[garbre]

I reject the premise that the nervous system has "bandwidth" in a sense comparable to digital communications. Yes, nerves fire in discrete action potentials, but every step of nervous transmission also involves a processing step. Let's not forget: a huge benefit of neural nets is dimensionality reduction, which is at once compression but also the extraction and abstraction of salient information. Does this represent the gain or loss of information? It's a basically meaningless question; the question is how does the system as a whole work, and how well?

Nor is it clear what the endpoint of a communication is. This is another issue. Does information get counted twice if it's used by both unconsciously by the brainstem as well as rising into awareness and is used by the neocortex? The list of questions can go on.

This bandwidth thing is one of the questions I find frustrating, on par with people wondering if a simulated piece of brain has feelings (the answer is NO). Why is left as an exercise for the reader.

[Veedrac]

Shanon pretty clearly teaches us that bandwidth is a fundamental thing you can't circumvent by this sort of argument. It might do other stuff on top (though a lot of communication in the spine is latency-critical and at least some of it is point-to-point), but ultimately this doesn't change that bandwidth is how fast you can throw bits, whatever processing you do on them on the way or form they happen to take.

> This bandwidth thing is one of the questions I find frustrating, on par with people wondering if a simulated piece of brain has feelings (the answer is NO). Why is left as an exercise for the reader.

Now this is a hot take.

[dr_dshiv]

But doesn't Shannon rely on symbols and alphabets? What if the information is presymbolic?

Smolensky's pdp paper modeled presymbolic processing with the harmonium, the first restricted boltzman machine.

[gugagore]

No it doesn't rely on symbols.

You have a piece of copper and circuitry between your house and your ISP. Back in the day, there was no digital processing. It's just copper, amplifiers, filters, and mechanical switches. Why did dial-up internet never exceed (within a factor of 2) 30 kbps? Because that's the bandwidth of the channel. It's not that modem designers missed a more complicated, neuronal, way to encode the information.

It's really amazing that information and bandwidth can be as fundamental as temperature and mass. There's nothing symbolic about it in that lens. Symbols only come in because we know how to do important computations in the digital domain.

Analog television, FM radio, telegraph lines, telephone lines, smoke signals, the human vocal tract, all of them have bandwidths.

[gji]

I'm pretty sure the way analog degrees are freedom are mapped onto symbols is very important. In principle, if you have infinite SNR over a limited bandwidth, you can have infinite rate of data transfer - e.g. if you can have infinitely fine voltage resolution (in reality limited by the thermal noise floor, but you can always increase transmit power). So in that sense the mapping between information and bandwidth depends on SNR.

From the wiki page on QAM: "Arbitrarily high spectral efficiencies can be achieved with QAM by setting a suitable constellation size, limited only by the noise level and linearity of the communications channel." [https://en.wikipedia.org/wiki/Quadrature_amplitude_modulatio...]

[gugagore]

Unfortunately I used bandwidth informally (how most people use it), to mean something measured in bits per second, not Hertz.

You're absolutely right that SNR plays a role. But I don't see why you need to map to symbols.

[dr_dshiv]

Calculating Shannon entropy does rely on the symbolic alphabet and its probabilities of occurrance (see Wikipedia on Shannon entropy); however, I don't know how bandwidth is calculated. What makes you think it is as fundamental as temperature? One thing I know is that thermodynamic entropy has never been fully commensurated with information entropy -- unless someone has a ref otherwise.

Dialup internet did exceed 30kbps -- and that's because the bandwidth of the channel (the copper wire) was not the limiter. That's why DSL works and can in theory reach 1 gbps (https://en.m.wikipedia.org/wiki/Digital_subscriber_line)

I believe it is the channel plus the receiving mechanism plus the sending mechanism plus the encoding mechanism that determine the bandwidth. I am not asserting this, but that is my understanding.

[count]

Dial up internet used an analog transfer domain to encode the information. DSL does not, and is an entirely different technology (and is not 'dial-up').

56kbps modems and the like relied on digital telephone lines. I'm not sure where the 30kbps number comes from though - earlier pre-digital modems did go faster than that. Although you could argue those were 'pre-internet' as well...

[dr_dshiv]

Wait, but that's my whole point -- it's the same channel, but higher bandwidth.

[carrozo]

I keep thinking of this piece:

https://aeon.co/essays/your-brain-does-not-process-informati...

[jkachmar]

I don't particularly like that essay because the author seems focused on the idea that "your brain is a computer" is a metaphor rather than a theory (see [1] for a more nuanced discussion).

The author correctly points out that past eras developed metaphors to explain how the mind might work based on the technological innovations they were familiar with, but I think there's a lot more nuance in the computational theory of the mind.

Namely that the notion of computation is much more abstract, and potentially more portable across disciplines, than some of the historical examples that the author of that Aeon piece brings up.

Anyway, obviously I don't have any real answers but for whatever reason the brain-as-a-computer theory rings pretty true for me and I've enjoyed reading essays and watching talks about the topic [2] [3].

[1] https://medium.com/the-spike/how-to-find-out-if-your-brain-i...

[2] https://medium.com/the-spike/yes-the-brain-is-a-computer-11f...

[3] https://www.youtube.com/watch?v=lKQ0yaEJjok

^-- This is the first part in an ongoing series of lectures that Joscha Bach has been giving at the Chaos Communication Congress; if you watch it and find it interesting you should check out the proceeding installments.

[jv22222]

I followed your links and ended up in this rather excellent essay:

https://medium.com/the-spike/your-cortex-contains-17-billion...

One of the final points the author makes is that the brain might be a neural network made up of as many as 89 million neural networks.

That's a staggering concept.

If true, I wonder how anyone stays sane with that level of entropy in the system!

[Veedrac]

The "neural network of neural networks" thing is a bit of lavish exaggeration TBH, because a network of networks is just a larger network. The human brain has about 100tn synapses, which I think is a less obscure statistic to marvel about.

[feedbeef]

I keep thinking of this:

https://waitbutwhy.com/2017/04/neuralink.html

[codetrotter]

From the page you linked:

> The better we could communicate on a mass scale, the more our species began to function like a single organism, with humanity’s collective knowledge tower as its brain and each individual human brain like a nerve or a muscle fiber in its body. With the era of mass communication upon us, the collective human organism—the Human Colossus—rose into existence.

I like thinking about us this way too, as being both individuals but at the same time also forming a sorts of organism together.

What originally got me thinking about us this way was something that Sun Tzu wrote in his book The Art of War.

I think this might be the part of that book that made me think of it like this:

> The skillful tactician may be likened to the shuai-jan. Now the shuai-jan is a snake that is found in the ChUng mountains. Strike at its head, and you will be attacked by its tail; strike at its tail, and you will be attacked by its head; strike at its middle, and you will be attacked by head and tail both.

> Asked if an army can be made to imitate the shuai-jan, I should answer, Yes. For the men of Wu and the men of Yueh are enemies; yet if they are crossing a river in the same boat and are caught by a storm, they will come to each other's assistance just as the left hand helps the right.

http://classics.mit.edu/Tzu/artwar.html

[feedbeef]

> > With the era of mass communication upon us, the collective human organism . . . rose into existence.

> I like thinking about us this way too, as being both individuals but at the same time also forming a sorts of organism together.

You may be interested in Paul Stamets' thoughts on this, essentially, that the invention of the Internet was an evolutionary inevitability.

https://youtu.be/90vhfdj1zic?t=977

[jv22222]

That is a very provocative article. Actually, I don't quite understand the a-ha moment of the article.

Where he says... "From this simple exercise, we can begin to build the framework of a metaphor-free theory of intelligent human behaviour"

Um, why?

I don't get why the dollar bill example somehow means that we don't store memories in our neurons?

What am I missing?

Thanks in advance for helping me grok this!

[tlb]

Some discussion from 2016: https://news.ycombinator.com/item?id=19352920

[jv22222]

Ah yes, I'm glad it's not just me. Thanks for posting, very helpful.

[grayed-down]

Great piece. Thanks for posting!

[tantalor]

The spinal cord itself is pretty limited in terms of processing power; just reflexes as far as I know. So the comparison between something basic like coax or fiber optic cable is fair.

The piece talks about transmitting 4k movies over nerve fibers. I take that to mean: if you removed the nerve from the body and use it purely as an OSI level 1 physical layer. There is no neural net. There is no processing.

[ladberg]

If you could perfectly simulate a brain down to every atom, why wouldn't it have feelings? It would be indistinguishable from the real thing...

[larkery]

As a thought experiment that might point you toward why some people say not: if you make an atom-perfect simulation of two 1kg spheres orbiting each other in an empty universe, would that produce any gravitation?

[coffeeiscold]

If it was well simulated, yes it would produce simulated gravity. Why should there be any expectation that the simulated reality affect the non simulated reality? If you start down that path then you might conclude that no other person has feelings if it doesn't affect you.

[DennisP]

And the simulation would produce simulated feelings, but that doesn't mean there would actually be qualia.

[coffeeiscold]

By "actually" are you again inferring the requirement for cross over between realities? If the simulated brain was experiencing something, then that "something" is an experience in the frame of the simulation. Or perhaps your argument is that, because WE dont identify the simulated brain as a person its experience is irrelevant?

[DennisP]

By asserting that the simulated brain is "experiencing" something, you're assuming it does have qualia.

We actually have no idea how a bunch of atoms interacting create qualia, or even whether they do. There's no math to tell us that a configuration of atoms makes qualia, or what qualia it makes. We have no way of distinguishing between a conscious being who experiences, and a philosophical zombie with the same behavior but no internal experience.

Therefore we can't know whether a simulation of atoms actually does capture what's necessary for qualia.

[coffeeiscold]

If we are going to doubt something that looks and acts like it has qualia, then the same is true for any other human.

[feanaro]

Even though the analogy is not really valid, the answer is probably yes, because simulation (computation) requires energy.

[jtsiskin]

I don’t see how this analogy holds. Gravitation is a physical effect, of course it can’t be produced by software; feelings are not.

[grayed-down]

I don't understand your rebuttal. Feeling are not a physical effect?

[TheOtherHobbes]

"If"

[swordsmith]

Your issue makes sense when talking about intra-cortical communication between neurons. It is a reasonable thing to speculate, given the right definition, for signal transmission in the peripheral nervous systems -- i.e. what is the bandwidth of the nerve bundle that transmit signals received by the motor neurons that stimulate your hand muscles to contract