Pan-neuronal functional imaging and anesthesia

摘要 挥发性麻醉药产生全身麻醉的所有阶段，包括昏迷、健忘、止痛 和肌肉放松。一旦进入这种生理状态，体验、记忆和身体 对极度疼痛的反应都丧失了。然而，我们仍然不能机械地理解这种状态是如何 麻醉是在神经系统内产生的，因此复杂的精神活动在退化时被消融。 生理学被保存下来。到目前为止，研究基本上沿着两条道路进行：要么是毛利率 使用fMRI和EEG测量整个大脑区域的神经元活动(这基本上是 受分辨率限制)，或在分子水平上分析以寻找挥发性麻醉剂的特定受体 (它在很大程度上已经崩溃)。令人惊讶的是，患者仍然可以迅速从这种状态中恢复过来， 经验性的临床实践已经降低了麻醉的风险，以至于它现在是一种基本的和 普遍接受的现代医学实践的一部分。幸运的是，使用新的荧光显微镜， 我们现在能够实时、活体和同时以分辨率成像神经元活动 捕捉单个神经元和复杂神经元网络的整个群体的活动。在这项研究中， 我们将这项技术应用于线虫，我们能够捕捉到整个神经系统的活动， 以及我们捕捉体感皮质区域的小鼠。为了弄清……的影响 临床麻醉完成后，从最简单、最易驯服的生物开始将是有意义的 已知麻醉是可诱导的神经元结构。C.elegans提供了一种简单的、映射良好的 神经系统(302个神经元)，很好地描述了行为范例和顺从的遗传学。此外，C. Elgans是麻醉学中公认的模型系统，并显示出不同的大体阶段。 在麻醉状态下的行为类似于人类。使用细胞内钙离子的荧光指示剂GCaMP 在神经元启动子下转基因表达的浓度，我们可以捕获多个 光学的、非侵入性的和平行的神经元。我们的实验系统将允许我们测量 了解单个神经元内的大规模神经元回路是如何在离散的微妙变化中 神经动力学导致整个神经系统水平的严重但可逆的功能缺陷 这会导致止痛和身体上的平静。我们的研究将确定挥发性麻醉剂对 从单个神经元到整个神经系统，神经元的复杂性不断增加。当前的技术在 哺乳动物系统的规模仅限于大脑的小部分。我们将开始互补 小鼠躯体感觉皮层的成像实验将启动我们的发现的翻译 和技术应用于哺乳动物系统。

Abstract Volatile anesthetics produce all stages of general anesthesia including unconsciousness, amnesia, analgesia and muscle relaxation. Once placed into this physiological state, the experience, memory and physical response to excruciating pain are all lost. However, we still do not understand mechanistically how this state of anesthesia is produced within neuronal systems such that complex mental activity is ablated while vestigial physiology is preserved. To date, research has proceeded along essentially two tracks: either the gross measurement of neuronal activity in entire regions of the brain using fMRI and EEG (which are fundamentally limited by resolution), or analysis at the molecular level looking for specific receptors for the volatile anesthetics (which has largely foundered). Astonishingly, patients can nevertheless be promptly retrieved from this state, and empirical clinical practice has reduced the risk of anesthesia to the extent that it is now an essential and universally accepted part of the modern practice of medicine. Fortunately, using novel fluorescent microscopy, we are now able to image neuronal activity in real-time, in vivo, and at resolutions capable of simultaneously capturing the activity of individual neurons and entire populations of complex neuronal networks. In this study, we apply this technique to C. elegans in which we are able to capture the activity of the entire nervous system, and to the mouse in which we capture regions of the somatosensory cortex. To discern the effect by which clinical anesthesia is achieved, it would make sense to begin with the creature with the simplest, most tractable neuronal architecture in which anesthesia is known to be inducible. C. elegans offers a simple well-mapped nervous system (302 neurons), well characterized behavioral paradigms and amenable genetics. Moreover C. elegans is well established as a model system in anesthesiology, and displays distinct stages of gross behavior under anesthesia similar to humans. Using GCaMP, a fluorescent indicator of intracellular calcium concentration expressed transgenically under a neuronal promoter, we can capture the activity of multiple neurons optically, non-invasively, and in parallel. Our experimental system will allow us to measure activity of the individual neurons within large-scale neuronal circuits to understand how subtle modifications in discrete neuronal dynamics lead to the gross but reversible functional defects at the level of the overall nervous system that result in analgesia and physical quiescence. Our study will define the effects of volatile anesthetics over increasing neuronal complexity from individual neurons to the entire nervous system. Current technology within mammalian systems is limited in scale to small subsections of the brain. We will begin complementary imaging experiments in the somatosensory cortex of the mouse that will initiate the translation of our findings and techniques to mammalian systems.