[FieldTrip] Source localization using DICS for EEG data from combined MEG/EEG recordings

[Rojas, Don]

Marcel,

Also, you might check your volume conductor. I've seen a similar error when there were NaNs in the surface normals.

Don

Sent from my iPad

On Jul 2, 2012, at 4:12 AM, "Johanna Zumer" <johanna.zumer at donders.ru.nl<mailto:johanna.zumer at donders.ru.nl>> wrote:

Dear Marcel,
I might have seen a similar error before when the number of channels in 'elec' do not match the number of channels in 'freq'.   Could that be the cause?

Also, does it matter that you are setting cfg.grad=elec, rather than cfg.elec=elec?

To debug, it might be best to first call leadfield=ft_prepare_leadfield() to ensure that is computed correctly, and then set that output to cfg.grid.leadfield=leadfield, in your call to ft_sourceanalysis.

cheers,
Johanna

2012/6/26 Marcel Heers <marcel.heers at googlemail.com<mailto:marcel.heers at googlemail.com>>
Dear all,

I am trying to perform source localization in the frequency domain
from EEG data using DICS. The data were recorded combined with MEG
(Neuromag data format).  The volume conductor is a 3 shell realistic
head model created with bemcp.
When running DICS with the following settings

cfg                   = [];
cfg.method       = 'dics';
cfg.grad            = elec;
cfg.frequency    = 14;
cfg.vol              = vol_eeg;
cfg.dics.projectnoise = 'yes';
cfg.dics.lambda       = 5;
source = ft_sourceanalysis(cfg, freq);


I am am getting the following error message:

??? Error using ==> svd
Input to SVD must not contain NaN or Inf.

Error in ==> beamformer_dics>pinv at 568
  [U,S,V] = svd(A,0);

Error in ==> beamformer_dics at 314
        filt = pinv(lf' * invCf * lf) * lf' * invCf;              %
Gross eqn. 3, use
        PINV/SVD to cover rank deficient leadfield

Error in ==> ft_sourceanalysis at 584
      dip(i) = beamformer_dics(grid, sens, vol, [],
squeeze(Cf(i,:,:)), optarg{:});


and I am not sure what might be the cause.

Maybe anyone can help me! Thank you in advance!

Marcel
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