Pan-neuronal functional imaging and anesthesia

全神经元功能成像和麻醉

基本信息

批准号：
10685271
负责人：
Christopher W Connor
金额：
$ 35.9万
依托单位：
BRIGHAM AND WOMEN'S HOSPITAL
依托单位国家：
美国
项目类别：
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/10685271
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 Defect Diffuse Elderly Electroencephalography Exposure to Functional Imaging General Anesthesia Human Image Image Analysis Individual Isoflurane Lead Length Light Measurement Measures Microscopy Modification Molecular Analysis Mus Muscle relaxation phase Nervous System 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 Volatilization Zebrafish awake clinical risk connectome differential expression drug action experimental study fluorophore functional magnetic resonance imaging/electroencephalography in vivo infancy medical specialties neural network neuronal circuitry novel post-operative cognitive dysfunction promoter receptor two-photon

项目摘要

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，例如异氟烷，可产生全身麻醉的所有阶段，包括意识不清、健忘症、镇痛和肌肉松弛。尽管它们无处不在，但其基本作用机制这些药物仍然未知。阐明临床麻醉产生的机制是麻醉学专业中尚未解答的基本研究问题。挥发性的日常使用麻醉药并非没有临床风险。婴儿期多次接触麻醉剂可能导致行为异常麻醉后老年人会出现晚年生活问题和持续的术后认知功能障碍。从历史上看，该领域的研究沿着两条轨道进行：要么通过分子分析寻找特定的挥发性麻醉剂的受体（这种方法由于与挥发性麻醉剂的弥漫性相互作用而很大程度上失败了许多受体的作用不能适当地结合），或神经元活动的总体测量使用脑电图和功能磁共振成像来分析大脑的整个区域（这从根本上受到分辨率的限制）。显然，有突触尺度和脑电图尺度之间的长度分辨率存在巨大差距。我们假设发病时麻醉的效果，以及由此导致的意识丧失，是由于人与人之间的沟通中断造成的。远低于脑电图和功能磁共振成像分辨率极限的小神经元网络水平的神经元。我们研究麻醉剂对完整的、活的神经网络内相互通讯的影响，神经元分辨率。我们使用线虫，这种生物具有最简单、最容易处理的神经元结构已知这种麻醉是可诱导的。使用光片显微镜，结合固定和钙- 在神经元启动子下表达的敏感荧光团，以及我们定制的超级计算工具链图像分析和信号提取，我们基本上跟踪和捕获整个神经系统的活动并检查其在不同水平的麻醉暴露下的行为，标准化为使用的可比水平人体手术。使用双光子成像，我们能够在小鼠和在清醒和麻醉状态下提取体感皮层选定区域的活动。我们将使用线虫中固定神经元荧光团的差异表达系统，以允许精确的在光片成像下识别单个神经元。与秀丽隐杆线虫连接组结合，我们将确定麻醉状态与意识状态下的神经元通路，麻醉药如何改变化学和电突触连接来诱导这些状态，神经元连接的变化允许麻醉状态恢复到意识状态，从而描绘出麻醉的机制老年人的临床术后认知功能障碍和年轻人的神经发育障碍。我们将把我们的成像和分析技术扩展到脊椎动物斑马鱼，在脊椎动物斑马鱼中建立系统发育桥梁麻醉剂的作用从简单的生物到人类。我们将证明神经元的这些变化活动与人类脑电图中观察到的麻醉的总体统计特征一致。