Volume conduction model for EEG DICS beamforming

[Jared Van Snellenberg]

Hi Robert,

I'm using the BEM head model you supplied, and have a quick question about
it. From plotting the results of this approach, the grid appears to only
extend as low as the level of the anterior commisure. Is this intended? If
so, I presume it's because of the difficulty in localizing deep sources?
Thanks in advance.

-Jared


On 7/7/07, Robert Oostenveld <r.oostenveld at fcdonders.ru.nl> wrote:
>
> 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
>
> ----------------------------------
> The aim of this list is to facilitate the discussion between users of the
> FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG
> and EEG analysis. See also
> http://listserv.surfnet.nl/archives/fieldtrip.html and
> http://www.ru.nl/fcdonders/fieldtrip.
>



--
Jared Van Snellenberg
Social Cognitive Affective Neuroscience Unit
http://scan.psych.columbia.edu
(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
_______________________________
"Luck is the residue of design"
-Attributed to Branch Rickey, former US Baseball Administrator, and also to
John Milton. Go figure.

----------------------------------
The aim of this list is to facilitate the discussion between users of the FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html and http://www.ru.nl/fcdonders/fieldtrip.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.science.ru.nl/pipermail/fieldtrip/attachments/20070806/73d0c9dc/attachment.html>