Rat Study Suggests Different Reward System in Teen BrainA laboratory study on rats has led researchers to propose that the growing adolescent brain causes teens to be more susceptible to developing disorders like addiction and depression.

The University of Pittsburgh study compared the brain activity of adolescent and adult rats involved in a task in which they anticipated a reward.

The researchers found increased brain cell activity in an area of the brain called the dorsal striatum (DS) — a site commonly associated with habit formation, decision-making, and motivated learning.

However, when adult rats were exposed to the situation, this area of the adult rat brain did not become activated by an anticipated reward.

“The brain region traditionally associated with reward and motivation, called the nucleus accumbens, was activated similarly in adults and adolescents,” said Bita Moghaddam, Ph.D., a coauthor of the paper. “But the unique sensitivity of adolescent DS to reward anticipation indicates that, in this age group, reward can tap directly into a brain region that is critical for learning and habit formation.”

Rather than studying the difference or similarities between the behaviors of adolescents and adults, researchers studied brain actions to see if similar activities were present among the two groups.

The researchers’ predictions proved accurate. Even though the behavior was the same for both adult and adolescent rats, the researchers observed age-related neural response differences that were especially dramatic in the DS during reward anticipation.

This shows that not only is reward expectancy processed differently in an adolescent brain, but also it can affect brain regions directly responsible for decision-making and action selection.

“Adolescence is a time when the symptoms of most mental illnesses—such as schizophrenia and bipolar and eating disorders—are first manifested, so we believe that this is a critical period for preventing these illnesses,” Moghaddam said.

“A better understanding of how the adolescent brain processes reward and decision-making is critical for understanding the basis of these vulnerabilities and designing prevention strategies.”

Researchers state that future research will continue to compare adolescent and adult behavior, especially as it relates to stimulants—such as amphetamines—and their influence on brain activity.

Researchers published a paper on their findings in the Proceedings of the National Academy of Sciences.

Source: University of Pittsburgh