Friday, 07 Nov, 2008 Science

Scientists at the University of Chicago used brain scans to discover that aggressive youngsters might, in fact, enjoy causing pain to other people.

Researchers found that when an unusually aggressive teen watched a video of someone causing pain to another person by accident or intentionally, an area responsible for rewards highlighted in his brain. The brain of young people, who did not show signs of aggressiveness, did not show such signals.

According to Jean Decety, Professor in Psychology and Psychiatry at the University of Chicago and an internationally recognized professional on empathy and social neuroscience, it was the first time that scientists applied fMRI scans to investigate the conditions that might incite empathy. He said that the study could help people figure out the ways to work with violent youngsters.

The study showed that the natural empathetic impulse of some violent juveniles could be disturbed in such a way that they may show an increase in aggression. The research and its results were published in the latest issue of Biological Psychology. The scientific work was supported by the National Science Foundation, informs the official website of the University of Chicago.

The study involved 8 boys aged between 16 and 18, who registered aggressive behavior disorder by starting a fight, using a weapon and/or robbing their victim. These boys were compared to a group of teenagers who did not show any signs of aggression.

Aggressive teens watched clips that featured accidental and intentional causes of pain, including the drop of heavy bowl on ones hands and stepping on ones foot on purpose.

"The aggressive youth activated the neural circuits underpinning pain processing to the same extent, and in some cases, even more so than the control participants without conduct disorder," said the lead researcher.

A strong turn on of the amygdala and ventral striatum (area that reacts to feeling rewarded) in the brain of an aggressive youngster meant that he enjoyed watching others being in pain. The other group of boys, who did not have signs of violent behavior, had their brain activating the area the reacts for self-regulation.

A similar study was conducted on children aged between 7 and 12, who watched cartoons that featured accidental and intentional causes of pain. When children saw someone get hurt by accident, their brain reported signals in the same area that lighted up when children were hurt or when they saw someone get hurt. When they watched someone get hurt on purpose, their brain showed signals in the area that is associated with moral reasoning.