[FieldTrip] How can I use DICS to get the waveforms?
"Jörn M. Horschig"
jm.horschig at donders.ru.nl
Tue Apr 2 09:32:16 CEST 2013
Dear Xiao,
the DICS algorithm computes power of a certain frequency band of *one
*time window (it works in the frequency domain with the cross-spectral
density matrix, i.e. no time axis anymore). The source.avg.pow field
contains thus the power value of this one time-frequency bin. I assume
you want to get time-spectral evolution information? In that case it
might be best to use the LCMV beamformer in the time-domain, extract the
spatial location (voxel) of interest and apply the whatever-Fourier
transform (short time, wavelet, welch, taper) on that. Please have a
look at our various tutorials, for example:
http://fieldtrip.fcdonders.nl/tutorial/beamformer (on DICS)
http://fieldtrip.fcdonders.nl/tutorial/beamformingextended (appendix for
LCMV)
http://fieldtrip.fcdonders.nl/tutorial/connectivity (also includes LCMV)
And here for the DICS paper:
http://www.ncbi.nlm.nih.gov/pubmed/11209067
Best regards,
Jörn
On 4/1/2013 4:05 PM, ?? wrote:
> Dear all,
> I use DICS-beamformer to get the source,as follow:
> cfg = [];
> cfg.frequency = freqP.freq;
> cfg.elec = grid.cfg.elec;
> cfg.method = 'dics';
> cfg.keeptrials = 'yes';
> cfg.grid = grid;
> cfg.vol = vol;
> cfg.dics.lambda = '5%';;
> cfg.dics.realfilter = 'yes';
> source = ft_sourceanalysis(cfg, freqP);
> source =
>
> dim: [19 25 19]
> freq: 17.9481
> cumtapcnt: 3
> pos: [9025x3 double]
> inside: [1x4686 double]
> outside: [1x4339 double]
> method: 'average'
> avg: [1x1 struct]
> cfg: [1x1 struct]
>
> source.avg
>
> pow: [1x9025 double]
> is it right? if I want to get the waveforms in order to do the
> correlation,how can I do ?
> thanks,
> best
> xiao
>
>
> _______________________________________________
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> fieldtrip at donders.ru.nl
> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip
--
Jörn M. Horschig
PhD Student
Donders Institute for Brain, Cognition and Behaviour
Centre for Cognitive Neuroimaging
Radboud University Nijmegen
Neuronal Oscillations Group
FieldTrip Development Team
P.O. Box 9101
NL-6500 HB Nijmegen
The Netherlands
Contact:
E-Mail: jm.horschig at donders.ru.nl
Tel: +31-(0)24-36-68493
Web: http://www.ru.nl/donders
Visiting address:
Trigon, room 2.30
Kapittelweg 29
NL-6525 EN Nijmegen
The Netherlands
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