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

项目总结/摘要 目前的建议的目标是确定如何分子和系统水平的机制，大脑修复 相互作用影响小鼠局灶性缺血后的行为恢复。中风导致直接的结构性损伤， 局部电路和间接功能损害的全球网络，可导致行为缺陷， 多个域。中风后的神经可塑性涉及病变周围组织内的分子变化， 受到远离伤害的遥远地区的影响。在系统层面，功能性磁共振成像 研究表明，中风的恢复与大脑的功能重组有关， 形成新的或替代的电路。直接受影响的大脑区域重新映射到邻近组织， 行为恢复在更广泛的范围内，静息状态功能连接的模式在2008年逐渐正常化。 患者恢复良好。虽然在人类和动物模型中进行的功能性神经成像研究 一致地表明中风后功能性脑组织的局部和整体变化，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，以支持中风后的恢复需要更直接的检查， 不断发展的本地和全球连接结构。在分子水平上，有限的数据表明， 出现在中风后的梗死周围皮层和远端的同侧对侧皮层。的表达增加 在病变周围组织中发现了可塑性相关基因，包括涉及轴突发芽的那些基因。增长 相关蛋白43（GAP-43）是在轴突生长锥、突触和神经元中发现的整合膜蛋白。 广泛诱发局灶性缺血后。这种蛋白质可能驱动梗死周围的解剖学连接， 支持中风后功能恢复。然而，轴突发芽在功能性神经可塑性中的作用 局灶性缺血后的情况尚未研究。我们假设GAP-43依赖的轴突发芽是 当地电路维修和重新融入全球网络所需的，这一不断发展的过程推动了程度 中风后的行为恢复我们进一步假设，轴突发芽可以通过神经细胞的生长来调节。 与损伤部位功能性连接的兴奋性节点的活动，这些活动依赖性过程 依赖于GAP-43在体内测试这一假设的关键障碍是无法连续检查 全球网络的连通性，因为它的演变与恢复，并纵向检查子单元的重新映射电路 随着时间的推移而变化。我们已经克服了这些障碍，通过集成光学固有信号成像， 光遗传学更直接地探测局部电路连接。我们将使用这项技术来确定：1）如何 局部回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 GAP-43依赖性轴突发芽是局部和/或整体运动网络修复和行为所必需的。 恢复，以及3）兴奋性运动节点中的活动是否调节局部/全局运动网络修复和行为 恢复，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.