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Neurovis: Visualizing brain signals in 3D in real-time

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Re: Neurovis: Visualizing brain signals in 3D in real-time

#31

Post by nabla9 »

omginternets wrote: post #19
frereubu wrote: post #18

Earlier quoted context omitted.

Yep, only EEG gives you that kind of information. fMRI takes a lot of post-processing with complex statistics to produce any kind of useful information. I worked on a study that used fMRI to study the involvement of early visual areas in the cortex during reading tasks, and when processing long runs we'd get on with other stuff while the data was being processed. There isn't any existing tech to take surface data and…

> fMRI takes a lot of post-processing with complex statistics to produce any kind of useful information. So does EEG. The reason EEG is closer to real-time than fMRI is because of the sampling rate. With fMRI, .9 Hz is considered quite good. For EEG, 2000 Hz is considered standard.

Standard? 2000 Hz sampling rate may be used with intracranial electrodes.

If the EEG is measured from the scalp 200-250 Hz sampling rate is usually good enough. It enables EEG recordings up to 80-90 Hz. Most clinical uses are interested EEG below 40 Hz.

Re: Neurovis: Visualizing brain signals in 3D in real-time

#32

Post by omginternets »

nabla9 wrote: post #31
omginternets wrote: post #19

Earlier quoted context omitted.

> fMRI takes a lot of post-processing with complex statistics to produce any kind of useful information. So does EEG. The reason EEG is closer to real-time than fMRI is because of the sampling rate. With fMRI, .9 Hz is considered quite good. For EEG, 2000 Hz is considered standard.

Standard? 2000 Hz sampling rate may be used with intracranial electrodes. If the EEG is measured from the scalp 200-250 Hz sampling rate is usually good enough. It enables EEG recordings up to 80-90 Hz. Most clinical uses are interested EEG below 40 Hz.

My mistake: I got mixed up and reported standard sampling rates for MEG.

You are, of course, correct.

Re: Neurovis: Visualizing brain signals in 3D in real-time

#34

Post by GistNoesis »

omginternets wrote: post #30
GistNoesis wrote: post #29

Earlier quoted context omitted.

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.

>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…

>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.

Re: Neurovis: Visualizing brain signals in 3D in real-time

#35

Post by SubiculumCode »

frereubu wrote: post #18
xab9 wrote: post #14

Earlier quoted context omitted.

I had multiple MR and CT scans, some EEG - from all these only EEG is kinda "realtimish", isn't it? Do we have any technology in these days that can _map_ surface electrical changes to brain internals (depth data) or anything that can work in true 3d?

Yep, only EEG gives you that kind of information. fMRI takes a lot of post-processing with complex statistics to produce any kind of useful information. I worked on a study that used fMRI to study the involvement of early visual areas in the cortex during reading tasks, and when processing long runs we'd get on with other stuff while the data was being processed. There isn't any existing tech to take surface data and…

There are real questions regarding the degree of locality information from eeg. The temporal resolution though is measured in ms.

There are real time fMRI research...particularly in the use of classifiers. The temporal resolution tends to be around 2-7 seconds (2 seconds for each acquisition, but the hemodynamic response is over the course of 7+ seconds..

Re: Neurovis: Visualizing brain signals in 3D in real-time

#36

Post by neuromantik8086 »

yoz-y wrote: post #26
GistNoesis wrote: post #24

Earlier quoted context omitted.

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 inver…

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.

The eye blinks... oh the eye blinks! Many a datapoint has been rendered useless by a dry contact lens.

Re: Neurovis: Visualizing brain signals in 3D in real-time

#37

Post by SubiculumCode »

stinos wrote: post #23
frereubu wrote: post #17

Earlier quoted context omitted.

If you mean surface electrodes, then that is EEG: ElectroEncephaloGram. If you mean electrodes inside the brain, then you're talking brain surgery. I'm not sure what point you're making here - could you elucidate?

I did mean electrodes in the brain (or spine) and mentioned that for completeness, to make it clear there's another method besides fMRI and EEG. Which indeed has the obvious disadvantage it involves some surgery, but does the type of signal recorded with it does have advantges over the other methods.

When available in humans, that data is amazing. It is used frequently in animal models though.

Re: Neurovis: Visualizing brain signals in 3D in real-time

#38

Post by neuromantik8086 »

omginternets wrote: post #30
GistNoesis wrote: post #29

Earlier quoted context omitted.

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.

>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…

And in an ideal world you want an even more direct measure than BOLD, which is why folks are examining perfusion imaging.

Re: Neurovis: Visualizing brain signals in 3D in real-time

#39

Post by neuromantik8086 »

GistNoesis wrote: post #24
BucketSort wrote: post #6

The consumer grade EEG's you would use for this, like Open BCI, place rudimentary sensors on the scalp. There just isn't enough information from these types of sensors to give you a real look at what signals are occurring in the brain. This is a fundamentally flawed premise and is nothing more than a toy. Real brain research must be done with FMRIs or much more accurate EEG's than consumers have access to, and instit…

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 inver…

Maybe try infrared?

https://en.wikipedia.org/wiki/Functional_near-infrared_spect...

Re: Neurovis: Visualizing brain signals in 3D in real-time

#40

Post by SubiculumCode »

arca_vorago wrote: post #9
BucketSort wrote: post #6

The consumer grade EEG's you would use for this, like Open BCI, place rudimentary sensors on the scalp. There just isn't enough information from these types of sensors to give you a real look at what signals are occurring in the brain. This is a fundamentally flawed premise and is nothing more than a toy. Real brain research must be done with FMRIs or much more accurate EEG's than consumers have access to, and instit…

What is the most advanced open source solution to the brain computer interface issue? Afaik they had gotten pretty good at decoding even the low sensor density data into actionable input, but all solutions suffer from input/compute lag. So that said, FMRI's won't work for realtime will it due to how long scans take? So EEG's seem to be the only choice. Perhaps to make up for accuracy you have to increase sensor densi…

There are real time fMRI applications. You just won't get to have one in your home. 3 Tesla's dude. That makes metal fly, and is hyper expensive.
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