[HN Gopher] How the Eon Team Produced a Virtual Embodied Fly
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How the Eon Team Produced a Virtual Embodied Fly
Author : LopRabbit
Score : 72 points
Date : 2026-03-15 23:44 UTC (2 days ago)
(HTM) web link (eon.systems)
(TXT) w3m dump (eon.systems)
| rustyhancock wrote:
| The piece I'm not quite understanding is. To what extent is this
| really simulating the brain accurately?
|
| It appears to behave accurately but it seems from reading the
| background which is largely above my head that those behaviours
| are in effect implementations not directly from data.
|
| I.e. a pattern in the neural simulation is interpreted as groom.
| And then a groom behaviour is in effect played back
|
| Walk pattern recognition is translated into walking (effectively
| this is a animation).
|
| Does it matter? I'm not sure but I think it's the difference
| between playing a running animation or running in QWOP
| bananzamba wrote:
| I had exactly the same question. In the linked tweet the CEO
| claims it's not an animation. But in the article they imply
| certain animations are played when a specific signal is
| detected.
|
| I think a full simulation without these precreated animations
| would be more convincing that they actually fully simulated a
| fly's behavior. It's very easy to make it look like real
| behavior using animations, videogames do exactly that.
| wzdd wrote:
| They've basically taken three separate models, one for fly
| vision, one for the fly brain, and one for the fly body, and
| bolted them together Frankenstein style.
|
| They've taken the connectome, which is a map of how neurons in
| the brain are connected to each other, and then created a fly
| brain using artificial spiking neurons connected together using
| that same connectome.
|
| So the neurons are not remotely accurate. The interesting point
| they're making is that even with these simplified neurons they
| still see plausible behaviours (i.e. simulate the presence of
| sugar by stimulating a gustatory neuron -> neurons associated
| with lowering the proboscis for feeding are triggered). So they
| make the case that a lot of information is encoded simply in
| the connectome.
|
| The body isn't connected up to the brain in the way we'd
| expect. "Input" comes from a completely separate neural network
| which they've trained to simulate appropriate CNS neurons, and
| output is looking at "descending" (efferent I guess) neurons in
| a very basic way. It's not completely playing an animation, but
| the level of connectivity is very low dimensional. It's not
| clear how much control they have, but for example I imagine
| they have a spiking threshold for the proboscis below which
| it's lowered and above which it's raised, which is sort of like
| you being able to stick your tongue completely out or pull it
| completely in but nothing else.
|
| So it's not especially bioplausible. The most interesting part
| is that leaky-integrate-and-fire connectome-based brain model
| which they're using, even though it is also very limited (for
| example, it doesn't learn).
|
| Demo looks very cool though. Much credit for being so explicit
| about what's going on in it in that post. And I was immediately
| filled with ideas about what they could do next to improve it,
| which to me is a signal of good research.
| zarzavat wrote:
| > The fly body is not currently driven by the full downstream
| motor hierarchy of the biological fly. Instead, we use a small
| number of descending outputs as a practical interface between
| the connectome model and the biomechanics
|
| > [...] Steering in our model is driven through the neurons
| DNa01 and DNa02 (Yang et al., 2024), which are implicated in
| turning. Forward velocity is modeled by activation of oDN1
|
| It seems that currently only WASD control is working. But even
| that is impressive! This is essentially an NPC driven by a real
| connectome.
| SayThatSh wrote:
| I saw a short clip on this project the other day and was
| thinking along the same lines! They animated the flies' mouth
| part (proboscis?) lowering and I was wondering if they were
| truly reading the motor commands for that from the brain.
| lambdaloop wrote:
| There is sooo much hype around this, when the Eon team did
| almost nothing new compared to the published research. (For
| context I did my PhD in a fly motor control lab and still
| follow this field. My colleagues are authors on the research
| papers Eon used.)
|
| I want to highlight some limitations of the current state of
| research as well, based on questions that many neuroscientists
| in this field are struggling with.
|
| - The movement of the legs is not modeled at a fine level, just
| whether fly is moving forward or turning. This is because we
| don't have great data on fly leg movements on all these
| situations, and ventral nerve connectome is still in progress
|
| - By the way the brain connectome still has a lot of errors and
| needs more proofreading. Also the identity of many
| neurotransmitters and synaptic strength of connections is
| unknown. Many are identified through our knowledge of fly
| genetics which won't translate to humans. In current research,
| scientists add some finetuning to match some behavior to
| account for those unknowns.
|
| - There's definitely fly behavior data at the level of making
| decisions, but not much at level of limb kinematics. Even where
| data is available, it's unclear how to evaluate the simulated
| fly against the data. How do you know you got it right?
|
| When I saw the Eon announcement, I was curious how they tackled
| these challenges. Seems like they didn't. It looks like they
| forked a few research repositories and vibe coded something to
| combine them.
|
| I'll give them props for the videos and marketing though, it's
| crazy to see so many people interested in this research field!!
| jmrko wrote:
| Have a look at this comment from Ken Hayworth, a highly respected
| scientist in the field, which I am copying here from a twitter
| post by him
| (https://x.com/KennethHayworth/status/2032604687212392562). I
| also just came back from the Cosyne 2026 conference, and the work
| was unfortunately not met with great enthusiasm, despite the
| media attention: My statement regarding the misleading EON
| Systems "fly upload" video:
|
| The hundreds of researchers who make up the Drosophila
| neuroscience community are making good progress toward eventually
| understanding how the intelligent behaviors of a fruit fly are
| produced by computations in its neural circuits. Obtaining the
| structural connectome of the fly brain and ventral nerve cord was
| a significant milestone in that quest, as was obtaining an
| estimate of neurotransmitter types for each cell type. What is
| currently most lacking is a catalog of the precise
| electrophysiological and molecular dynamics of each neuron and
| synapse type. Dozens of on-going electrophysiological, genetic,
| and behavioral experiments are beginning to fill in those
| details. But completing that task will likely take many years,
| possibly decades, of more research. At the end of that long road,
| I have no doubt, there will be a detailed paper, published in a
| high-quality journal with full details and carefully peer-
| reviewed, which will at long last make the true statement "we've
| uploaded a fruit fly". And that future paper will have a
| supplementary video much like the EON Systems one, showing a fly
| navigating a virtual environment. But, unlike the misleading EON
| Systems video, that future video will be real... all 100,000+
| neurons displaying dynamics that reflect those that would occur
| in the real fly engaged in the same sensory-motor behaviors. That
| paper will represent the crowning achievement of a successful
| Drosophila neuroscience field.
|
| What EON Systems' misleading video and claim has done today is to
| try to steal that future victory and take its valor for their
| own, all in the hopes of raising some cash from naive investors
| who think they might get to human uploads soon, and all while
| riding a tide of hype they generated in the gullible public. The
| result has been a wave of secondary reporting that grossly
| mischaracterizes the current state of neuroscience progress,
| implying that it is much further along than it currently is.
|
| As a member of the Drosophila research community, and as a long-
| term advocate of brain preservation for eventual mind uploading,
| I feel it is my responsibility to call out this reprehensible
| behavior. Neuroscience technology is progressing fast enough that
| we are now able to obtain structural connectomes of small
| organisms like the fruit fly. But neuroscience understanding is
| progressing much more slowly. True uploading, even for a fruit
| fly, is likely years to decades away. Even obtaining a mouse
| connectome seems likely to be a decade or more away. Human
| uploading is simply not on any reasonable research or investment
| timeline, unless such a timeline includes many decades of
| methodical basic neuroscience research. Of course, we can
| preserve human brains today using aldehyde fixatives as is done
| in all of today's connectomics studies. But we will not be able
| to upload a human brain for many decades, perhaps centuries to
| come.
|
| Please do not let today's real scientific progress in
| connectomics and brain preservation be drowned out by misleading
| hype.
|
| -Kenneth Hayworth
| mbbutler wrote:
| But Eon's tagline is "Solving brain emulation as an engineering
| sprint, not a decades-long research program"! How could they
| have ever gone wrong?
| zarzavat wrote:
| This seems petty. Basically he's annoyed that a commercial
| entity made a video based on published research rather than an
| academic group.
|
| As far as I can tell the blog post does a good job of citing
| sources - they go over and above what a commercial entity is
| required to disclose (I.e. nothing). No good deed goes
| unpunished.
|
| I thought the whole point of academia was to do research for
| the benefit of society. Research is published so that society
| can make use of it. Not to give academics "thunder".
|
| If you don't want anyone to read your papers there's a simple
| solution: don't publish them.
| throwaway3446 wrote:
| Look at it from Ken's perspective though. He's one of the few
| people who have moved this field forward by solving very hard
| problems over decades.
|
| Now a startup comes in and publishes a cool video that claims
| to solve a big chunk of what he wants to do / contribute to
| over the rest of his career, like "hey that was easy!".
|
| He says the video is very misleading, and that's just a fact.
|
| It's hard to see for someone outside of this how insulting
| that can feel to someone in his position, and that's why it
| can come across as petty.
|
| Also, your summary of his criticism isn't quite right, read
| it more carefully. It would apply equally if an academic
| group had done that. It's more a case of academic standards
| for communication meeting silicon valley bluster.
| causal wrote:
| Petty? He's accusing them of fraud, and if he's right then
| yeah we should all be disappointed in Eon's deceptive
| marketing.
|
| Fully simulating a drosophila has been a high goal for a very
| long time and great claims require great proof, but Eon has
| been stingy with the details (and no this blog post does not
| reveal much beyond chaining together lots of impressive
| sounding words).
|
| Imagine the skepticism on HN if someone declared they
| invented AGI. Similar level claim.
| pratelsingh wrote:
| good morning sir, great hustling, Mumbai style
| lproven wrote:
| I wrote this up for the Register, and while I am not a
| neuroscientist, I tried to explain this is just a combination of
| chunks of existing work...
|
| https://www.theregister.com/2026/03/16/digital_fruit_fly_bra...
| mschuster91 wrote:
| > and while I am not a neuroscientist, I tried to explain this
| is just a combination of chunks of existing work
|
| Which most complex technology is these days, even the most
| impactful. Docker is a fancy wrapper around Linux cgroups,
| Kubernetes combines that with etcd, and stuff like AWS EKS
| combines that with hypervisors (which I think were based on
| Linux KVM for a long time).
| logicprog wrote:
| I think the fact that it's chunks of exist and work plugged
| together is what makes it so impressive to me in the sense that
| it means that we're actually building somewhat reusable modular
| architecture for doing this that people can actually repeat and
| build on separately and so on. And thanks for the future, I
| think. Also, I have to say, excellent article.
| lproven wrote:
| Thanks very much indeed!
|
| There is a level where the criticisms of the neuroscientists
| are both entirely legitimate _and_ at the same time probably
| not really valid.
|
| Again, to go to an SF reference, the Australian hard-SF
| writer and mathematician Greg Egan has gone into this at some
| depth. I can't call which story to mind now, but he imagined
| a scenario in one of his where the tech is available to do a
| full whole-body in-silico emulation of a human: every
| dendrite of every brain cell, every action potential
| propagating along it, every neurotransmitter diffusing across
| every synapse.
|
| And what the people running the simulations _AND THE PEOPLE
| BEING SIMULATED_ discover is that you don 't need it most of
| the time.
|
| In the story, doing the neocortex of the brain and a coarser
| sim of the underlying structures is enough to support full
| consciousness. For the peripheral nervous system, an even
| lower-level sim is enough: your limbs still feel right. For
| the sympathetic nervous system, you don't bother at all --
| just simulate overall excitation levels.
|
| Don't bother doing whole muscles, as most people aren't
| consciously aware of them anyway, even when running or doing
| sport -- any more than we're aware of breathing.
|
| You downgrade the sim of everything except the important bits
| to a coarse low-res approximation and most of the time you
| wouldn't be able to tell -- but it's much faster and takes
| much less CPU time, so the same compute substrate can
| simulate more people faster for a given amount of resources.
|
| No, this is _not_ a full simulation of all the nerve cells in
| a fly brain, but it seems like it does more or less what a
| fly would do anyway. It seems quite possible that for a fly,
| a coarse low-level generalised simulation might be enough to
| produce something that walks like a fly, feeds like a fly,
| and maybe flies like a fly and breeds like a fly.
|
| I don't think a fly "knows" which leg to move when walking. I
| suspect a horse doesn't. I barely do, and I only have 2 of
| them.
|
| Crude abstracted low-level sims with the right structure
| might be enough to get the desired behaviour and have a model
| that's good enough that its behaviour is indistinguishable
| from the original.
|
| In human terms... if we ever get to the point that we can
| simulate a brain in a jar, if the sim "lies" to the brain and
| tells it a body is there, and is doing the normal body stuff
| and walking and swinging its arms and whatever, that might be
| enough to "feel real" to the mind in the simulated body.
|
| Do it for an athlete or sports player or a gymnast or a
| bodybuilder and they'd notice. They'd know. But most of us
| never would.
|
| You can't feel your individual toes unless you stub one. So
| don't simulate them.
|
| A low-res fly brain model connected to a lower-res overall
| ventral nerve cord connected to a trivial fly muscle body
| which doesn't even simulate individual muscles might be
| enough that the fly does everything a fly can do.
| logicprog wrote:
| Agreed.
|
| I think there's another layer to this too, which is that --
| if you've already scanned and uploaded a person's mind, the
| original person is presumably dead, or at least a
| completely separate person from the one in the simulation.
| Moreover, really, no matter how much versimilitude you pour
| into your simulation, it's never really going to be exactly
| the same. Hence, if we're being clear-eyed about this,
| presumably the point of doing a brain upload like that
| isn't to get immortality for a particular person or
| something, its just to get a much more advanced and human-
| like form of artificial intelligence.
|
| At which point, if we don't _need_ a perfectly accurate
| neurological and physical simulation to get something that
| mostly "walks," talks and acts like a human, or something
| very similar, why would we bother doing it at all?
|
| And yeah, although you could obviously assume that perfect
| simulation of all of the physical and chemical and
| neurological processes is necessary to get something to
| even slightly functions, considering the fact that people
| can function with 90% of their brain entirely gone, I'm not
| sure how accurate that is.
| causal wrote:
| I'm not an expert in the field, but this reads like someone
| trying to sound impressive by using big words without providing
| any solid detail.
| pvillano wrote:
| I think the research Eon is citing will be seen as a much more
| important step on the path to AGI than language models.
| bobsmooth wrote:
| So how close are we to Cyberpunk-style braindances?
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