Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus;
Neurotechnology Center, University of Colorado Anschutz Medical Campus.
J Vis Exp. 2024 Sep 20(211). doi: 10.3791/67039.
Mice navigate an odor plume with a complex spatiotemporal structure in the dark to find the source of odorants. This article describes a protocol to monitor behavior and record Ca transients in dorsal CA1 stratum pyramidale neurons in the hippocampus (dCA1) in mice navigating an odor plume in a 50 cm x 50 cm x 25 cm odor arena. An epifluorescence miniscope focused through a gradient-index (GRIN) lens imaged Ca transients in dCA1 neurons expressing the calcium sensor GCaMP6f in Thy1-GCaMP6f mice. The paper describes the behavioral protocol to train the mice to perform this odor plume navigation task in an automated odor arena. The methods include a step-by-step procedure for the surgery for GRIN lens implantation and baseplate placement for imaging GCaMP6f in CA1. The article provides information on real-time tracking of the mouse position to automate the start of the trials and delivery of a water reward. In addition, the protocol includes information on using an interface board to synchronize metadata describing the automation of the odor navigation task and frame times for the miniscope and a digital camera tracking mouse position. Moreover, the methods delineate the pipeline used to process GCaMP6f fluorescence movies by motion correction using the NorMCorre algorithm followed by identification of regions of interest with EXTRACT. Finally, the paper describes an artificial neural network approach to decode spatial paths from CA1 neural ensemble activity to predict mouse navigation of the odor plume.
老鼠在黑暗中利用复杂的时空结构来引导气味羽流，以找到气味的来源。本文描述了一种在 50cm×50cm×25cm 气味场中监测行为并记录在海马 CA1 背侧锥体神经元（dCA1）中钙瞬变的方案，以监测在气味羽流中导航的小鼠。通过梯度折射率（GRIN）透镜聚焦的荧光显微镜对表达钙传感器 GCaMP6f 的 Thy1-GCaMP6f 小鼠的 dCA1 神经元中的钙瞬变进行成像。本文描述了训练小鼠在自动化气味场中执行此气味羽流导航任务的行为方案。该方法包括用于 GRIN 透镜植入和成像 CA1 中 GCaMP6f 的基板放置的手术的逐步过程。文章提供了有关实时跟踪小鼠位置的信息，以自动启动试验并提供水奖励。此外，该方案还包括有关使用接口板同步描述气味导航任务自动化和显微镜以及数字摄像头跟踪鼠标位置的帧数的元数据的信息。此外，该方法描述了用于使用 NorMCorre 算法进行运动校正来处理 GCaMP6f 荧光电影的流水线，然后使用 EXTRACT 识别感兴趣区域。最后，本文描述了一种人工神经网络方法，用于从 CA1 神经元群体活动解码空间路径，以预测老鼠对气味羽流的导航。
