Dear Alfonso and others,

I have finished some preliminary second-level analyses and want to explore some of the results further. However, I want to be sure that I have understood the analyses steps to properly interpret some of the results:

Data:
I have 2 groups (A and B), 3 covariates of no interest (age, IQ, gender), and 3 covariates of interest (I, II, III)

Analyses (seed-voxel):

1. I have looked for between subject effects with a GLM with A,B, age, IQ, gender and the contrast (1 -1 0 0 0). This gave a region X
2. Separate regression analyses with all, age, IQ, gender, covariate I and the contrast (0 0 0 0 1). This gave region Y.

Post-hoc analyses:
I then used SPM8 to explore and plot the fitted responses in regions X and Y. If I understand correctly, these values stored in Y.mat would correspond to the z-scores that were fed into the second-level analyses - is this correct?

If so, how should positive and negative z-scores be interpreted? E.g. positive z-score is positive functional connectivity between regions, negative z-score indicates a negative functional connectivity?

Also, if group A has mainly positive z-values in region X, and group B has mainly negative values, does this mean that the functional connectivity difference was driven by the increased functional connectivity in group A vs negative connectivity in group B?

Any thoughts on this would be greatly appreciated!

Many thanks,
Merina