2025-11-03 サセックス大学
<関連情報>
- https://www.sussex.ac.uk/research/full-news-list?id=69414
- https://www.cell.com/cell/fulltext/S0092-8674(25)01138-9
- https://www.nature.com/articles/s41559-023-02291-7
- https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3002422
ゼブラフィッシュはスペクトル情報を利用して視覚的な背景を抑制します Zebrafish use spectral information to suppress the visual background
Chiara Fornetto ∙ Thomas Euler ∙ Tom Baden
Cell Published:November 3, 2025
DOI:https://doi.org/10.1016/j.cell.2025.10.009
Graphical abstract
Highlights
- Zebrafish use fading spectral content in water to suppress visual background
- They do this by contrasting, not summing, inputs from distinct ancestral cone types
- Vertebrate cone diversity may reflect ancestrally aquatic “non-color” functions
- Mammalian cone loss may reflect rapid terrestrialization, not nocturnal ancestry
Summary
Vision first evolved in the water, where the spectral content of light informs about viewing distance. However, whether and how aquatic visual systems exploit this “fact of physics” remains unknown. Here, we show that zebrafish use “color” information to suppress responses to the visual background. For this, zebrafish divide their intact ancestral cone complement into two opposing systems: PR1/4 (“red/UV cones”) versus PR2/3 (“green/blue cones”). Of these, the achromatic PR1 and PR4, which are retained in mammals, are necessary and sufficient for vision. By contrast, the color-opponent PR2 and PR3, which are lost in mammals, are neither necessary nor sufficient for vision. Instead, they form an “auxiliary” system that spectrally suppresses the “core” drive from PR1 and PR4. Our insights challenge the long-held notion that vertebrate cone diversity primarily serves color vision and further hint at terrestrialization, not nocturnalization, as the leading driver for visual circuit reorganization in mammals.
視覚行動の基礎としての祖先光受容体の多様性 Ancestral photoreceptor diversity as the basis of visual behaviour
Tom Baden
Nature Ecology & Evolution Published:22 January 2024
DOI:https://doi.org/10.1038/s41559-023-02291-7
Abstract
Animal colour vision is based on comparing signals from different photoreceptors. It is generally assumed that processing different spectral types of photoreceptor mainly serves colour vision. Here I propose instead that photoreceptors are parallel feature channels that differentially support visual-motor programmes like motion vision behaviours, prey capture and predator evasion. Colour vision may have emerged as a secondary benefit of these circuits, which originally helped aquatic vertebrates to visually navigate and segment their underwater world. Specifically, I suggest that ancestral vertebrate vision was built around three main systems, including a high-resolution general purpose greyscale system based on ancestral red cones and rods to mediate visual body stabilization and navigation, a high-sensitivity specialized foreground system based on ancestral ultraviolet cones to mediate threat detection and prey capture, and a net-suppressive system based on ancestral green and blue cones for regulating red/rod and ultraviolet circuits. This ancestral strategy probably still underpins vision today, and different vertebrate lineages have since adapted their original photoreceptor circuits to suit their diverse visual ecologies.
水から陸へ:空気中での視覚のための光受容回路の進化 From water to land: Evolution of photoreceptor circuits for vision in air
Tom Baden
PLOS Biology Published: January 22, 2024
DOI:https://doi.org/10.1371/journal.pbio.3002422
Abstract
When vertebrates first conquered the land, they encountered a visual world that was radically distinct from that of their aquatic ancestors. Fish exploit the strong wavelength-dependent interactions of light with water by differentially feeding the signals from up to 5 spectral photoreceptor types into distinct behavioural programmes. However, above the water the same spectral rules do not apply, and this called for an update to visual circuit strategies. Early tetrapods soon evolved the double cone, a still poorly understood pair of new photoreceptors that brought the “ancestral terrestrial” complement from 5 to 7. Subsequent nonmammalian lineages differentially adapted this highly parallelised retinal input strategy for their diverse visual ecologies. By contrast, mammals shed most ancestral photoreceptors and converged on an input strategy that is exceptionally general. In eutherian mammals including in humans, parallelisation emerges gradually as the visual signal traverses the layers of the retina and into the brain.
