Thread

Surprisingly complex waves reveal the brain's inner workings

253 points · 98 comments · ibobev

paimapi · 1790798924 · focus · HN ↗
Bit of a sensationalist title - EEG/iEEG measurements have led to worthwhile clinical outcomes but also are an avenue for bunk pseudosccience so it pays to be careful whenever you see the words 'brain waves' paired with some large claim.
More accurate, much less sexy title: Intracranial Recordings Uncover Spiral and Concentric Brain Waves During Memory Tasks" (study completed only on small cohorts of epilepsy patients performing constrained memory tasks).
No inner workings revealed or laid bare, just another piece of evidence contributing to a small part of the debate in cortical electrophysiological studies on whether or not some data measures can be discarded as the downstream, messy noise of the neurons firing or actual, high-fidelity signals of activity
1. Animats · 1790803315 · focus · HN ↗
  And still all slow stuff, 4 to 12 Hz. There must be something in the brain that clocks faster, but nobody seems to have found it yet.
  1. LoganDark · 1790803455 · focus · HN ↗
    I wouldn't be so sure that the brain necessarily clocks faster than that. I think it's more likely that faster chains of thought are defined by the flow of the waves rather than their frequency.
  2. mr_toad · 1790806152 · focus · HN ↗
    Seems to be pretty much in line with human reaction times?
  3. TeMPOraL · 1790807710 · focus · HN ↗
    It's way out of my area of expertise, but my suspicion is that all these 4-12 Hz waves bouncing around in a 3D structure may be interfering to produce signals that tick much faster, and some functionality of the brain is clocked on that.
    There's this thing called "scissor effect", where when you have two wavefronts colliding at an angle, you get an apparent wave that moves much faster than either of the input waves - if you do that with light, you can trivially exceed the speed of light. Now this isn't an information-carrying wave, but I believe you can still use this phenomenon as a "virtual clock", to synchronize a bunch of independent receivers to act on a frequency faster than the real, interfering clock signals.
    Well, that, or the brain is just such a mess that it acts as a spread-spectrum source and none of the high frequencies are above the noise floor.
    EDIT: and of course a little background research after writing this comment revealed it's already settled (through more invasive probing) that the human brain has elements operating in kilohertz range - the mystery isn't whether this happens, but how it adds up to cognition and consciousness.
  4. ACCount39 · 1790809153 · focus · HN ↗
    There are faster waves than that, but the brain just doesn't seem to be fully synchronous. It doesn't have to have a fast "clock tree" if a lot of the low timescale activity is inherently async.
    It's not at all how humans build computational devices. But humans run digital signals at gigahertz rates and do intelligent design. Nature doesn't do either.
    I suspect that there are numerous advantages to silicon computation that biological neurons can't touch, but the brain is no slouch either - it was optimized for millions of years to be good for what it does. It's very good at what it does - sometimes because of, and sometimes despite its architecture.
    It's honestly amazing that the brain even works as well as it does, given how slow neurons are. I suspect that distributed population coding that seems to be endemic to neural networks can also serve as a workaround for neurons being unreliable, slow to recover and subject to fatigue.
    randomImmigrant · 1790827542 · focus · HN ↗
    > if a lot of the low timescale activity is inherently async.
    But it isn’t. Every neuron runs the core circadian transcription-translation feedback oscillations. Every neuron is on a roughly 24 hour loop, synchronized by the master circadian oscillator, a clump of about 20k cells called the Suprachiasmatic nucleus.
    The faster oscillations nest under that one, including the oscillations in firing rates.
    Jet lag is when the synchrony and phase hierarchy breaks. Shift work does the same.
    Now the brain doesn’t have a fast global clock like a chip. But that’s very much part of the evolutionary design. It’s not very energy efficient to have a fast global clock. And in a system like the brain, what purpose would it serve? In the brain, timing is information. You want the slow arrival of some signal to be slow so you can actually assign some meaning to it. A fast global clock would throw those gaps away.
    In fact, there are neuromorphic and RACE logic chips that dump the global clock for the same efficiency reasons.
    ACCount39 · 1790839987 · focus · HN ↗
    Being clocked by the day-night cycle is very much not low timescale.
    randomImmigrant · 1790865718 · focus · HN ↗
    Yes. But you don’t want synchrony in low timescale in a system like the brain, where synchrony in long time scales is constantly being negotiated between the cells, and kept in sync with the environment.
  5. rhyperior · 1790816297 · focus · HN ↗
    What makes you think that a clock-timing analogy even applies to brains doing work?
  6. randomImmigrant · 1790827983 · focus · HN ↗
    Gamma waves go up to 100 Hz. High gamma and ripples measured deeper in the brain during memory consolidation can briefly fire up to 200 Hz.
    But speed isn’t all that useful, here. Neuronal activity is slow, but you can cancel it out, and control it mid firing. You have subdendritic and sub-axonal processing, so you can shoot off a signal, then tamp it down as it’s traveling, or ramp it up for some stretches of your axon, etc. Getting message fastest from cell A to cell B isn’t what we’ve needed. Rather, you get rich information that can have all kinds of impacts on cells along the way.
  7. b00ty4breakfast · 1790832627 · focus · HN ↗
    what makes you think that brains are comparable to man-made computers in this regard?
2. plastic-enjoyer · 1790805520 · focus · HN ↗
  >also are an avenue for bunk pseudosccience so it pays to be careful whenever you see the words 'brain waves' paired with some large claim.
  What makes you make such an accusation?
  1. Scrapemist · 1790806966 · focus · HN ↗
    His brain waves
  2. paimapi · 1790807404 · focus · HN ↗
    this was the first web search result for brain wave pseudoscience:
    <a href="https://sciencebasedmedicine.org/brain-wave-pseudoscience/" rel="nofollow">https://sciencebasedmedicine.org/brain-wave-pseudoscience/
  3. jibalt · 1790850407 · focus · HN ↗
    Numerous well known facts.
3. bbor · 1790808087 · focus · HN ↗
  Idk… I follow EEG science pretty closely now that the BCI industry is exploding post-DL, and this seems like a very accurate title.
  Inner workings are indeed being uncovered; what would that look like, if not this…? We’re not going to find, like, a blueprint hidden in there somewhere with marginalia from god. Spiral and concentric brainwaves sound pretty damn compelling and specific, not just a tweak of our definition of noise in this data.
  A better piece of evidence is that this is quanta. I’ve literally never seen a sensationalist or inaccurate or less than fascinating article make it to their site. I’m gonna need a ton more critique from randos on HN to seriously consider that this might be the first.
  BTW, hug your loved ones, y’all. EEG has been mostly bunk applications for consumers/non-scientists for years, like “biofeedback” therapy, but we are now extremely likely to see the first polygraph that actually works in our lifetimes, not to mention all the other crazy shit. Imagine how seriously things change when every government can load a truth-telling helmet into every cop car :(
  On the upside it’ll make for some wild HCI someday, perhaps, if we make it that far. The scene from Westworld S04 (my favorite piece of lost media) with Dolores creating a 3d narrative world with words and gestures that matches what she’s envisioning comes to mind, for one thing… the dream.
  1. cpill · 1790821104 · focus · HN ↗
    wow, they made a forth session of West world...?
4. pedalpete · 1790812234 · focus · HN ↗
  I work in neurotech and specifically with EEG, some would find it surprising that I 100% agree with this take.
  When we understood the world of fluid-dynamics, we looked at the body as blood going through a pump delivering materials (oxygen, minerals, etc) to different parts of the body. We though to ourselves "we know how this works!".
  Then we discovered electricity, slapped our collective foreheads and said "oh! It's electrical!" now I get it.
  We still don't.
  Let's learn what we can from what we can and use this knowledge to our benefit, but let's not assume we understand the underlying mechanisms just because we can find correlations.
  1. randomImmigrant · 1790827297 · focus · HN ↗
    Well put!
    We’re finding out though that the brain is, yes, a fluid dynamic system, an electromagnetic system (though we know way less about the magnetism that we’d like), AND a mechanical system. Wonder how many more ands we’d have to add by the time we figure it out.
  2. TeMPOraL · 1790842838 · focus · HN ↗
    We were not wrong, though. Major functional component of the body is the pump pushing around a fluid that distributes materials around the body. Electricity is another functional layer. And on top of the fluidic layer, it turned out many of the disributed material aren't inert building block, but chemical signals and machines, too.
    I think the main error is in people trying to explain a complex machine through one mode of "how it works". The second error is people trying to accuse other people of doing that.
    Today, anyone with half a brain and an ounce of interest could look at any of the large machines that operate in their environment - buses, trains, construction equipment - and quickly discover that such machines have fluids being pumped, air being pumped, mechanical linkages and electric circuits used for both power delivery and control, many or all of these things having - at a higher level - feedback loops designed in for autonomous control/self-balancing, and of course there's a whole economic and social layer on top, that's key to explaining why the machine works the way it does.
    Why wouldn't it be any different with the human body?
    pedalpete · 1790850734 · focus · HN ↗
    The point is not that these ideas were wrong, but that they were incomplete, yet were assumed to be complete.
    Anamon · 1791023660 · focus · HN ↗
    We're at the point of one such being mainstream-popular again.
    "I get it, the brain is just an LLM!"

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