Visual cortex circuits mediating arousal and visual discrimination

项目概述：唤醒状态转换是由意想不到的或令人厌恶的刺激引起的， 环境的背景。这些过渡使大脑对感官输入更加警觉， 目标导向行为的感官处理VIP神经元解除兴奋性神经元的抑制，并且已知改变 对自上而下或神经调节输入的兴奋性感觉处理。VIP神经元激活， 他们对环境变化的反应和他们的活动在唤醒增加期间增加。但据 不清楚唤醒的变化如何导致VIP激活，或者VIP神经元是否确实调节感觉处理， 一种依赖唤醒状态的方式唤醒状态由该部位释放的去甲肾上腺素（NE）控制 蓝斑核（LC），其响应于上下文变化而发射并投射到皮层。LC-NE信令是 在唤醒状态转换后VIP激活的假定介导者，但这种机制从未被 实验解决。在这个建议中，我将使用视觉皮层作为模型来测试假设， 唤醒状态转换通过LC-NE介导的VIP激活来改变皮层感觉处理，以优化 情境依赖的目标导向行为 视觉皮层中的兴奋性神经元在增强的唤醒状态下变得更具选择性和可靠性。在 目的1，我将研究VIP神经元在介导这些和其他视觉处理变化中的作用， 双波长双光子钙成像，同时记录兴奋性和VIP神经元， 不同的唤醒状态然后，我将使用光标记来检查VIP活动的时间模式，因为它涉及到 视觉处理的变化。然后，我将测试VIP驱动的视觉处理变化是否反映了 使用光遗传学VIP刺激对视觉处理的唤醒状态。在目标2中，我将研究 使用光标记、LC轴突成像和NE成像的LC-NE和VIP活性之间的关系。我将测试如果LC- NE刺激驱动VIP激活并在V1中使用LC轴突光遗传学改变视觉处理。在目标3中， 我将通过一项学习性视觉辨别任务，将这些发现与目标导向行为联系起来。我会决定 LC轴突和VIP神经元活性预测的歧视的准确性和改善兴奋性编码。 最后，我将在任务期间光遗传学地激活或抑制VIP神经元，以直接测量它们的贡献。 唤醒驱动的辨别准确性的变化。麻省理工学院的苏尔研究小组是一个理想的环境， 我将继续进行本建议书中概述的研究，并接受培训，为我的职业生涯做好准备， 独立调查员我将有机会掌握苏尔研究小组开创的技术， 包括下一代双波长双光子成像、光标记、行为的定量分析 及其神经元相关物，光遗传学操作和神经元群体的计算分析， 检查感觉处理和编码的变化。综合考虑，研究项目、培训计划和 研究环境创造了一条通往未来独立的道路，非常适合我的职业目标。

Project Summary: Arousal state transitions are evoked by unexpected or aversive stimuli that change the context of the environment. These transitions prime the brain to be more alert to sensory input and optimize sensory processing for goal-directed behavior. VIP neurons disinhibit excitatory neurons and are known to alter excitatory sensory processing in response to top-down or neuromodulatory input. VIP neurons activate in response to contextual changes and their activity increases during periods of increased arousal. However, it is unclear how changes in arousal lead to VIP activation, or indeed if VIP neurons modulate sensory processing in an arousal-state-dependent manner. Arousal state is controlled by norepinephrine (NE) release from the locus coeruleus (LC), which fires in response to contextual change and projects to the cortex. LC-NE signaling is a putative mediator of VIP activation following arousal state transitions, but this mechanism has never been experimentally addressed. In this proposal, I will use the visual cortex as a model to test the hypothesis that arousal state transitions modify cortical sensory processing through LC-NE mediated VIP activation to optimize context-dependent goal-directed behavior. Excitatory neurons in the visual cortex become more selective and reliable during increased arousal states. In Aim 1, I will examine the role of VIP neurons in mediating these and other changes in visual processing by using dual-wavelength two-photon calcium imaging to simultaneously record excitatory and VIP neurons during different arousal states. I will then use optotagging to examine the temporal pattern of VIP activity as it relates to changes in visual processing. I will then test if VIP-driven changes in visual processing mirror the effects of arousal states on visual processing using optogenetic VIP stimulation. In Aim 2, I will examine the relationship between LC-NE and VIP activity using optotagging, LC axonal imaging, and NE imaging. I will then test if LC- NE stimulation drives VIP activation and alters visual processing using LC axonal optogenetics in V1. In Aim 3, I will relate these findings to goal-directed behavior using a learned visual discrimination task. I will determine if LC axonal and VIP neuronal activity are predictive of discrimination accuracy and improved excitatory encoding. Finally, I will optogenetically activate or inhibit VIP neurons during the task to directly measure their contribution to arousal-driven changes in discrimination accuracy. The Sur research group at MIT is an ideal environment to pursue the research outlined in this proposal and to receive training that will prepare me for a career as an independent investigator. I will have the opportunity to master technologies pioneered in the Sur research group, including next-generation dual-wavelength two-photon imaging, optotagging, quantitative analyses of behavior and its neuronal correlates, optogenetic manipulations, and computational analysis of neuronal populations to examine changes in sensory processing and encoding. Taken together, the research project, training plan, and research environment create a path to future independence well suited to my career goals.