Hi, Andrew

Thank you so much for your quick reply and suggestions. I have re-modelled No Trauma/Trauma as 1,-1 and similarly changed the interaction column in the design matrix to test this interaction (1,-1,1,-1) between trauma and diagnosis. I obtained an identical sub-network at T=8.5 as when the interaction was modelled as 1,-1,2 -2 and unfortunately the connectivity strengths extracted for these connections in this sub-network remain mostly zeros.

To answer your question, the structural connectivity matrices are thresholded by a minimum FA value of 0.2, and our matrices do contain some zero values however the percentage of zeros present in these are not too far off from other datasets we previously analysed for which we were able to obtain connection strengths. Our pipeline involves combining 86 cortico-subcortical nodes (desikan-killianey atlas, freesurfer v6.0) and edges are derived from performing CSD tractography (lmax=4) on a 32 gradient diffusion-weighted images (1b0, b-value of 1000m/s^2)

I really appreciate that you would be willing to have a look at these connectivity matrices for us. I could transfer these to you separately.

Many Thanks,
Laura