Hi Wen-Ching
> Hi SPM users and developers:
> I got an effect which I can not understand.
> Using second order (random effect) analysis, I obtained the group maps
> for activation and deactivation in a study. However, when I extracted
> the
> associated BOLD signals from those deactivation-mapped regions and
> averaged the BOLD curves from all the subjects, I got the BOD curves
> which looked like activation. They were above the baseline during
> the ON periods.
> It sounds too strange and I wonder how can this be explained.
I guess it depends of the contrasts you used - I guess you have a block
design - it is possible that OFF periods varies if they follow cond A or
B .. probably we need more details to know what happened ..
Best
Cyril
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