Dear Dr. Alfonso,
I have a set of task-induced fMRI data with a 2 groups (patient, control) *3 conditions (task1, task2, baseline) design. Now, I hope to examine the group difference in connectivity induced by task. Using ROI-to-ROI analysis, I extract the r value (after Z transformation) for each condition and subject. However, I just focus on how the particular task component (task minus baseline) modulate the connectivity among ROIs. Could I use difference in r value derived from r of task minus r of baseline to conduct the group analysis? or I must use a 2*3 ANOVA analysis for r value?
A related question is how 'conn' calculates the relative r value among two or more conditions?  For example, if I set (1 -1) for condition contrast (task vs. baseline), is the result a effect size for r of task contrast to r of baseline?  What the result represent? How to explain the results?
Thanks!
Ivan