Dear Tomohisa,
> There are two tasks (A, B) and a control (C). I made comparisons
> between task A - B and con_AB.img was created. As I wanted to exclude
> negative contribution from task B, I used ImCalc and masked con_AB.img
> (i1) with con_BC.img (or it should be con_B.img, anyway it is i2) with
> expression of 'i1-i1.*(i2<0).'
Although this is an ingenious use of ImCalc I do not think it is
necessary. You can address these sorts of questions using masking at
the level of SPM display. If you want to show regions that activate
more in A than B, but only in voxels where B is not less than C, then
simply mask [exclusively] the contrast A - B with C - B. Do this in
the results section.
I hope this helps - Karl
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|