[FieldTrip] Intertrial coherence (phase locking factor)

Beom Jun Min mbj0310 at gmail.com
Sun Mar 23 03:14:34 CET 2014

Hello trippers,

I am confused with the 'cfg.method' for ITC.

After examining the previous discussion list, I found method for ITC
calculation as below.

*tmpdat = freq.fourierspctrm;*
*tmpdat = tmpdat./abs(tmpdat); % this will normalise each trial for its
*itc = abs(mean(tmpdat)); % this will give the itc*

In addition, for this method, the ft_freqanalysis should have configuration
as below.

*cfg = [];*
*cfg.keeptrials = 'yes';*
*cfg.keeptapers = 'yes';*
*cfg.output     = 'fourier';*
*cfg.channel    = 'all';*
*cfg.method     = 'mtmfft';*
*cfg.foi        = 20:1:60;*
*cfg.toi = -0.5:0.01:1.5;*
*cfg.tapsmofrq = 4;*
*cfg.taper = 'hanning';*

However, I use 'wavelet' for the calculation of gamma band now.

Should I use 'mtmfft' for the calucation of ITC?

In case of 'wavelet', the result of itc has 4-D data - trial (averaged) *
channel * freq * time
Meanwhile, in case of 'mtmfft' the result has 3D data - trial (averaged) *
channel * freq without time.
Which structure is right?

And, if I want to calculate the mean value of ITC of a group,
is the order of the processing below right? :
preprocessed data of each individual -> time-frequency analysis ->
calculate ITC -> grandaverage

With regards.

BeomJun Min, M.D.

Department of Medical System Engineering (DMSE)
Gwangju Institute of Science and Technology (GIST)
261 Cheomdan-gwagiro(Oryong-dong), Buk-gu, Gwangju
500-712, Republic of Korea (South)
Phone: +82-62-715-3266 / Fax: +82-62-715-3244
E-mail: mbj0310 at gmail.com, http://bmssa.gist.ac.kr
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