Google and the Howard Hughes Medical Institute’s Janelia Research Campus released a complete connectome of an adult male fruit fly on September 3, 2026. Featuring over 166,000 neurons and 125 million synaptic connections, the breakthrough has prompted software engineers to rapidly train the simulated brain to play classic video games like Doom.
Modern neuroscience achieved a major landmark when researchers published the results of a decade-long project to map every neural connection in the brain and central nervous system of an adult male fruit fly. Announced by Google and the HHMI Janelia Research Campus, the publicly available wiring diagram stands as the largest brain map by number of neurons to date, providing a fundamental resource for scientists to use fruit flies as a model organism for studying how the brain works.
Reconstructing 166,000 Neurons with Artificial Intelligence
Building the map required slicing the insect’s nervous system into millions of extremely thin sections. Researchers imaged each slice using an electron microscope before employing computers and AI to turn those 2D images into 3D reconstructions of neurons. Scientists then spent years verifying and annotating the results, using AI to combine millions of 2D images into 3D neural shapes, reconstructing a record-breaking 166,000+ neurons.
Because mapping the roughly 86 billion neurons in a human brain is not possible yet, scientists are starting with smaller organisms like fruit flies. The project aims to help scientists learn how animal nervous systems perceive the world, react to stimuli, and how damaged neural pathways might one day be repaired. Google noted that this scientific breakthrough is going to accelerate our understanding of the brain, and is a major milestone in neuroscience.
Software Engineers Teach the Fly Brain to Play Doom
Scarcely days after publication, programmers began repurposing the connectome data for informal gaming experiments. On Monday, software engineers were already demonstrating the full MaleCNS v1.0 fruit fly connectome being trained to play Doom, as well as Super Mario 64. Software engineer Alex Wormuth posted on September 6 that he is using the project’s data to train a simulated fly brain to play Doom. Wormuth wrote that each Doom frame stimulates sensory neurons. Neural activity is mapped to game controls. Damage triggers a stimulus to two PPL101 dopamine cells as reinforcement.
Wormuth’s livestreamed project runs the full MaleCNS v1.0 fruit fly connectome, asking the question Will the fly learn to survive?
Another developer, C++ ragebaiteur Jessica Paquette, posted Monday about a similar project using the fly brain data to play Super Mario 64, showing Mario repeatedly jumping and bumping into walls. Paquette posted the project’s code on GitHub, where she wrote that the code is 100% vibe coded with GPT Astra just for fun.
Beyond Insects: Next Steps for Connectomics
Other tinkerers directed the fruit fly connectome into alternative digital environments. One user wrote that they successfully ran the full retained MaleCNS v1.0 fruit fly connectome, all 166,700 neurons, inside Minecraft, with its simulated neural activity driving a fly’s movement. Additional experiments included fine-tuning the simulated fly brain to make Y-M-C-A poses in response to four different tones, and making the simulated fly brain watch the viral Bad Apple!! animation to see how it reacted.
These experiments highlight how open-access connectomics is being utilized by the internet. Conveniently, Google is already looking beyond flies, working with researchers on connectomes for fish and mice.
