Visual cortex is not merely a passive recipient of retinal inputs. It is also responsive to other sensory modalities, particularly audition. While auditory signals have been shown to penetrate early visual cortices, the mechanisms driving these responses remain poorly understood.
To examine how audition shapes vision, we used functional MRI to investigate whether audiovisual interactions modulate the gain of responses in human early visual cortices. Specifically, we measured voxel-wise contrast-response functions (CRF), while participants viewed horizontally drifting gratings paired with auditory motion that was directionally congruent or incongruent with the visual motion, or stationary. We show that congruent audiovisual motion enhances voxel-wise contrast sensitivity whereas incongruent motion reduces it, manifesting as a robust contrast gain modulation across areas V1–V3.
This direction-selective enhancement is nicely captured by a divisive normalization model incorporating auditory-driven feedback modulation. Our findings provide compelling evidence for cross-modal interactions at early stages of visual processing, driven by contrast gain modulation –a bidirectional modulation in sensitivity that maintains the balance between local excitatory and inhibitory activity. Together, these results reveal that audiovisual interactions can alter a cornerstone property of vision, highlighting the dynamic role of early visual cortex in multisensory processing.
We thank the members of the Ling Lab for providing helpful feedback and comments on this work, and for their assistance in MRI data collection. This work was supported by the National Research Foundation of Korea (NRF) Grant RS-2024-00407838 to M. Park and by the National Institutes of Health (NIH) Grant EY028163 to S.
Psychological and Brain Sciences, Boston University, Boston, MA, USA Center for System Neuroscience, Boston University, Boston, MA, USA The authors declare no competing interests. Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material.
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