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Cubic millimetre of brain mapped at nanoscale resolution

nature.com

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Re: Cubic millimetre of brain mapped at nanoscale resolution

#61

Post by sdenton4 »

Terr_ wrote: post #31
nicklecompte wrote: post #14

Earlier quoted context omitted.

Crow/parrot brains are tiny but in terms of neuron count they are twice as dense as primate brains (including ours): https://www.sciencedirect.com/science/article/pii/S096098221... If someone did this experiment with a crow brain I imagine it would look “twice as complex” (whatever that might mean). 250 million years of evolution separates mammals from birds.

I expect we'll find that it's all a matter of tradeoffs in terms of count vs size/complexity... kind of like how the "spoken data rate" of various human languages seems to be the same even though some have complicated big words versus more smaller ones etc.

Birds are under a different set of constraints than non-bat mammals, of course... They're very different. Songbirds have ~4x finer time Perception of audio than humans do, for example, which is exemplified by taking complex sparrow songs and showing them down until you can actually hear the fine structure.

The human 'spoken data rate' is likely due to average processing rates in our common hardware. Birds have a different architecture.

Re: Cubic millimetre of brain mapped at nanoscale resolution

#63

Post by alanbernstein »

cyberax wrote: post #36
throwup238 wrote: post #12

> The 3D map covers a volume of about one cubic millimetre, one-millionth of a whole brain, and contains roughly 57,000 cells and 150 million synapses — the connections between neurons. This is great and provides a hard data point for some napkin math on how big a neural network model would have to be to emulate the human brain. 150 million synapses / 57,000 neurons is an average of 2,632 synapses per neuron. The adu…

On the other hand, a significant amount of neural circuitry seems to be dedicated to "housekeeping" needs, and to functions such as locomotion. So we might need significantly less brain matter for general intelligence.

Or perhaps the housekeeping of existing in the physical world is a key aspect of general intelligence.

Re: Cubic millimetre of brain mapped at nanoscale resolution

#64

Post by michaelhoney »

steve_adams_86 wrote: post #57
nicklecompte wrote: post #14

Earlier quoted context omitted.

Crow/parrot brains are tiny but in terms of neuron count they are twice as dense as primate brains (including ours): https://www.sciencedirect.com/science/article/pii/S096098221... If someone did this experiment with a crow brain I imagine it would look “twice as complex” (whatever that might mean). 250 million years of evolution separates mammals from birds.

This might be a dumb question, because I doubt the distances between neurons makes a meaningful distance… But could a small brain, dense with neurons like a crow, possibly lead to a difference in things like response to stimuli or “compute” speed so to speak?

Actually I think that's pretty plausible. Signal speed in the brain is pretty slow - it would have to make some difference

Re: Cubic millimetre of brain mapped at nanoscale resolution

#66

Post by LargoLasskhyfv »

nicklecompte wrote: post #14
jamiek88 wrote: post #9

Earlier quoted context omitted.

My god. That is stunning. To think that’s one single millimeter of our brain and look at all those connections. Now I understand why crows can be so smart walnut sized brain be damned. What an amazing thing brains are. Possibly the most complex things in the universe. Is it complex enough to understand itself though? Is that logically even possible?

Crow/parrot brains are tiny but in terms of neuron count they are twice as dense as primate brains (including ours): https://www.sciencedirect.com/science/article/pii/S096098221... If someone did this experiment with a crow brain I imagine it would look “twice as complex” (whatever that might mean). 250 million years of evolution separates mammals from birds.

IIRC bird brains are 'packed/structured' very similar to our cerebellum.

So one would just need to pick that little cube out of our cerebellum, to have that 'twice as complexity'.

Re: Cubic millimetre of brain mapped at nanoscale resolution

#67

Post by rmorey »

falcor84 wrote: post #45
rmorey wrote: post #41

Earlier quoted context omitted.

we are nowhere near whole human brain volume EM. the next major milestone in the field is a whole mouse brain in the next 5-10 years, which is possible but ambitious

What am I missing? Assuming exponential growth in capability, that actually sounds very on track. If we can get from 1 cubic millimeter to a whole mouse brain in 5-10 years, why should it take more than a few extra years to scale that to a human brain?

assuming exponential growth in capacity is a big assumption!

Re: Cubic millimetre of brain mapped at nanoscale resolution

#68

Post by Terr_ »

sdenton4 wrote: post #61
Terr_ wrote: post #31

Earlier quoted context omitted.

I expect we'll find that it's all a matter of tradeoffs in terms of count vs size/complexity... kind of like how the "spoken data rate" of various human languages seems to be the same even though some have complicated big words versus more smaller ones etc.

Birds are under a different set of constraints than non-bat mammals, of course... They're very different. Songbirds have ~4x finer time Perception of audio than humans do, for example, which is exemplified by taking complex sparrow songs and showing them down until you can actually hear the fine structure. The human 'spoken data rate' is likely due to average processing rates in our common hardware. Birds have a diff…

You misunderstand, I'm not making any kind of direct connection between human speech and bird song.

I'm saying we will probably discover that the "overall performance" of different vertebrate neural setups are clustered pretty closely, even when the neurons are arranged rather differently.

Human speech is just an example of another kind of performance-clustering, which occurs for similar metaphysical reasons between competing, evolving, related alternatives.

Re: Cubic millimetre of brain mapped at nanoscale resolution

#69

Post by dsalfdslfdsa »

throw310822 wrote: post #55
throwup238 wrote: post #12

> The 3D map covers a volume of about one cubic millimetre, one-millionth of a whole brain, and contains roughly 57,000 cells and 150 million synapses — the connections between neurons. This is great and provides a hard data point for some napkin math on how big a neural network model would have to be to emulate the human brain. 150 million synapses / 57,000 neurons is an average of 2,632 synapses per neuron. The adu…

Or you can subscribe to Geoffrey Hinton's view that artificial neural networks are actually much more efficient than real ones- more or less the opposite of what we've believed for decades- that is that artificial neurons were just a poor model of the real thing. Quote: "Large language models are made from massive neural networks with vast numbers of connections. But they are tiny compared with the brain. “Our brains…

"Efficient" and "better" are very different descriptors of a learning algorithm.

The human brain does what it does using about 20W. LLM power usage is somewhat unfavourable compared to that.

Re: Cubic millimetre of brain mapped at nanoscale resolution

#70

Post by out_of_protocol »

steve_adams_86 wrote: post #57
nicklecompte wrote: post #14

Earlier quoted context omitted.

Crow/parrot brains are tiny but in terms of neuron count they are twice as dense as primate brains (including ours): https://www.sciencedirect.com/science/article/pii/S096098221... If someone did this experiment with a crow brain I imagine it would look “twice as complex” (whatever that might mean). 250 million years of evolution separates mammals from birds.

This might be a dumb question, because I doubt the distances between neurons makes a meaningful distance… But could a small brain, dense with neurons like a crow, possibly lead to a difference in things like response to stimuli or “compute” speed so to speak?

Regarding compute speed - it checks out. Humans "think" via neo cortex, thin ouside layer of the brain. Poor locality, signals needs to travel a lot. Easy to expand though. Crow brain have everything tightly concentrated in the center - fast communication between neurons, hard to have more "thinking" thing later (therefore hard to evolve above what crows currently have)
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