Problem with data from BESA

[Michael Wibral]

Hi,

I have imported averaged  EEG data from BESA (std 81 electrodes, average
refrence) using the .mul format and the corresponding .sfp file to
import the electrode locations. The import into fieldtrip seems to work
fine with these formats (it didn't when I tried .avr and .elp...).
However, the maps look very different from what I see in BESA (more like
something differentiated / inverted from the BESA maps - the foci are
clearly shifted). Do I have to tell Fieldtrip somewhere that this is EEG
data, so that it doesn't do the things it would when dealing with MEG
gradiometer data? Or is there something I have to do to let fieldtrip
know that the data are average reference data. I can't find anything in
the tutorials on this matter.

Thank you very much for any help on this,

Michael Wibral

M. Wibral Dipl. Phys.
Max Planck Institute for Brain Research
Dept. Neurophysiology
Deutschordenstrasse 46
60528 Frankfurt am Main
Germany

Phone:       +49(0)69/6301-83849
                 +49(0)173/4966728
Fax:           +49(0)69/96769-327
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