Georgios Kafetzis

S-cone-specific circuitry in the outer plexiform layer of a cone-dominant mammal | PNAS In the vertebrate retina, short wavelength-sensitive S-cones and their downstream interneurons play unique roles in both image forming and non-imag...

Extremely proud to share our publication on S-cone circuitry in the ground squirrel, newly available this week in PNAS. We've been staring at these reconstructions for a long time, and I'm excited for others to see the results. 1/n

www.pnas.org/doi/10.1073/...

Ending my #FluorescenceFriday with this beautiful avian retina image depicting the beautiful stratification in the avian eyes.
This is where complexity meets art.
#retina #avian #bird #plexiformlayer

Just gonna put this here for now
www.science.org/doi/10.1126/...
bsky.app/profile/jlst...

Happy to share Jialin's first publication. She did a great job exploring the transition to land in animals. Co-supervised by the great Jordi Paps and me and in collaboration with Davide Pisani and @phil-donoghue.bsky.social

Jaxley: differentiable simulation enables large-scale training of detailed biophysical models of neural dynamics - Nature Methods Jaxley is a versatile platform for biophysical modeling in neuroscience. It allows efficiently simulating large-scale biophysical models on CPUs, GPUs and TPUs. Model parameters can be optimized with ...

I am super happy to share that our project on training biophysical models with Jaxley is now published in Nature Methods: www.nature.com/articles/s41...

Single-nucleus profiling highlights the all-brain echinoderm nervous system A sea urchin is a head with a brain-like organization and a vertebrate-type retinal signature.

Our study, just published in #ScienceAdvances and funded by @hfspo.bsky.social, explores the post metamorphic cell composition of the sea urchin juvenile, revealing that its body is head-like. Long considered brainless creatures, they’re all brain instead!
www.science.org/doi/10.1126/...

We’re hiring! Join the Sivyer Lab at The University of Sydney as a Postdoctoral Research Fellow in Neurodegeneration within the Snow Vision Accelerator, a $50M initiative tackling glaucoma and optic nerve disease. iPSCs, electrophysiology, drug discovery, and gene therapy.

Zebrafish use spectral information to suppress the visual background Vertebrate eyes first evolved in water, where spectral content rapidly fades with distance. Zebrafish exploit this loss by antagonizing cone signals to suppress the background, pointing to distance es...

Excited to share our paper now published in Cell!
'Zebrafish use spectral information to suppress the visual background'

Huge thanks to @neurofishh.bsky.social & @teuler.bsky.social

@cellpress.bsky.social @cp-cell.bsky.social

👇🏻
www.cell.com/cell/fulltex...

Now out in Cell! Congratulations to all involved, especially
@chiarafornetto.bsky.social

For a breakdown, see the bluetorial from when we posted the preprint: bsky.app/profile/neur...

Funding: @erc.europa.eu @wellcometrust.bsky.social @ukri.org @leverhulme.ac.uk @thelisterinstitute.bsky.social

The evolutionary origins of synaptic proteins and their changing roles in different organisms across evolution Nature Reviews Neuroscience - Recent studies have shed further light on the evolutionary origins of chemical synapses, In this Review, Colgren and Burkhardt explore how ancient proteins were...

First neurons didn’t appear overnight. We trace their roots to ancient secretory cells - showing how lifestyle & behavior shaped the evolution of first synapses.🧠🌊 #Evolution #Neuroscience

Our latest in @natrevneuro.nature.com
Link: rdcu.be/eMX3E

@jeffcolgren.bsky.social @msarscentre.bsky.social

Did transposable elements shape brain evolution — and if so, which ones, and in which cell states and lineages? Led by @tyamadat.bsky.social, we explored this question in cerebellum development using sequence-based deep learning models!
www.biorxiv.org/content/10.1...

Vision scientist Teresa Puthussery receives MacArthur ‘genius’ award - Berkeley News Puthussery’s discoveries about the retina are paving the way for new treatments for eye disease and vision loss

Teresa Puthussery, a UC Berkeley vision scientist whose insights into the retina could one day help those with vision loss regain their sight, has been named a 2025 MacArthur “genius” Fellow. news.berkeley.edu/2025/10/08/v...

Comparative single-cell multiomic analysis reveals evolutionarily conserved and species-specific cellular mechanisms mediating natural retinal aging. Biological age is a major risk factor in the development of common degenerative retinal diseases such as age-related macular degeneration and glaucoma. To systematically characterize molecular mechani...

Our latest manuscript is out, and this one tackles the problem of cellular aging in the retina, using comparative multiomic analysis of zebrafish, mouse, and humans. What led us to work on aging after studying development and regeneration? Explainer follows./1
www.biorxiv.org/content/10.1...

#FluorescenceFriday
#Seahorse retina stained with #GNB3 (green) + #DAPI (cyan). GNB3 labels cone photoreceptors + ON #bipolarcells, tracing pathways from outer to inner retina. Amazing to see conserved visual #circuits in this non-traditional model

Hm, above PMID is misdirecting, sorry. Was referring to "A comment on the origin of the vertebrate eye" by P. Satir

does not work currently. Please see Fig3 and corresponding section in our manuscript too😊
2/2

Different homologies between amphi. and vert. photosensitive structures have been suggested over the decades (e.g. PMID 11135183 and refs), but in amphi. there's no evidence for both ciliary and rhabdomeric components in a single structure. As such, a 1-to-1 w/ either retina or pineal likely..
1/2

Although urochordates are closer to vertebrates and can illuminate many questions on evolution (e.g. PMID 39443803), they have followed quite wild trajectories (e.g. PMID 25008364) and likely retain only rudimentary photoreceptive clusters.. no co-presence of rhabd.-ciliary, so hard to homologize

Hi, thanks so much for your (spot on!) comments and your interest in the field! 😊 In the manuscript, we do touch on cephalochordates and urochordates, albeit not extensively. Let me answer to your comments below separately:

Extremely grateful to @wellcometrust.bsky.social @vetenskapsradet.bsky.social @erc.europa.eu @hfspo.bsky.social @ukri.org @leverhulme.ac.uk @thelisterinstitute.bsky.social for their generous support of our eye evolution endeavours 👁️🦗🐋

So the retina wasn’t built de novo.

Instead, it is likely rooted in an ancestrally median, already complex eye — lateralized & rewired to solve early chordate sensory challenges.

More here:
www.biorxiv.org/content/10.1...
and curious what you think!

8/8

..with a huge payoff, in gradual steps:
✅Choice of right depth
✅Body Posture
✅Visually - guided locomotion, eventually

7/n

Because ambient light is messy — especially underwater.🌊

By shifting photon-detecting circuits sideways, you tune them to visual light gradients → disentangling confounding variables..

6/n

But why lateralize an already complex median eye? 🤔

5/n

But what if the sequence is backwards?

We argue that
bipolar cells were there 𝑒𝑎𝑟𝑙𝑦 — integral parts of parallel
microcircuits in a median eye.

And strikingly,
already in two flavors: 𝐎𝐅𝐅 and 𝐑𝐨𝐝-𝐎𝐍!

4/n

The glue? Bipolar cells.

Long seen as a late innovation — the key step from proto-retina ➡️ modern retina that boosted complexity & computation.

3/n

Most bilaterians keep photoreceptor types separate.
But vertebrate eyes are a mash-up:

🪡Ciliary (rods & cones) and
💈Rhabdomeric (ganglion, amacrine, horizontal)
…all packed into a multilayered circuit.

2/n

a black and white dog is sitting on a couch with its tongue sticking out . ALT: a black and white dog is sitting on a couch with its tongue sticking out .

👁️The retina — strikingly conserved across vertebrates, but an oddity among bilaterians!

So how did it evolve?

With @mikebok.bsky.social, @neurofishh.bsky.social and @denilsson.bsky.social, we argue that retinal complexity may 𝑝𝑟𝑒𝑑𝑎𝑡𝑒 𝑡ℎ𝑒 𝑒𝑦𝑒 𝑖𝑡𝑠𝑒𝑙𝑓.

www.biorxiv.org/content/10.1...
1/n

Huge congratulations Idoia!! 🎉🦈