I have a maybe basic question about 2nd-level ttest with covariate. Suppose I assess a contrast A and a covariate B with a 1-sample t-test, so my design matrix will consist of one column for the group contrast effect and another column for the group variation on the covariate, and a contrast of [1 0] gives me brain clusters activated to the contrast and [0 1] gives me brain clusters whose activities elicited by the contrast are significantly (and positively) modulated by the covariate. 

My question is, if I want to find areas which are both significantly activated by the contrast and whose activities elicited by the contrast are significantly modulated by the covariate, what is the most appropriate way? Should I look at the 2 activation maps and find overlapping regions? Or if I set the contrast as [1 1] does it give me the same (or very similar) results? 

Thanks,

Robin