11/ We cannot say for sure, but VL1 projection neurons likely gate plasticity through inhibition, shouting at Kenyon cells, yet keeping learning locked.

(Maybe for the best: the VL1 projection neurons detect pyrrolidine, a real stinker. Better steer clear than to learn it as good! 😷)

10/ We biologists love a clean, simple rule, right?

But then came the VL1 projection neurons...

VL1 projection neurons break the rule — despite weak connectivity, they drive large Kenyon cell responses yet fail to support learning.

Why, oh, WHY? 😫

#uglydatawreckingourbeautifultheoriesagain

9/ This connectivity–function relationship sets the stage for learning: odors that activate many Kenyon cells are easy to learn.

Those that barely activate a few?

Basically unlearnable. 🤡

8/ Likewise, odors that activate highly connected projection neurons, like fruit odors, drive broad Kenyon cell responses.

Odors that activate poorly connected projection neurons, like those made by toxic microbes, not so much.

🍇🍎 Fruit odors get the hand.

🦠👾 Toxic microbe odors get the foot.

7/ Structure matters.

Highly connected projection neurons broadcast their signal loud and clear, reaching and activating many Kenyon cells.

Weakly connected ones fade into the noise.

What the brain builds, the brain listens to.

6/ The wiring is mostly random — as predicted by theory — but some projection neurons connect far more often than chance.

As if the dice were loaded. 🎲🎲🎲

5/ When looking at the connections between projection neurons and Kenyon cells we found clear biases.

Some projection neurons connect up to fifteen times more often than others.

Some occupied expansive stretches of connectivity estate, while others were left with just a narrow strip.

4/ The mushroom body is built like an expansion layer: a small number of projection neurons feed into thousands of Kenyon cells.

Classic theories predict that wiring is random, giving every odor an equal shot at being learned. 💯

But ugly data got in the way of these beautiful theories... 🧌

3/ Why?

Learning centers like the mushroom body face an existential dilemma: they need enough coding capacity to represent as many stimuli as possible while still prioritizing cues that matter most for survival.

How does the mushroom body balance this tension between capacity and selectivity?

1/ Hello Drosophila-philists and braino-maniacs! 👋🪰🧠🧪

The Caron lab has a new preprint, and it is about 🥁🥁🥁 democracy!

Neuro-democracy, to be precise. So: drop EVERYTHING and listen up — a 🧶!

www.biorxiv.org/content/10.1...