philip lelyveld The world of entertainment technology

We Induced Smells With Ultrasound

We pointed an ultrasound probe at the scent-processing region of the brain to obtain different sensations. Different focal spots corresponded to different smells, which we’ve replicated first-try on two people and validated with a blind trial. ...

Instead, we found that you can place the transducer on the forehead and aim the ultrasound downward towards the olfactory bulb. While this isn’t a perfect solution because the frontal sinuses can weaken the signal, careful device positioning above the sinuses still allows us to reach our general target region. ...

We have managed to induce four different sensations, all of them in two people:

The sensation of fresh air, with a lot of oxygen

The smell of garbage, like few-day-old fruit peels

An ozone-like sensation, like you're next to an air ionizer

A campfire smell of burning wood

We distinguish between a smell and a sensation here because, subjectively, they feel different. The smells are strong and localized to the noise, almost like you could sniff around and find the source. The sensations are more diffuse: a weak, slow-onset impression of a smell, often paired with other (likely placebo) feelings, such as a light tingling on the face. ...

The reason stimulating olfactory sensations is interesting is not just "VR for smells", as one might initially assume. The nose has 400 distinct receptor types, and we can distinguish subtle combinationsof their activations, so they could serve as a channel of writing directly into the brain, as a means of non-invasive neuromodulation.

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. ...

People are able to develop synesthesia - being able to hear colors and see smells, and it might be possible to extend that to semantics. However, at this stage it is speculative. ...

See the full story here: https://writetobrain.com/olfactory?utm_source=substack&utm_medium=email