In vivo imaging of supragranular circuit plasticity in mouse visual cortex

描述(由申请人提供)：这项提案试图调查在单眼剥夺过程中，小鼠初级视觉皮质中双眼反应的经验依赖性重组的细胞底物。要使用的方法是测量个体转基因小鼠眼睛特异性反应和神经回路纵向解剖变化的有效手段：(1)经颅固有信号光学成像，(2)钙指示剂荧光和基因标记神经元的双光子显微镜。以前的研究发现，颗粒外层是调节快速的、依赖活动的视觉皮质可塑性的部位，其解剖学变化在速度和幅度上与视觉反应的变化相当。在这项提议中，将通过描述在单眼剥夺过程中初级视觉皮质双眼区域中基因标记的颗粒上兴奋性神经元的亚群在体内发生的生理和解剖学变化来更详细地研究这一现象。由于小鼠初级视皮层没有眼优势柱，功能性双光子显微镜将用于在单眼剥夺期间将单个基因标记神经元的眼睛特异性反应与相应的解剖学变化联系起来。生理和解剖学的变化将在单眼剥夺的三个不同时间阶段的背景下描述：(1)对被剥夺的眼睛失去反应，(2)睁开眼睛的反应急剧增加，被剥夺的眼睛反应略有增加，以及(3)在重新打开被剥夺的眼睛后，反应恢复到其初始状态。这一提议的成功将提供对视觉皮质可塑性过程中发生的变化的深入了解，并可能为进一步研究发育早期和成人可塑性背后的分子机制揭开序幕。此外，阐明视觉皮质可塑性的底物是支持后天脑异常(如弱视)治疗的基础的一个基本问题。

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).