Visual cortex circuits mediating arousal and visual discrimination

项目摘要：唤醒状态转换是由意外或厌恶的刺激引起的，这些刺激改变了 环境的上下文。这些转变使大脑对感官输入更加警觉，并进行优化 目标导向行为的感觉加工。血管活性肠肽神经元抑制兴奋性神经元，并已知改变 对自上而下或神经调节输入作出反应的兴奋性感觉处理。VIP神经元在脑内激活 对环境变化的反应和他们的活跃度在觉醒增强的时期增加。然而，它是 尚不清楚觉醒的变化如何导致VIP的激活，或者VIP神经元是否确实调节了 一种唤醒状态依赖的方式。觉醒状态受去甲肾上腺素(NE)释放的控制 蓝斑(LC)，对环境变化做出反应并投射到大脑皮层。LC-NE信令是 可能是觉醒状态转换后VIP激活的中介，但这一机制从未被 实验解决的。在这个提案中，我将使用视觉皮质作为模型来检验假设 唤醒状态转换通过LC-NE介导的VIP激活来修改皮质感觉加工，以优化 上下文相关的目标导向行为。 视觉皮质中的兴奋性神经元在觉醒状态增加时变得更具选择性和可靠性。在……里面 目的1，我将研究血管活性肠肽神经元在调节这些和其他视觉处理变化中的作用 双波长双光子钙离子成像同时记录兴奋性神经元和血管活性肠化神经元 不同的唤醒状态。然后，我将使用光学标记来检查VIP活动的时间模式，因为它与 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 利用视神经VIP刺激的视觉处理中的唤醒状态。在目标2中，我将考察两者之间的关系 用光标记、LC轴突成像和NE成像研究LC-NE和VIP活性之间的关系。然后我会测试LC是否- 在V1中，NE刺激利用LC轴突的光遗传学来驱动VIP的激活并改变视觉处理。在《目标3》中， 我将使用习得的视觉辨别任务将这些发现与目标导向行为联系起来。我会决定是否 LC轴突和VIP神经元活动可预测识别的准确性和兴奋性编码的改善。 最后，我将在任务中通过光基因激活或抑制VIP神经元来直接测量它们的贡献 以唤醒为驱动的辨别准确率的变化。麻省理工学院的苏尔研究小组是一个理想的环境 继续本计划中概述的研究，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首创的技术， 包括下一代双波长双光子成像、光学标记、行为定量分析 和它的神经元相关性，光遗传操作，和神经元群体的计算分析 检查感觉处理和编码的变化。总而言之，研究项目、培训计划和 研究环境创造了一条未来独立的道路，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.