Fly Brain HubWhat is a fly brain, and what can it do now?
The "fly brain" in these projects is a wiring diagram: a table of which neuron connects to which, and how many synapses lie between them. A wiring diagram does not run on its own.
The measured part: wiring diagrams
166,000+MaleCNS v1.0An adult male's whole central nervous system (2026-09)139,255FlyWire (FAFB v783)An adult female whole brain, proofread3,016Larval connectomeFirst complete map of an entire insect brain (2023)
The chosen part: what the wiring leaves out
- Excitatory or inhibitory?
- Inferred from neurotransmitter predictions
- How strong is a synapse?
- Most projects use the raw synapse count as the weight
- Time constants, thresholds
- Chosen per project, usually the Shiu et al. 2024 model
Machine learning decides weights by training. Here they are replaced by counts off a microscope. Are weights learned, or measured?
What it can and cannot do
Now possible
- It runs faster than real timeOne second of fly life in 0.29 s on one GPU
- It has a body and a worldFar enough to drive servos on a real hexapod robot
- The wiring computes94% on handwritten digits, wiring never changed
- Circuits can be verifiedOne reflex reduced to 173 NAND gates, checked exhaustively
Still not possible
- It does not learnIts author writes that the fly mostly walks into walls
- It is not whole-brain emulationIts README opens by saying exactly that
- Headline count is not the simulated count166,700 in the title, 12,260 actually stepped
- Rewiring is still unansweredOne project published the measured reasons why
What arrived is not a mind. It is a shared testbed.
What gets listed here
Only what could be confirmed from the primary source is listed. Two things count for a lot: whether controls were run, and whether the failures were written down.Editorial policy / Submit a project
A note on numbers: projects using the same MaleCNS release quote 24.5 to 25.6 million synapses. They count different things, so check which release and which quantity a figure refers to.