source positions - brain regions

[Nathan Weisz]

dear help-list,

sorry for what appears to be a very basic question.
i'm just starting to explore the source analysis possibilities that
fieldtrip offers. for this i downloaded a EEG tutorial dataset from
eeglab, did eeglab2fieldtrip, and the timelockanalysis. now i wanted
to estimate the source waveforms of the erp.

%this is my input:
vol   = [];
vol.r = 12 * [0.88 0.92 1.00]; % radii of spheres, the head radius is
12 cm
vol.c = [1 1/80 1];            % conductivity
vol.o = [0 0 0];

tmp=data.elec;
tmp.pnt=tmp.pnt*12;


cfg=[];
cfg.method='lcmv';
cfg.vol=vol;
cfg.elec=tmp;
cfg.resolution=1;

datamn=sourceanalysis(cfg,dataav);

%this is the output
datamn =

       xgrid: [-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10]
       ygrid: [-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10]
       zgrid: [-8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10]
         dim: [21 21 19]
         vol: [1x1 struct]
        time: [1x256 double]
         pos: [8379x3 double]
      inside: [1x4811 double]
     outside: [1x3568 double]
      method: 'average'
         avg: [1x1 struct]
         cfg: [1x1 struct]

there were no error or warning messages, so from the basic structure
things seem to be ok.
the time courses of my source activity appears to be saved in
datamn.avg.mom.

 >> size(datamn.avg.mom{datamn.inside(1)})

ans =

      3   256


however now i'm a little bit stuck. from here, what is the best
method of finding out which dipoles correspond (very roughly) to
which brain regions, so i can extract specifically those to look at
the sourcewaveforms? unfortunatley no mri.
I am aware of the sourceplot function, but was uncapable of producing
a meaningful output.

thanks in advance for any hints & best wishes,
nathan



--------------------------------
Dr. Nathan Weisz
Dept. of Psychology
University of Konstanz
P.O. Box D25
78457 Konstanz, Germany

Tel: ++49-7531-884612
Email & Chat-AV: nathanweisz at mac.com
Homepage: http://homepage.mac.com/nathanweisz/start/research.html