Ultracortex not seeing alpha waves at O1 O2

vaibhav2912vaibhav2912
edited August 2016 in Headware
I am very new to the BCI realm. I have access to the OpenBCI V3 board. I know alpha waves are very easy to find and this is a silly question but please help me out here. Since, last few days I am trying to see my alpha waves particularly in the O1 and O2 region. But I don't see the spikes of around 8-12Hz when I close my eyes. I am also using the Ultracortex Mark III headset. I have read the blog by chip about the alpha waves and tried to follow along. I think I am following the steps properly but I don't see any alpha waves. Thanx in advance.

Comments

  • wjcroftwjcroft Mount Shasta, CA
    You can also look in the Parietal lobe at say P3 or P4 or Pz. There is a time lag sometimes between when you close the eyes and the alpha shows up. Are you recording, then looking at the recording? Or are you trying to peek at the screen while your eyes are supposedly closed. 

    You can also try this with paste and cup electrodes. Another trick sometimes used is to move your reference electrode from the ear lobe say into a frontal position. Finally, some people just have weak alpha. Try with another friend hooked up.

  • vaibhav2912vaibhav2912
    Yes, I am recording the data. Even when playing it back I can't see the alpha waves. I am using chip's Python spectrograms to better see the alpha waves, no alpha waves in spectrograms either. I see some random peaks around 10hz even with my eyes open. I think some peaks I see in the eyes closed recordings are the same random ones and closing my eyes is not making any difference. I have also tried the gold cup electrodes that came with the research bundle of openBCI board with ten20 paste. No success.

    I'll try the electrode locations u mentioned. I'll also try the gold cup electrodes at these P3, P4 and Pz and report back. Thank you for the reply
  • wjcroftwjcroft Mount Shasta, CA
    edited August 2016
    You can also try uptraining your alpha with some neurofeedback. 


    Neuromore has some designs for this as well.

  • vaibhav2912vaibhav2912
    Thanks.. I'll give these a try.
  • vaibhav2912vaibhav2912
    edited March 2019
    The problem with the alpha is solved I guess. I just tried adjusting the headset properly for my head size and it worked. I have the medium size of the headset which is still big for my head.
    Now that I see the alpha, I have another problem. My alpha is weak, I understand that because some people just have weaker alpha. I took readings with my eyes closed and another reading with my eyes open the whole time and used EEGrunt and python to plot the spectrogram and power spectrum of the signal the different electrodes. My best results are at the electrode O2. So the following images show the spectrogram and power spectrum for electrode O2 which is my channel 6.
    My problem is when I try to generate a baseline reading with my eyes open the whole time just looking around and looking at the computer screen I still generate signal peak in alpha range. After many tests my eyes closed alpha seems to be centered at 11.7097Hz. To show this I am including the results in the following images.


    image

    I then tried to look at the movie playing at 10Hz speed. I generated this movie by using chip's Matlab code. The results are:

    image

    It seems like I am always generating the signals in alpha range of frequencies which make it very difficult for me to actually recognise the signals which are being generated specifically as a response to me watching a 10Hz movie.
    I appreciate the help.
  • vaibhav2912vaibhav2912
    edited August 2016

  • wjcroftwjcroft Mount Shasta, CA
    edited August 2016
    It could be that (with yourself as subject) that eyes open/closed alpha is not your best strategy for BCI EEG feature extraction. Nor SSVEP. Have you considered a P300 or Motor Imagery approach? There are threads on the forum here that cover P300 spellers and MI.

  • vaibhav2912vaibhav2912
    Okay.. I'll check those out.. thank you
  • wjcroftwjcroft Mount Shasta, CA
    This other thread mentions Nek's SSVEP setup with stim frequencies at 11,12,13,14,15,16,17,18 hz


    He found better S/N by using sinusoidal intensity modulation, vs. square waves. Another thread here,

  • wjcroftwjcroft Mount Shasta, CA
    His June 2016 paper is here,


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