Hello jwrenjarvis,

Using your contrast, this might not necessarily due to false anticorrelations because here you are looking at the difference between two conditions (groups here). If you reverse the contrast (1 for psychiatric population, -1 for controls, 0 for the other covariates) you would get the same but positively correlated. The interpretation for me would be that the psychiatric population has a local increase of correlation in the amygdala compared to the control group.

Then to talk about connectivity, you would need to check the effect size, or the average connectivity of each group (1 for psychiatric population, 0 for controls, 0 for the rest ; then 0 for psychiatric, 1 for controls, 0 for the rest) to check the average connectivity per group. Indeed, an increase of correlation can either be an increase of positive connectivity (controls have 0 or positive connectivity in amygdala when looking at the average connectivity), or a reduction or even nullification of negative connectivity/anti-correlation (controls have a negative/anti correlation in the amygdala when looking at the average connectivity). You can also look at the effect size by plotting a barplot using REX (use a F-Test: [1 0 0 0 0; 0 1 0 0 0] then click Results Explorer then click Rex).

In the first case (increase of connectivity), this would potentially be interpreted as an increase of emotions (fear?), in the second case it would be a bit more complicated, as a reduction of negative connectivity, as negative connectivity is considered by some authors as still being a kind of connectivity (but with opposite phase), while others consider it evidence of segregation. Thus, I would consider interpreting the 2nd case in light of the results from other seeds (or from Intrinsic Connectivity Correlation using voxel-to-voxel, as this can guide you towards knowing if there is an increase of overall connectivity in the amygdala for example or a reduction).

Hope this helps,
Best regards,
Stephen