Scientists Just Downloaded a Fly Brain Into a Computer! Or did they?

By ​Servi Bulu

​For any of us who have watched The Matrix, the possibility of uploading a conscious brain into a computer, despite still being quite uncanny, is also a familiar concept. Now, in an X post shared by Eon Systems CEO Michael Andregg, researchers claim to have not only emulated an entire fruit fly brain in a digital setting but also given it a body that the brain controls freely (Michael Andregg).

Artificial intelligence isn’t anything new to us at this point. However, this is a little different. The whole-brain emulation claimed by Michael Andregg is supposed to be exactly what it sounds like: it’s a near-exact replica of all ~125,000 neurons and 50 million connections of a fruit fly brain dropped into a virtual environment, “using the pre-existing FlyWire connectome, a Princeton-led effort to create a complete wiring diagram of a fruit fly brain”.
But this claim of “a real fly in a virtual environment” is a little complicated, receiving some pushback from the scientific community: after the post, other scientists in the field took notice, and not in a very positive way. “Extraordinary claims require extraordinary evidence, not just cool visuals,” claimed one scientist as a response (Michal Janusewski). Questions came fast: Did the simulation show known markers of working memory? How was the brain actually controlling the body without a modeled nerve cord? Where was the data, the peer review, the write-up?
Eon Systems did, in fact, end up publishing their results in a blog post titled “How the Eon Team Produced a Virtual Embodied Fly”, and explained their methodology. So, what did they actually build? 
By taking the preexisting components (the computational brain model mentioned above by Shiu et al (2024), and a virtual body model, NeuroMechFly by Wang-Chen et al. (2024)), Eon Systems connected them in a closed loop, which means that the sensory events in the virtual space, picked up by the body feed into the brain model, and selected outputs from the brain model control the body model (“How the Eon Team Produced a Virtual Embodied Fly”). The brain model follows a 4-step cycle, repeating every 15 milliseconds: (1) something happens in the environment, (2) the digital neurons pick up on the change and propagate activity, (3) the signals of a small, hand-picked set of neurons are read, and translated into high-level commands such as turn left, walk forward or backward, groom, feed. (3) The body moves according to these commands, and the whole cycle is repeated again. This does sound sophisticated, and it is, but it is not “a real fly in a digital environment”. In a real fly, thousands of neurons would handle the translation from intention into movement, but the model does not simulate them; instead, it informs the choice between a couple of predetermined options and lets the execution be handled by a pre-built machine, the body model, that does the actual walking.  
Even Eon Systems themselves address in their blog post that the activity displayed in the viral video is “somewhat decorative”. The thing that looks like a fly is not behaving that way because the brain is an actual fly’s brain, and the brain of a fly knows how to walk or groom like a fly. It’s because the body model is programmed to behave exactly like a fly when it receives the “walk” command.
The story and the video are ultimately less about a fly and more about the headline, at least that’s what it feels like when you dig a little deeper. The actual engineering work done by the team is real and interesting, but it also stands on the shoulders of decades of work that will never trend on social media or reach such a breadth of audience as this story has. Most people who saw the fly walking around will never read the blog post or see the backlash, but they will carry a sense that someone put an actual animal in a virtual environment, and it worked. Neuroscience is very easily sensationalized; people are curious about the vast possibilities associated with the brain’s mysterious nature, and scientists and communicators bear the responsibility of telling the correct story, even if it might turn out to be a little less exciting or less viral. 

References
1. “How the Eon Team Produced a Virtual Embodied Fly.” Eon.systems, 2024, eon.systems/updates/embodied-brain-emulation. Accessed 24 Apr. 2026.
2. Michael Andregg [@michaelandregg]. "We've uploaded a fruit fly. We took the  @FlyWireNews connectome of the fruit fly brain, applied a simple neuron model ( @Philip_Shiu Nature 2024) and used it to control a MuJoCo physics-simulated body, closing the loop from neural activation to action. A few things I want to say about what this means and where we're going at @eonsys." Twitter, Mar 8, 2026, https://x.com/michaelandregg/status/2030764512488677736.
3. Michal Janusewski [@michalj]. "Extraordinary claims require extraordinary evidence, not just cool visuals." Twitter, Mar 10, 2026, https://x.com/michalj/status/2031400471655506352.