> Another problem we are presently discussing internally is that SPM does
> not represent MEG gradiometers correctly and SPM5 source reconstruction
> is only correct for CTF data recorded with 'raw' setting. I'm not sure
> what kind of montage you have in BTi, but if you have things like 3rd
> gradient or planar gradiometers I'd be extra-careful. Feel free to play
> around but please send us the details before you try to publish
> anything. Most of these problems will hopefully be resolved in SPM8.
>
Minor postscript: SPM can represent gradiometers correctly, but only 1st
order gradiometers (via
the positions of the two component coils); it does not currently allow
for synthetic 3rd-order gradients
created by a second set of reference coils (eg in CTF machines).
Rik
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DR RICHARD HENSON
MRC Cognition & Brain Sciences Unit
15 Chaucer Road
Cambridge, CB2 7EF
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URL: http://www.mrc-cbu.cam.ac.uk/~rik.henson
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