Measuring brain synchronization using PLV calculation of 2 subjects EEG recordnigs

ashkan · July 22, 2019, 3:34am

Hello everyone,

I'm an IT student and for some parts of my PhD project I need to measure brain synchronization of multiple individuals using PLV calculations.

I have 2 EEG datasets (1 minute each) which I took from 2 x 32 electrodes LiveAmp EEG caps at the same time while my subjects performing a joint task.

I'm not very familiar with all these neuroscience stuff but after reading a lot of publications I found that I need to use PLV method for measuring brain synchrony.

Could someone please help me on how to use Brainstorm to measure synchrony between 2 brains?

Thank you

Francois · July 23, 2019, 2:07pm

You would need first to learn how to use Brainstorm in general. Follow all the introduction tutorials at least until #19, using the example dataset provided:
https://neuroimage.usc.edu/brainstorm/Tutorials

Then you could read this advanced tutorial that deals more specifically with EEG:
https://neuroimage.usc.edu/brainstorm/Tutorials/Epilepsy

Finally, you will need to find a way to import your recordings into Brainstorm. I don't know what file formats you can export your data to. The list of supported file formats is available here:
https://neuroimage.usc.edu/brainstorm/Introduction#Supported_file_formats

When you have your recordings in the database, it will be very straightforward to compute PLV between pairs of signals.

If you don't want to go through all this training, you could try to reuse directly parts of the Matlab scripts for the PLV computation:

github.com

brainstorm-tools/brainstorm3/blob/master/toolbox/connectivity/bst_connectivity.m#L489


    FreqBands = [];            

    

% ==== PLV ====

case 'plv'

    bst_progress('text', sprintf('Calculating: PLV [%dx%d]...', size(sInputA.Data,1), size(sInputB.Data,1)));

    Comment = 'PLV: ';

    % Get frequency bands

    nFreqBands = size(OPTIONS.Freqs, 1);

    BandBounds = process_tf_bands('GetBounds', OPTIONS.Freqs);

    

    % ===== IMPLEMENTATION G.DUMAS =====

    % Intitialize returned matrix

    R = zeros(size(sInputA.Data,1), size(sInputB.Data,1), nFreqBands);

    % Loop on each frequency band

    for iBand = 1:nFreqBands

        % Band-pass filter in one frequency band + Apply Hilbert transform

        if isConnNN

            DataAband = process_bandpass('Compute', sInputA.Data, sfreq, BandBounds(iBand,1), BandBounds(iBand,2), 'bst-hfilter-2019', OPTIONS.isMirror);

            HA = hilbert_fcn(DataAband')';

            HB = HA;

        else

ashkan · July 23, 2019, 11:30pm

Thanks Francois for the information. Let me try to see if I can do that.