5 ms·

I reject the premise that the nervous system has "bandwidth" in a sense comparable to digital communications. Yes, nerves fire in discrete action potentials, b

by garbre 7y ago

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.

carrozo 7y ago
I keep thinking of this piece: https://aeon.co/essays/your-brain-does-not-process-information-and-it-is-not-a-computer https://aeon.co/essays/your-brain-does-not-process-informati...
- feedbeef 7y ago
  I keep thinking of this: https://waitbutwhy.com/2017/04/neuralink.html https://waitbutwhy.com/2017/04/neuralink.html
  - codetrotter 7y ago
    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 http://classics.mit.edu/Tzu/artwar.html
    - feedbeef 7y ago
      > > 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 https://youtu.be/90vhfdj1zic?t=977
- jkachmar 7y ago
  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-is-a-computer-644a1a4fed1b 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-11f630cad736 https://medium.com/the-spike/yes-the-brain-is-a-computer-11f... [3] https://www.youtube.com/watch?v=lKQ0yaEJjok 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 7y ago
    I followed your links and ended up in this rather excellent essay: https://medium.com/the-spike/your-cortex-contains-17-billion-computers-9034e42d34f2 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 7y ago
      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.
- jv22222 7y ago
  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 7y ago
    Some discussion from 2016: https://news.ycombinator.com/item?id=19352920 https://news.ycombinator.com/item?id=19352920
    - jv22222 7y ago
      Ah yes, I'm glad it's not just me. Thanks for posting, very helpful.
- grayed-down 7y ago
  Great piece. Thanks for posting!
Veedrac 7y ago
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 7y ago
  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 7y ago
    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.
    - dr_dshiv 7y ago
      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 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.
ladberg 7y ago
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...
- TheOtherHobbes 7y ago
  "If"
- larkery 7y ago
  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?
  - jtsiskin 7y ago
    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 7y ago
      I don't understand your rebuttal. Feeling are not a physical effect?
  - feanaro 7y ago
    Even though the analogy is not really valid, the answer is probably yes, because simulation (computation) requires energy.
  - coffeeiscold 7y ago
    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.
    - 7y ago
tantalor 7y ago
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.
swordsmith 7y ago
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

by garbre 7y ago

carrozo 7y ago

I keep thinking of this piece: https://aeon.co/essays/your-brain-does-not-process-information-and-it-is-not-a-computer https://aeon.co/essays/your-brain-does-not-process-informati...

feedbeef 7y ago
I keep thinking of this: https://waitbutwhy.com/2017/04/neuralink.html https://waitbutwhy.com/2017/04/neuralink.html
- codetrotter 7y ago
  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 http://classics.mit.edu/Tzu/artwar.html
  - feedbeef 7y ago
    > > 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 https://youtu.be/90vhfdj1zic?t=977
jkachmar 7y ago
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-is-a-computer-644a1a4fed1b 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-11f630cad736 https://medium.com/the-spike/yes-the-brain-is-a-computer-11f... [3] https://www.youtube.com/watch?v=lKQ0yaEJjok 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 7y ago
  I followed your links and ended up in this rather excellent essay: https://medium.com/the-spike/your-cortex-contains-17-billion-computers-9034e42d34f2 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 7y ago
    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.
jv22222 7y ago
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 7y ago
  Some discussion from 2016: https://news.ycombinator.com/item?id=19352920 https://news.ycombinator.com/item?id=19352920
  - jv22222 7y ago
    Ah yes, I'm glad it's not just me. Thanks for posting, very helpful.
grayed-down 7y ago
Great piece. Thanks for posting!

Veedrac 7y ago

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 7y ago
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 7y ago
  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.
  - dr_dshiv 7y ago
    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 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.

ladberg 7y ago

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...

TheOtherHobbes 7y ago
"If"
larkery 7y ago
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?
- jtsiskin 7y ago
  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 7y ago
    I don't understand your rebuttal. Feeling are not a physical effect?
- feanaro 7y ago
  Even though the analogy is not really valid, the answer is probably yes, because simulation (computation) requires energy.
- coffeeiscold 7y ago
  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.
  - 7y ago

tantalor 7y ago

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.

swordsmith 7y ago

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