Pan-neuronal functional imaging and anesthesia

全神经元功能成像和麻醉

• 批准号: 10406651
• 负责人: Christopher W Connor
• 金额: $ 37.87万
• 依托单位: BRIGHAM AND WOMEN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2027-08-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10406651
• 关键词: Absence of pain sensation; Amnesia; Anesthesia procedures; Anesthesiology; Anesthetics; Animals; Architecture; Back; Behavior; Brain region; Caenorhabditis elegans; Calcium; Chemicals; Clinical; Communication; Complex; Conscious; Custom; Defect; Diffuse; Elderly; Electroencephalography; Exposure to; Foundations; Functional Imaging; Functional Magnetic Resonance Imaging; General Anesthesia; Human; Image; Image Analysis; Individual; Isoflurane; Lead; Length; Light; Measurement; Measures; Microscopy; Modification; Molecular Analysis; Mus; Muscle relaxation phase; Nervous system structure; Neurodevelopmental Impairment; Neurons; Operative Surgical Procedures; Pathway interactions; Phylogenetic Analysis; Physiological; Population; Problem behavior; Research; Resolution; Signal Transduction; Somatosensory Cortex; Supercomputing; Synapses; System; Techniques; Time; Unconscious State; Zebrafish; awake; clinical risk; connectome; differential expression; drug action; experimental study; fluorophore; in vivo; infancy; medical specialties; neural network; neuronal circuitry; novel; post-operative cognitive dysfunction; promoter; receptor; two-photon

Volatile anesthetics, such as isoflurane, produce all stages of general anesthesia including unconsciousness, amnesia, analgesia and muscle relaxation. Despite their ubiquity, the fundamental mechanisms of action of these drugs remains unknown. Elucidating the mechanisms by which clinical anesthesia is produced is the foundational unanswered research question in the specialty of anesthesiology. The routine use of volatile anesthetics is not without clinical risk. Multiple exposures to anesthetics in infancy leads to possible behavioral problems in later life, and persistent post-operative cognitive dysfunction is seen in the elderly after anesthesia. Historically, research in this field has proceeded along two tracks: either molecular analysis looking for specific receptors for the volatile anesthetics (an approach that has largely foundered due to diffuse interactions with many receptors whose effects do not combine appropriately), or the gross measurement of neuronal activity in entire regions of the brain using EEG and fMRI (which are fundamentally limited by resolution). Clearly, there is an enormous gap in length resolution between synaptic-scale and EEG-scale. We hypothesized that the onset of anesthesia, and hence the loss of consciousness, is due to disruption in the communication between neurons at the level of small neuronal networks that lie well below the resolution limit of EEG and fMRI. We study the effect of anesthetic agents on intercommunication within intact, living neural networks, with single neuron resolution. We use C. elegans, the creature with the simplest, most tractable neuronal architecture in which anesthesia is known to be inducible. Using light-sheet microscopy, a combination of fixed and calcium- sensitive fluorophores expressed under neuronal promoters, and our customized supercomputing toolchain for image analysis and signal extraction, we track and capture the activity of essentially the entire nervous system and examine its behavior under varying levels of anesthetic exposure normalized to comparable levels used in human surgery. Using two-photon imaging, we are able to perform similar experiments in the mouse and extract activity from selected regions of the somatosensory cortex in both awake and anesthetized states. We will use a system of differential expression of fixed neuronal fluorophores in C. elegans to allow the precise identification of individual neurons under light-sheet imaging. In combination with the C. elegans connectome, we will determine the neuronal pathways that underlie anesthetized vs conscious states, how anesthetics alter chemical and electrical synaptic connections to induce these states, the changes in neuronal connectivity that permit the anesthetized state to resolve back into consciousness, and hence delineate the mechanisms of clinical post-operative cognitive dysfunction in the old and neurodevelopmental impairment in the young. We will extend our imaging and analysis techniques into vertebrate zebrafish, building a phylogenetic bridge in the action of anesthetics from simple creatures to humans. We will demonstrate that these changes in neuronal activity are consistent with the gross statistical hallmarks of anesthesia seen in the EEG in humans.

挥发性麻醉剂，如异氟醚，会产生全身麻醉的所有阶段，包括昏迷， 健忘、止痛、肌肉松弛。尽管它们无处不在，但其基本作用机制 这些药物仍然不为人知。阐明临床麻醉产生的机制是 麻醉学专业尚未回答的基础性研究问题。Volatile的常规用法 麻醉药并非没有临床风险。婴儿期多次接触麻醉药可能导致行为 老年人麻醉后会出现晚年生活问题和持续性的术后认知功能障碍。 从历史上看，这一领域的研究沿着两条道路进行：要么是寻找特定的分子分析 挥发性麻醉剂的受体(一种由于弥漫性相互作用而基本上失败的方法 许多受体的作用没有适当地结合)，或者对神经元活动的粗略测量 使用脑电和功能磁共振成像(这两种技术基本上受到分辨率的限制)对整个大脑区域进行成像。显然，有 突触尺度和脑电尺度之间在长度分辨率上的巨大差距。我们假设起病时间 麻木，因此失去知觉，是由于 位于EEG和fMRI分辨率极限以下的小型神经元网络级别的神经元。我们 研究麻醉剂对完整的、活的神经网络内相互通信的影响 神经元分辨率。我们使用线虫，这种生物具有最简单、最易驯服的神经元结构 已知哪种麻醉是可以诱导的。使用光片显微镜，固定和钙的组合- 在神经元启动子下表达的敏感荧光团，以及我们为 图像分析和信号提取，我们跟踪和捕获基本上整个神经系统的活动 并检查其在不同麻醉剂暴露水平下的行为，这些麻醉暴露水平归一化为 人体外科手术。利用双光子成像，我们能够在小鼠和 从清醒和麻醉状态下的躯体感觉皮质的选定区域提取活性。 我们将在线虫中使用固定神经元荧光团的差异表达系统来允许精确的 在光片成像下识别单个神经元。结合线虫连接体， 我们将确定麻醉和清醒状态下的神经通路，麻醉剂如何改变。 化学和电突触连接诱导这些状态，神经元连接性的变化 允许麻醉状态分解到意识中，从而描绘出 老年人术后认知功能障碍和年轻人神经发育障碍的临床研究。我们 将我们的成像和分析技术扩展到脊椎动物斑马鱼，在 麻醉剂从简单生物到人类的作用。我们将证明神经细胞的这些变化 活动与人类脑电中看到的麻醉的粗略统计特征是一致的。