Scans revealed a distinct lack of activation in the ventral prefrontal cortex the brain region that helps to regulate our emotions and control our impulses.

WSJ: Neurocriminology: Inside the Criminal Mind

When they were faced with tossing or keeping their own items, the hoarders' brain responses also differed from that of the other participants: they showed excessive activation in the anterior cingulate cortex, a brain region involved with decision-making, particularly in situations involving conflicting information or uncertainty.

CNN: STORY HIGHLIGHTS