[FieldTrip] Create BEM model for EEG source localisation

Maria Pefkou Maria.Pefkou at unige.ch
Mon Mar 26 18:05:36 CEST 2012


I forgot to mention before that right now I'm running fieldtrip-20120325
under Ubuntu 10.04.

On 26 March 2012 18:01, Maria Pefkou <Maria.Pefkou at unige.ch> wrote:

> Dear FieldTrip users,
>
> I started using the toolbox fairly recently to analyse EEG data and I have
> huge trouble making a BEM model, which I need for source localisation.
> Following the online tutorial, I processed my subjects' individual
> structural MRIs in FreeSurfer and MNE and managed to prepare the
> triangulated mesh. However, my problem is the volume conduction model. I
> can get a singleshell one, using the ft_prepare_singleshell function, but
> as far as I understand it is excusively used for MEG data. I came to this
> conclusion because when I try to compute the forward model, given that I
> provide information about the electrodes position, I always get the
> following error:
>
> "unsupported volume conductor model for EEG".
> I guess this is because the vol.type is 'nolte' and there is no such case
> for EEG data, at least not in the ft_prepare_vol_sens.m function, which is
> automatically called.
>
> I have tried to prepare a BEM model using the ft_prepare_headmodel
> function with cfg.method='bemcp' or cfg.method='dipoli' but I was
> unsuccessful.
> The problem is that, after having tried various functions/options, I lost
> the general picture and I'm running in circles... The question is: I have a
> segmented mri, how can I get a BEM model out of this? I must be missing a
> fundamental part of the procedure but I can't quite find out what it is.
> Any suggestions/help would be very much appreciated.
>
> Thank you in advance,
> Maria Pefkou
>
> ------------------------------------------
> Research Assistant
> Functional Brain Mapping Lab
> University of Geneva
>
>
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