Screenshot saying “Nanosymposium- Photoreceptors and Retinal Circuitry. Sunday Nov 16 1-2:45pm Room 32A”
At #SfN2025? Come check out the Photoreceptors & Retinal Circuits nanosymposium at 1! I’ve heard all the cool kids will be there and the chair is an absolute rockstar.
In this #TopicalReview, Victor Calbiague-Garcia of sorbonne-universite.fr et al. review current knowledge of #amacrine cells & discuss how emerging approaches are advancing our understanding of their function 👁️ 🐁
🔗 Read it here: physoc.onlinelibrary.wiley.com/doi/10.1113/...
12/n Massive thanks to everyone involved in this project, specially the co-first authors giulia, francesco, and Thomas, @oliviermarre.bsky.social and to our institute, institut de la vision 🙌
#Neuroscience #Retina #VisionScience
11/n This way, this inhibition “piggybacks” on existing circuits. Revealing that the retina doesn’t build new circuits for every computation — it repurposes existing ones, using limited wiring to perform multiple computations efficiently. ♻️
10/n Mechanistically, we propose that ON stimulation in the surround may trigger crossover inhibition that suppresses wide-field GABAergic amacrine cells—normally responsible for surround suppression—thereby disinhibiting distant OFF ganglion cells.
9/n Together, this shows that the RBC–AII pathway, long known for relaying rod signals in dim light, also contributes to surround modulation in OFF ganglion cells. 😲
8/n So we took it further — we hyperpolarized AII amacrines optogenetically.
When we did, the surround responses in OFF ganglion cells dropped significantly.
7/n Then we tested the role of inhibition:
Blocking glycinergic transmission reduced these responses.
And who’s glycinergic? The AII amacrine cells. 👀
6/n This setup let us directly stimulate individual rod bipolar cells while recording retinal output in real time.
Result? Activating single RBCs drove responses in OFF ganglion cells far beyond their receptive field center 💥
5/n So, to tackle this we combined:
✨ Optogenetics — to control specific neurons
✨ Two-photon holography — to activate single cells precisely
✨ Multi-electrode recordings — to monitor hundreds of ganglion cells simultaneously
4/n But proving this might be a bit tricky.
Classical pharmacology isn’t specific enough:
•Drugs like strychnine block all glycinergic cells.
•And rod activation can trigger multiple parallel circuits.
We needed something sharper. ⚡
3/n Our hunch: a circuit best known for rod vision — the rod bipolar (RBC) → AII amacrine pathway — might also shape these surround responses under brighter conditions. 🌙➡️💡
2/n Previous studies pointed to horizontal or amacrine cells, but we wondered if another pathway might be at play. 🔍
1/n In the retina, some OFF ganglion cells — which usually respond when light decreases — also respond to increases in light in their surround.
This is called an antagonistic surround modulation.
But… how does that happen? 👁️
🚨 New preprint out from our lab!
📄 The Rod Bipolar Cell Pathway Contributes to Surround Responses in OFF Retinal Ganglion Cells
👉 www.biorxiv.org/content/10.1...
If you’re curious about how the retina’s “middlemen” shape what we see, check out our review here:
👉 physoc.onlinelibrary.wiley.com/doi/10.1113/...
To help orient the field, we compiled key data in Tables 1 and 2—summarizing what's known about amacrine subtypes so far.
This includes their light responses, morphology, transcriptomic identity, synaptic partners, and potential roles in retinal computation.
Yet big questions remain.
Do amacrine cells act as independent circuit elements, each with a dedicated function?
Or are they interconnected within a broader recurrent inhibitory network that shapes visual output in a more dynamic way?
From genetic access and morphological reconstructions to light response profiling and circuit-level dissection, new tools are helping reveal how these neurons encode complex visual features—sometimes even across distinct dendritic compartments.
🚨 New review out in
@jphysiol.bsky.social
!
We're excited to see our review published, diving into the astonishing diversity of amacrine cells—inhibitory interneurons in the retina.
🔗 physoc.onlinelibrary.wiley.com/doi/10.1113/...
