Cubic millimetre of brain mapped at nanoscale resolution • Hacker News Board

Re: Cubic millimetre of brain mapped at nanoscale resolution

#201

Post by wrycoder » Mon, May 13, 2024, 2:24 PM UTC

kthejoker2 wrote: post #77

Intralexical wrote: post #74

Earlier quoted context omitted.

Try asking an LLM about something which is semantically patently ridiculous, but lexically superficially similar to something in its training set, like "the benefits of laser eye removal surgery" or "a climbing trip to the Mid-Atlantic Mountain Range". Ironically, I suppose part of the apparent "intelligence" of LLMs comes from reflecting the intelligence of human users back at us. As a human, the prompts you provide…

> Try asking an LLM about something which is semantically patently ridiculous, but lexically superficially similar to something in its training set, like "the benefits of laser eye removal surgery" or "a climbing trip to the Mid-Atlantic Mountain Range". Without anthropomorphizing it, it does respond like an alien / 5 year old child / spec fiction writer who will cheerfully "go along with" whatever premise you've lai…

Gruesomely useful in a war situation, unfortunately. I wonder at what point the LLMs would "realize" that "surgery" doesn't apply to that.

Re: Cubic millimetre of brain mapped at nanoscale resolution

#202

Post by habi » Mon, May 13, 2024, 2:28 PM UTC

dredmorbius wrote: post #190

talsit wrote: post #6

Earlier quoted context omitted.

Using a Microtome ( https://en.m.wikipedia.org/wiki/Microtome ).

NB: tome in Microtome has the same root as the T in CAT scan: computer aided tomography . Which is to say, slimly-sliced cabbage^W X-ray scans. It's also the tome as in book, more properly one volume of a multi-volume (or multi-part) set, though it now generally simply means any large book. https://www.etymonline.com/search?q=tome >

https://en.wikipedia.org/wiki/Tomography: `The word tomography is derived from Ancient Greek τόμος tomos, "slice, section" and γράφω graphō, "to write" or, in this context as well, "to describe."`

Re: Cubic millimetre of brain mapped at nanoscale resolution

#203

Post by Terretta » Mon, May 13, 2024, 5:29 PM UTC

dmarble wrote: post #167

NexusMethod wrote: post #156

After reading through all comments as of 2024/05/11 I (as a professor at some major university) am quite surprised that not one single comment has asked the obvious question (instead of dishing out loads of (partial) "textbook knowledge" about brain functions, the difference between mammals and birds, AI and LLM etc.), which would be: what do all those strange structures and objects do which we know nothing about wha…

I'm in awe at the complexity and unknowability of it all, but I also have to chuckle at the thought that some portion may be vestigial. I'm particularly fond of the "Egg shaped object with no associated processes". :)

Sure, if you think of it as an egg, instead of as a galaxy of electrons and atoms so dense as to have structure big enough for us to give it the label "egg shaped object".

What if it's a "wireless" device?

Re: Cubic millimetre of brain mapped at nanoscale resolution

#204

Post by lanstin » Mon, May 13, 2024, 8:01 PM UTC

themoonisachees wrote: post #193

lanstin wrote: post #72

Earlier quoted context omitted.

LLM does not know math as well as a professor, judging from the large number of false functional analysis proofs I have had it generate will trying to learn functional analysis. In fact the thing it seems to lack is what makes a proof true vs. fallacious, as well as a tendency to answer false questions. “How would you prove this incorrectly transcribed problem” will get fourteen steps with 8 and 12 obviously (to a st…

LLMs do not know math, at all. Not to sound like one myself, but they are stochastic parrots, and they output stuff similar to their training data, but they have no understanding of the meaning of things beyond vector encodings. This is why chatgpt plays chess in hilarious ways also. An LLM cannot possibly have any concept of even what a proof is, much less whether it is true or not, even if we're not talking about m…

That said, they are surprisingly useful. Once I get the understanding thru whatever means, I can converse with it and solidify the understanding nicely. And to be honest people are likely to toss in extra \sqrt{2} and change signs randomly. So you have to read closely anyways.

Re: Cubic millimetre of brain mapped at nanoscale resolution

#205

Post by RaftPeople » Fri, May 17, 2024, 2:12 PM UTC

nicklecompte wrote: post #90

Animats wrote: post #28

Earlier quoted context omitted.

How's OpenWorm coming along?

Badly: https://www.lesswrong.com/posts/mHqQxwKuzZS69CXX5/whole-brai... (the comments have some updates as of 2023) Almost every other cell in the worm can be simulated with known biophysics. But we don't have a clue how any individual nematode neuron actually works. I don't have the link but there are a few teams in China working on visualizing brain activity in living C. elegans, but it's difficult to get good measu…

Here's a timely bit of new research: https://www.science.org/doi/10.1126/sciadv.adk0002

Summary (my paraphrasing):

They partially figured out how two neurons (AVA, AVB) control forward and backward movement, previous theories assumed one neuron controlled forward and one controlled backward, but that didn't correctly model actual movement.

They found that AVA+AVB combine in a complex mechanism with two different signaling/control methods acting at different timescales to produce a graded shifting between forward+backward when switching directions, as opposed to an on/off type switch (that previous models used but didn't match actual movements).

Interesting learnings from this paper (at least for me):

1-Most neurons in worm are non-spiking (I had no idea, I've read about this stuff a lot and wasn't aware)

2-Non-spiking neurons can have multiple resting states at different voltages

3-Neurons AVA and AVB are different, they each have different resting state characteristics and respond differently to inputs