Looking for some advice.
I have a mood induction experiment with many subjects, 1 group, and 2
conditions.
In SPM I have created T-Contrasts to produce activation (condition A -
Condition B), and have identified desired ROI's.
Everything seems to have gone smoothly up until this point.
Then, I try to extract the DVR's from the respective Subject's ROI's and
calculate BP with BP=DVR-1. This is where things look a bit fishy...I
get some individual subject negative values and if I average per
condition, for some ROI's I get negative average BP's as well. I can't
make any sense of this. I would expect that I should only have positive
BP's (at least positive averages) for regions that were found to be
significant on the SPM analyses. Anyone have any suggestions.
Thanks so much,
PET Newbie
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