Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Neurons unexpectedly encode information in the timing of their firing

quantamagazine.org

Post reply on HN
Print view View original

51–60 of 116 posts

Re: Neurons unexpectedly encode information in the timing of their firing

#51

Post by sdwr »

HarHarVeryFunny wrote: post #29

The headline seems to be somewhat at odds with explanation of this "phase precession" is the body of the article: "The phenomenon is called phase precession. It’s a relationship between the continuous rhythm of a brain wave — the overall ebb and flow of electrical signaling in an area of the brain — and the specific moments that neurons in that brain area activate. A theta brain wave, for instance, rises and falls in…

Fire together, wire together refers to the connection between two neurons strengthening.

Firing just before the recipient neuron fires strengthens the bond, and firing afterwards/off tempo weakens the bond.

It's an elegant concept, because it handles neural weights, a non-linear activation function, and clock speed with a simple, distributed rule.

Re: Neurons unexpectedly encode information in the timing of their firing

#52

Post by stinos »

bena wrote: post #47
stinos wrote: post #39

Earlier quoted context omitted.

I mean, we can't really completely inspect a working brain to see what's happening. To get that level of inspection, we'd need to dig into the brain while it is functioning. Unfortunately, this kills the patient Leave out the completely and it's a different story though: it's perfectly possible to 'dig in while functioning' i.e. inspect small parts using electrode arrays and that will not kill the patient and only do…

That's kind of why I said completely. Our ability to know how a brain works on the level of how well we know, say, the combustion engine works is severely limited by the fact that we're dealing with living beings and that the state of consciousness of the subject matters.

That's kind of why I said completely.

Sort of, but to people not knowing anything about it it might sound as if it's impossible to do anything at all in vivo so I added some information about what is possible if you do not want a 'complete' recording.

Re: Neurons unexpectedly encode information in the timing of their firing

#54

Post by skohan »

tgbugs wrote: post #49

Rate coding vs temporal coding is literally a meme in neuroscience because the two camps seem to refuse to compromise. Everyone else has realized that both happen depending on how that particular part of the nervous system works, or even what particular kind of information is flowing through it. This title reads like it was written by a rate coder who woke up one day and was like "Woah, you mean ... there might be mo…

I feel like the more you learn about neuroscience, the more you learn how precise and complex neural information processing is. For instance, there's evidence that at least some neurons "record" information about their activity in the form of RNA. Also the placement of synapses in the dendritic arbour matters, and some synapses can act like logic gates with respect to the synapses farther down the same branches.

I think there almost certainly must be neural behavior which codes fairly simply based on rate, but it's very difficult to believe that there isn't neural computation based on precise timing relationships.

Re: Neurons unexpectedly encode information in the timing of their firing

#55

Post by HarHarVeryFunny »

sdwr wrote: post #51
HarHarVeryFunny wrote: post #29

The headline seems to be somewhat at odds with explanation of this "phase precession" is the body of the article: "The phenomenon is called phase precession. It’s a relationship between the continuous rhythm of a brain wave — the overall ebb and flow of electrical signaling in an area of the brain — and the specific moments that neurons in that brain area activate. A theta brain wave, for instance, rises and falls in…

Fire together, wire together refers to the connection between two neurons strengthening. Firing just before the recipient neuron fires strengthens the bond, and firing afterwards/off tempo weakens the bond. It's an elegant concept, because it handles neural weights, a non-linear activation function, and clock speed with a simple, distributed rule.

Right, but first the "recipient" neuron needs to fire, which requires integrated synaptic inputs to cross some threshold, which requires input spikes to arrive close to the same time.

This phase precession mechanism being discussed is what allows inputs arriving from different distances (i.e. with different signal travel times) to arrive close to the same time such that the recipient fires. Once it fires, then "fire together, wire together" can strengthen/weaken the synapses as appropriate.

Re: Neurons unexpectedly encode information in the timing of their firing

#57

Post by HarHarVeryFunny »

bena wrote: post #30
Robotbeat wrote: post #4

I find a lot of the common explanations of how the brain works in neuroscience to be unsatisfying… compared to molecular biology, it just feels like often we don’t have a solid (falsifiable, etc) grasp of what’s actually happening, yet… too much handwaving (for instance, the lack of any specifics on where precisely some data is located… even “it’s stored in the connections” seems not quite true or falsifiable… althou…

I mean, we can't really completely inspect a working brain to see what's happening. To get that level of inspection, we'd need to dig into the brain while it is functioning. Unfortunately, this kills the patient. And then the brain stops working. It's a black box essentially. We have tools that allow us some degree of insight, but honestly, it is incredibly difficult and progress is slow and staggered.

That's what rats are for. For some experiments the research animal will be immediately "sacrificed" then have it's brain sliced and diced for inspection. Brings a whole new meaning to "thank you for your service".

Re: Neurons unexpectedly encode information in the timing of their firing

#58

Post by rewq4321 »

skohan wrote: post #54
tgbugs wrote: post #49

Rate coding vs temporal coding is literally a meme in neuroscience because the two camps seem to refuse to compromise. Everyone else has realized that both happen depending on how that particular part of the nervous system works, or even what particular kind of information is flowing through it. This title reads like it was written by a rate coder who woke up one day and was like "Woah, you mean ... there might be mo…

I feel like the more you learn about neuroscience, the more you learn how precise and complex neural information processing is. For instance, there's evidence that at least some neurons "record" information about their activity in the form of RNA. Also the placement of synapses in the dendritic arbour matters, and some synapses can act like logic gates with respect to the synapses farther down the same branches. I th…

> there's evidence that at least some neurons "record" information about their activity in the form of RNA

Source? I'm not a neuroscientist, but I'd have thought that I'd have heard of this if there were legit evidence. Are you saying that neurons might use RNA as a sort of "long-term" memory of activation patterns? This seems really unlikely! But again, I'm not a neuroscientist.

Re: Neurons unexpectedly encode information in the timing of their firing

#59

Post by airstrike »

mikewarot wrote: post #16
radicaldreamer wrote: post #6

Earlier quoted context omitted.

There’s a strong bias toward things that are model-able in neuroscience. The role of microtubules, for example, are mostly ignored even though they may explain the complexity of cognition displayed by relatively “simple” brains.

Fringe Tangent: It's possible those microtubules in our brains are 1 dimensional superconductors, and thus might be capable of holding Qubits. We might have quantum memory. https://arxiv.org/ftp/arxiv/papers/1812/1812.05602.pdf

This is why I come to HN daily. Thanks for the very interesting read.

Re: Neurons unexpectedly encode information in the timing of their firing

#60

Post by munificent »

Robotbeat wrote: post #46
munificent wrote: post #32

Earlier quoted context omitted.

> My benchmark of "this thing is well understood" is that it's possible to build that thing, or a replacement for it, again. Something I've been thinking a lot about lately: Implicit in statements like this is the idea of a system . That some complex-seeming artifact is actually composed of a relatively smaller number of essential things and all of the observed complexity is just emergent properties of the simpler un…

> but there may simply be no "first principles" for what makes an organism tick and almost all of its complexity may be irreducible. There may be absolutely no separation between "fundamental property" and "implementation detail". It may be that no terms in the grand equation of life cancel out. But this is NOT true of all biology. I picked molecular biology as an example for exactly this reason. It’s driven by evolu…

> And the insistence that “biological systems are entirely non reducible complexity” feels just a bit too much like a cop-out.

What insistence do you refer to?

Post reply on HN