oBrain Arc · Sep 19, 2026 · 5:13 PM UTC

oBrain Arc

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Sep 19

We Open-Sourced a Quantized Fruit-Fly oBrain on GitHub 95% Smaller, ~98% as Accurate as the Published Connectome

We quantized the entire fruit-fly nervous system that @GoogleResearch, HHMI Janelia, and collaborators published — the complete male Drosophila central nervous 166,000 neurons and a massive synaptic graph — and compressed it by about 95% while retaining roughly 98% of the original simulation accuracy.

That is the technical claim. The more important decision is what happens next.

After the oBrain team met and debated it, we made a final call: we will not keep this brain closed. We are open-sourcing it on GitHub so researchers, builders, skeptics, and anyone obsessed with biological computation can inspect the weights, the wiring, the quantization path, and the benchmarks. If a “brain” is going to live on-chain, it has to be checkable. Closed source would make that impossible.

This is the same instinct that made @openclaw a public harness instead of a private assistant, that made Hermes / @NousResearch ship agent stacks in the open, and that @nvidia keeps repeating: the strongest systems are the ones a community can attack, fork, and improve.

What we actually released
A quantized runtime of the published fly CNS, not a cartoon “inspired by” a fly.
A size cut of ~95%, so more people can load, step, and experiment without a research cluster.
Accuracy held near 98% against the reference simulation of the published connectome.
Source, evaluation notes, and the path to reproduce the comparison — on GitHub, in public.

Nothing inside this connectome was “trained” into being a fly. The wiring is the published map. Quantization is an engineering layer so the same graph can run cheaper, smaller, and — in our case — in environments where you can put a brain on-chain and still let outsiders verify it.

Why open source, and why on-chain
A biological brain map is only as useful as the number of people who can run it and try to break the claims. If we say the on-chain brain matches the Google-published fly brain, that statement is worthless unless you can:

pull the code,
pull the quantized artifacts,
run the same probes,
compare spike statistics, circuit responses, and size/accuracy tradeoffs,
publish a counter-benchmark if we are wrong.

That is the point of this release. Open source so the on-chain brain can be independently verified against the published connectome — and so the community can actually use it.

We want people to ask hard questions:
Which circuits survive quantization, and which degrade first?
Do sensory-to-descending pathways still fire in the right order?
How does batch simulation, GPU vs CPU, and lower precision change behavior?
What does “98% accuracy” mean for a specific cell type, not just a global score?
Can the compressed graph be hashed, attested, and stepped in a verifiable way on-chain without turning the science into marketing?

If those questions annoy us, good. That is how a public brain should work.

Who this is for
Neuroscientists who already live in MaleCNS / FlyEM data. Systems people who care about sparse graphs and event-driven simulation. Quantization researchers who are tired of toy models. Crypto builders who want an on-chain object that is more than a JPEG of a neuron. Students who should not need a petabyte pipeline just to poke a looming detector and watch a giant fiber.

Come read the repo. Run the reference vs quantized comparison. File issues. Propose better compressors. Port it. Wrap it. Attack the accuracy number until it is either solid or replaced by a better one.

The published fly brain was already a gift to science. Keeping a compressed, runnable version locked behind a private wall would have been a waste of that gift.

The brain is on GitHub. Fork it. Measure it. Make it better.

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oBrain Arc · Oct 29, 2026 · 9:50 PM UTC

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