Scientific Results

Colored visual stimuli evoke spectrally tuned neuronal responses across the central nervous system of zebrafish larvae

Year: 2020

Authors: Fornetto C., Tiso N., Pavone FS., Vanzi F.

Autors Affiliation: European Lab Nonlinear Spect LENS, Via Nello Carrara 1, I-50019 Sesto Fiorentino, FI, Italy;‎ Univ Padua, Dept Biol, Via Ugo Bassi 58b, I-35131 Padua, Italy
Show more [ 3 ]‎ Univ Florence, Dept Phys & Astron, Via G Sansone 1, I-50019 Sesto Fiorentino, FI, Italy
Show more [ 4 ]‎ CNR, Natl Res Council, Natl Inst Opt INO, Largo Enrico Fermi 6, I-50125 Florence, FI, Italy
Show more [ 5 ]‎ Univ Florence, Dept Biol, Via Madonna Piano 6, I-50019 Sesto Fiorentino, FI, Italy

Abstract: Background Visually guided behaviors such as optomotor and optokinetic responses, phototaxis, and prey capture are crucial for survival in zebrafish and become apparent after just a few days of development. Color vision, which in zebrafish is based on a spatially anisotropic tetrachromatic retina, provides an additional important component of world representation driving fundamental larval behaviors. However, little is known about the central nervous system (CNS) circuitry underlying color vision processing downstream of the retina, and its activity correlates with behavior. Here, we used the transparent larva of zebrafish to image CNS neurons and their activity in response to colored visual stimuli. Results To investigate the processing of chromatic information in the zebrafish larva brain, we mapped with cellular resolution, spectrally responsive neurons in the larva encephalon and spinal cord. We employed the genetically encoded calcium indicator GCaMP6s and two-photon microscopy to image the neuronal activity while performing visual stimulation with spectrally distinct stimuli at wavelengths matching the absorption peaks of the four zebrafish cone types. We observed the presence of a high number of wavelength-selective neurons not only in the optic tectum, but also in all other regions of the CNS, demonstrating that the circuitry involved in processing spectral information and producing color-selective responses extends to the whole CNS. Conclusions Our measurements provide a map of neurons involved in color-driven responses, revealing that spectral information spreads in all regions of the CNS. This suggests the underlying complexity of the circuits involved and opens the way to their detailed future investigation.

Journal/Review: BMC BIOLOGY

Volume: 18 (1)      Pages from: 172  to: 172

KeyWords: Color vision; Zebrafish; Calcium imaging
DOI: 10.1186/s12915-020-00903-3