Inhibitory regulation of neural circuit plasticity in visual cortex

描述（由申请人提供）：在青春期早期的关键时期，视觉皮层中的电路布线受到感官体验的强烈影响。在这一关键时期，由于白内障或斜视而发生的视觉体验退化会损害立体视觉和高空间频率视觉的发育，从而导致弱视的病因。这个建议的长期目标是了解感觉经验如何在关键时期对皮层回路产生影响，特别强调抑制性神经元的作用。为了确定感觉经验如何作用于抑制性神经元以控制电路可塑性，我们提出了三个具体的目标， 我们实验室里已经使用的最先进的技术。为了验证这一假设，即改变的视觉诱导抑制反应的快速丧失，然后门兴奋性可塑性，我们使用2-光子在体内成像可视化特定类型的兴奋性和抑制性神经元在视觉皮层的警觉小鼠，然后靶细胞贴补丁记录这些神经元在皮层层。这种方法提供了最高的时间和空间分辨率。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。为了确定兴奋性/抑制性网络可塑性的空间和时间动力学，我们使用高速双光子体内显微镜同时成像数百个神经元表达一种新的，非常敏感的遗传编码的钙指示剂（GCaMP 6）。我们遵循相同的神经元群体之前和在小鼠的眼优势可塑性，其中特定群体的抑制性神经元用遗传编码的红色荧光团双标记。在第三个目标，我们测试的假设，单眼剥夺首先改变突触连接快速尖峰的中间神经元。为此，我们使用激光扫描谷氨酸解开和通道视紫红质辅助电路映射。这项工作将大大推进我们对抑制可塑性的理解，并解决抑制可塑性的目标。 NEI的斜视、弱视和视觉处理项目，旨在“增加对关键期的理解，以确定经验如何改变发育中视觉系统的连通性”

DESCRIPTION (provided by applicant): 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 stereopsis and high spatial 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"