[FieldTrip] volume conduction model missing .mat

Akiko Ikkai akiko.ikkai at gmail.com
Thu Feb 9 23:04:30 CET 2012


I'm trying to create a volume conduction model for my EEG study based on
anatomical MRI, and having trouble with ft_prepare_bemmodel

when I run
cfg                = [];
cfg.tissue         = [7 4 1]; % value for brain, skull, and scalp
cfg.conductivity   = [1 1/80 1]*.33; % after standard_BEM.zip data
cfg.isolatedsource = true;
cfg.method         = 'dipoli';
cfg.sourceunits = 'mm';
cfg.mriunits = 'mm';
vol = ft_prepare_bemmodel(cfg, seg4bem);

I get the following error message while ft_prepare_bemmodel is running:

Fatal error in dipoli:  interface
/private/tmp/tpd8a04422_e19e_4978_9b9b_56d1f2696492.tri and
/private/tmp/tp313c9a32_1991_4df6_a404_8efc41b6302e.tri intersect
 at vertex 1402 of /private/tmp/tpd8a04422_e19e_4978_9b9b_56d1f2696492.tri

Warning: an error ocurred while running dipoli
> In dipoli at 94
  In ft_prepare_bemmodel at 112
Error using ==> fread
Invalid file identifier.  Use fopen to generate a valid file identifier.
Warning: File '/private/tmp/tp0c0779e3_a657_4ca5_b9e1_845f41e9574a.ama' not
> In dipoli at 102
  In ft_prepare_bemmodel at 112

and the output vol is missing .mat, which causes an error
during ft_sourceanalysis.
>> vol
vol =
            cond: [0.3300 0.0041 0.3300]
             bnd: [1x3 struct]
          source: 3
    skin_surface: 3
            skin: 1
            type: 'dipoli'

Does anyone know how to correct for "fatal error" so
that ft_prepare_bemmodel creates the correct volume conduction model? I
opened .tri file and removed line 1402, but got the same results.

Thanks in advance! Akiko

Akiko Ikkai, Ph.D.
Postdoctoral Fellow
Department of Psychological and Brain Sciences
Johns Hopkins University
Ames Hall, 3400 N. Charles St.
Baltimore, MD 21218
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