Inhibitory regulation of neural circuit plasticity in visual cortex

描述(申请人提供)：在青春期早期的关键时期，视觉皮层的回路连接受到感官经验的强烈影响。在这一关键时期，白内障或斜视引起的视觉体验下降会损害立体视觉和高空间频率视觉的发展，从而导致弱视的病因。这项建议的长期目标是了解感觉体验如何在关键时期对皮层电路产生影响，特别是强调抑制性神经元的作用。为了确定感觉体验如何作用于抑制神经元来控制电路可塑性，我们提出了三个利用状态的具体目标 已经在我们的实验室中发挥作用的尖端技术。为了验证视力改变会导致抑制反应迅速丧失，进而开启兴奋性可塑性的假说，我们使用双光子活体成像技术对警觉小鼠的视皮层中特定类型的兴奋性和抑制性神经元进行可视化，然后将靶细胞贴片记录跨皮质层连接到这些神经元上。这种方法提供了可用的最高时间和空间分辨率。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活体显微镜同时成像数百个神经元表达一种新的、极其敏感的遗传编码钙指示物(GCaMP6)。我们在小鼠的眼睛优势可塑性之前和期间跟踪相同的神经元群体，其中特定群体的抑制性神经元被基因编码的红色荧光团双重标记。在第三个目的中，我们测试了单眼剥夺首先改变到快速放电中间神经元的突触连接的假设。为此，我们使用激光扫描谷氨酸去化和通道视紫红质辅助的电路标测。这项工作将极大地促进我们对抑制可塑性的理解，并解决 NEI的斜视、弱视和视觉处理程序“增加对关键期的理解，以确定经验如何改变发育中的视觉系统的连通性”

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"