Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan.
Department of Health Sciences, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.
PLoS One. 2024 Sep 17;19(9):e0308573. doi: 10.1371/journal.pone.0308573. eCollection 2024.
Advances in fluorescence imaging technology have been crucial to the progress of neuroscience. Whether it was specific expression of indicator proteins, detection of neurotransmitters, or miniaturization of fluorescence microscopes, fluorescence imaging has improved upon electrophysiology, the gold standard for monitoring brain activity, and enabled novel methods to sense activity in the brain. Hence, we developed a lightweight and compact implantable CMOS-based lensless Ca2+ imaging device for freely moving transgenic G-CaMP mouse experiments. However, without a lens system, determination of regions of interest (ROI) has proven challenging. Localization of fluorescence activity and separation of signal from noise are difficult. In this study, we report an ROI selection method using a series of adaptive binarizations with a gaussian method and morphological image processing. The parameters for each operation such as the kernel size, sigma and footprint size were optimized. We then validated the utility of the algorithm with simulated data and freely moving nociception experiments using the lensless devices. The device was implanted in the dorsal raphe nucleus to observe pain-related brain activity following a formalin test to stimulate pain. We observed significant increases in fluorescence activity after formalin injection compared to the control group when using the ROI determination algorithm.
荧光成像技术的进步对神经科学的发展至关重要。无论是特定表达指示剂蛋白、检测神经递质，还是荧光显微镜的小型化，荧光成像技术都改进了电生理学——监测大脑活动的金标准——并使检测大脑活动的新方法成为可能。因此，我们开发了一种基于 CMOS 的轻量级、紧凑型无透镜 Ca2+成像设备，用于转基因 G-CaMP 小鼠的自由活动实验。然而，由于没有透镜系统，确定感兴趣区域 (ROI) 一直具有挑战性。荧光活性的定位和信号与噪声的分离都很困难。在这项研究中，我们报告了一种使用一系列具有高斯方法和形态图像处理的自适应二值化的 ROI 选择方法。针对每个操作（如核大小、标准差和足迹大小）优化了参数。然后，我们使用无透镜设备对模拟数据和自由移动的伤害感受实验进行了验证。该设备被植入背缝核，以观察福尔马林刺激引起疼痛后的与疼痛相关的大脑活动。与对照组相比，在使用 ROI 确定算法后，福尔马林注射后荧光活性显著增加。
