Microendoscopic calcium imaging of the primary visual cortex of behaving macaques

• Main Authors: Mineki Oguchi, Jiang Jiasen, Toshihide W. Yoshioka, Yasuhiro R. Tanaka, Kenichi Inoue, Masahiko Takada, Takefumi Kikusui, Kensaku Nomoto, Masamichi Sakagami
• Format: Article
• Language: English
• Published: Nature Publishing Group 2021-08-01
• Series: Scientific Reports
• Online Access: https://doi.org/10.1038/s41598-021-96532-z

Abstract In vivo calcium imaging with genetically encoded indicators has recently been applied to macaque brains to monitor neural activities from a large population of cells simultaneously. Microendoscopic calcium imaging combined with implantable gradient index lenses captures neural activities from deep brain areas with a compact and convenient setup; however, this has been limited to rodents and marmosets. Here, we developed miniature fluorescent microscopy to image neural activities from the primary visual cortex of behaving macaques. We found tens of clear fluorescent signals from three of the six brain hemispheres. A subset of these neurons showed clear retinotopy and orientation tuning. Moreover, we successfully decoded the stimulus orientation and tracked the cells across days. These results indicate that microendoscopic calcium imaging is feasible and reasonable for investigating neural circuits in the macaque brain by monitoring fluorescent signals from a large number of neurons.