We do need to be careful linking cause to effect. Do the brains react this way after conditioning and linking a successful beating of someone else to a feeling of vindication? Or do the brains react this way to begin with, causing the person to become a bully?
We now how easy it is to change your brain. Simply doing a puzzle changes your brain. I was bullied badly as a kid - if I was wired up and shown film of my bullies being attacked as I was, my brain might also show some interesting rejoicing. Or after the trauma of the very bad bushfires that sent me into serious PTSD, I know if I had been wired up then shown footage of bushfires, they would have seen some very strong responses. I don't think my responses would be so strong now.
This perhaps points at a way to measure success of rehabilitation, or perhaps a direction to take treatment in each individual case. You need to find out WHY seeing someone being hurt is apparently pleasurable, and find other more constructive ways to stimulate pleasure centres.
Marg