Inhibitory regulation of neural circuit plasticity in visual cortex

摘要 在青春期早期的关键时期，视皮层中的电路连接受到 感官体验。视力下降，如白内障或斜视，在此过程中 关键期损害了僵持和高频率视觉的发展，从而促进了 弱视的病因。这项提议的长期目标是理解感官 在关键时期，经验对大脑皮层回路产生影响，特别强调 抑制性神经元的作用。确定感觉体验如何作用于抑制神经元至门控电路 可塑性我们提出了三个具体的目标，利用已经在发挥作用的最先进的技术 在我们的实验室里。为了检验视力改变会导致抑制反应迅速丧失的假设， 然后门兴奋性可塑性，我们使用双光子体内成像来可视化特定类型的 清醒小鼠视皮层兴奋性和抑制性神经元及靶细胞贴片记录 通过大脑皮层传递到这些神经元。这种方法提供了最高的时间和空间分辨率 可用。通过比较随时间变化的反应，我们将揭示跨层可塑性的编排。 为了确定兴奋/抑制网络可塑性的空间和时间动力学，我们使用高速 双光子活体显微镜同时成像数百个神经元表达一种新的，极端的 敏感的基因编码钙指示剂(GCaMP6)。我们遵循的是相同的神经元群体 在小鼠眼优势可塑性之前和期间，特定群体的抑制性神经元 用基因编码的红色荧光团进行双重标记。在第三个目标中，我们检验假设 单眼剥夺首先会改变突触与快速放电的中间神经元的连接。要做到这一点，我们使用 激光扫描谷氨酸去除和通道视紫红质辅助的电路标测。这项工作将 大大提高了我们对抑制可塑性的理解，并解决了斜视的目标， 弱视，和NEI的视觉处理程序，以增加对关键时期的了解 以确定体验如何改变正在发展的视觉系统中的连通性

ABSTRACT During critical periods of early adolescence, the wiring of circuitry in visual cortex is strongly influenced by sensory experience. Degraded visual experience, as occurs from cataracts or strabismus, during this critical period impairs the development of steopsis and high sptial frequency vision, thereby contributing to the etiology of amblyopia. The long term objectives of this proposal are to understand how sensory experience exerts its influence on cortical circuitry during the critical period, with particular emphasis on the role of inhibitory neurons. To determine how sensory experience acts on inhibitory neurons to gate circuit plasticity we propose three specific aims that leverage state-of-the-art techniques that are already working in our laboratories. To test the hypothesis that altered vision induces a rapid loss of inhibitory responses, which then gates excitatory plasticity, we use 2-photon in vivo imaging to visualize specific types of excitatory and inhibitory neurons in visual cortex of alert mice and then target cell attached patch recordings to these neurons across cortical layers. This approach provides the highest temporal and spatial resolution available. By comparing responses over time, we will reveal the choreography of plasticity across layers. To determine the spatial and temporal kinetics of excitatory/inhibitory network plasticity, we use high-speed 2-photon in vivo microscopy to simultaneously image hundreds of neurons expressing a new, extremely sensitive genetically encoded calcium indicator (GCaMP6). We follow the same populations of neurons before and during ocular dominance plasticity in mice where specific populations of inhibitory neurons are double labeled with a genetically encoded red fluorophore. In the third aim we test the hypothesis that monocular deprivation first changes the synaptic connectivity to fast-spiking interneurons. To do so we use laser scanning glutamate uncaging and channelrhodopsin-assisted circuit mapping. This work will significantly advance our understanding of inhibitory plasticity and address objectives of the Strabismus, Amblyopia, and Visual Processing Program of the NEI to "increase understanding of the critical period in order to determine how experience alters connectivity in the developing visual system"