Emil Olsson¹ (emilolsson94@gmail.com), Michael Epstein^2,3, Juneau Wang³, Karen Tian³, Brian Maniscalco¹, Jennifer Motzer³, Angela Shen¹, Minh Nguyen¹, Meera Sriram¹, Sydney Liu¹, Olenka Graham Castaneda¹, Maggie Zhang¹, Yuzheng Wu¹, Diana Gamboa³, Richard Brown⁴, Victor A. F. Lamme⁵, Hakwan Lau^6,7, Biyu J. He⁸, Jan W. Brascamp⁹, Ned Block^10,11, David Chalmers^10,11, Rachel Denison³, Megan Peters^{1,12,13,14,15}; ¹Department of Cognitive Sciences, University of California Irvine, ²Center for Brain Imaging, New York University, ³Department of Psychological & Brain Sciences, Boston University, ⁴Department of Humanities, LaGuardia Community College; The Graduate Center, City University of New York, ⁵Department of Psychology, University of Amsterdam, Amsterdam, ⁶Department of Biomedical Engineering and Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, ⁷RIKEN Center for Brain Science, ⁸New York University Grossman School of Medicine, ⁹Department of Psychology, Michigan State University, ¹⁰Department of Philosophy & Center for Neural Science, ¹¹Department of Psychology, New York University, ¹²Department of Logic & Philosophy of Science, University of California, ¹³Center for the Neurobiology of Learning & Memory, University of California, ¹⁴Center for Theoretical Behavioral Sciences, University of California, ¹⁵Program in Brain, Mind, & Consciousness, Canadian Institute for Advanced Research

Recurrent processing in early visual cortex underlies figure-ground segregation and has been proposed as a neural correlate of visual awareness. Human fMRI studies have demonstrated figure-ground modulation in early visual cortex, but how this modulation varies with stimulus strength and across visual areas V1-V3 is not well characterized. Here, we measure figure-ground modulation across human V1-V3 using carefully controlled stimuli. We collected fMRI data from 27 participants across two independent sites (BU n=15, UCI n=12). Using an event-related design, participants viewed briefly-presented (250 ms) texture-defined figures at five stimulus strength levels, behaviorally calibrated per participant. Critically, the stimuli control for low-level confounds, with matched luminance across strength levels and elimination of T-junctions at figure edges. Using preregistered behavioral and analytic pipelines with pRF mapping and a spatial localizer, we identified voxels in V1-V3 responsive to figure locations and computed figure-ground modulation (response to figure-present minus figure-absent). Voxels were grouped as “figure-positive” (enhanced response to figure presence) or “figure-negative” (suppressed response) based on this modulation. Across V1-V3, roughly half of the figure-responsive voxels showed figure-positive modulation and half showed figure-negative modulation, a ratio that was consistent across visual areas and robust to different classification criteria. We examined how figure-ground modulation varied as a function of stimulus strength and across the visual hierarchy. In both figure-positive and figure-negative voxels, figure-ground modulation responses remained stably present across areas V1-V3 (with numerically largest responses in V1), and increased modestly with stimulus strength, suggesting that figure-ground segregation involves coordinated and stable excitatory and inhibitory processes. This characterization of distinct figure-positive and figure-negative response populations, and their consistency across visual areas and stimulus strengths, sets the stage for future studies testing the functional role of figure-ground modulation in visual processing and experience.

Acknowledgements: Acknowledgements: Templeton World Charity Foundation 0567 to BH, JB, NB, DC, MP, and RD, startup funding from the University of California Irvine and support from the Canadian Institute of Advanced Research to MP, startup funding from Boston University to RD, and BU UROP funding to DG.