GCA prediction of increased/ decreased activity

Dear experts
I have one quick question about GC with the REST tool box in rest fMRI data. I have run a voxel-wise GCA using fit coefficients on the L/R amygdalae as a mask. I found significant predictions of activity in the amygdala for activity in specific cortical areas and also the other way around.
I was wondering whether it is possible to differentiate between positive (increased activity) and negative (decreased activity) correlations between the amygdala and the rest of the brain. I would greatly appreciate if you could mention whether this analysis already provide this information or it is necessary to run further tests.
If yes, I am not sure which value should i check for (e.g, "z")
Thank you for your attention.
S