Here's another fMRI on college students brains as they performed two tasks, one designed to reward that student, the other designed to earn money for a charity.

The scans showed that a certain area of the brain was active when earning money for a charity. The researchers think this is a good test for altruism. When interviewed, the students who asserted that they were altruistic were usually the same students whose brain scan also showed them to be altruistic.

http://news.yahoo.com/s/nm/20070122/...altruism1_dc_1