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Neurons unexpectedly encode information in the timing of their firing

quantamagazine.org

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

#41

Post by l33t2328 »

BitwiseFool wrote: post #8
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 had a crazy idea about neurons that I'll share here, because why not? What if each time a neuron sends a signal to another neuron the potential required for that connection decreases slightly? So the next time there's an action potential between neurons it's more likely to go where it has already gone. In other words, frequent connections make that same pathway more readily traversed. Could it be that a memory is s…

Is this not the idea of a synapse? A pathway that is easier to take because it has been taken before?

I only have an AI understanding here, so this could be too simple.

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

#42

Post by [deleted] »

im3w1l wrote: post #35
alexmorley wrote: post #14

> For decades, neuroscientists have treated the brain somewhat like a Geiger counter: The rate at which neurons fire is taken as a measure of activity, just as a Geiger counter’s click rate indicates the strength of radiation. This hasn't been true for at least 20 years. There's a classic paper showing evidence of this in 1993 (O'Keefe and Reece) in rats. And has been an active area of discussion both before and sinc…

https://en.wikipedia.org/wiki/Neural_coding is pretty good too.

[deleted]

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

#43

Post by HarHarVeryFunny »

munificent wrote: post #32
londons_explore wrote: post #26

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. Kidneys probably meet that criteria - we have dialysis machines which allow someone to survive without kidneys almost perfectly. Yet the idea of replacing someones brain with something artificial and having them function as normal is still a LOOOOOOONG way off.

> 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…

Evolution is an incremental mechanism, which is to say that it preserves most of what it has previously done (DNA encoded) and just makes small changes on top of that. IOW it is essentially structure preserving, and any change that undoes anything that still has value is likely to be maladaptive and not preserved (as opposed to repurposing of gills into ears, etc, where the original function is not being used).

Of course evolution is also messy and isn't operating out of a playbook of decomposable single-function parts. Experiments with evolving electronic hardware have resulted in circuits taking advantage of all sorts of nasty non-linear analog effects, as you might expect.

Still, given the inherently incremental nature of evolution, it is highly likely to result in a system of parts operating with some degree of independence to each other. While there are still many aspects of the brain's functioning we don't understand, it's pretty apparent that it is composed of functional parts like this - cortex, hippocampus, cerebellum, basal ganglia, etc.

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

#44

Post by mstipetic »

meowkit wrote: post #21
mstipetic wrote: post #13

Earlier quoted context omitted.

I have a completely layman theory that that’s what dreams are. Worn out pathways that our ego or consciousness is not letting through to us, but are being used in our subconscious, being able to manifest themselves finally. That’s why we can see things that are bothering us or on our mind in the background there

https://www.biorxiv.org/content/10.1101/2020.07.24.219089v1 It’s recently suggested there is nothing special about dreaming - its just a confluence of himan interpretation with a mechanism to stop you from going blind.

When I went to a therapist and we went to analyze my dreams it got weird how many details and meanings one could find there

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

#46

Post by Robotbeat »

munificent wrote: post #32
londons_explore wrote: post #26

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. Kidneys probably meet that criteria - we have dialysis machines which allow someone to survive without kidneys almost perfectly. Yet the idea of replacing someones brain with something artificial and having them function as normal is still a LOOOOOOONG way off.

> 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 evolution with all its messiness, but yet it DOES have some reducible complexity. There really is DNA that is transcribed via certain molecules to RNA which is transcribed by other molecules into protein via a sequence of certain amino acids coded by the DNA base pairs. There is reducible complexity in spite of the crazy messiness of evolution, and it ends up looking a lot like some of our engineered systems in some instances (ie we can use the language of information theory and bits to describe encoding of genomes). We are able to use this to actually develop vaccines specifically using mRNA as a delivery mechanism, with specific, engineered changes to the transcribed viral protein spike to improve the vaccine’s effectiveness.

What I see in neuroscience looks a lot like genomics and inheritance before the discovery of DNA. And the insistence that “biological systems are entirely non reducible complexity” feels just a bit too much like a cop-out. This is not magic. If you are a neuroscientist optimistic about the field, then you must also believe there is some reducible complexity in there that will be discovered. I do get the feeling, based on research progress like in this article, that there really are some breakthroughs coming in really understanding what’s going on.

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

#47

Post by bena »

stinos wrote: post #39
bena wrote: post #30

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. 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.

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.

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

#48

Post by bena »

nosianu wrote: post #31
bena wrote: post #30

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. 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.

You might want to ask Google about two-photon microscopy links. Example papers: https://pubmed.ncbi.nlm.nih.gov/25391792/ -- "Two-photon excitation microscopy and its applications in neuroscience" https://www.nature.com/articles/s41598-018-26326-3 -- "Three dimensional two-photon brain imaging in freely moving mice using a miniature fiber coupled microscope with active axial-scanning" Sure, it's localized and you can…

So my point remains. I'm not saying there's nothing to learn. I'm saying that we cannot go deep. That we currently cannot understand the brain to the degree we understand other systems. And that there are fundamental difficulties because we're dealing with living beings.

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

#49

Post by tgbugs »

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 more to it than just averaging spike counts per unit time???"

edit: Hah, they are literally the first two headings in the wikipedia article on neural coding [0].

0. https://en.wikipedia.org/wiki/Neural_coding

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

#50

Post by mensetmanusman »

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 wish we had a large research effort on just trying to understand a cpu running windows 98.

E.g. put all of our best analysis tools to task against an operating pentium chip and see if we can determine from first principals that it is running a W98 screen saver.

That would give us a small sense of the challenge we are facing.

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