Space-division multiplexing optical coherence tomography for large-scale, millisecond resolution imaging of neural activity

 描述基于发生在毫秒时间尺度上的快速固有光信号的变化(例如，光散射和相位的变化)来对神经元活动进行成像有很大的兴趣。快速本征光信号与复折射率的变化有关 神经元膜附近的小体积变化，以响应与动作电位期间离子通量相关的快速渗透变化。光学相干层析成像(OCT)是一种新兴的生物医学成像技术，它可以提供微米级的空间分辨率和亚毫秒级的时间分辨率的无标签和深度分辨率的图像。OCT依靠检测内在的光学对比度，消除了潜在有毒的外源性造影剂或遗传编码指示剂的需要。OCT具有超过100分贝的灵敏度，使其能够检测与神经元活动相关的微弱散射变化。此外，OCT具有极好的相位灵敏度(&lt；1mlirad，对应于~100 pm的光路长度变化)，使其能够以超过10倍的信噪比检测与神经动作电位相关的纳米级膜位移。最近，我们团队开发了一种空分复用OCT(SDM-OCT)技术，它允许从多个样本位置进行并行和同步成像。在这个探索性项目中，我们计划评估使用高分辨率(&lt；3μm)和超高速(3.2M A扫描/S)SDM-OCT技术来成像和表征与活动相关的快速固有光信号变化，特别是相位变化的可行性。将使用体外大鼠2D神经培养和3D器官型海马培养进行验证实验，以将SDM-OCT成像的快速内在光信号变化与电生理刺激和神经活动记录相关联。由于每个垂直交叉 断层OCT图像将包含数百个神经元，利用空分复用技术可以同时记录来自数千个神经元的本征光学信号。如果成功，这种无标记成像技术可以成为一个强大的平台，同时研究网络中数千个神经元的行为，并有可能对基础脑研究产生重大影响。

 DESCRIPTION There is a great interest in imaging neuronal activity based on changes in fast intrinsic optical signals (e.g. changes in light scattering and phase) that occur on a millisecond timescale. Fast intrinsic optical signals are related to alteration in the complex refractive index and small volume changes near the neuron membrane, in response to the rapid osmotic changes associated with ion fluxes during action potentials. Optical coherence tomography (OCT) is an emerging biomedical imaging technology that provides label-free and depth-resolved images with micron-scale spatial resolution and sub-millisecond temporal resolution. OCT relies on detection of intrinsic optical contrast, eliminating the need for potentially toxic exogenous contrast agents or genetically- encoded indicators. OCT achieves over 100 dB sensitivity, enabling it to detect weak scattering changes associated with neuronal activity. In addition, OCT has extremely good phase sensitivity (<one millirad, corresponding to an optical path length change of ~100 pm), making it possible to detect nanometer-scale membrane displacement associated with neural action potentials with over 10x signal-to-noise ratio. Recently, our group developed a space-division multiplexing OCT (SDM-OCT) technology which allows parallel and synchronized imaging from multiple sample locations. In this exploratory program, we plan to evaluate the feasibility of using high resolution (<3 μm) and ultrahigh speed (3.2M A-scans/s) SDM-OCT technology to image and characterize activity-dependent fast intrinsic optical signal changes, especially phase changes. Validation experiments will be conducted using in vitro rat 2D neural cultures and 3D organotypic hippocampal cultures to correlate fast intrinsic optical signal changes imaged with SDM-OCT with electrophysiological stimulation and recording of neural activities. Since each vertical cross sectional OCT image will contain hundreds of neurons, intrinsic optical signals from thousands of neurons can be recorded simultaneously using the space-division multiplexing technology. If successful, this label-free imaging technology can become a powerful platform to investigate behavior of thousands of neurons in a network simultaneously, with the potential to significantly impact fundamental brain research.