Doodle Fly

A fruit fly’s whole brain plays a jumping game

bAt the controls

Its front legs press ◀ or ▶ when its steering neurons fire. Drag to look around.

cFrom the eyes to the buttons straight

dSpikes of identified neurons

eThe whole brain

All 138,639 neurons at their real positions, seen from behind. A dot darkens when it spikes.

How it works

Scientists sliced a fruit fly’s brain into 7,000 layers, imaged each one with an electron microscope and traced every neuron and synapse. That wiring diagram, the FlyWire connectome, is public. Doodle Fly loads all of it into your browser and simulates every neuron spike by spike, with the leaky integrate-and-fire model of Shiu et al. (2024).

The game finds the platform the fly can still reach; its direction becomes input to the LC10a neurons on that side, small-object detectors a fly uses to chase a target. The signal travels through the brain on its own. Six types of descending neurons, the brain’s cables to the body, decide the move: more spikes on the right than on the left means right. Nobody taught it: the left/right decision comes out of the wiring.

PartStatus
Who connects to whom, synapse counts, signFlyWire v783, unchanged
Neuron dynamics and parametersShiu et al. 2024, unchanged
Target on the left → left descending neuronsemerges from the wiring
Sugar → proboscis, looming → giant fibreemerges from the wiring
Which platform to aim for, input drive, spikes → buttonshand-made interfaces

Connectome: Dorkenwald et al. 2024, Schlegel et al. 2024 (CC BY-NC 4.0). Brain model: Shiu et al. 2024. Code: MIT.
Doodle Fly
Loading a whole fly brain · 138,639 neurons · ~34 MB
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