Chien Yu-Feng, Lin Jyun-Yi, Yeh Po-Ting, Hsu Kuo-Jen, Tsai Yu-Hsuan, Chen Shih-Kuo, Chu Shi-Wei
Department of Physics, National Taiwan University, Taipei 10617, Taiwan.
Department of Life Science, National Taiwan University, Taipei 10617, Taiwan.
Biomed Opt Express. 2020 Dec 8;12(1):162-172. doi: 10.1364/BOE.405738. eCollection 2021 Jan 1.
Studying neural connections and activities is fundamental to understanding brain functions. Given the cm-size brain and three-dimensional neural circuit dynamics, deep-tissue, high-speed volumetric imaging is highly desirable for brain study. With sub-micrometer spatial resolution, intrinsic optical sectioning, and deep-tissue penetration capability, two-photon microscopy (2PM) has found a niche in neuroscience. However, the current 2PM typically relies on a slow axial scan for volumetric imaging, and the maximal penetration depth is only about 1 mm. Here, we demonstrate that by integrating a gradient-index (GRIN) lens and a tunable acoustic GRIN (TAG) lens into 2PM, both penetration depth and volume-imaging rate can be significantly improved. Specifically, an ∼ 1-cm long GRIN lens allows imaging relay from any target region of a mouse brain, while a TAG lens provides a sub-second volume rate via a 100 kHz ∼ 1 MHz axial scan. This technique enables the study of calcium dynamics in cm-deep brain regions with sub-cellular and sub-second spatiotemporal resolution, paving the way for interrogating deep-brain functional connectome.
研究神经连接和活动是理解大脑功能的基础。鉴于大脑尺寸为厘米级且具有三维神经回路动力学，对于大脑研究而言，深部组织的高速体积成像非常必要。双光子显微镜（2PM）具有亚微米级空间分辨率、固有光学切片能力和深部组织穿透能力，在神经科学领域占据了一席之地。然而，当前的2PM通常依靠缓慢的轴向扫描进行体积成像，最大穿透深度仅约1毫米。在此，我们证明通过将梯度折射率（GRIN）透镜和可调谐声学GRIN（TAG）透镜集成到2PM中，穿透深度和体积成像速率均可显著提高。具体而言，一个约1厘米长的GRIN透镜可实现对小鼠大脑任何目标区域的成像中继，而一个TAG透镜通过100 kHz至1 MHz的轴向扫描可提供亚秒级的体积成像速率。该技术能够以亚细胞和亚秒级的时空分辨率研究厘米级深部脑区的钙动力学，为探究深部脑功能连接组铺平了道路。
