What does the cerebellum do? • Hacker News Board

Re: What does the cerebellum do?

#41

Post by bbor » Mon, Jan 08, 2024, 12:43 AM UTC

Amazing article, and for a layperson who’s been reading a lot of neuroscience, the perfect level of complexity. I love an article that makes you (internally) shout “why haven’t I wondered about that before?” over and over, so thanks for that. A compliment as to clarity of purpose, I suppose.

Materially;

  That’s bad news for anyone hoping to simulate a brain digitally. It means there’s a lot more relevant stuff to simulate (like the learning that goes on within cells) than the connectionist paradigm of treating each biological neuron like a neural-net “neuron” would imply, and thus the computational requirements of simulating a brain are higher — maybe vastly higher — than connectionists hope.

I get where she’s coming from, and she’s not wrong, but it seems like unnecessary detour to dunk on another AI “camp” in the field for drama points and satisfaction - the Marcus Maneuver, if you will. Connectionism isn’t a cult or an institution, it’s a paradigm that emphasis the utility of big nets of interconnected smaller pieces. Any self-avowed connectionist (are there any left? Honest question) could just retreat to “ok well it’s networks of brain cells plus smaller intracellular networks” and keep their paradigm. And all we can say to that is “ugh, I guess”, as far as I can tell!

Re: What does the cerebellum do?

#42

Post by Podgajski » Mon, Jan 08, 2024, 12:43 AM UTC

echelon wrote: post #8

jbandela1 wrote: post #4

> The cerebellum has a repeated, almost crystal-like neural structure: As a software engineer who did neurosurgery residency, my intuition/guess is that the cerebellum is kind of like the FPGA of the brain. The cerebrum is great for doing very complicated novel tasks, but it takes time and energy. The cerebellum on the other hand is specialized in being able to encode common tasks so it can do them with quickly and e…

What signals cause rewiring of the cerebellum? Is there any way to induce that state exogenously? Some thoughts include dopamine / pain receptor reinforced learning. Maybe there's a faster way?

I’m going to say it’s all about the glutamate.

https://www.nature.com/articles/s41467-023-38475-9

Re: What does the cerebellum do?

#43

Post by orena » Mon, Jan 08, 2024, 12:52 AM UTC

Come on, no one knows... after 10 years in computation neuroscience + experimental neuroscience. The slope of neuroscience advances in very very low (some will say negative). The slope of AI advances in much much higher. --> we will get an AI to understand the brain an explain to us, it will not come from a lab.

Just my point of view

Re: What does the cerebellum do?

#44

Post by h0l0cube » Mon, Jan 08, 2024, 1:02 AM UTC

cubefox wrote: post #12

So classical conditioning in humans requires special cells in the Cerebellum (Purkinje cells), which can even do single-cell learning. Which artificial neurons can't do, as only weights (artificial synapses) are updated. So how is classical conditioning actually implemented in artificial neural networks? I assume there is some minimum network which makes it work.

At a rough guess, each Purkinje cell is an MLP unto itself, and as the article states, this implies some orders of magnitude more computation for a brain simulation. I also heard something like 'a neuron is an MLP unto itself' on the Brain Inspired podcast. It's likely we've vastly underestimated the processing power of the brain.

Re: What does the cerebellum do?

#45

Post by mistersquid » Mon, Jan 08, 2024, 1:07 AM UTC

padolsey wrote: post #11

What a marvellous article. One thing I’ve never quite appreciated in neuroscience is how useful physical movement is as a debugging layer. During a task, in observing gaits, tremors, speed, accuracy, etc., you’re able to gain a deeper understanding of how cognition works for non-movement tasks. I guess cognition is, after all, still just movement, but through a conceptual plane instead of a physical one.

The first video linked in the OP is astonishing to me, a layperson with no medical training.

It's giving me lots to think about with regard to motor impairment. (Basically, I'm reviewing my prejudices and nodding due better understanding the plight of afflicted individuals.) [0]

[0] https://www.youtube.com/watch?v=FFki8FtaByw

Re: What does the cerebellum do?

#46

Post by h0l0cube » Mon, Jan 08, 2024, 1:09 AM UTC

This article made me wonder if dyspraxia was related to impaired or inhibited cerebellum function. A cursory search yields at least one article supports the idea:

> Results revealed that children with DCD had reduced grey matter volume in several regions, namely: the brainstem, right/left crus I, right crus II, left VI, right VIIb, and right VIIIa lobules

Re: What does the cerebellum do?

#47

Post by yjftsjthsd-h » Mon, Jan 08, 2024, 1:09 AM UTC

rzzzt wrote: post #13

NKosmatos wrote: post #7

Earlier quoted context omitted.

Both are spot on examples on what the cerebellum does. If I may, a third example/analogy that comes to mind is cache memory or L2ARC drives, at least that’s how I have it stored in my mind (pun intended) :-)

"The brain is like a computer that"-style analogies are rarely fitting, or so vague as to being almost useless. My fridge is an L2 cache for food I want to eat soon.

> My fridge is an L2 cache for food I want to eat soon.

I would think fridge is RAM, L2 is table, L1 is plate. (I am deliberately ignoring the pun potential for Cold Storage.)

But other than bickering about the exact mapping, I don't see the problem with that analogy?

Re: What does the cerebellum do?

#48

Post by [deleted] » Mon, Jan 08, 2024, 1:12 AM UTC

rzzzt wrote: post #13

NKosmatos wrote: post #7

Earlier quoted context omitted.

Both are spot on examples on what the cerebellum does. If I may, a third example/analogy that comes to mind is cache memory or L2ARC drives, at least that’s how I have it stored in my mind (pun intended) :-)

"The brain is like a computer that"-style analogies are rarely fitting, or so vague as to being almost useless. My fridge is an L2 cache for food I want to eat soon.

[deleted]

Re: What does the cerebellum do?

#49

Post by echelon » Mon, Jan 08, 2024, 1:27 AM UTC

armada651 wrote: post #20

echelon wrote: post #8

Earlier quoted context omitted.

What signals cause rewiring of the cerebellum? Is there any way to induce that state exogenously? Some thoughts include dopamine / pain receptor reinforced learning. Maybe there's a faster way?

> What signals cause rewiring of the cerebellum? Any signal, that's the point. The cerebellum learns the patterns of signals involved in motor control. This is why you train your skills by doing the correct movement over and over again. Once the cerebellum has adjusted to the correct motor signal patterns the correct movement will become effortless.

> This is why you train your skills by doing the correct movement over and over again.

Yes, but can you make this to go faster?

Re: What does the cerebellum do?

#50

Post by im3w1l » Mon, Jan 08, 2024, 1:28 AM UTC

cubefox wrote: post #12

So classical conditioning in humans requires special cells in the Cerebellum (Purkinje cells), which can even do single-cell learning. Which artificial neurons can't do, as only weights (artificial synapses) are updated. So how is classical conditioning actually implemented in artificial neural networks? I assume there is some minimum network which makes it work.

Well classical conditioning kind of only makes sense in the context of an agent that is receiving inputs and taking actions on them. Many neural networks don't solve problems of that type, and so have no need for classical conditioning.

But when you do have such a problem conditioning is not very complicated. The normal algorithms and neural structures are designed to learn stuff like "when a given input happens a certain action must be taken" and thats all you really need for conditioning. How it actually does it? Well I guess with gradient descent it would work something like this: Every time there is a puff of air the network will be like "damn I should have blinked to avoid this" and so it makes its current internal statement a little more likely to lead to blinking. Gradually as it happens more times it will learn a strong association for the ringing bell or whatever.

A small RNN could learn this.