"Scientists have uncovered a striking brain difference linked to psychopathy: people with psychopathic traits were found to have a striatum — a brain region tied to reward, motivation, and decision-making — that was about 10% larger on average than those without such traits. Using MRI scans and psychological assessments on 120 participants, researchers connected this enlarged brain region to thrill-seeking, impulsive behavior, and a stronger drive for stimulation."

Original Paper:

Larger striatal volume is associated with increased adult psychopathy

https://www.sciencedirect.com/science/article/abs/pii/S00223...