Volume conduction model for EEG DICS beamforming

[Robert Oostenveld]

On 7 Jul 2007, at 5:12, Jared Van Snellenberg wrote:

> Quick question about the BEM model you supplied--is it correct to
> just pass in the vol structure contained in the standard_vol.mat
> along with an elec structure containing the nx3 array of electrode
> coordinates in MNI space? That is, is the following correct:
>
> load standard_vol.mat
> cfg.vol=vol;
> cfg.elec=elec; %predefined; 59 electrode coordinates in MNI
> results=sourceanalysis(cfg,data);

Yes, but only if the electrode labels in your data match with the
complete set or a subset of the labels in elec (it is case
sensitive). The intersection of data.label and elec.label will be
used for sourecanalysis. However, for EEG source analysis your data
should be average referenced. And that is something that you do
during preprocessing (or optionally timelockanalysis). That means
that all channels in your data for which there is a corresponding
electrode position in the elec structure should be average referenced.

Prior to sourceanalysis, you can use the headmodelplot function (or
electroderealign with method=interactive) to check that the
electrodes ly on the skin compartment of the MNI head model.

regards,
Robert

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