Dear Vladimir
A lot of your WM activation looks like CSF to me, most likely this is caused by respiration and cardiac pulsation. There are methods to correct for this but unfortunately most of them require that you have sampled pulse and respiration along with your fMRI images. But you could start off with inclusion of the realignment parameters in the design matrix. I think there is some GM activation in your images, but I agree that it is difficult to find because of all the CSF/WM false positives. If you want to se maps of what physiological noise in fMRI images look like there are plenty of papers on this e.g. Lund et al. 2006.
Best
Torben
Torben Ellegaard Lund
Associate Professor, PhD
The Danish National Research Foundation's Center of Functionally Integrative Neuroscience (CFIN)
Aarhus University
Aarhus University Hospital
Building 10G, 5th floor, room 31
Noerrebrogade 44
8000 Aarhus C
Denmark
Phone: +4589494380
Fax: +4589494400
http://www.cfin.au.dk
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Den Uge:37 17/09/2011 kl. 11.55 skrev Vladimir Bogdanov:
> Dear SPM experts,
>
> I have some rather unexpected results. I not continuous cold pain task we achieved at the group level significant increase of the signal in white matter (see pictures 1 and 2 for group results). The strange issue it that it is present there not along with gray matter responses, but INSTEAD of them. This appears to be not the because of the smoothing or normalisation of the data. We smoothed only 6mm. The FEW<0.05 significant voxes in WM appear also the individual level (see pictures 3 and 4).
>
> I would appreciate any suggestions for interpretation and useful references!
>
> Thank you in advance!
>
> Sincerely yours,
> Vladimir
> <wm_responce_fwe_05.jpg><wm_responce_uncor_001.jpg><6052_cpt_nonnormalised_fwe_05.jpg><6052_cpt_normalised_fwe_05.jpg>
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