Neurons unexpectedly encode information in the timing of their firing • Hacker News Board

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

#21

Post by meowkit » Wed, Jul 07, 2021, 4:36 PM UTC

mstipetic wrote: post #13

BitwiseFool wrote: post #8

Earlier quoted context omitted.

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…

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.

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

#22

Post by vincent-toups » Wed, Jul 07, 2021, 4:37 PM UTC

This is what (mediocre) my PhD thesis was about.

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

#23

Post by seg_lol » Wed, Jul 07, 2021, 4:40 PM UTC

radicaldreamer wrote: post #6

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…

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.

Reverse lamp post? We don't routinely take MRIs because of false positives, meaning we might have more questions than answers so we won't ask.

Seems like neuroscience is still in the phase of reducing misunderstanding.

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

#24

Post by hall0ween » Wed, Jul 07, 2021, 4:40 PM UTC

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…

Agreed, that opening line suits neuroscience poorly. "For decades, meteorologists have treated the environment somewhat like a Geiger counter: the temperature is taken as a measure of energy, just as a...", it's ludicrous!

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

#25

Post by vincent-toups » Wed, Jul 07, 2021, 4:41 PM UTC

morpheos137 wrote: post #12

why is this unexpected?

The usual story is that neuron were initially characterized experimentally using current injections to which their firing times are (in a certain sense) maximally disordered and thus the response is characterized only by firing rate.

This idea is also born out in most real neural systems, where firing rate is well correlated with various sorts of feature presentation.

But at faster timescales other things seem to be going on.

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

#26

Post by londons_explore » Wed, Jul 07, 2021, 4:44 PM UTC

stinos wrote: post #7

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…

it just feels like often we don’t have a solid (falsifiable, etc) grasp of what’s actually happening, yet… It feels like that, because it is like that: there's probably way more which isn't known about the brain yet, than things known with a decent amount of certainty. Just skimming over recent papers in the fundamental area, a lot of that summarizes as 'So here we found that area A is connected to area B and modulat…

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.

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

#27

Post by cosmojg » Wed, Jul 07, 2021, 5:01 PM UTC

This has been somewhere between highly suspected and well established for a few decades now, certainly not unexpected. These findings simply back up the present consensus.

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

#28

Post by [deleted] » Wed, Jul 07, 2021, 5:02 PM UTC

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…

[deleted]

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

#29

Post by HarHarVeryFunny » Wed, Jul 07, 2021, 5:09 PM UTC

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 a consistent pattern over time, but neurons fire inconsistently, at different points on the wave’s trajectory. In this way, brain waves act like a clock, said one of the study’s coauthors, Salman Qasim, also of Columbia. They let neurons time their firings precisely so that they’ll land in range of other neurons’ firing — thereby forging connections between neurons."

My understanding of what they're saying is that it's related to "neurons that fire together wire together". Given different signal travel distances, it's necessary for neurons to fire at different times if they're to arrive at a given destination at the same time (in order to "wire together"). They achieve this timing by firing in synchrony with the theta brain waves that travel across regions.

So, with this understanding, I guess you could say the timing is encoding information, but really in essence it's only the relative spatial position - within the cortex - of the firing neuron that's being "encoded". A more useful way to view it is just that firing times are synchronized to theta waves in order to achieve larger scale coordination that compensates for signal travel distances.

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

#30

Post by bena » Wed, Jul 07, 2021, 5:10 PM UTC

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.