Nice study here of how different parts of the brain interact:
In their study, the Princeton researchers asked people to play the ultimatum game while the receiver's brain was scanned using functional magnetic resonance imaging, a technology that allows researchers to see what brain areas are active at all moments during the study. They found that the more unfair the offer, the more activity they saw in an area called the anterior insula, which is associated with disgust and other negative emotions.
Another brain area, the dorsolateral prefrontal cortex, which is associated with working memory and deliberative thought, also responded to unfair offers. When the researchers averaged the results from 19 subjects, who each played 10 rounds of the game with different proposers, they found that the activity of the emotion area exceeded that of the deliberative area in cases when the subjects rejected the offers. The reverse was true when they accepted offers.
"It is not only telling us that there is an emotional response but that there seems to be a competition between these different considerations or ways of processing the situation," said Jonathan Cohen, who directs Princeton's Center for the Study of Brain, Mind and Behavior and is a co-author of the study.