Washington University in Saint Louis, Department of Biomedical Engineering, Saint Louis, Missouri, United States, United States.
California Institute of Technology, Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, Pasadena, California, United States, United States.
J Biomed Opt. 2022 Sep;27(9). doi: 10.1117/1.JBO.27.9.096004.
Optical imaging of responses in fluorescently labeled neurons has progressed significantly in recent years. However, there is still a need to monitor neural activities at divergent spatial scales and at depths beyond the optical diffusion limit.
To meet these needs, we aim to develop multiscale photoacoustic tomography (PAT) to image neural activities across spatial scales with a genetically encoded calcium indicator GCaMP.
First, using photoacoustic microscopy, we show that depth-resolved GCaMP signals can be monitored in vivo from a fly brain in response to odor stimulation without depth scanning and even with the cuticle intact. In vivo monitoring of GCaMP signals was also demonstrated in mouse brains. Next, using photoacoustic computed tomography, we imaged neural responses of a mouse brain slice at depths beyond the optical diffusion limit.
We provide the first unambiguous demonstration that multiscale PAT can be used to record neural activities in transgenic flies and mice with select neurons expressing GCaMP.
Our results indicate that the combination of multiscale PAT and fluorescent neural activity indicators provides a methodology for imaging targeted neurons at various scales.
近年来，荧光标记神经元反应的光学成像技术取得了重大进展。然而，仍然需要在发散的空间尺度和超出光扩散限制的深度监测神经活动。
为了满足这些需求，我们旨在开发多尺度光声断层扫描（PAT），以使用遗传编码钙指示剂 GCaMP 对跨空间尺度的神经活动进行成像。
首先，我们使用光声显微镜表明，可以在不进行深度扫描的情况下，甚至在表皮完整的情况下，从苍蝇大脑中以体内方式监测到深度分辨的 GCaMP 信号，以响应气味刺激。我们还在小鼠大脑中进行了体内监测 GCaMP 信号的演示。接下来，我们使用光声计算机断层扫描，在超出光扩散限制的深度对小鼠脑片的神经反应进行成像。
我们首次明确证明，多尺度 PAT 可用于记录表达 GCaMP 的转基因果蝇和小鼠中选定神经元的神经活动。
我们的结果表明，多尺度 PAT 与荧光神经活动指示剂的结合为在各种尺度上成像靶向神经元提供了一种方法。
