Very excited about our new preprint, led by @gkafetzis.bsky.social /w @mikebok.bsky.social & @denilsson.bsky.social. We suggest that the vertebrate 'duplex' retina emerged from interconnecting two ancient median-eye microcircuits. Say goodbye to the 'simplex' retina - it probably never existed!

Our proposal for a ‘universal’ nomenclature for rod and cone types based on their evolutionary lineages that will equally apply to all vertebrate species is now out! Have a look and please consider adopting the system :)

Seeking input: A standardized nomenclature
for the rods and cones of the vertebrate retina

A number of us have been working on a proposal to bring various disconnected naming systems for the vertebrate rods and cones across species into alignment. The basic proposal looks like this:

For today's #fluorescenceFriday, a transgenic Danionella cerebrum, the world's (second) smallest vertebrate (yep, "stout infantfish" are smaller, but no one has made them glow yet!). Picci by our very own @xinwei-wang.bsky.social

Birds, reptiles and amphibians all still have it. What is the difference? Looks like the ancestors of mammals were much quicker to fully move to the land where the ancestral green/blue suppression was probably a bad thing, so they lost it.

This is key: In the water, spectrally broad ‘white’ light only exists in the foreground. In the background, spectral interactions of light with water mean that the image becomes increasingly monochromatic (i.e. green/blue).

The antagonistic input architecture to the fish eye can in fact already be seen without substantial manipulations: Fish have a massive ‘white bias’. Show them spectrally broad stimuli and their brain lights up like a Xmas tree. Show them ‘non-white stimuli’, and you get a greatly subdued response

By contrast, if we kill red or UV cones, vision is not fine.

In fact, if we kill green and blue cones, fish vision is fine. More than fine, in fact. It becomes less variable, because the green/blue system hangs in a delicate and mutually antagonistic balance.

To do so, their outer retina is fundamentally set up to contrast the signals from the colour opponent green and blue cones (which are lost in mammals) from those of red and UV cones (which are retained).

Nope! Not ancestrally. We show how that (zebra)fish, which retain the ‘original 4’ cones, ‘use colour information’ to auto-subtract the underwater background before the visual signal ever gets to the brain.

Rods give greyscale vision, but cones are for colour, right?

New @bioRxiv #preprint with @chiarafornetto.bsky.social and @teuler.bsky.social : www.biorxiv.org/content/10.1...

a GCaMP tadpole for #fluorescenceFriday as an introductory hello on BlueSky :) Transgenic by Lora Sweeney (ISTA), and picci by our postdoc Michi Forsthofer