Volume conduction model for EEG DICS beamforming

Jared Van Snellenberg jaredvs at GMAIL.COM
Fri Jun 29 03:31:32 CEST 2007

Hi all,

I'm currently working on a few DICS beamforming analyses for an EEG dataset 
I have, and I have a couple of questions regarding obtaining a good volume 
conduction model to include in the cfg.vol input to sourceanalysis.

I do not have MRIs or headshape information for my subjects, but of course 
I have electrode position information in spherical coordinates (stored in 
an elec structure imported from a BESA .elp file).

It's not clear to me how to generate a volume conduction model with this 
information, so any guidance here would be greatly appreciated. Ideally, I 
would like to use a 4-shell model. The FIELDTRIP documentation indicates 
that this model is implemented, but I can not seem to find the relevant 
function (and prepare_singleshell requires headshape information or an nx3 
sensor array--I presume in grid coordinates--that I do not have). Finally, 
all of the relevant prepare_XXX functions seem to indicate that they are 
specifically for MEG data, so I wanted to make sure that whatever approach 
I use is appropriate for EEG electrodes rather than MEG sensors.

Thank you very much,

Jared Van Snellenberg
Social Cognitive Affective Neuroscience Unit
(212) 854-7858 p
(212) 854-3609 f
Department of Psychology, Columbia University 
406 Schermerhorn Hall
1190 Amsterdam Avenue, Mail Code 5501
New York, NY 10027

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