RESEARCH Pattern forming mechanisms of color vision Zily Burstein1, David D. Reid1, Peter J. Thomas2, and Jack D. Cowan3 1Department of Physics, University of Chicago, Chicago, IL, USA 2Department of Mathematics, Applied Mathematics, and Statistics; Department of Biology; Department of Cognitive Science, Case Western Reserve University, Cleveland, OH, USA 3Department of Mathematics, University of Chicago, Chicago, IL, USA Keywords: Color vision, V1, Pattern formation, Turing mechanism ABSTRACT While our understanding of the way single neurons process chromatic stimuli in the early visual pathway has advanced significantly in recent years, we do not yet know how these cellsinteract to form stable representations of hue. Drawing on physiological studies, we offer adynamical model of how the primary visual cortex tunes for color, hinged on intracortical interactions and emergent network effects. After detailing the evolution of network activity through analytical and numerical approaches, we discuss the effects of the model 's cortical parameters on the selectivity of the tuning curves. In particular, we explore the role of the model 's thresholding nonlinearity in enhancing hue selectivity by expanding the region of stability, allowing for the precise encoding of chromatic stimuli in early vision. Finally, in theabsence of a stimulus, the model is capable of explaining hallucinatory color perception via a Turing-like mechanism of biological pattern formation. AUTHOR SUMMARY We present a model of color processing in which intracortical neuronal dynamics within thevisual cortex serve as the substrate for hue perception. Our analytical and numerical treatments of the emergent behavior seek to characterize the population dynamics underlying chromaticprocessing within the visual cortex, as well the roles of the various cortical parameters in determining the selectivity of the steady-state network response. We show that the system is self-organizing, capable of encoding stable representations of hue regardless of the stimulusstrength, and generating spontaneous color hallucinations in the absence of any input. INTRODUCTION Our experience of color begins in the early visual pathway, where, from the moment lightstrikes the retina, cone-specific neuronal responses set off the mechanisms by which the pho-tons'chromatic information is converted to the hues we ultimately see. While color vision scientists agree that the single-cell processing of chromatic stimuli occurs along the two inde-pendent cone-opponent L-M and S-(L+M) pathways ( Conway, Eskew, Martin, & Stockman, 2018 ;Kaiser & Boynton, 1996 ), there is yet no consensus as to how and where the divergent signals are synthesized to encode hue. To complicate matters, cone-opponency, observed in electrophysiological recordings of single neurons ( Shapley & Hawken, 2011 ), is often con-founded with hue-opponency, a phenomenon first theorized by Ewald Hering in the 19than open access journal Citation: Burstein, Z., Reid, D. D., Thomas, P. J., & Cowan, J. D. (2023). Pattern forming mechanisms of color vision. Network Neuroscience,7(2), 679-711. https://doi. org/10. 1162/netn_a _00294 DOI: https://doi. org/10. 1162/netn_a_00294 Received: 19 August 2022 Accepted: 17 November 2022 Competing Interests: The authors have declared that no competing interests exist. Corresponding Author: Zily Burstein ceburst@gmail. com Handling Editor: Gustavo Deco Copyright: © 2023 Massachusetts Institute of Technology Published under a Creative Commons Attribution 4. 0 International (CC BY 4. 0) license The MIT Press Downloaded from http://direct. mit. edu/netn/article-pdf/7/2/679/2118501/netn_a_00294. pdf by guest on 09 August 2024 