Fitting oscillations and one-over-F (FOOOF) enquiry

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#1

Hello. I have a question about the FOOOF models on Welch's Power Spectral Density (PSD), described here: https://neuroimage.usc.edu/brainstorm/Tutorials/Fooof

My objective is to compute the power spectrum density for a selection of electrodes using the Welch estimation density and determine the discrete frequency with the highest power magnitude within the alpha range (e.g., see: https://direct.mit.edu/jocn/article/32/1/1/95400/Individual-Alpha-Frequency-Predicts-Perceived).

I've followed the tutorial, but I'm not sure how to extract the single value I need. Where is it in the Matlab structure? (see "accessing FOOOF model parameters" in the tutorial)

Thank you very much!

#2

If you are only interested in the frequency that has the maximum power between 8 and 12 Hz, you don't need any model to your spectrum, and you probably don't need FOOOF.

You can get this directly from the PSD file:
https://neuroimage.usc.edu/brainstorm/Tutorials/ArtifactsFilter#On_the_hard_drive

Example based on the EEG/epilepsy tutorial:

PsdMat = in_bst_timefreq('sepi01/@rawtutorial_eeg/timefreq_psd_230117_1242.mat');
for iChannel = 1:size(PsdMat.TF,1)
    % Find the indices of the frequency bins of the alpha band
    iFreqs = find((PsdMat.Freqs >= 8) & (PsdMat.Freqs <= 12));
    % Find the maximum power
    [maxPower, maxIndex] = max(squeeze(PsdMat.TF(iChannel, :, iFreqs)));
    % Get the frequency value that has the max power
    maxFreq = PsdMat.Freqs(iFreqs(maxIndex));
    % Display the result 
    disp(sprintf('Channel %s: maxFreq=%1.2fHz, maxPower=%g', PsdMat.RowNames{iChannel}, maxFreq, maxPower));
end

You need to some basic skills in Matlab programming, and probably some of the information from the Scripting tutorial:
https://neuroimage.usc.edu/brainstorm/Tutorials/Scripting

#3

Thanks. Is there any way to do this using the GUI?

#4

You can do it visually...