[FieldTrip] 'powandcsd' on short time window

[Nenad Polomac]

Dear Fieldtrip users,

I have one problem and I hope that somebody has idea. For my source and
connectivity analysis I need cross spectrum matrix at 40Hz and for time
window of 50 ms(the effect is evoked gamma and it last less then 50 ms).
The problem is that for this very narrow window the best I can get is the
frequency resolution of 20Hz and that is far to low. I am trying now
different padding options but it seems it doesn't help. If I band pass
filter(35-45Hz) data before fft then result is as expected, but without
filtering I pickup wide range of frequencies(probably from 20-60Hz) even if
I specify cfg.foilim=[40 40]. Furthermore, all this stuff is included in my
cross spectrum and brought into the further calculations.
my code:
        cfg=[];
        cfg.toilim    = [0.03 0.08];
        data_redef= ft_redefinetrial(cfg, data);

        cfg = [];
        cfg.trials = 'all';
        cfg.keeptrials = 'no';
        cfg.channel    = 'MEG';
        cfg.method    = 'mtmfft';
        cfg.output    = 'powandcsd';
        cfg.tapsmofrq = 1;
        cfg.foilim    = [40 40];
        cfg.taper      =  'hanning';
        cfg.pad        =2;
        cfg.padtype='zero';
        gamma = ft_freqanalysis(cfg,  data_redef);

Thank you in advance!
Cheers,

Nenad
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