Some Basic Guidance

Hello All :grin:
First of all, thank you devs for making this software available for free, it is quite amazing.
I am a non-med / non-research individual interested in reviewing how my brain state responds to meditation and hypnosis. I am still learning how to work on the data acquired and fed to my PC from my Muse 2 headband. I would like some basic guidance which I have not been able to get a clear handle of:

  1. Is it correct to have overlapping frequencies when separating brainwaves into alpha, beta etc? I am using the pipeline editor to pre-process using a band filter but while constructing the pipeline, i noticed that I am overlapping some frequencies. Is that the correct approach? E.g.

    • Delta = 0.5 to 4 Hz
    • Theta = 4 to 8 Hz
    • Alpha = 8 to 13 Hz
    • Beta = 13 to 30 Hz
    • Gamma = 30 to 44 Hz

    The upper bound of each range is also the lower bound of the next range. How are you meant to handle this? Am I supposed to construct it as follows or are the above ranges accurate enough for non-professional purposes?

    • Delta = 0.50 to 3.99 Hz
    • Theta = 4.00 Hz to 7.99 Hz , etc....
  2. I have understood that the common way to characterize a brain state at any point of time is to calculate the relative power of a range to the the sum of all ranges in that particular time window. If my 4 to 8 Hz waves are most prominent at x time from the range of 0 to 44 Hz then I could consider myself to be in theta at that point in time. Where I am getting confused is how to make this comparison across channels. The Muse provides 4 channels ( TP9, AF7, AF8, TP10). Which of the following would be considered correct, or is there another way that is recommended?

    • Select one channel for the session and perform the relative power calc and use that?
    • Aggregate the power of each range per channel and divide by the aggregate total of all channels? i guess something like --> Sum(Rel PowTP9, Rel PowAF7....) / Sum(PowTP9, PowAF7....)

Your guidance would be highly appreciated

thanks

Is it correct to have overlapping frequencies when separating brainwaves into alpha, beta etc?

There is no problem with having overlapping frequencies. The measure for each frequency band is independent and depends on your scientific hypothesis. You could even have a large overlap between two bands (eg. 4-9Hz, 7-14Hz) if needed.

Where I am getting confused is how to make this comparison across channels

Comparing power values between brain regions does not necessarily make much sense. The power you obtain at one site depends on many factors: the quality of the connection with the skin, the depth and orientation of the brain sources you are trying to study...
You would more typically interested in comparing one given value between two experimental conditions, between a baseline and a task, or between two groups of subjects.

You can refer to this tutorial for resting state analysis:
https://neuroimage.usc.edu/brainstorm/Tutorials/RestingOmega

Hi and thanks for the quick feedback Francois,

  1. Appreciate the clarification about overlaps
  2. I never thought of it that way. I will review the link you have sent and rethink what I am trying to achieve.

Kind regards