[FieldTrip] Problems using .elp files

[B.Mouthaan at neuro.umcn.nl]

Dear Fieldtrippers,

I am using .avr files for source modelling on ERP data. From the ERP components, I have calculated the differencewaves in a .mat file. Until this it all went fine. However I get stuck at using .elp files.
I can succesfully create the headmodel with ft_prepare_singleshell(cfg,segementedmri) with the semi-realistic head model developed by Nolte (2003)
However when using ft_prepare_leadfield(cfg) I get problems.

My code is like this:

% discretize brainvolume in grid
cfg=[]
cfg.inputfile= 'C:\Users\Brian\Documents\MATLAB\AnalysisM\differencewave01'
[lbl] = importdata([subjectdata.subjectdir filesep subjectdata.electrodes]) % reading in .elp files

%renaming lbl.textdata to lbl.label, else it gives an error at ft_channelselection, because it is unable to read sens.label
oldField = 'textdata';
newField = 'label';
[lbl.(newField)] = lbl.(oldField);
lbl = rmfield(lbl,oldField);
cfg.elec= lbl
cfg.vol            = vol;
cfg.reducerank      = 3;
cfg.channel         = 'Fz'
cfg.grid.resolution = 1;   % use a 3-D grid with a 1 cm resolution
save cfg
[grid] = ft_prepare_leadfield(cfg);

When executing this I get the following commandscreen:
....
.....
using headmodel specified in the configuration
using electrodes specified in the configuration
??? Error using ==> ft_prepare_vol_sens at 110
the input does not look like EEG, nor like MEG

Error in ==> prepare_headmodel at 114
[vol, sens] = ft_prepare_vol_sens(vol, sens, 'channel', cfg.channel, 'order', cfg.order);

Error in ==> ft_prepare_leadfield at 159
[vol, sens, cfg] = prepare_headmodel(cfg, data);

I think this is because I use .elp files? The .elp files contain N rows and 3 columns representing xyz or spherical coordinates I assume. However this is the only information I have about the electrodes, so I have to do with it.

Any ideas?

Kind regards,

Brian






Het UMC St Radboud staat geregistreerd bij de Kamer van Koophandel in het handelsregister onder nummer 41055629.
The Radboud University Nijmegen Medical Centre is listed in the Commercial Register of the Chamber of Commerce under file number 41055629.

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