A fly connectome that learned language
The public MaleCNS v1.0 connectome (167,565 neurons, 25.6M synapses), trained as a spiking language model, now back in a simulated body. Trained flies: Frozen fly, step 14580, Frozen fly, step 14260, Frozen fly, step 12040, Step 14580 + 8 neuron types (each lived 30 simulated days with its trained synapses frozen). Data notice: every run is saved to the dataset Quazim0t0/MaleCNS-fly-space-runs; that includes your messages and a 48x64 copy of any picture.
The trained brain lives through simulated days (sugar, bitter and other senses each day) and adapts with homeostatic synaptic scaling towards the original fly's activity levels. Pick which synapses may change.
What this is
The MaleCNS v1.0 connectome, used as released, is the recurrent core of a spiking language model. Its synapse strengths were trained on text (and later captions); its wiring and neurons are the fly's. Two trained flies are offered. Both are the version whose trained synapses are frozen while the rest of the fly adapted for 30 simulated days, so each keeps its language and its feeding reflex:
- Frozen fly, step 14580: newest. Everything below plus a looped decoder, HRM refinement, MTP, document masking and 256-token text windows; trained with a neuron cut that skips the ~101,000 cells that never fire. Language CE on the test sentences 2.76.
- Frozen fly, step 14260: Looped decoder, HRM refinement, a JEPA objective on the brain's own state, a SmolLM2 judge whose verdicts were delivered as dopamine (with sugar or bitter taste), and a dopamine reward for using the picture. CE 2.79.
- Frozen fly, step 12040: the earlier vision + language fly (dopamine reward for looking). CE 3.18.
Each was converted to the MaleCNS edge table and back before being loaded; the rebuilt brain is identical.
Talk / pictures run the trained language model: text enters through the fly's non-visual sensory neurons, pictures through the photoreceptors of both eyes.
Sugar test and days run a separate whole-brain leaky integrate-and-fire model on the same synapses (after Shiu et al. 2024): taste neurons are driven at 150 Hz and the proboscis motor neuron MN9 is read. The sugar-like / bitter-like groups are labellar taste neuron types that excite / inhibit MN9 in the original wiring (MaleCNS carries no receptor labels).
Live as a fly: each day the fly experiences sugar, bitter and two sets of other senses, then every neuron scales its excitatory inputs towards its firing rate in the original connectome. Frozen keeps the language synapses fixed, bounded lets every synapse move within 0.5-2x, unbounded can run away.
Limits: spike rates in the fly model run high (compare brains, not absolute Hz); the language model is small and undertrained; captions reflect 48 x 64 images.