You write that "The olfactory bulb can vary in size by up to 3x, depending on "age and olfactory experience", so perhaps (we're making this up) with more usage your olfactory bulb might actually get bigger" which certainly does not seem out of the question. What we can assume with even greater likelihood is that the sense of smell works better when regularly stimulated. Even if your method did not have any commercial applications in entertainment it could likely (at least if this method scales beyond 4 distinct sensations) have therapeutic potential for people who suffer from blocked noses, chronic sinusitis, allergies or other conditions that block their sense of smell for physical reasons. It might even be used by Sommeliers to retain the capacity for their tradecraft while unable to use their actual nose while suffering from a cold. As we know that there is a strong association between smell and memory there are many other useful therapeutic and educational applications that come to mind if this technology can be made safe for broader consumer use. Right now, regardless of protocols used, you are somewhere on the spectrum between shining nascent lasers at your eyes to determine whether they work and emit light output (which doesn't scale with an increase in power) and the nobel prize worthy quadrant of Jonas Salk and Barry Marshall. While I do hope you succeed and I'd hate for you to be overly cautious I also hope your (olfactory) neurons survive!
As someone who was born without a sense of smell this is incredibly intriguing to me.
I've always wondered if there's gonna be a time in my life where I'd be able to experience *any* kind of smell through some new scientific discovery. And maybe this is it.
Could I shoot you guys a message when I make my way down to Caltech to try this out someday? :)
This is exceptionally cool!
It looks like this post isn’t getting much love though. I’ll see if I can get this post added to the second chance pool[1] and get it added to the front page!
All: if you seen a particularly good submission that has fallen through the cracks, please email hn@ycombinator.com so we can take a look and maybe put it in the second-chance pool (https://news.ycombinator.com/pool, explained at https://news.ycombinator.com/item?id=26998308), so it will get a random re-upment on HN's front page.
(Yes, it's permissible to request this for your own stuff, but we like it better when it's something you just ran across randomly and realized was interesting—as mmulet did in this case!)
I'd maybe make a hypothesis that a large portion of the space is "bad" smelling stuff: smoke or garbage. When people had covid-induced parosmia, it almost always seemed to be bad smelling stuff.
Super interesting! That would make sense, because a lot of the nose is presumably dedicated to smelling evolutionarily-relevant smells, most of which are "smells bad, avoid this". The method is very crude right now, but maybe with more fine-grained targetting we could better tune the smell profile.
Still have it, intermittently. A sort of nameless-but-familiar "chemical" smell that comes and goes, along with any sense of taste. That is, I have bad days with no taste, just a chemical smell. Other days I have a pretty good sense of smell, generally with a good sense of taste.
Intriguingly some of the really unpleasant smells never get through to me - I could probably work at a sewage works now. Worryingly I have next to no ability to smell burning, though I do now get the smell of natural gas (or the additive used to make it smell).
There has been promising work on olfactory training, which you can do very inexpensively at home. If you can, I would consider seeing any ENT first to rule out polyps, etc.
This is something I'm still testing, so take it with a bucket of salt, but I've found that exposing myself to very strong samples of things that I was unable to smell made something click again and I started to smell them again. Seems like something in there needs to be retrained to odors.
That's the basic method of retraining. I've got a bunch of essential oils in tiny jars and I regularly take a 20 second sniff of each whilst thinking strongly about the smell in context. For example, when I smell the lavender oil I recall the garden at my grandma's house which obviously was full of lavender. It's definitely helping, but there are still a lot of gaps.
I'm convinced that over the decades we'll continue to be a little surprised but just how much of our body-machinery is doing jobs of self-calibration, regulation, and safety-interlocks.
That was exactly my thought when reading the article and my personal experience with Covid. For a couple weeks, I perceived a persistent smell of something burning.
A smell of burning was how I suspected I had COVID the last time around. I was around some machines, I had to have someone else sniff around and let me know that nothing was actually burning.
Certainly! We didn't get a chance to test it on more people before we had to take it apart, but we thought the result was too cool to share. Would love to see other folks run with the idea!
It’s just a blog post. No academic is going to read it as more than a very promising early result.
The issue is that lay people read every paper or post as if it were a final proclamation. They’re not. Even a peer reviewed paper on the cover of Science or Nature is still not “proof” of anything, science doesn’t produce positive confirmation. It produces evidence that taken together suggest one prior is more likely than another.
Bayes Rule is very intuitive. We update the prior by the likelihood of the evidence under a given prior divided by the likelihood of the evidence. That’s all it is.
Unfortunately, there is a very strong motive to flag plant. Academia is a water full of sharks.
Oh god, do we really want to have the smells of sex when watching porn?
On the other hand, I see an opportunity even without tech: porn star perfume collabs: Spray some Gukki Bloom and press play on that video to smell what the star was wearing on the day.
But I guess high-end perfume brands don't want to be associated with actors of the flesh.
You're getting downvoted, likely for prudish reasons, but in all seriousness it doesn't seem unlikely that you're right.
The porn industry has historically been very quick to adopt new technologies, it's easy to see how this could benefit that industry, so it's a logical enough conclusion to draw. They'll very likely be the first commercial application of this, once viable.
The scene from Torrente comes to mind where the protagonist gives a set of anal beads to a gay guy who then identifies it as ar*e smell, hence it was used. Or smth like that :D.
Woah I didn't know about that theory, that's really interesting! If I understand correctly, it's that the ligand needs to both fit "physically" and also have the right vibrational mode to have high binding affinity / trigger the receptor? Sounds like the relevant frequencies would be in IR range, or roughly 10-100 terahertz. We're at 300 kHz, so 9 orders of magnitude lower, so we're likely not activating the receptors directly with that mechanism. But, maybe the acoustic radiation force from the ultrasound gives existing molecules in the air enough energy to increase the coupling? And nobody seems to really know how ultrasound neurostimulation really works, so who knows—maybe something similar even happens with neurotransmitters in cortex...
Well, if it’s waves, perhaps principles of consonance and dissonance might apply.
Robert Hooke thought so…
“Now as we find that musical strings will be moved by Unisons and Eighths, and other harmonious chords, though not in the same degree; so do I suppose that the particles of matter will be moved principally by such motions as are Unisons, as I may call them, or of equal Velocity with their motions, and by other har∣monious motions in a less degree.
I do further suppose, A subtil matter that incom∣passeth and pervades all other bodies, which is the Menstruum in which they swim which maintains and continues all such bodies in their motion, and which is the medium that conveys all Homogenious or Har∣monical motions from body to body.
Further I suppose, that all such particles of matter as are of a like nature, when not separated by others of a differing nature will remain together, and strengthen the common Vibration of them all against the differing Vibrations of the ambient bodies.
According to this Notion I suppose the whole Universe and all the particles thereof to be in a con∣tinued motion, and every one to take its share of space or room in the same, according to the bulk of its body, or according to the particular power it hath to receive, and continue this or that peculiar motion.
Two or more of these particles joyned immediately together, and coalescing into one become of another nature, and receptive of another degree of motion and Vibration, and make a compounded particle differing in nature from each of the other par∣ticles.
All bulky and sensible bodies whatsoever I suppose to be made up or composed of such particles which have their peculiar and appropriate motions which are kept together by the differing or dissonant Vibrations of the ambient bodies or fluid“
I had the same thought - I guess it's similar to that idea that if you had someone else's eyes, you might not perceive specific colours to be the same?
But actually it sort of makes sense since (from what I understand) is stimulating an external interface (the receptors), so you're mimicing what the effect a smell would have on you rather than the electrical signal created by the response to a stimulus?
Sorry it's unclear in the post, they weren't exactly the same! The numbers reported were on Lev, and we swept them around that range for me (Albert). But we didn't take down the exact values, so unfortunately I don't know how similar the maps were. iirc they were pretty different.
That's a really interesting concept! The wiki page right now ends in "example of a combination of smells that neutralise each other", which makes me wonder if the "olfactory white" combinations are actually tuned to neutralize? I suspect what we're hitting is a bunch of receptors, and the brain is interpretting it as a common strong and evolutionarily important smell (which I assume has stronger pathways by default).
I was an organic chemist, and as such worked I've worked in various "wet" laboratories. All of them had store rooms and cabinets with hundreds or thousands of bottles filled with horribly smelling goop. Besides the occasional terpenoid (naturally occurring things smelling like menthol, cloves or cinnamon) nearly everything there was liquid death.
These smells have everything: Harsh solvent-like stuff like strong alcohol or glue, rotten fish amines, off-sweet halocarbons, things like burnt plastics, excrement, or stuff that defies description as to their lingeringly terrible sensation of olfactory wrongness (selenium compounds).
There is actually a thing called "cadaverine", that should tell you enough.
Still, every sufficiently large storage space I rememebet had this identical, not unpleasant, thickly sweet, but not easily defined smell.
So to conclude, I think it's a brain glitch when we input everything, all the smells, at the same time.
I cant wait for the day when the perfume and food shops in the mall use this for truly targeted advertisement. Cue rise of ultrasound-proof hats and lawsuits by people who report feeling sick due to such ads.
Woah, that would be wild! It seems like most neonatal ultrasound reaches peak internal pressures of few-hundred kPa to 2 MPa. We ranged from 150-250 kPa. So, a little lower than the lower end of prenatal diagnostic imaging.
So, the pressures are high enough to be stimulating them! But most diagnostic imaging happens at 1-20 MHz, while most neurostimulation seems to occur at few-hundred kHz (we were at 300 kHz, on the mid-high end). So I don't think it's likely that babies are being sent smells?
Haha, luckily not! It's a very speculative link, so we didn't want to talk about "AI" too much in the main post. But we originally got interested in this concept because we are interested in other forms of input to the brain (other than the classic reading, listening, watching, etc). The nose is interesting because it seems to have many independent basis vectors and very sharp discrimination ability, so it might be a sensor into which you can pack many inputs. LLMs are just a proof-by-example that ~1k input dimensions is enough to really encode semantic meaning.
Totally! We think this is because the brain is hard-wired evolutionarily to interpret smells by danger level first. So maybe there's just more "bad smell" receptors, or maybe the brain treats unknown smells as "uh oh, danger". Lots of cool stuff to test!
The adult videos industry must be already closely looking at this, and I wouldn't be surprised if they don't finance related research soon in the future, it will be VHS vs betamax all over again.
Yes, to simulate pheromones and related stimulus, that too, but I'm sorry if you already don't know this but a faint smell of urine would be a big deal to a non-trivial amount of men for immersion, without going into too much detail "squirting" fans and all the ecosystem around such kind of fetishes.
If they’re using enough ultrasound energy to create a physical reaction inside the subjects head strong enough to smell like a burning camp fire, I can’t imagine they’d survive long enough to report it. Maybe I’m misunderstanding your implication?
maybe the ionized oxygen sensation, the ozone, the garbage and smoke are like a thin film of garbage and smoke particles in the nasal cavity experiencing mechanical stimulation. the mr guidance seems like a good idea, but the actual mount and targeting sounds crude, what are the odds it's just in the nasal cavity warming up and activating the gross stuff that lives in there?
i wonder if some kind of inhalable anesthetic would be a good control. ie, if the normal sensory pathways are blocked and the lifu stim of the olfactory bulb still creates the percept, then maybe it would be evidence that it is working as it appears...
My prediction is that in the not-to-distant future, we’re all going to live indefinitely in simulations that optimized for human experience. To do this, AIs will “highjack” our nervous systems and feed generated worlds to use to experience. This kind of thing makes it seem like it’s pretty realistic.
This is absolutely my question as well - curious if it's legal to do this, I'm guessing yes as it's an existing ultrasound device? But is there possibility of permanent damage?
It's objectively cool, but very curious about the safety as well.
This is the coolest part! Turns out, the powers you need are actually lower than what is used for imaging babies :) We measured our probe with a hydrophone on a computer-controlled scanner to get the pressure field, and made sure that it's below diagnostic levels (the generally accepted mechanical index limit is 1.9 and ours was 0.4 peak). We also made sure to avoid the eyes and keep thermals in check.
OK, I want to meet these guys. This writeup has several breathtaking (if you will) passages. Like:
> "We found different scents by steering the beam over ~14 mm (20 degrees at 4 cm radius). The distance between freshness and burning was ~3.5 mm."
> "The olfactory system potentially allows writing up to 400, if not 800 due to two nostrils, dimensions into the brain. That is comparable to the dimensionality of latent spaces of LLMs, which implies you could reasonably encode the meaning of a paragraph into a 400-dimensional vector. If you had a device which allows for this kind of writing, you could learn to associate the input patterns with their corresponding meanings. After that, you could directly smell the latent space."
This just makes me grin with total delight. Completely freaking fascinating.
> The olfactory system potentially allows writing up to 400, if not 800 due to two nostrils, dimensions into the brain. That is comparable to the dimensionality of latent spaces of LLMs, which implies you could reasonably encode the meaning of a paragraph into a 400-dimensional vector. If you had a device which allows for this kind of writing, you could learn to associate the input patterns with their corresponding meanings. After that, you could directly smell the latent space. A bit of ultrasound, a breath in - and you understood a paragraph.
Translation: We’re very concerned that the only projects getting funding right now have to use AI.
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