Developers are using a fruit fly's neural connectome to simulate its brain activity in games, showcasing the potential of neuroscience data in virtual experiments #
Developers are turning a newly mapped fruit fly nervous system into a bizarre gaming experiment, using its simulated neural activity in Minecraft and Beat Saber before one programmer decided the digital insect deserved a peaceful 'fruit fly heaven'.
The projects are based on MaleCNS v1.0, a detailed connectome, essentially a wiring diagram, of an adult male fruit fly's brain and central nervous system.
MaleCNS v1.0 was publicly released in June and formally described in Cell in September. Researchers from Google Research, HHMI Janelia and other institutions reconstructed more than 166,000 neurons and roughly 125 million synaptic connections.
Google said artificial intelligence helped combine millions of two-dimensional images into detailed three-dimensional reconstructions. Developers wasted little time putting that biological map into virtual worlds.
166,700 Simulated Neurons Enter Minecraft #
Developer Evan Sinclair Smith created NeuroCraft Fly, an experimental Minecraft project that runs a retained MaleCNS network containing 166,700 simulated neurons and 25,582,938 directed connections.
Events inside Minecraft, including food, light, nearby creatures and attacks, are converted into inputs sent through the neural model. Activity from selected neurons is then mapped to hand-chosen readouts that influence scripted body programs and the virtual fly's movement.
In other words, the simulated network influences what the virtual fly does, but it is not simply a biological brain dropped into Minecraft.
Smith explicitly cautioned against interpreting the project as proof that a conscious fly had been recreated digitally. The connectome provides the wiring, while developers still decide how virtual sensory information enters the network and how neural activity becomes movement.
Then Someone Made the Fly Play Beat Saber #
The experiments became even stranger when developer Lyra Bubbles posted a viral clip declaring that 'the fly brain can play Beat Saber'.
Beat Saber normally requires players to slash approaching blocks with virtual blades in time with music. However, the demonstration came with an important qualification. The developer later explained that the fly model was not yet independently learning and playing the entire game from scratch.
Its motor system had been overfit to reproduce a recorded movement sequence, while work continued on connecting visual information and using reinforcement learning to develop its responses.
Other developers have also connected MaleCNS simulations to games including Doom and Super Mario 64. One Doom implementation feeds pixels into thousands of sensory inputs before mapping activity from selected descending neurons to turning, movement and firing.
'Fruit Fly Heaven' Offers an Escape #
Watching the simulated insect repeatedly subjected to virtual danger apparently became too much for another developer. X user Macroblock announced a gentler project after seeing programmers place the fly in what they jokingly called increasingly nightmarish situations.
The developer began building 'fruit fly heaven', an open environment filled with grass, trees and fruit where the simulated fly can simply move around and feed rather than dodge enemies or endlessly swing at Beat Saber blocks.
Despite the dystopian jokes, none of these projects demonstrates that a living or conscious fly is suffering inside a computer.
What they do show is how quickly a major neuroscience dataset can become an experimental playground: within days of the connectome's formal publication in Cell, programmers were already testing what its 166,000-plus simulated neurons might do inside video games.
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