖的过程 靠GAP-43公路行驶。在体内验证这一假说的关键障碍是无法连续检查 随着恢复而发展的全球网络连接，并纵向检查重新映射的电路的子单元 因为它们会随着时间的推移而改变。我们通过将光学本征信号成像与 光遗传学更直接地探测本地电路连接。我们将使用这项技术来确定：1)如何 局部环路和全局网络的重新出现与局灶性缺血后的功能恢复有关，2)如果 依赖GAP-43的轴突萌发是局部和/或全局运动网络修复和行为所必需的 恢复，以及3)兴奋性运动节点的活动是否调节局部/全局运动网络修复和行为 如果这些变化依赖于GAP-43。

PROJECT SUMMARY/ABSTRACT The goal of the current proposal is to determine how molecular- and systems-level mechanisms of brain repair interact to influence behavioral recovery after focal ischemia in mice. Stroke causes direct structural damage to local circuits and indirect functional damage to global networks that can result in behavioral deficits spanning multiple domains. Neuroplasticity after stroke involves molecular changes within perilesional tissue that can be influenced by distant regions spared from injury. At the systems level, functional magnetic resonance imaging has revealed that recovery from stroke is associated with functional reorganization of the brain through the formation of new or alternative circuits. Directly impacted brain regions remap to adjacent tissue in concert with behavioral recovery. More globally, patterns of resting-state functional connectivity gradually normalize in patients experiencing good recovery. While functional neuroimaging studies in humans and animal models consistently demonstrate local and global changes in functional brain organization after stroke, it is unknown how these processes interrelate to support behavioral recovery. Understanding how (or if) remapped brain regions reintegrate into global networks to support recovery after stroke requires more direct examination of evolving local and global connectivity structure. At the molecular level, limited data suggest that new axons appear after stroke in periinfarct cortex and distant, homotopic contralateral cortex. Increased expression of plasticity-associated genes are found in perilesional tissue including those involved in axonal sprouting. Growth Associated Protein 43 (GAP-43) is an integral membrane protein found in axonal growth cones, synapses, and widely induced after focal ischemia. This protein might drive anatomical connections within the periinfarct that support functional restoration after stroke. However, the role of axonal sprouting in functional neuroplasticity following focal ischemia has not been examined. We hypothesize that GAP-43-dependent axonal sprouting is required for local circuit repair and reintegration into global networks, and this evolving process drives the degree of behavioral recovery after stroke. We further hypothesize that axonal sprouting can be modulated by neural activity in excitatory nodes functionally-connected to the site of injury, and these activity-dependent processes depend on GAP-43. Critical barriers to testing this hypothesis in vivo have been the inability to serially examine global network connectivity as it evolves with recovery, and longitudinally examine subunits of remapped circuits as they change over time. We have overcome these barriers by integrating optical intrinsic signal imaging with optogenetics to probe local circuit connectivity more directly. We will use this technology to determine: 1) how the reemergence of local circuits and global networks relate to functional recovery following focal ischemia, 2) if GAP-43-dependent axonal sprouting is required for local and/or global motor network repair and behavioral recovery, and 3) if activity in excitatory motor nodes modulates local/global motor network repair and behavioral recovery, and if these changes rely on GAP-43.