Optical properties of adult Drosophila brains in one-, two-, and three-photon microscopy

Kuo-Jen Hsu; Yen-Yin Lin; Ann-Shyn Chiang; Shi-Wei Chu

doi:10.1364/BOE.10.001627

Optical properties of adult Drosophila brains in one-, two-, and three-photon microscopy

Biomed Opt Express. 2019 Mar 5;10(4):1627-1637. doi: 10.1364/BOE.10.001627. eCollection 2019 Apr 1.

Authors

Kuo-Jen Hsu^{1

2}, Yen-Yin Lin^{2

3}, Ann-Shyn Chiang^{2

4

5

6

7}, Shi-Wei Chu^{1

8

9}

Affiliations

¹ Department of Physics, National Taiwan University, Taipei 10617, Taiwan.
² Brain Research Center, National Tsing Hua University, Hsinchu 30013, Taiwan.
³ [email protected].
⁴ Institute of Systems Neuroscience, National Tsing Hua University, Hsinchu 30013, Taiwan.
⁵ Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung 80780, Taiwan.
⁶ Kavli Institute for Brain and Mind, University of California at San Diego, La Jolla, CA 92093-0526, USA.
⁷ [email protected].
⁸ Molecular Imaging Center, National Taiwan University, Taipei 10617, Taiwan.
⁹ [email protected].

Abstract

Drosophila is widely used in connectome studies due to its small brain size, sophisticated genetic tools, and the most complete single-neuron-based anatomical brain map. Surprisingly, even the brain thickness is only 200-μm, common Ti:sapphire-based two-photon excitation cannot penetrate, possibly due to light aberration/scattering of trachea. Here we quantitatively characterized scattering and light distortion of trachea-filled tissues, and found that trachea-induced light distortion dominates at long wavelength by comparing one-photon (488-nm), two-photon (920-nm), and three-photon (1300-nm) excitations. Whole-Drosophila-brain imaging is achieved by reducing tracheal light aberration/scattering via brain-degassing or long-wavelength excitation at 1300-nm. Our work paves the way toward constructing whole-brain connectome in a living Drosophila.