Dear Dr. McLaren (and others),

I am running a multi-regional gPPI analysis and am wondering what the most efficient way to use the gPPI toolbox would be. Ultimately, I would like to create a n-region-by-n-region PPI connectivity matrix for each subject, which I will then do second-level statistics on.

At the moment I have calculated my contrast of interest for several ROIs in one subject and the results look sensible. I can see how I could potentially build a connectivity matrix in this fashion (i.e. by extracting the values from the gPPI results I can build a 'row' of my connectivity matrix one analysis at a time). However this is extremely time-consuming for the number of ROIs I plan to use (~20) and the number of subjects I plan to analyze. I imagine there is a much better way to utilize the toolbox than what I am currently doing. It seems to me that I am doing a lot of unneeded calculations outside of the regions I am interested in (and while that is an interesting question in itself, it is not what I want to do at the moment). Is there a way to limit my analysis just to the regions I want to investigate, therefore (hopefully) speeding up the analysis?

I hope this is clear. Apologies if this has been covered before.

Best,
Luke