Baroux, R. | bioRxiv Science

bioRxiv2026

Retinal adaptive mechanisms confer selectivity to homogeneous objects in natural scenes

Adaptive mechanisms in sensory neurons are crucial to transmit information in different contexts. In the retina, it is assumed that their role is to normalize neuronal responses to input statistics like mean and variance. However, this role has mostly been characterized with simple, artificial stimuli, and remains unclear for natural stimuli. Here we show that during their response to natural scenes, adaptive mechanisms reshape the feature selectivity of ganglion cells, the retinal output. We recorded retinal ganglion cell responses to rapid sequences of natural images in mice. Including a bio-inspired adaptive mechanism in an artificial neural network model was necessary to predict cell responses to new sequences of natural images. This adaptive mechanism tuned specific cell types to selectively respond to homogeneous regions situated within cluttered visual surrounds, a feature suited for detecting threats. Adaptive mechanisms do not merely normalize responses but actively enable new feature selectivity in the early visual system.

neuroscience↗

bioRxiv2025

Accurate spatiotemporal retinal responses require a color intensity balance fine-tuned to natural conditions

Color vision is vital for animal survival, essential for foraging and predator detection. In mice, as in other mammals, color vision originates in the retina, where photoreceptor signals are processed by neural circuits. However, retinal responses to stimuli involving multiple colors are still not well understood. One possible explanation of this knowledge gap is that previous studies have not thoroughly examined how neuronal activity adapts to a 30 seconds to a few minutes timescale when exposed to multiple color sources. To address this, we systematically varied the UV-to-green light balance with a custom-built stimulator targeting mice opsins spectra while recording retinal ganglion cell responses across the dorso-ventral axis of the retina using multielectrode arrays. Responses to full-field chirp and checkerboard stimulations with alternating UV and green light revealed that more than one order of magnitude of intensity difference favoring green M-opsin over UV S-opsin is needed for a balanced reliability in retinal ganglion cell responses in the ventral retina. An incorrect balance, with slightly increased UV light, silenced responses to green illumination. To determine if these values are consistent with natural conditions, we analyzed isomerisation rates in the mouse retina across different times of the day. We found that the M- to S-opsin activation ratio remains constant through the mesopic-photopic range, and that our empirically determined values in the ventral retina align well with these natural conditions. These lie far from a simple equalization of M- and S-opsin isomerisation rates, which we found only balances ganglion cell responses in the dorsal retina. In conclusion, a finely tuned color intensity balance matching natural light spectrum is essential for accurately measuring both fast temporal responses and detailed spatial receptive fields in the ventral retina.

neuroscience↗