[HN Gopher] Functional ultrasound through the skull
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Functional ultrasound through the skull
Author : lawrenceyan
Score : 65 points
Date : 2024-11-01 20:52 UTC (6 days ago)
(HTM) web link (brainhack.vercel.app)
(TXT) w3m dump (brainhack.vercel.app)
| _Microft wrote:
| Also check out their other post: https://brainhack.vercel.app/ae
|
| They are planning to locally change the electrical conductivity
| of brain tissue by focused ultrasound, modulate that with at few
| hundred kHz and do a lock-in (EEG) measurement to deduce
| electrical activity at that spot on the scale of 1mm. Pretty wild
| if that actually works.
| bbor wrote:
| Fascinating -- I thought ultrasound was already regularly in
| use for reading oxygenation levels, I had no idea it was new!!
| I've gotta try this. I don't love the modulation side, but the
| measurement side is incredible. Invasive tech is unnecessary
| and terrifying IMHO
| _Microft wrote:
| Modulation is part of the measurement process in that case.
|
| https://en.wikipedia.org/wiki/Lock-in_amplifier
| dr_dshiv wrote:
| "The thing that nobody tells you is that you can buy a real human
| skull online (shoutout to skullsunlimited.com). We did that, and
| then CT scanned it."
|
| This is an A+
| dr_dshiv wrote:
| "People often quote 22 dB/cm/MHz attenuation of ultrasound.
| Decibels are a logarithmic scale, so with 1.4 cm of roundtrip
| skull distance, and typical fUSI frequencies of 10 MHz, this
| would be 14 orders of magnitude of attenuation! In physics,
| there's a word for 14 orders of magnitude of attenuation. It's
| called zero, i.e., you will measure nothing.
|
| But where did the 22 dB/cm/MHz attenuation number come from? We
| were skeptical..."
| levocardia wrote:
| Skulls Unlimited really has their branding on point. I might
| just have to get one for the holidays.
| stavros wrote:
| Just a cool $1800 for a Halloween prop.
| trebligdivad wrote:
| 'Previous work showed that tofu is desirable as a phantom
| material, both because it is fast to get and because it has
| similar physical properties (density, speed of sound) as soft
| tissue.' Haha wonderful.
| robg wrote:
| Awesome! I know of efforts to leverage focused ultrasound to
| shorten sleep cycles and improve mental health. There's so much
| more possible in neuroscience, great to see this work is gaining
| steam.
| pedalpete wrote:
| I think you are referring to slow-wave enhancement wrt "shorten
| sleep cycles", which probably isn't the right way to look at
| it.
|
| We've been developing slow-wave enhancement for the past 4
| years using auditory stimulation.
|
| The problem with using focused ultrasound to accomplish this (I
| believe), is that the focal point creates heat, and I don't
| believe we want to be consistently creating hot spots of
| neurons in the brain.
|
| Other methods (acoustic, visual, haptic) have proven efficacy
| by "tricking" the brain into increasing slow-wave delta power,
| and tMCS (magnetic) coaxes the neurons into a slow-wave pattern
| - though this is not realistic outside of a clinical setting
| atm.
|
| Absolutely there is tons happening in neuroscience (lots here
| in Sydney, Aus), and focused ultrasound has it's place, but as
| a daily use, I'm not there with it yet.
|
| For treatment of depression, for diagnosis, etc, absolutely.
| Though in depression treatment, SAINT protocol tCMS is very
| impressive.
| robg wrote:
| I don't know how much is public, the method I've seen
| "bounces" around and aims for a more global effect. Like a
| sonicare for the brain. No idea if it will work long-term as
| intended, but seems worth trying.
| finnh wrote:
| love the writing in this
|
| "In physics, there's a word for 14 orders of magnitude of
| attenuation. It's called zero, i.e., you will measure nothing."
|
| Lots of great sentences in here as noted in the other comments.
| AlotOfReading wrote:
| As a point of comparison, GNSS works down to about 16 orders of
| magnitude attenuation (dbw).
| edelbitter wrote:
| Progress in making measurements through the skull useful might be
| how we finally get to precisely measure side-effects elsewhere:
| comparing healthy adult skulls to proper control groups. Always
| seemed odd to me how unspecific the thermal safety limits are,
| though the peak is expected depend on localized unknowns.
| IshKebab wrote:
| Yeah I did a (mostly failed) PhD on ultrasonic imaging and found
| many things that worked in simulations but not in practice. The
| fancier your imaging algorithm gets the most ill posed it becomes
| and more sensitive to noise and errors.
|
| Even if you add noise to your simulation , when you go to the
| real world it will have lots of sources of noise and errors that
| you didn't model. In this case I suspect aligning the CT scan
| with the ultrasound probe will be extremely difficult.
|
| Also there's a reason ultrasonographers are so highly paid, and
| it's mostly used for pregnancies. In normal tissue it kind of
| sucks as an imaging method. (On an absolute scale; obviously it's
| amazing technology.)
|
| Eh maybe it will work though. You never know.
| sfink wrote:
| Surely this is easily solved with time-reversed acoustics. Just
| stab a transmitter into the brain with an ice pick to the point
| you want to measure, and pick up the signal at lots of locations
| around the skull. Now you have both a mapping from an input
| signal (the reverse of the signal you picked up) that you can
| send to precisely target that point, and you know it looks like
| after it comes out from that point (the original signal you
| picked up).
|
| Now you can tell exactly what is going on and the person is
| thinking! Specifically it'll be either: (1) "oh my god, I have an
| ice pick in my brain" or (2) nothing, because they have an ice
| pick in their brain.
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