Imaging Synaptic Plasticity in the Visual Cortex in Vivo

本申请中提出的实验旨在研究树突棘的生长和回缩在 小鼠视皮层的经验依赖性可塑性。最近的证据表明，树突棘 在发育中的和成年的皮质中是动态的：每天都会出现新的棘突，并朝着轴突生长 当一些现存的脊椎收缩时，建立新的突触，破坏它们的突触连接。这些 突触连接性的变化可能在快速重新连接大脑皮质回路方面发挥重要作用 依赖经验的可塑性。脊柱生长和后退在多大程度上是功能性的基础 将在表达绿色荧光蛋白的转基因小鼠中检测皮质回路的变化 转基因。双光子激光扫描显微镜和本征信号光学成像将被重复使用 在体眼皮质优势在数周内的影像脊柱动力学和功能变化 相同的小鼠在单眼剥夺前后。通过成像图像中结构和功能的变化 同样的准备，将有可能确定突触消除是否导致功能丧失 剥夺眼睛的输入和新的突触形成是有经验的眼睛逐渐加强的基础 投入。体内电生理学和固定组织解剖学将被用来确定 图层在单眼剥夺后最先改变其响应性和连通性，并绘制地图 这些变化的进展通过皮质回路的剩余部分进行。这些加在一起， 实验应该提供对经验依赖的发生和发展的详细理解 感受野和突触水平的皮质结构和功能的变化。来自这些的结果 实验可能有助于提供合理的治疗方法来治疗弱视、暗点和 卒中。

The experiments proposed in this application investigate the roles of dendritic spine growth and retraction in experience-dependent plasticity in the mouse visual cortex. Recent evidence indicate that dendritic spines are dynamic in the developing and adult cortex: new spines appear daily and grow towards axons to establish novel synapses while some existing spines retract, breaking their synaptic connection. These changes in synaptic connectivity may play important roles in rapidly rewiring cortical circuits during experience-dependent plasticity. The extent to which spine growth and retraction underlie functional changes in cortical circuits will be examined in transgenic mice expressing a green fluorescent protein transgene. 2-photon laser scanning microscopy and intrinsic signal optical imaging will used to repeatedly image spine dynamics and functional changes in cortical ocular dominance in vivo over periods of weeks in the same mice before and after monocular deprivation. By imaging changes in structure and function in the same preparation, it will be possible to determine whether synapse elimination underlies the functional loss of deprived eye inputs and novel synapse formation underlies the gradual strengthening of experienced eye inputs. In vivo electrophysiology and fixed tissue anatomy will be used to determine which cells in which layers are the first to alter their responsiveness and connectivity following monocular deprivation and to map the progression of these changes through the remainder of the cortical circuit. Taken together, these experiments should provide a detailed understanding of the onset and progression of experience-dependent changes in cortical structure and function at the level of receptive fields and synapses. Results from these experiments may aid in the provision of rationally-based therapeutic approaches to amblyopia, scotoma, and stroke.