Combining different MEG sensortypes

[Laurence Hunt]

Hi guys - 

I believe this bug was fixed on 15th July this year, so any version of fieldtrip preceding this will still have a sign-difference issue between gradiometers and magnetometers. (This should not be an issue for an analysis using each modality separately (unless you are critically interested in dipole orientation), or analyses using SPM's source reconstruction routines (spm_eeg_invert_fuse estimates a scale factor for both magnetometers and gradiometers, and this factor can go negative as well as positive), but will be an issue for these beamformer source reconstructions). 

It would be great if someone was able to check this with a phantom - we are hoping to do something similar in Oxford soon.

Cheers,
Laurence

===========================================
Laurence Hunt, DPhil Student
 Centre for Functional MRI of the Brain (FMRIB), 
University of Oxford
lhunt at fmrib.ox.ac.uk
Phone: (+44)1865-(2)22738
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On 30 Nov 2010, at 20:18, Robert Oostenveld wrote:

> This reminds me of a bug that was in the code "once upon a time". That bug caused a sign difference on the gradiometer and magnetometers in the leadfield. Now hearing this problem, I am not 100% sure whether that bug has been resolved. 

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