inter trial coherence

[jan-mathijs schoffelen]

Dear Yu,

Ft_connectivityanalysis works also with different kinds of
electrophysiological data. It's on our list to make the documentation
to this function clearer. This will hopefully happen soon.
For now, I don't think this is the function you need for inter-trial
coherence. Ft_connectivityanalysis computes bivariate metrics, i.e.
measures of connectivity defined between channel pairs. In your case,
you want to estimate the consistency of oscillatory phase across
trials (and not the consistency of the phase difference between a pair
of channels across trials). So what you need to do is probably
something like this:

cfg = [];
cfg.output = 'fourier';
cfg.....
cfg.....
cfg.....
freq = ft_freqanalysis(cfg, data);

Next, to obtain the itc, do the following

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

Best wishes,

Jan-Mathijs


On Aug 11, 2010, at 4:25 PM, Yu He wrote:

> Thanks Roemer!
>
> I am not very clear about function of ft_connectivityanalysis. It is
> said "FT_CONNECTIVITYANALYIS computes various measures of connectivity
>  between MEG/EEG channels or between source-level signals." when you
> read
> the documentation reference.
>
> Is that only for between MEG/EEG channels?
>
> Regards,
>
> Yu
>
> ----------------------------------
> The aim of this list is to facilitate the discussion between users
> of the FieldTrip  toolbox, to share experiences and to discuss new
> ideas for MEG and EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html
>  and http://www.ru.nl/neuroimaging/fieldtrip.

Dr. J.M. (Jan-Mathijs) Schoffelen
Donders Institute for Brain, Cognition and Behaviour,
Centre for Cognitive Neuroimaging,
Radboud University Nijmegen, The Netherlands
J.Schoffelen at donders.ru.nl
Telephone: 0031-24-3668063

----------------------------------
The aim of this list is to facilitate the discussion between users of the FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html and http://www.ru.nl/neuroimaging/fieldtrip.