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bioRxiv · 10.1101/2020.09.19.304675

Dual GRIN lens two-photon endoscopy for high-speed volumetric and deep brain imaging

Chien, Y.-F.·Lin, J.-Y.·Yeh, P.-T.·Hsu, K.-J.·Tsai, Y.-H.·Chen, S.-K.·Chu, S.-W.
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Abstract

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.

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Chien, Y.-F., Lin, J.-Y., Yeh, P.-T., Hsu, K.-J., Tsai, Y.-H., Chen, S.-K., Chu, S.-W.. 2020-09-20. Dual GRIN lens two-photon endoscopy for high-speed volumetric and deep brain imaging. https://doi.org/10.1101/2020.09.19.304675

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