Trouble getting alpha waves, Cyton with Ultracortex

klamklam
edited May 2019 in Headware
Hi, I just recently bought a fully assembled Ultracortex Mark IV with the Cyton and Daisy boards. I followed the tutorials on setting up the device and the OpenBCI GUI, and I successfully managed to get some EEG data to appear.

However, when I tried the tests to see alpha waves, I have never been able to see a spike from the 10-12 Hz range. I do see a spike in 1 and 2 when I blink, so I know at least that works.
This is the the kind of data I typically get (https://i.imgur.com/TBTO7VT.png).

I have tried readjusting the position of the electrodes, but there aren't much changes the the readings unless there is movement (e.g. clenching my jaw).
I have also tried training my alpha waves with the BrainBay setup, but I haven't had any success with it.
I've tried testing with 4 or 5 other people, so I don't think it's just me having weak alpha.

I'm kinda at a loss as to what to do next. I'm relatively new at using BCIs and detecting EEG signals, so I'm not sure where to look. Thanks in advance!

Comments

  • wjcroftwjcroft Mount Shasta, CA
    edited May 2019
    Klam, hi.

    So with yourself and 5 others, none were able to see closed eyes alpha (8-12 Hz) increasing in the FFT graph? That seems unusual. Do you have some gold cups and paste you can compare the Ultracortex to?

    Since zero of your subjects shows alpha, I would begin to suspect something not optimal with your reference ear clip. (I assume at one ear lobe; Bias at other.) Have you tried swapping the two leads?

    Another technique you can try to get better Reference connection, is to take a small square (~ 2cm square) of cloth or paper towel, and soak this in a mild salt water (saline) solution. (Moist but not dripping.) You can also use the saline solution sold for eye irrigation in drugstores. Put this square in the jaws of the ear clip, so that when placed on the ear lobe, the wet cloth is between the skin and the contact on the clip.

    This kind of ear connection will increase the conductivity of your Reference signal.

    Have you used the GUI to check the impedance of your scalp electrodes?

    William
  • klamklam
    Hi William,

    Thanks for your suggestions. I do have some of the gold cups and Ten20 paste I could test with, and I was thinking of doing that next. I just wanted to make sure I haven't missed something more obvious first.

    Here is an updated screenshot of the GUI after I swapped the leads, used the wetted towel with saline, and with the impedances on (although I don't really know what I should be looking for):
    I still haven't gotten any alpha waves to show up with my eyes closed.

    Thanks again,
    Kevin
  • wjcroftwjcroft Mount Shasta, CA
    It looks like channel 16 on your last photo was the only one in use? It shows 5K ohms, which is good.

    In general when using the GUI, you can turn off unused channels to avoid cluttering the FFT and Time Series graphs with noisy traces.

    I would definitely use your gold cups and go through ALL the steps of the Cyton tutorial,

  • wjcroftwjcroft Mount Shasta, CA
    For following the tutorial, unplug the Daisy, so you are are following the exact same steps as the tutorial.
  • klamklam
    edited May 2019
    Hi. I just tried to complete the tutorial again (following all the steps with the gold electrodes). I successfully checked both my EKG and EMG, and I get the the same results that are shown in the tutorial images. However, when it comes to alpha waves, I don't get any response when I close my eyes (https://i.imgur.com/tpphVqF.png). Channel 7 responds to jaw clenches as shown in the tutorial, so I don't think it's a problem with the electrode.

    I will continue to test with other people, but I don't know what else I am doing wrong.
  • klamklam
    Actually, I just tested with 2 other people, and I managed to get consistent alpha signals from them. I tried with myself again afterwards, and now I think I personally have a weaker alpha wave, or I'm just really bad at blindly putting electrodes on myself. I tried some training in BrainBay and I managed to get a better signal (https://i.imgur.com/tS4kqg8.png).
  • wjcroftwjcroft Mount Shasta, CA
    Great! By the way, you can adjust the Time Series graph maximum down from the 200uV you currently have, to as low as you want. Your alpha waves on the time series are not very large. So you want to zoom in on that.
  • klamklam
    When I moved back to the Ultracortex setup, I could only reproduce the alpha signals in my 2 successful subjects weakly. Is there a way to improve these signals? I'm currently using the long comb electrodes; I don't know if they're less reliable.
  • wjcroftwjcroft Mount Shasta, CA
    The dry electrodes always result in some reduction in signal strength. I did mention the saline idea at the ear clips.

    More pressure on the scalp (by adjusting the electrode holders), should result in a modest increase in signal level.

    The long combs are more rounded and less 'pointy' than the default short combs. It's possible the pointier combs might contact deeper to the skin. However they don't do as well in longer hair.

  • SkalbeSkalbe Latvia
    Hi, klam!
    As you already have found out, alpha waves are not a given. I have found that numerous of my test subjects cannot produce reliable alpha waves, even though it is allegedly the 'hello, world!' of bci hacking. Then again, my own alpha waves always show up really strong and consistent. I practice quite a bit of meditation and yoga and have been doing it for years. After questioning my subjects, however, I usually found out that they do not actually feel relaxed with their eyes closed. Their minds are racing and most reported some anxiety background. Just food for thought.
  • klamklam
    Thanks for the insight Skalbe!

    I think you might be right about the relaxation part. I'm going to be using this for my thesis and I am already feeling the pressure even though I just started. I should probably try some relaxation exercises if I end up planning to use alpha waves further in my research.
  • SkalbeSkalbe Latvia
    If you can, do let us know if you find any hard correlations during your development. :)
  • retiututretiutut Louisiana, USA
    "however, I usually found out that they do not actually feel relaxed with their eyes closed."

    @Skalbe Good point! Similar to https://en.wikipedia.org/wiki/White_coat_hypertension

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