[FieldTrip] Granger Causality - different range of values based on conditions

[Kimaya Sarmukadam]

Dear Fiedtrippers,


I have been using the following code to calculate Granger Causality, across various conditions (ranging from 2.5 to 3 minutes long, 4 second epochs).


 cfg              = [];
   cfg.output       = 'fourier';
   cfg.method       = 'mtmfft';
   cfg.channel      = {'Fp1', 'Fp2', 'F7', 'F3', 'Fz', 'F4', 'F8', 'FT7', 'FC3', 'FCz', 'FC4', 'FT8', 'O1', 'Oz', 'O2', 'T7', 'T8', 'TP7', 'TP8'};


cfg.taper        = 'dpss';
   cfg.tapsmofrq    = 5;
   cfg.pad          = 'maxperlen';
   cfg.padtype      = 'zero';
   cfg.foilim       = [13 30];

cfg           = [];
   cfg.method    = 'granger';
   cfg.granger.method = 'bivariate';
   %cfg.hasjack = '0';
   grangerEC         = ft_connectivityanalysis(cfg, freqEC);

   cfg           = [];
   cfg.parameter = 'grangerspctrm';
   cfg.zlim      = [0 1];
   ft_connectivityplot(cfg, grangerEC);

For two conditions, the above code was able to evaluate granger causality between 0 and 1. However, for other conditions I am working on currently, the resulting values range from 0 to 4. Therefore, I was wondering whether there is an error in the code which does not pick up certain data for other conditions.

Below is a visual representation:

[cid:5b0676da-26fa-4371-9aef-d945d1139572]
Any help would be greatly appreciated.

Kind regards,

Kimaya Sarmukadam


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