[HN Gopher] Scientists discover mechanism of hearing
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Scientists discover mechanism of hearing
Author : thunderbong
Score : 87 points
Date : 2022-10-16 13:28 UTC (9 hours ago)
(HTM) web link (news.ohsu.edu)
(TXT) w3m dump (news.ohsu.edu)
| 1letterunixname wrote:
| WHAT?! :> I'm at ACL and can't hear a fucking thing. ;)
|
| I wonder about the limits of the muscles of the eardrum (TT and
| stapedius) to prevent hearing damage. For example, I recall
| awaking one morning being unable to hear because those muscles
| were isometrically flexing to a degree that prevented the eardrum
| from move normally. I thought I lost my hearing but then they
| started to relax over a few minutes.
|
| I don't know if anyone else can, but I can consciously make both
| eardrums vibrate creating a sound like a rumble.
|
| Last thing: I can hear my left eye move. I have a SCDS that I was
| able to identify myself as it's the only condition with this rare
| symptom. There is a tiny hole in the thin, porous bone between my
| inner ear and brain. It can be fixed surgically but requires
| brain surgery that effectively jacks the brain up and out of the
| way to be repaired by a surgical otolaryngologist. Eating chips
| is horrendously loud. Exercising leads to hearing my pulse. The
| risks of surgery though make me think it's worth enduring
| annoyances, although I don't know if it's causing extra cognitive
| load (distraction filtering) or balance problems. Oh and tinnitus
| from hell.. REEEEEE.
| 9wzYQbTYsAIc wrote:
| > I can consciously make both eardrums vibrate creating a sound
| like a rumble
|
| I can as well when I consciously try to pop my ear drums.
| [deleted]
| swayvil wrote:
| Was it always a big mystery?
|
| Or did we think we understood it the whole time, but only just
| recently discovered that we actually didn't?
| ncr100 wrote:
| Mystery.
|
| According to the article and the paper we now have a clear
| understanding of how it works - the proteins in worms (which
| are similar to humans in their hearing structures) and their
| function.
|
| So, unless I misread it, we absolutely know how sound > neural
| impulse works.
|
| More:
|
| > The initial step in the sensory transduction pathway
| underpinning hearing and balance in mammals involves the
| conversion of force into the gating of a mechanosensory
| transduction channel1. Despite the profound socioeconomic
| impacts of hearing disorders and the fundamental biological
| significance of understanding mechanosensory transduction, the
| composition, structure and mechanism of the mechanosensory
| transduction complex have remained poorly characterized. Here
| we report the single-particle cryo-electron microscopy
| structure of the native transmembrane channel-like protein 1
| (TMC-1) mechanosensory transduction complex isolated from
| Caenorhabditis elegans. The two-fold symmetric complex is
| composed of two copies each of the pore-forming TMC-1 subunit,
| the calcium-binding protein CALM-1 and the transmembrane inner
| ear protein TMIE. CALM-1 makes extensive contacts with the
| cytoplasmic face of the TMC-1 subunits, whereas the single-pass
| TMIE subunits reside on the periphery of the complex, poised
| like the handles of an accordion. A subset of complexes
| additionally includes a single arrestin-like protein, arrestin
| domain protein (ARRD-6), bound to a CALM-1 subunit. Single-
| particle reconstructions and molecular dynamics simulations
| show how the mechanosensory transduction complex deforms the
| membrane bilayer and suggest crucial roles for lipid-protein
| interactions in the mechanism by which mechanical force is
| transduced to ion channel gating.
|
| https://www.nature.com/articles/s41586-022-05314-8
| thelittleone wrote:
| Wow. For some reason I had always assumed worms cannot hear.
| vanderZwan wrote:
| I never thought about it before but if someone had asked me
| I probably would have guessed the same - humans are
| probably biased to assume hearing must involve ears.
|
| OTOH, detection of mechanical vibrations seems like the
| kind of adaptation to evolve early. Hearing is in some
| sense just a refinement of that, so at the very least the
| groundwork for it must be old.
| myself248 wrote:
| Smell (chemical environment) was probably the "original"
| sense, followed quickly by touch (slow macro pressure) and
| hearing (fast micro pressure). Pretty much every animal has
| those, even if they lack the brains to do much
| sophisticated with them.
|
| Sight came way, way, way, way, way, way, way later.
| Encoding language in sounds is an even more recent
| innovation, in the grand scheme.
|
| This may also be why we have such trouble assigning words
| to smells, and you can't write a poem to replace a hug, for
| instance. They're processed by entirely different, and far
| more primal, parts of the brain than language.
| swayvil wrote:
| >So, unless I misread it, we absolutely know how sound >
| neural impulse works
|
| Am I being unclear?
|
| I asked : did we always consider it to be a mystery? Or did
| we have a different model before? (Which just recently got
| replaced by this new, better, model)
| jcims wrote:
| Read the first word of the reply you're questioning.
| swayvil wrote:
| But then he says all that other stuff.
| etiam wrote:
| A good deal of this appears, in my opinion, to be the press
| release overselling what has been done in research with their
| employees involved now being published in Nature. The function
| on physical and physiological levels has largely been well
| understood and that knowledge still stands in the light of this
| publication.
|
| What the researchers are reporting appears to be a more
| detailed structural description of this sensory protein
| complex, and the additional structure information combined with
| simulations of known physics and chemistry in turn suggests
| additional detail about of how the "signal" occurs on the
| molecular level.
|
| Disclaimer that I didn't take time to read the whole thing now,
| but that's the gist of it from summaries and skimming.
|
| It is, with little doubt, some valuable pieces of information
| in the context Collective Knowledge of Mankind, and keeping
| large, complex, multipart molecular machines like this
| reasonably stable and normal for examination is arduous work,
| so I don't mean to denigrate the studies or the scientific
| paper, but as so often the way this is being spun in the press
| release is regrettable.
| formerly_proven wrote:
| Hearing is kind of fascinating if you calculate the power
| supplied to the eardrum in the ~0 dB range, we're talking about
| attowatts of sound power generating movements in the single-digit
| nanometer range, which is still picked up and converted to a
| neuronal response. Meanwhile the whole thing suppresses the far
| greater pressure fluctuations due to your heartbeat and other
| movements quite well, and can reasonably cope with a ~120 dB
| dynamic range (though this is damaging fairly quickly).
| xani_ wrote:
| And it does FFT in realtime too
| TaupeRanger wrote:
| It does extract frequency information but not via FFT. Just
| like the brain computes but not via Turing Machine.
| accountofme wrote:
| The brain doesn't compute it, the cochlear is an fft! It is
| a cone shaped structure (that is curled up) that is covered
| in hairs and neurons. The fatter end is used for low freq
| and the thinner end is used for hi freq. So the brain takes
| audio in the frequency domain, not as continuous samples!
|
| (I did an Anatomy degree almost 20years ago now, all from
| memory)
| BurningFrog wrote:
| Our hearing is vastly better than our sight.
|
| Human hearing can distinguish thousand of individual
| frequencies, with the highest frequency 1000x the lowest.
|
| Human sight can distinguish 3 broad frequency regions, with the
| highest frequency 2x the lowest.
|
| Where vision shines is distinguishing _where_ the signal comes
| from.
| lr4444lr wrote:
| How do you know those noises are suppressed and not just
| neurologically "filtered out" by the auditory cortex?
| nightfly wrote:
| leephillips wrote:
| As it is said in the article, "Scientists exploited the fact
| that the roundworm Caenorhabditis elegans harbors a
| mechanosensory complex very similar to that of humans." So, not
| only in worms.
| yjftsjthsd-h wrote:
| > very similar to that of humans.
|
| I hope it matches, of course, but I've seen enough rat
| studies to feel like that's weasel wording.
| tgv wrote:
| This isn't about a drug. Those have some very specific
| conditions under which they have to do their thing. This is
| about a mechanism for transducing oscillatory forces to a
| neuronal signal, and it describes the exact structure.
| There are still holes in the pathway, but it looks very
| interesting to me, and (from my lay understanding) generic
| enough. You wouldn't say that a study into a rat's retina
| is completely irrelevant to human eye sight, would you?
| yjftsjthsd-h wrote:
| > You wouldn't say that a study into a rat's retina is
| completely irrelevant to human eye sight, would you?
|
| Er, probably? Not _completely_ irrelevant, and perfectly
| valuable in laying out the groundwork for how we suspect
| things might work, but I also wouldn 't trust it until
| somebody had it separately verified that human retinas
| actually worked the same way.
|
| > and (from my lay understanding) generic enough
|
| Yes, _if_ that 's true then it's interesting. I'm just
| extremely cautious of assuming that the things in
| question are in fact the same. I think the drug analogy
| does in fact hold, because if the mechanisms were the
| same them I would expect artificially chemically altering
| them to play out the same. And also in fairness, that
| frequently does work! But it also doesn't work in many
| cases, hence my being extremely cautious until somebody
| actually does the leg work to verify that humans are
| actually the same.
| perth wrote:
| Is it true that rabbit's eyes are pretty close in
| structure to that of a human?
| tgv wrote:
| Mammals have similar retinas, but they've specialized
| differently. IIRC, the wiring to the visual cortex is
| also similar, including the optic chiasm.
| canadiantim wrote:
| The same mechanism is conserved in humans too, so this will
| directly impact our ability to help people with hearing
| disabilities.
| [deleted]
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