Calling for help vs. staying quiet

A University of Wisconsin study investigated rhesus monkeys in a stressful situation, correlating brain activity with the frequency of calls for help. The results indicate that two brain systems are involved, one more active in more fearful and quiet monkeys, and the other in more secure and vocal monkeys. The press release describes some possible implications for human behavior.

http://www.news.wisc.edu/10786.html