4 ms·

Also check out their other post: https://brainhack.vercel.app/ae https://brainhack.vercel.app/ae They are planning to locally change the electrical conductivit

Also check out their other post: https://brainhack.vercel.app/ae 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 2y ago
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 2y ago
  Modulation is part of the measurement process in that case. https://en.wikipedia.org/wiki/Lock-in_amplifier https://en.wikipedia.org/wiki/Lock-in_amplifier
  - bbor 2y ago
    Hmm, I see, I think understand a bit better now -- thanks. Is it fair to say that their claims about spatial resolution being >>> existing EEG options are jumping the gun? If I understand correctly, you need to be targeting individual 1mm^2 regions with individual acoustic lenses, which means 17,000 channels would required 17,000 separate, uniquely-tuned ultrasound emitters, yes? Even if that's possible without messing up the data (the MHz range is big, but is it that big?) it seems like a trivial impossibility to fit that in one headset -- even the standard 32-64 EEG channels alone seem like a long shot. But maybe I'm overly cynical, or one emitter could be used to usefully excite multiple regions at once? Another oddity in that paper is that it reads like we're trying to find persistent signals in the brain, like a needle in a haystack, whereas my understanding was that the field is moving decisively towards tracking signal changes over time in a given region. Is my intuition correct that accounting for a moving target would add considerable complexity to this approach? Either way, thanks for sharing the link. Definitely thought-provoking stuff...
    - raffihotter 2y ago
      Thanks for your questions! I was one of the people who worked on the project. To answer your questions: > Is it fair to say that their claims about spatial resolution being >>> existing EEG options are jumping the gun? If I understand correctly, you need to be targeting individual 1mm^2 regions with individual acoustic lenses, which means 17,000 channels would required 17,000 separate, uniquely-tuned ultrasound emitters, yes? Even if that's possible without messing up the data (the MHz range is big, but is it that big?) it seems like a trivial impossibility to fit that in one headset -- even the standard 32-64 EEG channels alone seem like a long shot. But maybe I'm overly cynical, or one emitter could be used to usefully excite multiple regions at once? Since the system is linear, you could use a single probe to focus at multiple spots. Each focus would be at a slightly different modulation frequency. > Another oddity in that paper is that it reads like we're trying to find persistent signals in the brain, like a needle in a haystack, whereas my understanding was that the field is moving decisively towards tracking signal changes over time in a given region. Is my intuition correct that accounting for a moving target would add considerable complexity to this approach? This method would indeed let you track signals that change over time. Lock-in-amplifiers can output time-varying signals.
      - agilaf 2y ago
        [dead]
      - deleted 2y ago
        [deleted]
      - deleted 2y ago
        [deleted]
      - deleted 2y ago
        [deleted]
      - bbor 2y ago
        I still have lots of questions, but I think that's on me haha. Thanks so much for taking the time for this, and for pushing forward the human race in such a groundbreaking manner. Hope y'all are doing well in these dark times.

bbor 2y ago

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 2y ago
Modulation is part of the measurement process in that case. https://en.wikipedia.org/wiki/Lock-in_amplifier https://en.wikipedia.org/wiki/Lock-in_amplifier
- bbor 2y ago
  Hmm, I see, I think understand a bit better now -- thanks. Is it fair to say that their claims about spatial resolution being >>> existing EEG options are jumping the gun? If I understand correctly, you need to be targeting individual 1mm^2 regions with individual acoustic lenses, which means 17,000 channels would required 17,000 separate, uniquely-tuned ultrasound emitters, yes? Even if that's possible without messing up the data (the MHz range is big, but is it that big?) it seems like a trivial impossibility to fit that in one headset -- even the standard 32-64 EEG channels alone seem like a long shot. But maybe I'm overly cynical, or one emitter could be used to usefully excite multiple regions at once? Another oddity in that paper is that it reads like we're trying to find persistent signals in the brain, like a needle in a haystack, whereas my understanding was that the field is moving decisively towards tracking signal changes over time in a given region. Is my intuition correct that accounting for a moving target would add considerable complexity to this approach? Either way, thanks for sharing the link. Definitely thought-provoking stuff...
  - raffihotter 2y ago
    Thanks for your questions! I was one of the people who worked on the project. To answer your questions: > Is it fair to say that their claims about spatial resolution being >>> existing EEG options are jumping the gun? If I understand correctly, you need to be targeting individual 1mm^2 regions with individual acoustic lenses, which means 17,000 channels would required 17,000 separate, uniquely-tuned ultrasound emitters, yes? Even if that's possible without messing up the data (the MHz range is big, but is it that big?) it seems like a trivial impossibility to fit that in one headset -- even the standard 32-64 EEG channels alone seem like a long shot. But maybe I'm overly cynical, or one emitter could be used to usefully excite multiple regions at once? Since the system is linear, you could use a single probe to focus at multiple spots. Each focus would be at a slightly different modulation frequency. > Another oddity in that paper is that it reads like we're trying to find persistent signals in the brain, like a needle in a haystack, whereas my understanding was that the field is moving decisively towards tracking signal changes over time in a given region. Is my intuition correct that accounting for a moving target would add considerable complexity to this approach? This method would indeed let you track signals that change over time. Lock-in-amplifiers can output time-varying signals.
    - agilaf 2y ago
      [dead]
    - deleted 2y ago
      [deleted]
    - deleted 2y ago
      [deleted]
    - deleted 2y ago
      [deleted]
    - bbor 2y ago
      I still have lots of questions, but I think that's on me haha. Thanks so much for taking the time for this, and for pushing forward the human race in such a groundbreaking manner. Hope y'all are doing well in these dark times.