Hi all,

When running a functional analysis and comparing two experimental conditions, we observed that there are some voxels/vertices where both condition A and condition B have a positive % signal change from baseline, and condition A has greater activity than condition B.

In other regions, both condition A and condition B have negative % signal change from baseline, but condition B has a greater absolute value % signal change (thus relative to baseline condition B has more "deactivation"--a term I am using since you all know what I mean even if the term itself is imperfect).

Since, in both cases, the % signal change is technically condition A > condition B, the between-conditions maps do not distinguish these two scenarios. FS-FAST sees these as being the same. Is there a way to tell FS-FAST to cluster these scenarios separately? Is there a compelling reason why I should not consider these different situations? It seems to me that the interpretation of what's taking place in these two scenarios is not identical. Agree or disagree? Can FS-FAST distinguish these with a flag I don't know about?

Thank you, ~Sue