4 ms·

I'm no expert, but what about seeing the brain using radio-waves diffraction pattern. You take an emitting antenna in-front of the person, 1 meter behind him y

I'm no expert, but what about seeing the brain using radio-waves diffraction pattern. You take an emitting antenna in-front of the person, 1 meter behind him you make a grid array of Software Defined Radios (like 10x10=100 SDR (SDR are so cheap that it will be ~ the price of an OpenBCI set) ), and you record the diffraction/interference pattern, then you software analyze it to produce a 3d image via solving the inverse scattering problem, to get the fluids flows and densities (you should even get the speeds through Doppler)). My simple back of the envelope calculations, says that at 5Ghz we should rather easily get a spatial resolution of lambda/4=1.5 cm, maybe more using super resolution techniques. Going to 60Ghz, we should soon be able to reach millimeters spatial resolution. It obviously won't reach the quality levels of FMRIs. Can someone from the field tell what kind of bandwidth we should expect from such a setup?

yoz-y 9y ago
EEG noise to signal ratio is so ridiculously low that you really need to be as close to the brain as possible. Any muscular activity produces electrical currents an order of magnitude higher. As a side note: what an FMRI sees and what an EEG measures is fundamentally different. EEG can reliably only detect the Pyramidal neurons in the cortex an MRI can see below that.
- GistNoesis 9y ago
  I'm not suggesting that we measure the signal emitted by the brain like EEG do. I'm suggesting that we look at the fluids movements like FMRI do but using diffraction like xray-imaging with bigger wavelengths.
  - omginternets 9y ago
    >I'm suggesting that we look at the fluids movements like FMRI do but using diffraction like xray-imaging with bigger wavelengths. What would we gain from using RF-diffraction as opposed to MR? The major advantage of fMRI is that you're measuring a so-called Blood-Oxygen-Level-Dependent (BOLD) signal. That is, you're looking at a contrast between oxygenated and de-oxygenated blood, which is more interesting than just looking at where blood (of all types) is going. The underlying assumption is that brain volumes consume oxygen at a rate roughly proportional to the level neuronal activity. As such, a BOLD signal is really what you want.
    - GistNoesis 9y ago
      >BOLD signal is really what you want Thank you so much (I have no medical knowledge and that is some key domain-knowledge I've missed). How much correlation with blood flow is there ? Maybe the BOLD signal can be reconstructed from the graphs of all mixed blood flow. >What would we gain from using RF-diffraction as opposed to MR? Main gain is practicality. Main usage would be for brain interface. This is phase contrast tomography, so you can get the refractive index of the materials inside, and their speed. It won't be as precise as MRI, but it will be more practical. More portable. It doesn't use magnets so not limited by maximum magnetic fields. It is more scalable if you have compute power, meaning you can add some SDR to increase the resolution and bandwidth if necessary. Time resolution would probably be better as it doesn't need moving parts (if beam forming). It's cheaper. It's non invasive and usable 24/7. We already have wifi imaging, so this is just putting it in favorable condition so as to extract more info from the brain. Basically until we can get the full connectome activation real time, we are just side-channel attacking the brain to extract some info. I'm just trying to grasp how much and how useful is the info we can get using existing techniques. For example you put this device inside every monitor screen (for 60Ghz or in a TV sized box for 5Ghz) and a software controlled radio emitter behind the back of your head. And if the useful info bandwidth is sufficient we could have vastly better interface to the computer. This can probably be adapted for room-sized continuous body health monitoring if the resolution is not sufficient or if the info extracted is not relevant enough.
      - omginternets 9y ago
        >Thank you so much My pleasure :) >This is phase contrast tomography, so you can get the refractive index of the materials inside, and their speed. This is way outside of my domain of competence, but if I understand correctly, this would not constitute a BOLD signal? I'm skeptical of the idea that blood diffusion alone correlates with cerebral activity. With fMRI, you're looking at temporary gradients of de-oxygenated hemoglobin rather than a net direction of blood movement. This is sometimes confused with "blood flow", and I've been guilty of interchanging the two terms myself :/ I suspect the fluid dynamics of blood in the head is outrageously noisy and difficult to contrast out or filter though statistical means (because it's roughly random). Concerning the relationship between neural activity and BOLD signal this paper [https://www.nature.com/articles/35084005 https://www.nature.com/articles/35084005] is a good starting point. I'll see if I can dig up the PDF for you.
- neuromantik8086 9y ago
  The eye blinks... oh the eye blinks! Many a datapoint has been rendered useless by a dry contact lens.
neuromantik8086 9y ago
Maybe try infrared? https://en.wikipedia.org/wiki/Functional_near-infrared_spectroscopy https://en.wikipedia.org/wiki/Functional_near-infrared_spect...

yoz-y 9y ago

EEG noise to signal ratio is so ridiculously low that you really need to be as close to the brain as possible. Any muscular activity produces electrical currents an order of magnitude higher. As a side note: what an FMRI sees and what an EEG measures is fundamentally different. EEG can reliably only detect the Pyramidal neurons in the cortex an MRI can see below that.

GistNoesis 9y ago
I'm not suggesting that we measure the signal emitted by the brain like EEG do. I'm suggesting that we look at the fluids movements like FMRI do but using diffraction like xray-imaging with bigger wavelengths.
- omginternets 9y ago
  >I'm suggesting that we look at the fluids movements like FMRI do but using diffraction like xray-imaging with bigger wavelengths. What would we gain from using RF-diffraction as opposed to MR? The major advantage of fMRI is that you're measuring a so-called Blood-Oxygen-Level-Dependent (BOLD) signal. That is, you're looking at a contrast between oxygenated and de-oxygenated blood, which is more interesting than just looking at where blood (of all types) is going. The underlying assumption is that brain volumes consume oxygen at a rate roughly proportional to the level neuronal activity. As such, a BOLD signal is really what you want.
  - GistNoesis 9y ago
    >BOLD signal is really what you want Thank you so much (I have no medical knowledge and that is some key domain-knowledge I've missed). How much correlation with blood flow is there ? Maybe the BOLD signal can be reconstructed from the graphs of all mixed blood flow. >What would we gain from using RF-diffraction as opposed to MR? Main gain is practicality. Main usage would be for brain interface. This is phase contrast tomography, so you can get the refractive index of the materials inside, and their speed. It won't be as precise as MRI, but it will be more practical. More portable. It doesn't use magnets so not limited by maximum magnetic fields. It is more scalable if you have compute power, meaning you can add some SDR to increase the resolution and bandwidth if necessary. Time resolution would probably be better as it doesn't need moving parts (if beam forming). It's cheaper. It's non invasive and usable 24/7. We already have wifi imaging, so this is just putting it in favorable condition so as to extract more info from the brain. Basically until we can get the full connectome activation real time, we are just side-channel attacking the brain to extract some info. I'm just trying to grasp how much and how useful is the info we can get using existing techniques. For example you put this device inside every monitor screen (for 60Ghz or in a TV sized box for 5Ghz) and a software controlled radio emitter behind the back of your head. And if the useful info bandwidth is sufficient we could have vastly better interface to the computer. This can probably be adapted for room-sized continuous body health monitoring if the resolution is not sufficient or if the info extracted is not relevant enough.
    - omginternets 9y ago
      >Thank you so much My pleasure :) >This is phase contrast tomography, so you can get the refractive index of the materials inside, and their speed. This is way outside of my domain of competence, but if I understand correctly, this would not constitute a BOLD signal? I'm skeptical of the idea that blood diffusion alone correlates with cerebral activity. With fMRI, you're looking at temporary gradients of de-oxygenated hemoglobin rather than a net direction of blood movement. This is sometimes confused with "blood flow", and I've been guilty of interchanging the two terms myself :/ I suspect the fluid dynamics of blood in the head is outrageously noisy and difficult to contrast out or filter though statistical means (because it's roughly random). Concerning the relationship between neural activity and BOLD signal this paper [https://www.nature.com/articles/35084005 https://www.nature.com/articles/35084005] is a good starting point. I'll see if I can dig up the PDF for you.
neuromantik8086 9y ago
The eye blinks... oh the eye blinks! Many a datapoint has been rendered useless by a dry contact lens.

neuromantik8086 9y ago

Maybe try infrared? https://en.wikipedia.org/wiki/Functional_near-infrared_spectroscopy https://en.wikipedia.org/wiki/Functional_near-infrared_spect...