I would like to perform a test (presumably in 3dMEMA) to see whether a covariate affects activation on a task. I hypothesize that there is a correlation between the covariate and activation (e.g., the greater the covariate, the more activation). I have two groups; I expect there to be a correlation with activation in one group but not in the other group. Is this a test that can be done using 3dMEMA? Or would I run 3dMEMA on the group that has the correlation, create a mask of regions that show that correlation and then look at the other group to show that they don’t show a similar effect?