Mapping The Motor Cortex

[Bruce] sent us another fantastic final project from the ECE4760 class at Cornell. What you see above is an array of 36 near infra red LEDs shining into this young man’s brain for the purpose of spectroscopy. Light bounces back differently based on brain activity (blood flow). For this project, they are mapping their motor cortex and displaying it on a PC using a java app. You can see the entire rig, as well as the readings in the two videos after the break.

When this tip came in, one of our writers,[Jesse Congdon], chimed in as well.

hey I actually used to work in this as an intern, at Upenn. two frequencies of near infrared light are used that both penetrate skin and bone, one bounces off of blood in general and the other bounces off oxygenated blood. Since your brain actually regulates the flow of blood to parts that are in use you can see brain activity by looking at blood flow, but then you also need to see if the brain is actually using that blood, so oxygenation gives you a full picture. The frontal cortex is a nice place to measure cause there is no hair on that portion of the skull, and it gives you emotional responses and the “aha!” moment when you figure out a problem.

One article from way back said the system was going to be used as a lie detector, since when you lie you think about the truth and the lie simoltaneously and show an increase in activity.

It’s tough though to categorize a response since you can’t really establish “base line” activity by turning off the brain

24 thoughts on “Mapping The Motor Cortex

  1. “you can’t really establish “base line” activity by turning off the brain”

    Oh, I don’t know about that… about 15 minutes of just about any popular reality TV show ought to do the trick.

    1. We actually got some really interesting results with some expert at meditation. The problem being that it would be impossible to find enough pro mediators to fill a study.

      Even then your brain is chugging away. “don’t think about mediation don’t think about meditation”… “I can’t stop thinking about stopping thinking about mediation!”

  2. This doesn’t make any sense to me.

    Are they suggesting that infrared LED light will penetrate cranial bone? If not (and I suspect it will not), then how can you possibly map blood flow on the surface of the brain?

    I’d be surprised if there is any tangible connection between blood flow in the scalp and blood flow in the brain.

    1. Yeah sounds like your classical BS to me too, and not only does it work through the skull but also through his hair supposedly.

      Still, nice project site, including datasheet pdf’s, I wish more projects were that thorough.

    2. That was my first thought too. But apparently at the right wavelengths, it penetrates the skull enough to make it work. I Googled up several other examples of this technique, even a Wikipedia article on it. Amazing.

    3. Materials are not just ‘perfectly opaque’ or ‘perfectly transparent’ to every frequency of EM radiation (and hence light). Bone and skin are no different. The key here is to find a light frequency that they are partially or mostly transparent to (which is not necessarily in the visible range), but is significantly opaque to the thing you are trying to see (i.e. blood.) An obvious example is the x-ray – flesh is quite transparent to it but bone isn’t.

      1. Yeah yeah, ladidah and whatnot, and there is a wikipedia page.. yeah OK, homeopathy is also sold in real shops you know.
        I’m sure you emanate IR but you’d see the damn surface vessels of the skull if anything and not the bloodflow in the brain.

        I like to watch fringe too though, don’t get me wrong.

        Anyway I think I hear the mailman with the x-ray glasses I ordered.

      2. I’m also suspicious of the technique used.
        While I’m at least willing to firstly believe in it possibly working (somehow), I don’t see there on their site that they did enough tests to verify it.

        The test they conducted only showed “unique activity on a specific channel”, which can, in the case tested, anything.

        Most likely they’re just monitoring the blood flow on the skin, as stated here before.

        I’d like to see a lot more test results before I’d dare to show this article to my colleagues, promising them “a brand new way to monitor brain activity”. [ You know, we’re those guys still believing in fMRT and stuff ;) ]

      3. Whatnot, you really should look up what you’re discussing, before lumping it in with utter bunk like homeopathy. You will find many respectable references; and if you can’t be bothered with reading enough to figure that out, try this page:

        Which has a picture that clearly shows even visible red light can penetrate a human skull, as well as a much better description.

        Removing the effects of hair, skin, surface vessels, and skull is just a matter of signal processing. What’s left is a very coarse representation of blood flow on the surface of the brain.

        There is no reason to doubt whether the technique works. Whether they have successfully implemented it, or whether the returned data is particularly useful, is a different matter.

      4. So I skimmed that site and see this picture of their ‘deep’ vs shallow detection
        And notice that is requires a light source and isn’t passive (and presumably would require you to shave the contact points to remove the hair to prevent mad scattering), and is not very deep at all.
        Also note that they speak about purely experimental fake tissue they tested on.
        Also consider that in the center of the brain are large vessel which would ‘blow out’ any successful peering inside with a set of point detectors, and if it was possible to passively see inside then you would have more luck making an array and using a lens so you could focus.

        I stand by my view that this thing from the OP will not lead to useful information at all.

        And sure I grant you you can get information about surface inflammation and such, but I conclude you cannot usefully see inside the brain with that setup as done in the article from the OP (original post).
        That was why I mentioned the fringe TV show earlier, where they also on a regular basis take something that has a scientific base and then draw it into phantasy.

        For those interested here’s a vein resin cast picture of the brain:
        Note that it’s laying upside down there (and is slightly unsettling if you are sensitive to that kind of thing obviously).

  3. At first I was surprised by such a cool project. Then I looked at their site and would fail them. The circuit they use is by no means sensitive enough for the brain. They are simply detecting changes in the skin.

  4. “Since your brain actually regulates the flow of blood to parts that are in use you can see brain activity by looking at blood flow”

    Using the BOLD response is at best a correlate of neural activity, and given the limited resolution of an imaging device it requires very careful experiments to use the data properly. Furthermore, this device only appears to map surface response, rather than volumetric like with FMRI, which would give a very fuzzy projection. BOLD response is unfortunately the best observational tool we have for noninvasive measurements in humans.

    However, the future is optogenetics! It’s amazing what sort of things you can do with it, giving accuracy that we never had before with BOLD response or a electrophysiology device (how do you know what you’ve probed? how do you know your probe hasn’t moved and touched another neuron? how do you know you’re array pins didnt bend?):

  5. near infrared is also used on the ISS to help heal any wounds in half the time it usually takes. they also grow all their plants with em. I see this working as yes the near infrared can penetrate through bone and hair and scalp. maybe they might find a cure for baldness as a side pseudo effect.

  6. “you can’t really establish “base line” activity by turning off the brain”
    Don’t they have politicians in New York? If not, there are plenty in Washington.

    I’ll grant that certain frequencies of the near-infrared end of the Electro-Magnetic spectrum, can, and do, penetrate cranial sub-structure, but; unless the sensors are positioned on the antithetical-hemisphere how could they be certain of receiving the Electromotive force?
    If one frequency bounces off of blood in general the interspersed vessels would act in a manner akin to an Faraday cage randomly scattering the irradiation with deflections and reflections (I’m getting the mental image of a human LASER). And the same may be said for the second frequency and the other bounces off oxygenated blood. with the added dimension that your brain actually regulates the flow of blood to parts that are in use.

    And “Since Your brain actually regulates the flow of blood to parts that are in use you can see brain activity by looking at blood flow”
    You will never be able to tell where neurons are firing as You are merely tracking where blood went after the fact.
    Not sure of Your baldness, but what of the hereditary baldness caused by excessive testosterone production, (ala Bruce Willis) that the fairer sex can’t get enough of?

    If, as it currently stands, they use the system as a Lie Detector, a lot of people will get screwed had, coming and going.

  7. First point:
    There’s no result! They didn’t even measure SNR.
    Second point:
    The frontal lope is not the motor cortex.
    Third point:
    To get information about deeper regions (ca. 3cm) it’s necessary find out, how deep you penetrate the scull. Run-time-measurement or interference would be proper methods but the first one is on the scale of 1 ns and below and the second method would require coherent light with intensities so high, there would be no chance to avoid damage to the biological object, you are looking at. (With OCT, you can only achieve a penetration depth of 3mm.)
    That’s why brain activity imaging using NIRS is only adequate if you know, that there will be a specific response to any specific stimulus that you like to verify. Anyway, if you build measuring systems, you have to find out if/how they work (repeatability, SNR,…).
    The project is nice anyway but they spent hours and days for building the hardware but write on their site
    “Unfortunately, we ran out of time to conduct additional tests.” and sadly, the only test they made isn’t really a measurement.
    Sorry for my bad English.

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