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Comment by jbandela1 | Hacker News Reader

> 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 efficiently. A lot of our motor learning is in fact wiring the cerebellum correctly.

This can actually lead to an interesting amnesia, where a person can learn a skill (cerebellum) but not remember learning the skill (cerebrum). So you could end up with a person who would think that he had never seen a basketball hoop or basketball before but could be doing layups, dunks, and 3 pointers with ease.

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> So you could end up with a person who would think that he had never seen a basketball hoop or basketball before but could be doing layups, dunks, and 3 pointers with ease.

I know a lot of people with the opposite problem.

Thanks for that. Don’t often laugh at a comment

What a great comment, seriously.

It just made me start thinking and then I realized perhaps another analogy is a just in time compiler where code or skills used often enough, your body manages to compile into native neurological code and stores that appropriately.

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.

It would be a useful analogy for someone intricately familiar with computers but who was only sort of vaguely familiar with the concept of eating, has thought about houses only on occasion, and knows about refrigerators only insofar as they’re a food-related thing inside a house.

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

A less-volatile form of L2 cache.

Food pocketed in my cheeks are the CPU registers?

Some fridges are like magnetic tapes, with files from 1978.

> 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?

Cold storage is my freezer. There's often a delay between when I need it and when it is ready.

AC outlet is the clock speed!

Here comes the Forkbus! brm brm

What's wrong with the fridge analogy?

It's an analogy for a reason. It bothers me when people combat analogies so incredibly hard. Of course, it is not really fitting or the same thing - it's an analogy.

It is always funny to see brain metaphors morph to resemble our current stage of technological development, as the years go by. First it was anima, or hydraulic analogies of spirits and fluid moving through the body. Then it was clocks, the mechanistic processes of the brain. And so on and so on until today we metaphorize the brain to be like computer hardware. In vogue as well is comparing it to neural networks, due to the influence of machine learning and AI today. I wonder what metaphors we will come up with next.

http://mechanism.ucsd.edu/teaching/w12/philneuro/metaphorsan...

I always liken this process of reality being a fractal boundary of mandelbrot and our attempts to understand it through language and metaphors as a way to approximate and fit that boundary. Consider the successive colored stripes like a updated and accurate metaphors in the following video

https://youtu.be/u_P83LcI8Oc?si=ObkNyUfCCSUCb0Vt

I wonder if each iteration gets closer as we go

Though it's not like we're flitting from one bad analogy to another. Hydraulics are a great metaphor for understanding how computers work, for example.

Some 50 year old cartoons about said topic... https://github.com/larsbrinkhoff/crunchly

The next metaphor would be quantum computers.

There are a few that have started suggesting quantum mechanics playing a large role in cognition, but very few take them seriously (obviously it has an effect, but likely much can be understood more classically, etc).

The fact that few are moving toward that style of thinking seems to give a bit more credibility to NNs being closer to the correct model. If spiking NNs take off more, we'll probably see more arguments around that, and if Blue Brain's full in-silico modeling takes off we may see the succinct description given by those studies used to describe ideas. However, to first approximation, NNs and spiking NNs aren't really a bad way to reason about large descriptions of brain dynamics, in many circumstances.

There’s zero evidence that there’s anything more quantum mechanical about the brain than a brick. IE: Physical and chemical interactions that emerge from quantum behavior, but can be modeled just fine without QM.

Instead people seem to just equate two different complex things they don’t understand with each other.

Your comment has a feel to it of a rebuttal; but I hope it's clear that the original comment has effectively this same stancen as this.

I didn’t disagree with the what you said, but I think some people may have misinterpreted it.

I always thought neural networks were an example of the analogy working the other direction. Instead of modeling our brain on the technology of the time, we chose to model the next technology on how we think our brains work?

Heh not sure if you're aware, but our brain seems to have a special treatment or logic for contextualizing "high technology", as indicated by one well-documented failure modes: the "influencing machine" is a feature of schizophrenia which features a delusion that contemporary high technology (magnets, pneumatics, gears, mind-control drugs, satellites, prob AI now, etc) is being used by mysterious attackers to control the sufferers body and mind: https://en.m.wikipedia.org/wiki/On_the_Origin_of_the_%22Infl...

Though not mentioned in the post, schizophrenia (oddly enough) is also tied to cerebellar dysfunction: https://neuro.psychiatryonline.org/doi/10.1176/jnp.12.2.193#...

But air looms are real: https://www.theairloom.org/

In all honesty, I believe the reverse is true. Our technology seems modeled after humans and the environment we inhabit. Airplanes being glorified birds, wheels being glorified feet, computers being glorified brains or neural networks...well.

It's hard to imagine two objects in the vehicle-ground-interface conceptual space much farther away from one another than feet and wheels.

Try to spend more time imagining and entertaining that thought. They both have the same function but execute it differently.

I did. They still don't have anything in common other than being means to locomotion across the ground. Unlike, f.e. cameras that are directly inspired by the eye, airplane wings being directly inspired by bird wings. Wheels are not directly inspired by anything biological, they are probably invented from log-bearings for easier dragging of heavy things across ground.

This actually happened to me when I lost most of my memory in an accident. I couldn’t even remember my job tasks enough to describe how to do them. They were repetitive, though, with it all in my intuition or muscle memory. I could do the stuff without knowing why I was doing it. My friends and I joked I was the Jason Borne of the place. It’s a strange feeling, too, because I could feel like something was missing as I acted.

I was also a supervisor in a competitive company with people gunning for my job. The Recession was not a good time to be disabled. I feared demotion or termination. I hid my injury while trying to get back in mental shape. They chalked up occasional forgetfulness to the stress we were all under and my constant partying. (That was before I was in a relationship with Jesus Christ and gave up those sins.)

Eventually, one of my recovery strategies was to take note of the specific things I did on instinct, think about why I did them, and re-create the mental models. I’d also just ask people how they did things and what they learned works best. Many were people I trained with my prior techniques who re-taught them to me. By practicing those, I both re-learned my mental model of how to do the job and connected it with the instinctual wiring.

There were one or two other trucks that helped. That was the part relevant to your comment, though. I never quite got back to my old level of performance. Capitalizing on how intuitive memory is different than conscious memory has helped me in many places ever since. I just keep breaking it into simple things that I repeat over and over to. Then, keep applying those pieces in new ways to keep my brain fresh.

Yeah, the discussion of classical conditioning led me to the same sort of conclusion. The fact that cerebelum has been growing faster in human like primates as a percentage of our already larger brains, well, I can't help but think that all our social reactions, drives, and complex needs are essentially some kind of cooption of this FPGA for optimization purposes. Like cerebrum does training and cerebelum et al do evaluation.

I am way more interested in how you gave up $800,000+ a year to do software engineering.

Obviously not OP and not in this position, but I have worked with people who left surgical training positions and their reasons were health and a realisation that they would miss every family milestone, never get a real break and have every part of their life revolve around their job with the money and god-like power not compensating for that.

Obviously that’s one side of the equation, I don’t have any surgeon friends I know well enough to give the opposing view.

Some can do it. Are they really different than the rest?? Perhaps higher tolerance to stress or even thriving in it?

OP said "did" implying finished. It's a six year residency minimum, though the first year is general surgery. It's not often people do the whole damn thing, then decide to bail. Usually it's after 2 or 3 years

Though some people are less burdened by golden handcuffs and sunk-cost fallacy

Plus, I've never met a happy (or sane) neurosurgeon

I'm in no way even close to being in the medical field, but I could see it as an unreconcilable dichotomy between the hippocratic oath and the fact you're going to be causing damage no matter what.

Sure, the hemmhorage needs to be fixed, so you're preventing further damage, but every cut may cause unknown ramifications. Anyway, I'm postulating a neurosurgeon would be aware of this, and have to carry that around with them.

Medicine as a career offers immense personal fulfillment, variety, human interaction, and prestige at the expense of dealing with difficult outcomes and ranges of personal sacrifice -- neurosurgery as a specialty just takes all of these to their extremes.

I value the former and find ways to discount the latter. So I am very happy. Though sane or not would be up to others.

$800,000 is a lot of money, even after taxes you'd only have to work a few years at that salary before you could live reasonably comfortably for the rest of your life without working at all.

Seems perfectly reasonably to switch to a lower stress career at some point.

The personalities attracted to the role aren’t really amenable to thinking that way.

There's also lifestyle inflation, and of course retiring early rarely impresses your spouse.

People do change, especially when exposed a long time to stressful environnement. Ask post-burnout fellow. Fortunately most re evaluate their life before going to burn out.

Neurosurgery residency is very, very, very intense. Unfortunately not everyone finishes. When I was in medical school, I remember some general surgery residents quiting after falling asleep in the middle of an operation; another neurosurgery resident I rotated with was pretty miserable, I found out later he quit. I would have liked to be a neurosurgeon, but simply didn’t have the physical stamina.

I ended up becoming a radiologist. Never heard a radiology resident quiting, although have seen a few residents get kicked out for mental issues or gross incompetence.

> gross incompetence

How on Earth do you get to "resident" and have "gross incompetence"?

There are sooo many gates before getting to be a "resident" that this completely baffles me.

Undergrad/premed: live with family, have 100% 24/7 familial support of your education, living at home with all of your essential basic living needs taken care of.

Residency: move to a different location away from family, no longer living in a dormitory environment with the expectations associated with being a student but are now a real adult making your way in the world. Suddenly you have to make the whole package work on your own without laundry/cooking/mental health/financial support.

Now you can no longer put 100% of yourself into your studies, but instead can only manage the 60 or 70% that most people can muster when they have to actually maintain their physical existence while also meeting their professional expectations.

It happens. Often incompetence is specific to one specialty - neurosurgery is competitive, so you can assume that anyone who gets it has at least adequate grades/test scores. But that doesn't mean that they're clinically worth a damn.

I'm an anesthesiologist. There are people who wash out because they just don't have the temperament for it. They're not dumb, they're not even bad doctors, they just aren't mentally equipped to sit back and relax while running a code.

Assuming they only got as far as their residency (and didn't end up as attending physician), it's possible that they didn't see themselves spending a full 7 years as a resident doctor (making under $100k/year working 80+ hour weeks) only to spend the rest of their lives doing more of the same except with a much higher salary. If they already graduated their residency then the reasoning is the same except it's be a much harder decision because of the sunk cost.

This comment is the best example of why I come to read comments in HN.

Do you think this could be responsible for some part of "muscle memory"? Sometimes when I switch to other identities (DID), they can forget steps. That presumably happens because those steps are automatic for me, so I don't have to think about them, but when others try to do the same thing (not think about them), the automatic thing doesn't happen, and they end up missing the step entirely. They have to remind themselves to think consciously even about things that are normally automatic for me, because they don't have the same muscle memory.

I also wonder if neurodivergency affects this region. I'm autistic, so my brain is detail-oriented. Sometimes it feels like I can perceive "neural circuits" that are implemented by the so-called FPGA. When I have a compulsive behavior or trigger, I can sometimes observe the entire execution flow, not just the result. I think that's neat.

> A lot of our motor learning is in fact wiring the cerebellum correctly.

That got me interested: since the wiring is so long (from limbs to cerebellum), what kinds of motor learning?

Do we know, if cerebellum needs more energy than the rest of the brain?

> That got me interested: since the wiring is so long (from limbs to cerebellum), what kinds of motor learning?

I'd imagine it's things like training a dominant hand. The skills required for precise motor control, to produce the right movements for e.g. handwriting. Since the wiring is so long, and feedback is delayed, you need to be able to precalculate these movements.

Also imagine how e.g. an intent to move somewhere actually gets implemented. You don't always have to think about each individual step of walking, or pay explicit attention to things like your sense of balance. You probably don't even have to choose that you're going to walk, or think about how to get up. When you want to go somewhere, you just do it, and somehow it's all calculated for you and happens.

When you try to move a specific limb, how do you know which muscles correspond to that limb? In fact, how many of those muscles can you even individually address? You can learn to individually address them, but I bet you don't come with that ability by default.

Then of course there's the question of what even causes your limbs to move once you will them to move.

What do you mean? The cerebellum is closer to the spinal cord than the rest of the brains. And there's no learning happening anywhere but the brain, vertebrates don't have distributed central nervous system like octopuses do. The only thing vertebrate limbs can do on their own are certain hardcoded reflex actions.

So the spinal cord is only a wire and, besides reflexes, there is no processing done anywhere else, but the brain?

How about neurons in the gut, I've read somewhere that intestines are lined up with some neural "mesh". Is that only for signal transmission?

There is processing in the autonomous nervous system, all sorts of regulation, and adaptation, perhaps something that could be called learning – we don’t really know what happens in the gut nerve complex yet, as it’s so recent "discovery".

Fully autonomous muscle movements like heartbeat, or the peristaltic motion of the gut, are not directly controlled by the brain, but they certainly respond to signals sent by the brain – eg. brain processes sensory data, determines there’s a danger, upregulates the pituitary gland which starts secreting adrenocorticotrophic hormone, which once it reaches your adrenal glands, causes them to start producing adrenaline, which in turn causes all sorts of changes all over the body related to the fight-or-flee reaction.

The skeletal muscle, though – I don’t think its innervation is capable of anything but reflexive motion without the brain telling it what to do.

I thought the cerebellum predated the rest ?

Out of curiosity, having the kind of weird symptoms not far from what you describe as weird amnesia, do you know any books / resources to understand advanced brain neurology like this ?

Thanks in advance

https://www.amazon.com/Principles-Neural-Science-Fifth-Kande...

Thanks a lot

This is great and I agree with the reprogrammable part.

However think of it more like switch or a router between the PNS/CNS (minus vision) and the “higher brain“ longer term planning systems.

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?

Pain or satisfaction, probably.

When a motion "feels good", or is painful, probably means you learn. So chase those.

Train harder. Develop habits.

I think we're in the "punch card" phase of biology. I'd be willing to bet (timeline uncertain) that there will be shortcuts to this process.

For now, opportunity cost rules the day. I'm 120% maxed out.

You'd have to apply an adverse stimulus in under a ~5ms threshold to actions that were 'wrong'. It would depend on the exact task you're trying to do though. That would then cause other areas to potentiate that specific movement/firing as incorrect.

Its a active area of research in sports and DoD. As you'd theoretically be able to train marksmen and athletes at a much faster and better rate. However, even really really fast computers aren't quite fast enough to apply the adverse stimulus to 'wrong' movements/firing.

Also, your computer better be really accurate and never mess up, or that person is going to have a hell of a time retraining their brain. Also, their brain may view that the clouds/temperature/itchy grass/breakfast are the reasons for the adverse stimulus, as this is all happening at in subconscious time frame. So, good luck there.

This is great info, thanks!

The pattern of muscle activation timing in the correct move form needs to be figured out by exploration of the space.

We don't typically efficiently explore the space. This is why coaches exist.

The feedback loops are often long. Getting a review on a performance, etc.

If a device were set up to trigger pain within some milliseconds of an incorrect activation, surely we could speed this up?

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

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

Psilocybin and other psychedelics may be that exogenous agent, they release Brain-derived neurotrophic factor (BDNF) [0], which plausibly could cause “rewiring of the cerebellum” [1][2], and may even do this with sub-perceptible (micro)doses [3].

[0] https://pubmed.ncbi.nlm.nih.gov/37280397/

[1] https://www.nature.com/articles/s41386-022-01389-z

[2] https://www.frontiersin.org/articles/10.3389/fpsyt.2021.7246...

[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8033605/

Its striated structure matches sequential timed operations.

mk-ultra project monarch

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