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Comment by tbenst | Hacker News Reader

This is fun, and the modeling is cool for sure, but it's well known that ultrasound can be used with surgical precision in the human brain.

Focused ultrasound is already used for non-invasive neuromodulation. Raag Airan's lab at Stanford does this for example using ultrasound uncaging.

https://www.frontiersin.org/journals/neuroscience/articles/1...

https://www.sciencedirect.com/science/article/pii/S089662731...

Also see the work by Urvi Vyas, eg

https://pubmed.ncbi.nlm.nih.gov/27587047/

I don't mean to discount the cool imaging-related reconstruction of a point spread function, but rather to say that ultrasound attenuation through the skull an soft tissue has already been well characterized and it's not a surprise that it is viable to pass through.

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Correct me if I’m wrong - but the novel thing is not that it’s possible for ultrasound to pass through the skull, but that it’s possible for it to pass through the skull and back in a way that an image can be reconstructed.

Precisely

OpenWater wiki > Neuromodulation: https://wiki.openwater.health/index.php/Neuromodulation

OpenwaterHealth/opw_neuromod_sw: https://github.com/OpenwaterHealth/opw_neuromod_sw :

> OpenWater's Transcranial Focused Ultrasound Platform. open-LIFU is an ultrasound platform designed to help researchers transmit focused ultrasound beams into subject’s brains, so that those researchers can learn more about how different types of ultrasound beams interact with the neurons in the brain. Unlike other focused ultrasound systems which are aimed only by their placement on the head, open-LIFU uses an array to precisely steer the ultrasound focus to the target location, while its wearable small size allows transmission through the forehead into a precise spot location in the brain even while the patient is moving.

FWIU NIRS is sufficient for most nontherepeautic diagnostics though. (Non-optogenetically, infrared light stimulates neuronal growth, and blue and green lights inhibit neuronal growth)

Not to mention transcranial doppler ultrasound for measuring blood flow.

To my knowledge, transcranial doppler doesn’t form images. It just gives you a single channel measurement that is very low resolution.

The method we’re proposing would have mm resolution.

A commercial medical ultrasound imaging device in doppler mode can pick up and map onto the image plane some of the vessels in the brain through the skulls. But mostly just through the temporal bones(where the skulls is like 1-2mm thick). (The commercial machines run doppler on lower frequency than imaging signal so you get no s tructural image this way, only the color doppler map(unless you find a place in the skull where an emissary vein passes through the bone table where the image signal can ride through))

Does viable transcranial doppler for poeple without fontanelles actually exist?

Through the temporal bone of most people you can catch some sparse doppler signals with average hospital gear.

The fontanelles enable good ultrasound imaging on an entirely different level. A highres greyscale image vs a few sparse blobs of doppler from major vessels.

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