DICS power

Cristiano Micheli michelic72 at GMAIL.COM
Thu Aug 14 12:11:17 CEST 2008

Hi All
I have a problem with DICS's power and my simulations. I simulate an
external virtual channel coupled with MEG activity in a specific frequency
band (around 20 Hz).
I use DICS and submethod 'ref_chan'  and i can localize 1 source (even 2 if
they are distant) but only if I use coherence as a functional parameter and
With power i always see a bright spot in the middle of the brain. 
Should i select some options to account for decreased sensors' sensibility
in depth?
Since I used anyway coherence parameter for localization I did not pay
attention to this before but somehow it looks strange to me.
I attach the code and power image.

    cfg           = [];
    cfg.grid      = grid_; 
    cfg.method    = 'dics';   
    cfg.projectnoise = 'yes';
    cfg.reducerank = 2;
    cfg.lambda    = 0; 
    cfg.refchan   = refch;
    cfg.frequency = 20;
    cfg.hdmfile   = 'myheadmodel.hdm';
    sourcecond    = sourceanalysis(cfg, freqcond);

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/fcdonders/fieldtrip.
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