Eonsys releases video of a simulated fly, running on the connectome (scanned brain) of a real fly
A digital fly brain with 125,000 neurons now controls a physics-simulated body, closing the perception-action loop.
Eon Systems PBC has crossed a major threshold in neuroscience and AI by demonstrating the world's first embodied whole-brain emulation. The company integrated its computational model of an entire fruit fly brain—built from the FlyWire connectome and containing over 125,000 neurons and 50 million synapses—with a physically simulated fly body in the MuJoCo environment. For the first time, sensory input flows into this digitally reconstructed biological brain, activity propagates through its complete neural circuitry, and the resulting motor commands drive a simulated body, closing the sensorimotor loop.
This achievement is a qualitative leap beyond prior work, which either modeled brains without bodies or animated bodies without connectome-derived brains. Projects like DeepMind's RL-controlled fly or OpenWorm's C. elegans simulation (with only ~302 neurons) lacked this full integration of a scanned biological connectome with physics. The emulated fly brain, which previously predicted motor behavior with 95% accuracy in a disembodied state, now generates multiple distinct behaviors through its own circuit dynamics within a simulated world.
The implications are profound for both basic science and the long-term goal of whole-brain emulation. Eon's mission is to scale this technology, currently amassing data to attempt a digital emulation of a mouse brain—a vastly more complex system with roughly 70 million neurons. The research combines expansion microscopy for ultra-detailed neural mapping with thousands of hours of functional imaging to capture live network activity. Successfully closing the perception-action loop in a fly provides a critical proof-of-concept and technical blueprint for understanding and eventually emulating more complex brains, potentially including humans.
- First-ever integration of a complete biological connectome (125k neurons, 50M synapses) with a physics-simulated body, closing the sensorimotor loop.
- Generates multiple distinct, naturalistic behaviors through the emulated brain's own circuit dynamics, unlike prior RL-controlled simulations.
- Serves as a critical proof-of-concept for Eon's roadmap to emulate a mouse brain (70M neurons) and lay groundwork for human-scale emulation.
Why It Matters
This provides the first blueprint for creating truly sentient digital beings by directly emulating biological intelligence, not just approximating it with AI.