Hi all -
I'm currently running a PPI analysis looking at connectivity differences between two conditions (e.g., studying emotional words > studying non-emotional words) and using the amygdala as the seed region. At the group level, I know that setting the group t-contrast to [1 0 0] shows me regions that positively correlate with amygdala for emotional study > non-emotional study (that's the direction that I have the contrasts set up at the individual level). But what would be the interpretation - if any - of the reverse contrast (that is, setting it to [-1 0 0])? Does that show regions that negatively correlate with amygdala activity for emotional study > non-emotional study, indicating that those regions show decreased or disrupted activity as amygdala activity increases? Or, does the [-1 0 0] contrast show regions that positively correlate with amygdala for non-emotional > emotional? Or is the reversed contrast not interpretable?
Any help is much appreciated in advance. Thanks!
-Brendan Murray
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