Imaging Cortical Circuitry During General Anesthesia-Induced Analgesia

项目摘要/摘要 全麻药以浓度依赖的方式作用于中枢神经系统(CNS)以诱导 失去知觉并阻断疼痛的体验。尽管我们对分子的理解取得了进展 全麻药的机制，麻醉药是如何改变中枢神经系统功能以消除痛觉的 不是很清楚。取得进展的一个主要障碍是缺乏对普遍程度的理解 麻醉药在电路水平上发挥作用，特别是在大脑皮层处理 与疼痛体验相关的信息。大脑皮层回路对感觉刺激的处理是紧密的。 由功能不同的皮质神经元亚群调节，这些亚群在 调节局部神经活动和信息处理。然而，功能上不同的亚群 在全身麻醉过程中，大脑皮层神经元对网络活动改变的作用在很大程度上仍未被探索。 这项提议旨在解决两个关键问题： (1)是皮质内功能不同的神经元(例如，兴奋性与抑制性，以及分子上的 抑制性中间神经元的不同亚类)对全身麻醉药具有不同的敏感性？(具体 目标1和2) (2)哪些功能不同的神经元亚群被伤害性刺激激活，这些是 全身麻醉过程中的反应有变化吗？(具体目标3) 用微型荧光和双光子钙显像法同时监测肌动蛋白的体内活性 在小鼠全身麻醉期间，数百个单独的神经元在其较大的皮质集合中，这是 该提案旨在揭示一种主要的挥发性麻醉剂异氟醚产生的机制 止痛药。遗传方法将被用来选择性地荧光标记功能不同的亚群 大脑皮层神经元。为了确定功能不同的皮质神经元群体是否存在差异 在异氟醚麻醉的影响下，监测麻醉前、麻醉中和麻醉后的神经活动以进行比较 (1)兴奋性神经元对抑制性神经元的反应和(2)分子上不同的抑制性亚群的反应 中间神经元占整个神经元总数的比例。这些不同神经元亚群的反应将 然后在急性、有害刺激期间进行监测，以确定异氟醚麻醉如何干扰 产生止痛的大脑皮层回路。这些研究集中在两个区域，这些区域涉及到 痛觉：前扣带回(ACC)和初级躯体感觉(SI)皮质，分别 处理疼痛的情感和区别方面。

PROJECT SUMMARY/ABTRACT General anesthetics work in a concentration-dependent manner on the central nervous system (CNS) to induce loss of consciousness and block the experience of pain. Despite advances in our understanding of the molecular mechanisms of general anesthetics, how anesthetics alter CNS functioning to abolish the perception of pain is not well understood. A major impediment to progress has been a lack of understanding as to how general anesthetics exert their effects at the circuit level, particularly within regions of the cerebral cortex that process information relevant to the experience of pain. The processing of sensory stimuli by cortical circuits is tightly regulated by functionally distinct subpopulations of cortical neurons that have dissociable contributions in modulating local neural activity and information processing. However, how functionally distinct subpopulations of cortical neurons contribute to altered network activity during general anesthesia remains largely unexplored. This proposal aims to address two key questions: (1) Are functionally distinct neurons within the cortex (e.g., excitatory versus inhibitory, as well as molecularly distinct subclasses of inhibitory interneurons) differentially susceptible to general anesthetics? (Specific Aims 1 and 2) (2) Which subpopulations of functionally distinct neurons are activated by noxious stimuli, and are these responses altered during general anesthesia? (Specific Aim 3) Using miniature epifluorescent and two-photon calcium imaging to simultaneously monitor the in vivo activity of hundreds individual neurons within their larger cortical ensembles in the mouse during general anesthesia, this proposal aims to uncover the mechanisms through which a major volatile anesthetic, isoflurane, produces analgesia. Genetic approaches will be used to selectively fluorescently label functionally distinct subpopulations of cortical neurons. To determine whether functionally distinct populations of cortical neurons are differentially affected by isoflurane anesthesia, neural activity is monitored before, during and after anesthesia to compare the responses of (1) excitatory versus inhibitory neurons and (2) molecularly distinct subpopulations of inhibitory interneurons to the overall neuronal population. The responses of these distinct neuronal subpopulations will then be monitored during an acute, noxious stimulus to determine how isoflurane anesthesia interferes with cortical circuitry to produce analgesia. These studies are focused on two regions implicated in the generation of the pain percept: the anterior cingulate (ACC) and primary somatosensory (SI) cortices, which respectively process the affective and discriminative aspects of pain.