Dear SPM experts!
I am just at the beginning of using SPM for fMRI data and encountered
some difficulties with looking at different conditions within in a set
where I don't know if the data are problematic or I am doing some
mistakes by setting the contrast. However it is a very simple paradigm
with two conditions of movements (AandB)each movement occurring twice
within a set (_A_B_A_B_). We want to compare differential effects
between A and B. If look at the respective epochs, e.g only at A by
setting the contrast to 1 0, the activation map looks definetly
different to the other condition, e.g looking at B (0 1). However,
setting A to -1 and B to 1 (or vice versa) within the contrast manager
the result is almost zero activation. Changing threshold from 0.05 to
0.01 doesn't have much effect.
Is there anything wrong the way I set up the contrast for this
comparison.
Second, is there any possibility to add two study sets together while
the order of the epochs is different(e.g. _A_B_A_B_ and _B_A_B_A_),
again I am interested in differential effects between A and B.
Thanks for any help,
Bjoern
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