Imaging Synaptic Plasticity in the Visual Cortex in Vivo

描述（由申请人提供）：本申请中提出的实验研究树突棘生长和收缩在小鼠视觉皮层中的经验依赖性可塑性中的作用。最近的证据表明，树突棘在发育和成年皮层中是动态的：新的棘每天出现并向轴突生长以建立新的突触，而一些现有的棘缩回，破坏它们的突触连接。这些突触连接的变化可能在经验依赖性可塑性过程中快速重布线皮层回路中发挥重要作用。在表达绿色荧光蛋白转基因的转基因小鼠中，将检查脊髓生长和回缩在皮质回路功能变化的基础上的程度。2-光子激光扫描显微镜和内在信号光学成像将用于在单眼剥夺之前和之后的数周内重复成像相同小鼠体内的脊柱动力学和皮质眼优势的功能变化。通过在相同的制备中成像结构和功能的变化，将有可能确定突触消除是否是剥夺的眼睛输入的功能丧失的基础，以及新的突触形成是否是经验丰富的眼睛输入的逐渐加强的基础。将使用体内电生理学和固定组织解剖学来确定哪些细胞在哪些层中首先改变其单眼剥夺后的反应性和连接性，并绘制这些变化通过皮质回路其余部分的进展。总之，这些实验应该提供一个详细的了解的发病和发展的经验依赖性变化的皮层结构和功能的感受野和突触的水平。这些实验的结果可能有助于提供合理的弱视，暗点和中风的治疗方法。

DESCRIPTION (provided by applicant): 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 indicates 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.