Region of interest like-analysis that represents connectivity


I have started to implement a ROI based analysis using anatomical masks per the instructions here:

Some of the masks I have created are the combination of two regions, e.g., hippocampus and caudate. I am interested in performing something similar to a ROI analysis after this, such that what I am using represents two regions and connectivity between them as opposed to the regions alone (e.g., hippocampus + caudate + hippocampus-caudate connectivity). Is such an analysis possible? If so, what would it be called, and could you send resources on it?