[FieldTrip] Calculating single PLI value for a frequency band

e0046902 at gmail.com e0046902 at gmail.com
Sun Apr 3 06:42:50 CEST 2022

Dear all,


I am novice to EEG analysis and I am trying to calculate Phase Lag Index for
my resting state data.


I have redefined the data as 2 sec trials and then run ft_frequencyanalysis
with "powandcsd" as cfg.output:


cfg = [];

cfg.length = 2;

data_trials = ft_redefinetrial(cfg, data);


cfg              = [];

cfg.method = 'mtmfft';

cfg.taper = 'hanning';

cfg.foilim = [8 13]; % I want to look only at alpha band

cfg.keeptrials = 'yes';

cfg.pad='nextpow2' ;


freq = ft_freqanalysis(cfg, data_trials);

 cfg = [];

cfg.method    = 'wpli';

PLI= ft_connectivityanalysis(cfg, freq);


With the above script, I get an output of PLI with the dimension of trials x
channel x channel x frequency. 


Is there a way I can get one PLI index for each trial, for each channel
combination, across the frequency band I specified. Essentially, how can I
get PLI values with dimensions: trials x channel x channel


I am very new to this so any help is appreciated. Also, If I am trying to
filter my results to only the alpha band (8-13hz), is what I am doing the
correct way to achieve this?


Thank you,



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