In vivo imaging of supragranular circuit plasticity in mouse visual cortex

描述（由申请人提供）：该提案旨在研究单眼剥夺期间小鼠初级视觉皮层中双眼反应的经验依赖性重组的细胞基质。所使用的方法是测量个体转基因小鼠中眼特异性反应和神经回路解剖学纵向变化的有效手段：（1）经颅内在信号光学成像，和（2）钙指示剂荧光和遗传标记神经元的双光子显微镜。先前的研究发现，颗粒外层是介导快速的、活动依赖的视觉皮层可塑性的位点，其解剖学变化的速度和幅度与视觉反应的变化相当。在这个建议中，这种现象将进行更详细的研究，通过表征在单眼剥夺期间在初级视觉皮层的双眼区中的遗传标记的颗粒上兴奋性神经元的子集中体内发生的生理和解剖学变化。由于小鼠初级视觉皮层是缺乏眼优势柱，功能性双光子显微镜将被用来关联眼睛特异性反应的单，遗传标记的神经元与相应的解剖学变化，因为它们发生在单眼剥夺。生理学和解剖学变化将在单眼剥夺的三个时间上不同的阶段的背景下表征：（1）对剥夺眼的反应丧失，（2）睁眼反应的急剧增加和剥夺眼反应的轻微增加，以及（3）在重新睁开剥夺眼后反应恢复到其初始状态。这一提议的成功将提供对视觉皮层可塑性过程中发生的变化的深入理解，并为未来研究探索发育早期和成人可塑性的分子机制提供了一个画布。此外，阐明视觉皮层可塑性的基板是一个基本的问题，支持治疗获得性脑异常（如弱视）的基础。

DESCRIPTION (provided by applicant): This proposal seeks to investigate the cellular substrates that underlie the experience-dependent reorganization of binocular responses in the mouse primary visual cortex during monocular deprivation. The methods to be used are efficient means of measuring changes in eye-specific responses and neural circuit anatomy longitudinally in individual transgenic mice: (1) transcranial intrinsic signal optical imaging, and (2) two-photon microscopy of calcium indicator fluorescence and genetically labeled neurons. Previous studies have found extragranular layers to be the locus mediating rapid, activity-dependent visual cortical plasticity, with anatomical changes comparable in speed and magnitude to the change in visual responses. In this proposal, this phenomenon will be investigated in greater detail by characterizing the physiological and anatomical changes occurring in vivo in subsets of genetically labeled supragranular excitatory neurons in the binocular zone of the primary visual cortex during monocular deprivation. Since the mouse primary visual cortex is devoid of ocular dominance columns, functional two-photon microscopy will be used to correlate eye-specific responses of singly, genetically labeled neurons with corresponding anatomical changes as they occur during monocular deprivation. The physiological and anatomical changes will be characterized in the context of three temporally distinct phases of monocular deprivation: (1) loss of response to the deprived eye, (2) a dramatic increase in open eye response and a slight increase in deprived eye response, and (3) a return of responses to their initial state after re-opening the deprived eye. The success of this proposal would provide an in-depth understanding of the changes that occur during visual cortical plasticity and could unveil a canvas for future studies investigating the molecular mechanisms that underlie plasticity early in development and in adult. Moreover, elucidating the substrates of visual cortical plasticity is a fundamental issue that supports the basis for treatment of acquired brain abnormalities (e.g. amblyopia).