I use a combination of experimental and computational approaches to investigate the ways in which zebrafish and chick retinas process visual information. On the experimental side, I use multielectrode arrays (MEAs) to record the activity of large populations of retinal ganglion cells in response to a variety of spectrally-appropriate visual stimuli. Computationally, I use a variety of techniques, including spike sorting, dimensionality reduction, clustering and spike-triggered analysis techniques.
[3] Seifert, M., Roberts, P. A., Kafetzis, G., Osorio, D., Baden, T., 2023. Birds multiplex spectral and temporal visual information via retinal On- and Off-channels. Nat. Commun., 14:5308 (19 pages). DOI (bioRxiv) (Data & Code)
This is the first large-scale survey of retinal ganglion cell functions in an avian retina. We discovered that, rather than using functionally opposite pairs of retinal output channels (the mammalian approach), chicks encode the polarity, timing, and spectral composition of visual stimuli in a highly correlated manner: fast achromatic information is encoded by Off-circuits, and slow chromatic information overwhelmingly by On-circuits. Further, we found that most retinal output channels combine On- and Off-circuits to simultaneously encode, or multiplex, both achromatic and chromatic information.
[2] Wang, X., Roberts, P.A., Yoshimatsu, T., Lagnado, L., Baden, T., 2023. Amacrine cells differentially balance zebrafish colour circuits in the central and peripheral retina. Cell Rep., 42(2):112055 (22 pages). DOI (bioRxiv) (Data)
We imaged light-driven signals from the axon terminals of retinal bipolar cells in the presence and pharmacological absence of inhibition from amacrine cells in larval zebrafish. It was found that complex interactions within the inner retina that underlie greyscale visual processing tasks are intricately balanced via the On-channel so as to make no notable alteration in the pre-existing population representation of colour information.
[1] Zhou, M., Bear, J., Roberts, P.A., Janiak, F.K., Semmelhack, J., Yoshimatsu, T., Baden, T., 2020. Zebrafish Retinal Ganglion Cells Asymmetrically Encode Spectral and Temporal Information across Visual Space. Curr. Biol., 30(15): 2927-2942. DOI (bioRxiv) (Data & Code)
We charted the functional diversity of retinal ganglion cells in larval zebrafish. The study revealed substantial regionalization, including a UV dominance in the acute zone, and the presence of a pervasive, spectrally opponent slow blue-Off system.
Paul Roberts - Mathematical Biologist 