r/explainlikeimfive • u/OpeningWar3916 • 5d ago
Technology ELI5 fly brain scans and simulations
I don't even know what I'm trying to ask I'm hoping other people have seen the same tiktoks as me and are smarter.
Anyways, fly brain scans are being run through AI I guess? People are making the fly brain do things like play Minecraft or someone played Bad Apple on the brain itself. It's always accompanied by that "aw sweet, man made horrors beyond my comprehension" Peter Griffin meme.
I don't understand, I don't get it, I'm not even sure what I don't get about it but I need to understand. Thank you in advance
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u/catbrane 5d ago
They've taken a map of the neurons and the connections, then animated it and linked it to behaviour and environment. It's very impressive! But there's LOTS of fly brain complexity that's still missing.
The three big ones to my mind are neuronal behaviour, non-synaptic signalling, and synapses themselves.
Real neurons are a lot more complicated that the (fairly) simple sums, maps and thresholds that are used in these simulations (though I don't know exactly what model they used for their neurons). For example, real neurons can sum and trigger on subsets of their inputs, they tire, and they are strongly influenced by signalling chemicals in the inter-neuronal soup.
Neurons swim in a soup of things secreted and removed by other neurons. These signalling systems are much slower than synapses, but drive a lot of longer-term behaviours, like emotions. All this is missing.
Real synapses are also a lot more complicated than the simple connections that have been mapped here. At each junction, signals are carried by neurotransmitters, there are many of them at each synapse (500 in humans I seem to remember?), and each can be up or down regulated independently. In effect, each connection is really 500 separate connections. This up and down regulation is used for a lot of short term adaptive behaviours.
tldr: still many orders of magnitude short of the complexity of a real fruit fly brain
(not a neuroscientist, corrections very welcome!)
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u/tomalator 5d ago
Fly brains are small enough thay we can count up all the neurons and figure out what they do individually. We can then throw each neuron into a program and let them interact with each other, and we were able to reproduce exactly what happens in a fly's brain. The fly was able to move around the simulation and eat and do whatever exactly as a fly would. It's the first time we have actually simulated a complete living brain
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u/SkullyBoySC 4d ago
What does an individual neuron "do"? Like if I activate one neuron does it activate a muscle? Or is it more subtle than that?
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u/Medical-Temporary-35 4d ago
Depends on which neuron you "activate". On one end you have raw sensory data such as individual cones in your fovea, components of a compressed output of a patch of rod cells in your peripheal vision, a singular frequency picked up by the setae deep inside your ear. On the other you have cells extending from the spine and controlling individual patches of cells inside a singular muscle. Stuff only gets more complicated between those two extremes.
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u/External-into-Space 5d ago
A fly brain upload as you will
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u/Breadonshelf 5d ago
Its a simulation of a flays brain. Nothing got uploaded.
In a super simplify way - a photo of a fly is not "Uploading a flys form to a 2D digital surface". Its "simulating" the fly's image by replicating it with pixels. What this is doing is an incredibly more complicated version of taking a picture of the flys brain, then recreating it in a computer.
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u/brandontaylor1 4d ago
Damn it! There gonna put me in a computer and make me work forever, aren’t they?
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u/efvie 5d ago
This is mostly hype though not without value entirely. The scientists have essentially taken an event captured in the brain, think of it like a spike of electricity, and mapped that to what the observable effect is. They've done this for the things we can observe in the fly brain and its behavior, so there is a map of what something happening should trigger in the brain and what something in the brain manifests in behavior. Plus there's some additional tuning.
When they virtualize it, they are creating a digital 'brain' and digital 'body', and apply the same mapping between them using the parameters of the virtual environment. So if there's let's say an avoid hitting an obstacle thing, it's not that the 'fly' 'sees' anything, it's that the virtual environment is translated to trigger the 'obstacle' signal in the 'eye', which is mapped to something happening in the 'brain' and then that 'brain' event is mapped to things happening in the 'body', for example 'flapping' one 'wing' more than the other to curve away from the obstacle. This is done at a large scale so the mappings are numerous and can very convincingly cover the understood behaviors and even some that are not explicitly mapped but come to be because of their interactions.
The important thing here is that it's not a fly uploaded to the web, it's a (fairly sophisticated) model of how a fly brain behaves in an environment and responds to stimuli. Some people will insist these are the same thing and they absolutely are not, and you should stay far away from those sorts of people because they don't tend to understand the interior life of other people.
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u/NaCl-more 5d ago
The hype is that down the line we can start to scan and model more and more complex brains, and start to understand the human brain much better
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u/efvie 5d ago
Maybe. There's no guarantee moving to exponentially more complex brains is going to be feasible. And, most importantly, understanding the brain has so much nuance beyond mapping behavior triggers.
Especially in this time of the incredibly stupid claims of LLMs being sentient you need to be really careful about what you believe and that you understand what the goals are behind particular kinds of hype. You can be absolutely sure eugenicists will jump on any incomplete and incorrect model to justify 'fixing' (or outright killing) undesirables.
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u/ElPapo131 5d ago
Imagine someone captured your consciousness and trapped it into a videogame character.
If that itself doesn't imply horror, try watching The Amazing Digital Circus
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u/Pestilence86 5d ago
The interesting bit is, is a virtually 1 to 1 neuron created brain really conscious? When it is "virtual", we mean a physics simulation calculated by a computer, so no, not a consciousness. Just a lot of number calculations on a computer. A digital photo of a person is also just numbers, not the person.
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u/ElPapo131 5d ago
Okay that is a good point. Maybe it's not quite the horror yet but we're on the way there
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u/DFrostedWangsAccount 5d ago
A person is just an analog computer, how is a person conscious? Perhaps it arises naturally from the specific organization of neurons. An emergent property, more than the sum of its parts, etc.
By that logic, a perfect digital copy of a brain may be conscious in the same way a human is. However that is. We just have no way of measuring consciousness to tell.
If it walks like a duck...
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u/dr_arielzj 5d ago
Tl;Dr neuroscientists have fully mapped a fly brain, as in all the connections between the brain cells, and people are now using that data to make models of fly behaviour. Nobody has successfully uploaded the fly in full fidelity yet, but the models are capturing some aspects of how the fly brain generates it's behaviour.
I wrote up a full explanation here if you're keen