Dear Andrew and Giulia
Thanks for the example , it is very useful.

Still have two questions maybe not related to NBS but to statistics in general that you could please kindly acknowledge...
1. under this ancova example , do we need to perform a multiple comparison correction if we perform any additional ttest on the same matrices but  with a different group definition ? in other words i found a significant network with this design but also want to look for differences re-arranging a sub group distribution according to clinical properties.. lets say i split the patients group in two and compare them with individual t test using the same design agaisnt all the controls.

2. is there a way to define a contrast that only shows the effect of covariates alone? (not accounting for the groups differences) or shall i modify the design matrix ?

Thanks for your patience and grateful help!
sincerely, Juan P