Sturdier Brain Networks May Help Children Resist Peer Pressure
New imaging study sheds light on adolescent decision-making


by Tom Valeo

September 19, 2007

Children who have a greater ability to resist peer pressure also have stronger connections among regions in their frontal lobes and other brain areas, according to a study conducted by Tomáš Paus at the University of Nottingham in England.

Bradley L. Schlaggar, who has done his own research on brain development, called the study “interesting, novel and provocative.”

“I don’t think there was any anticipation that such an investigation would yield such clear results,” said Schlaggar, assistant professor of pediatrics, radiology, neurology, and neurobiology and anatomy at Washington University School of Medicine in St. Louis.

During adolescence, the frontal lobes of the brain undergo rapid development, with the axons in that region gaining a coat of fatty myelin, which insulates them, facilitating the transmission of signals. This enables the frontal lobes to communicate more effectively with other brain regions and incorporate those signals into higher-level decision making. This type of “executive control” over impulses and perceptions originating in other parts of the brain gradually produces the judgment, self-control and analytical ability characteristic of adults—and important for resisting peer influence.

To determine who was better able to resist peer influence, Paus presented 46 10-year-olds a series of questions and statements such as, “I worry what others think of me,” along with giving them behavioral tests and an intelligence test. Then 35 of the children took turns lying in an a functional magnetic resonance imaging (fMRI) scanner, watching video images of hands manipulating a phone, pencil and other objects in either a neutral way or an angry way as the scanner took images of their brain activity. While in the scanner, they also watched videos of facial expressions that changed from neutral to angry.

Children who recorded a stronger reaction to angry movements and facial expressions while in the machine scored lower on those interview statements and questions that measured their resistance to peer influence. They also displayed less self-monitoring while taking other tests and scored lower on tests of impulse control.

These findings, reported in The Journal of Neuroscience in July, are important “if we are to understand how the adolescent brain attains the right balance between acknowledging the influences of others and maintaining one’s independence,” Paus said in a statement about the work.

He plans to do follow-up studies with these children to determine if these differences in brain connectivity predict which children later will display greater resistance to real-life peer influence.

Schlaggar co-authored a study published in June that revealed how coordinated networks of brain activity in adults govern most goal-oriented activity, including reading, listening to music or searching for a pattern. However, these networks appear to be merged in children and to separate only gradually during adolescence. Understanding this change may lead to a better understanding of conditions of impaired impulse control, such as Tourette’s syndrome and attention-deficit disorder, Schlaggar said.

The Paus study points to the importance of self-regulation, Schlaggar said. “Your sense of yourself and how you relate to others is going to fall under the category of executive control or impulse control,” he said. “Individuals who have trouble controlling their impulses will be most likely to respond inappropriately to peer influence.”

In Schlaggar’s opinion, studies such as this that use fMRI and other imaging techniques to link brain functions to real-world behavior will help shed light on the brain’s role in everyday problems—such as the potential negative effect of peer influence.

“The development of temperament, emotional regulation and social interaction in adolescents is a field that needs a lot of attention,” he said. “This kind of approach will help bring disciplines together to help understand the basic mechanisms of emotional and cognitive development.”