Photoacoustic Microscopy of the Awake Mouse Brain

项目摘要 神经科学中的一个长期存在的技术挑战是神经系统的高分辨率功能和分子成像。 唤醒老鼠的大脑这种需要是明显和紧迫的，因为麻醉可以显着减少整体的 大脑活动并改变多种形式的大脑动力学。麻醉的深刻影响可能会混淆 传统显微镜的读数，这需要麻醉动物的准备，因此施加 对基本神经科学发现的解释和翻译的重大限制。此外，无能 对清醒的大脑进行成像，与麻醉的大脑进行直接比较， 在检查全身麻醉在进展中的重要而难以捉摸的作用方面， 多种危及生命的脑部疾病（例如，缺血性中风和阿尔茨海默病，这是主要的 在美国死亡和残疾的原因）。为应对这一挑战，最近的努力扩大了 荧光显微镜的范围到清醒的大脑。当分子成像技术进步的时候 并迅速扩大了我们对行为背后的神经活动的理解，高分辨率的功能性 共同进化的血流动力学的成像福尔斯落在后面。该项目旨在连接日益增长的技术 通过开发第一种用于功能成像的光声显微镜（PAM）仪器， 在清醒小鼠中以高时空分辨率观察脑血流动力学和代谢。前所未有的 所提出的唤醒大脑PAM的速度（1 MHz A线速率），通过宽场的创新设计实现 光-机混合扫描和MHz重复率双波长拉曼激光器，将超过 现有的多参数PAM的两个数量级，并将使时空可视化的 大脑对神经刺激和疾病发作的功能和代谢反应， 麻醉剂。同一PAM的统计、谱和相关分析的互补算法 数据集将通过实现同步和全面的量化来进一步推动技术的发展 血红蛋白的总浓度和氧饱和度、血流和灌注以及代谢供应 微观层面的需求。这一技术创新将在以下领域开辟新的令人兴奋的机会： 基础和转化神经科学，包括缺血性脑损伤中麻醉神经保护的机制研究 在这个项目中提出的中风。反过来，这项中风研究将提供一个理想的环境，以评估 在临床上重要的脑部疾病的背景下唤醒大脑MHz-PAM，并为未来的研究铺平道路 神经血管耦合和神经调节的重要性。这些努力，共同拥有的潜力， 建立PAM作为大脑研究的新技术。

PROJECT SUMMARY A long-standing technical challenge in neuroscience is high-resolution functional and molecular imaging of the awake mouse brain. The need is evident and pressing, because anesthesia can significantly reduce the overall brain activity and alter multiple forms of brain dynamics. The profound effects of anesthesia may confound the readouts of conventional microscopies, which require preparations of anesthetized animals, and thus impose significant limitations on the interpretation and translation of basic neuroscience findings. Moreover, incapable of imaging the awake brain for direct comparison with the anesthetized counterpart, conventional microscopies are of very limited utility in examining the important yet elusive roles of general anesthesia in the progression of multiple life-threatening brain disorders (e.g., ischemic stroke and Alzheimer's disease, which are the leading causes of death and disability in the United States). In addressing this challenge, recent efforts have extended the scope of fluorescence microscopy to the awake brain. While this molecular imaging technology advances and rapidly expands our understanding of the neural activities underlying behavior, high-resolution functional imaging of the coevolving hemodynamics falls far behind. This project aims to bridge the increasing technology gap by developing a first-of-a-kind photoacoustic microscopy (PAM) instrumentation for functional imaging of cerebral hemodynamics and metabolism at high spatiotemporal resolution in awake mice. The unprecedented speed of the proposed awake-brain PAM (1 MHz A-line rate), enabled by the innovative designs of wide-field optical-mechanical hybrid scan and MHz-repetition-rate dual-wavelength Raman laser, will exceed that of the existing multi-parametric PAM by two orders of magnitude and will enable spatiotemporal visualization of the functional and metabolic responses of the brain to neural stimulations and disease onsets without the influence of anesthesia. The complementary algorithms for statistical, spectral and correlation analysis of the same PAM dataset will further push the technology envelope by enabling simultaneous and comprehensive quantification of the total concentration and oxygen saturation of hemoglobin, blood flow and perfusion, and metabolic supply and demand at the microscopic level. This technology innovation will open up new and exciting opportunities in basic and translational neuroscience, including the mechanistic study of anesthetic neuroprotection in ischemic stroke proposed in this project. In turn, this stroke study will provide an ideal setting to assess the potential of awake-brain MHz-PAM in the context of a clinically important brain disease and pave the way for future studies of neurovascular coupling and neuromodulation in the awake brain. These efforts, together, hold the potential to establish PAM as a new enabling technology in brain research.