PT  - JOURNAL ARTICLE
AU  - Yu-Feng Chien
AU  - Jyun-Yi Lin
AU  - Po-Ting Yeh
AU  - Kuo-Jen Hsu
AU  - Yu-Hsuan Tsai
AU  - Shih-Kuo Chen
AU  - Shi-Wei Chu
TI  - Dual GRIN lens two-photon endoscopy for high-speed volumetric and deep brain imaging
AID  - 10.1101/2020.09.19.304675
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.09.19.304675
4099  - http://biorxiv.org/content/early/2020/09/20/2020.09.19.304675.short
4100  - http://biorxiv.org/content/early/2020/09/20/2020.09.19.304675.full
AB  - Studying neural connections and activities in vivo 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, current 2PM typically relies on slow axial scan for volumetric imaging, and the maximal penetration depth is only about 1 mm. Here, we demonstrate that by integrating two gradient-index (GRIN) lenses into 2PM, both penetration depth and volume-imaging rate can be significantly improved. Specifically, an 8-mm long GRIN lens allows imaging relay through a whole mouse brain, while a tunable acoustic gradient-index (TAG) lens provides sub-second volume rate via 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.Competing Interest StatementThe authors have declared no competing interest.