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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

#21

Post by frereubu »

This quote - "facilitating intuitive interpretation of complex phenomena" - makes me very suspicious. Inference in neuroimaging is complex and you need to take a great deal of care when interpreting data. There isn't really such a thing as a good outcome from "intuitive" interpretation of neuroimaging data.

For example, there was a story in 2011 about some research that said the brain's "love centre" was being activated by a video of a vibrating and ringing iPhone. They were talking about the insular cortex, but the insular cortex is also involved in vomiting.

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

#22

Post by frereubu »

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.

Thanks for the clarification. I've only worked with fMRI, so wasn't aware of the ins and outs of EEG processing despite being aware of the spacial / temporal resolution difference. It makes this method even more suspicious!

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

#23

Post by stinos »

frereubu wrote: post #17
stinos wrote: post #12

Earlier quoted context omitted.

FMRIs or much more accurate EEG's Or neural recordings with electrodes. Better spatial resolution than EEG and fMRI and way better time resolution than fMRI.

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.

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

#24

Post by GistNoesis »

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 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?

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

#25

Post by EmlynC »

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 many open-source solutions for BCI projects like BCI2000 (http://www.schalklab.org/research/bci2000), OpenVibe (http://openvibe.inria.fr/) and EEGLab (https://sccn.ucsd.edu/eeglab/index.php). That's based on the kinds of tools that our customers use. Most of these, aren't as pretty as tool like Neurovis, but in reality most of the information that we make use of to control prosthetics or signal intention involve looking at the temporal-frequency relationships between and within broad regions of the brain. There isn't a lot that you gain from just looking at the brain light up like this for BCI — the main use for a visualisation like this, is as the docs say, for diagnosis and determination of epilepsy since in epilepsy the activity you'd see is much higher than usual.

EEG has better temporal resolution than FMRI; you are measuring the electrical activity rather than vascular changes, the former changes more rapidly than the other. EEG, however, is just the surface activity of the brain, so you don't get information about 'deeper' (physically) brain processes; this is where FMRI is invaluable. EEG is also limited to the size of the electrodes and how many electrodes you can physically place in one location. 256 electrodes on an EEG cap is about the limit you can get to.

Electrocorticography (ECog) involves implanting electrodes on the dura, this can substantially improve the density of electrodes in a given area, however this doesn't measure deep brain activity and we have no way of leaving the electrode grid in place for long periods of time without risking infection. For BCI, we've been able to classify more classes of data using ECog than EEG — research by Kyousuke Kamada and Gerwin Schalk are informative. It's a very promising area if we can work out how to implant the electrodes, seal the skull and telemeter data out.

Magnetoencephalography (MEG) can help with measuring deep brain activity, but there are other tradeoffs to consider. Essentially, the point where we are now is combining multiple techniques to get the best temporal, spatial and frequential compromises.

Thus in answer to your question; no FMRI is not great for realtime responses, measuring the electrical activity has better temporal properties so EEG and ECog work better here. Sensor density is part of the problem, but once you solve density you then need to consider how you'll deal with deep brain measurements.

Background; I own a company that distributes BCI equipment for g.tec medical engineering in the UK. We've been operating in this space for 8 years. I have a PhD in Pharmacology and a speciality in electrophysiology.

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

#26

Post by yoz-y »

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…

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.

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

#27

Post by yoz-y »

xab9 wrote: post #14
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 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?

You can do LORETA inverse solution to go from EEG to voxels which approximate internal sources. The problem is that this model does several suppositions about the brain structure that may or may not be true. In my opinion, surface currents are only good for surface sources, as the neurons in cortex are aligned and thus generate relatively strong currents in comparison to neurons inside the brain which are positioned "randomly".

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

#29

Post by GistNoesis »

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.

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.

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

#30

Post by omginternets »

GistNoesis wrote: post #29
yoz-y wrote: post #26

Earlier quoted context omitted.

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.

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 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.

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