Hi,
In my first-level model, the activation period of interest had 3 conditions (A, B, and C). The brain regions that conform to my hypothesis should demonstrate linear graded activation among the three condition, that is, strongest during A condition, then B, and weakest in C. To isolate these brain regions, the contrast I plan to use is "1 0 -1" for A, B, and C. Is this contrast what I need? But it looks to me that this contrast just compare A with C (because it seems equal to the contrast "1 -1" for A and C and has nothing to do with B).
How about if the activation period of interest had 4 conditions (A, B, C, and D). Is the contrast I need is "-3 -1 1 3"?
Thank you.
Manuel
|