Biological reasons why teenagers may take greater risks – and therefore be in more danger of experiencing a serious allergic reaction

Previous studies have found that teenagers tend to be more sensitive to rewards than either children or adults.

Now Professor Russell Poldrack, a professor in the departments of Psychology and Neurobiology at the Univeristy of Texas, Austin, and colleagues have used functional Magnetic Resonance Imaging technology (fMRI) to study the brain activity of teenagers.

In the study, participants ranging in age from eight to 30 performed a task in which they had to categorise an abstract image into one of two categories and were told the correct answer. To ensure motivation, they were given cash rewards for each correct answer.

What most interested the researchers was how each participant's brain responded to the difference between an expected outcome of an action and the actual outcome as they learned to categorize the images. The researchers explained that learning seems to rely on ‘prediction error’ because if the world is exactly as you expected it to be, there is nothing new to learn.

Previous research has shown that the dopamine system in the brain is directly responsive to prediction errors. Researchers therefore measured so-called positive prediction error signals in the participants' brains as the participants discovered the results of their answers and the size of their rewards.

Teenagers showed the highest spikes in these prediction error signals, which likely means they had the largest dopamine response.

Dopamine is known to be important for the motivation to seek rewards. It follows, then, that the greater prediction error signals in the adolescent brain could result in increased motivation to acquire more positive outcomes, and therefore greater risk-taking.

Poldrack is confident future studies will further explore the biological reasons for stereotypical adolescent behaviour.

Jessica R Cohen, Robert F Asarnow, Fred W Sabb, Robert M Bilder, Susan Y Bookheimer, Barbara J Knowlton, Russell A Poldrack. A unique adolescent response to reward prediction errors. Nature Neuroscience, 2010; 13 (6): 669

Courtesy of Science Daily

Also see article Teen Troubles.

First published in June 2010

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