Two Glowing Yellow Markers Represent the Giant Fibers — the Escape Command Neurons

A digital fly walks across windows, grooms, sleeps, and flees the cursor using the same neural circuits as a real insect. The fly's brain window displays 23,210 real neuron soma positions from FlyWire v783, with live spikes flashing at actual neuron locations. Two glowing yellow markers represent the Giant Fibers — the escape command neurons.

Users can click any brain region to stimulate it, triggering real network responses: clicking the Giant Fiber causes escape, DNg11 triggers grooming, and DNa01/02 on one side causes turning. The body is procedural since FlyWire provides only brain wiring, not body geometry. It features a tripod gait, visible wing-beat, altitude-scaled flight, grooming, and sleep postures.

The loop closes body-to-brain: gait rhythm feeds the circuit's real ascending proprioceptive neurons in phase with the legs, and fast cursor motion stimulates sensory wind partners. Requirements include macOS 13+ and Xcode Command Line Tools (Swift 5.9+). No permissions or entitlements are needed — everything the fly senses (cursor, window frames, clicks-as-taps, thermal state) is permission-free. A fly icon appears in the menu bar for quitting.