Imaging Cortical Circuitry During General Anesthesia-Induced Analgesia

项目总结/摘要 全身麻醉剂以浓度依赖性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。尽管我们对分子生物学的理解有了进步， 全身麻醉剂的机制，麻醉剂如何改变中枢神经系统功能，消除疼痛的感觉， 没有很好地理解。取得进展的一个主要障碍是缺乏对普遍性如何的理解， 麻醉剂在回路水平上发挥作用，特别是在大脑皮层的处理区域内。 与疼痛体验相关的信息。大脑皮层回路对感觉刺激的处理过程与大脑皮层回路紧密相连， 由功能不同的皮质神经元亚群调节，这些亚群在神经元中具有可分离的贡献。 调节局部神经活动和信息处理。然而，功能上不同的亚群 在全身麻醉期间，皮质神经元的神经元参与改变的网络活动仍然在很大程度上未被探索。 这项建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 抑制性中间神经元的不同亚类）对全身麻醉药的敏感性差异？（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 在全身麻醉期间改变的反应？（具体目标3） 使用微型落射荧光和双光子钙成像来同时监测 在全身麻醉的小鼠中，数百个单独的神经元在其较大的皮层集合体中， 一项提案旨在揭示一种主要的挥发性麻醉剂异氟烷产生 analgesia.遗传方法将用于选择性荧光标记功能不同的亚群 大脑皮层神经元为了确定功能上不同的皮质神经元群体是否在神经元的分化中存在差异， 受异氟醚麻醉的影响，在麻醉前、麻醉中和麻醉后监测神经活动，以比较 （1）兴奋性与抑制性神经元的反应和（2）抑制性神经元的分子不同亚群的反应。 中间神经元与整个神经元群体的比例。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，以确定异氟烷麻醉如何干扰 皮层回路产生镇痛作用。这些研究主要集中在两个区域， 疼痛感受器：前扣带回（ACC）和初级躯体感觉（SI）皮质，分别 处理疼痛的情感和辨别方面。

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.