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An adult fruit fly brain has been mapped

economist.com

171–180 of 208 posts

Re: An adult fruit fly brain has been mapped

#171

Earlier quoted context omitted.

Fortunately, the whole chain of slicing, imaging, and analysis are now at least partially automated, so in theory you can repeat the process with nothing more than some time on the equipment and a bit of compute. In practice, I suspect there's a fair bit of grad student manual labor that keeps the pipeline flowing...

They crowdsourced three million manual corrections to the AI output, yeah.

That sounds like a great training set then.

Re: An adult fruit fly brain has been mapped

#172

Related: my favorite HN comment ever from a similar submission a year ago: > There's lots of very exciting work going on around the fully mapped fruit fly connectome. For example, I'm a CTO of a stealth startup that aims to do for utilitarianism what carbon credits did for environmentalism. We are selling 'utility credits' which translates directly into us simulating trillions and trillions of fruit fly brains in a s…

About as useful as the carbon credits themselves

I think that was the joke

Re: An adult fruit fly brain has been mapped

#173

Related: my favorite HN comment ever from a similar submission a year ago: > There's lots of very exciting work going on around the fully mapped fruit fly connectome. For example, I'm a CTO of a stealth startup that aims to do for utilitarianism what carbon credits did for environmentalism. We are selling 'utility credits' which translates directly into us simulating trillions and trillions of fruit fly brains in a s…

For anyone curious about the real critique of utilitarianism behind the joke, it's called a utility monster:

https://en.wikipedia.org/wiki/Utility_monster

Re: An adult fruit fly brain has been mapped

#174

Interesting stuff, but I don't understand HOW they've done it. There's something called Connectome Annotation Versioning Engine (CAVE). Which appears to be software(?) which allows researchers to examine a dataset and annotate it in some way. Presumably the dataset consists of images of the neurons themselves and the job is to map which neurons touch which other neurons? That's the thing I am not understanding. How d…

You perform chemical fixation and heavy metal staining, then some form of serial sectioning. You can either image the sections themselves or serially image the block face.

The sections can be imaged with TEM or SEM in high vacuum, the block face can be imaged with SEM.

The resulting 3d volume can be segmented with neural networks.

CAVE is for manual editing / correction on top of the automatically generated segmentation.

Re: An adult fruit fly brain has been mapped

#175

It was my understanding that all this connectome-based research was largely a deadend, because it doesnt capture dynamics, nor a vast array of interactions. if you've ever seen neurones being grown (go search YT), you'll see it's a massive gelatinous structure which is highly plastic and highly dynamic. Even in the simplest brains (eg., of elgans), you get 10^x exponential growth in number of neurones and their conne…

That's a bit like saying that sequencing the genome was a dead end, because it doesn't capture the molecular biology of the encoded proteins. Assuming the connectome is accurate, it's a major advance in our knowledge of neuroanatomy.

Re: An adult fruit fly brain has been mapped

#176

Earlier quoted context omitted.

It’s a neural network without weights. And it doesn’t have a body. Figuring out the behaviour of the neurons could take decades, although I have no doubt that people will eventually. And simulating a whole fruit fly body seems like it’s going to be out of reach for a very long time.

> It’s a neural network without weights. It has approximate weights. Neuron connection strength is determined by the number of synapses (1-100s, sometimes 1000s), the type of synapse neurotransmitter, and the number of receptors. The connectome has 1 and 2 and is only missing 3. The number of receptors may not even be that important- the fact that the number of synapses is important may well mean the number of recept…

> Neuron connection strength is determined by the number of synapses (1-100s, sometimes 1000s), the type of synapse neurotransmitter, and the number of receptors.

But the astrocytes are dynamically modulating the signal at the synapse, it doesn't seem like we really know "the" weight.

Re: An adult fruit fly brain has been mapped

#177
post #147
post #139

Earlier quoted context omitted.

This reminds me of the coastline paradox. I wonder if it applies to mapping an organism’s brain. For example, one can say they know the length of Scotland’s coastline but as the resolution increases, so does the coastline’s length. It’s infinite.

The resolution increases but the information doesn't. Apply some compression algorithm on the higher resolution coastline and you will find that you can reduce size massively. Same with LLMs and same with mapping the brain probably.

Why would the information not increase? If your unit is, say, 10 meters, you would only be able to see a straight line instead of curve.

Re: An adult fruit fly brain has been mapped

#178

Do we have an accurate model of a single neuron or very small group of neurons? I understand the reality may be chaotic, but I would hope to have a simulation such that it mirrors the evolution of neurons to a reasonable extent.

> Do we have an accurate model of a single neuron

No.

Many unknowns and even more being discovered regularly (e.g. tunneling nanotubes connecting neurons dynamically)

Re: An adult fruit fly brain has been mapped

#179
post #170

Earlier quoted context omitted.

About as useful as the carbon credits themselves

Curious if you could elaborate? It seems like the issue isn’t carbon credits, but the lack of a regulated level of carbon that would make them effective. Market incentives work best with dollar incentives, not virtue points.

I am no specialist, but carbon credits seem like they can work to me. The problem is they need to be very carefully analyzed. Here in Brazil there have been cases of people illegally seizing protected forests (far off in Amazon regions) and making huge amounts of money selling off carbon credits simply for 'not taking the forest down' (it could be even worse: taking down the forest for even more 'reforestation credits'). Usually most of those 'pay someone not to pollute' can be very problematic, because in principle anyone can declare (misleading) intent to pollute any amount and thus could get infinite credits.

So this kind of scenario has to be carefully taken into account in favor of scenarios which lead to actual emission reductions. It's not a simple fungible asset or commodity as some (naively) assume.

Re: An adult fruit fly brain has been mapped

#180

Related: my favorite HN comment ever from a similar submission a year ago: > There's lots of very exciting work going on around the fully mapped fruit fly connectome. For example, I'm a CTO of a stealth startup that aims to do for utilitarianism what carbon credits did for environmentalism. We are selling 'utility credits' which translates directly into us simulating trillions and trillions of fruit fly brains in a s…

They have a branding opportunity. Karma Kredits Perhaps a co-branding opportunity with Krispy Kreme donuts? Buy a donut, and experience some Joy, which handily comes with Karma Kredits to offset that Joy. Have some KK with the KK!

https://kk.org/
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