Summary: Researchers examine the teenage brain to explain why behaviour changes so dramatically during adolescence.
Source: The Conversation.
Parents and teachers are painfully aware that getting a teenager to focus on what adults deem important is often a lost cause. Offers of rewards or stern warnings frequently fail, for reasons that include growing independence and social pressures from peers.
Recent research published in Nature Communications suggests a more fundamental explanation: the adolescent brain itself is wired differently during this period of development.
Adolescence begins with the biological changes of puberty and ends when a young person attains a stable, independent role in society. It is also a time of dramatic brain reorganisation. After years of expansive growth in grey matter, the brain begins a process of thinning. This reduction in grey matter appears to reflect synaptic pruning—a refinement that removes unnecessary neural connections and improves processing efficiency. The pruning proceeds from the back to the front of the brain, leaving the prefrontal cortex, which supports executive functions like decision-making and cognitive control, among the last regions to mature.
At the same time, the brain’s networks are reorganised: local circuits give way to broader, long-range connections that integrate activity across different regions. These structural and functional upgrades are essential for mature cognitive control. Yet adolescence is also marked by heightened impulsivity, sensation-seeking and risk-taking. One notable feature of adolescent behaviour is difficulty matching actions to likely rewards or punishments—an inability to reliably weigh effort against outcome.
In a mature brain, this balance arises from effective communication between the prefrontal cortex—responsible for planning and cognitive control—and evolutionarily older subcortical reward systems such as the striatum and anterior cingulate cortex. These systems together allow us to perform a kind of internal cost-benefit analysis, adjusting effort and strategy to the potential payoffs. Psychologists call this the ability to adapt cognitive performance to environmental demands.
High versus low stakes
The new study examined brain activity in people aged 13 to 20 using functional magnetic resonance imaging (fMRI) while participants played a game that offered either high or low monetary rewards or penalties for correctly sorting images. Normally, higher stakes motivate better performance. However, the study found that only the oldest participants (19–20-year-olds) reliably improved performance when the stakes were increased. Younger adolescents performed less efficiently regardless of whether rewards or punishments were large or small.
Neuroimaging showed that the better-performing older participants engaged prefrontal regions more strongly and exhibited stronger functional connections between the prefrontal cortex and subcortical reward areas such as the striatum. In other words, as the brain matures, a “cool” cognitive control system increasingly modulates a “hot” motivational system, enabling a more appropriate alignment of behaviour with likely outcomes. When this connectivity is still developing, younger teens struggle to match what they do with what they can gain or lose.
This pattern of adolescent brain activity differs from patterns linked to adult impulsivity and sensation-seeking, which tend to reflect a generally under-responsive reward system rather than a lack of connectivity between control and reward regions.
These findings have practical implications. Simply increasing rewards to motivate young adolescents may not work. A more effective approach may be to provide clear, detailed information about decisions and their consequences to help offset the imbalance between motivation and cognitive control. For example, rather than offering a cash incentive to encourage a teen to apply to a particular university, arranging multiple campus visits and giving concrete information about courses, student life and career pathways may better support their decision-making.
Of course, adolescents are not simply limited by immature wiring. Risk-taking can serve a developmental purpose: exploring new environments, forming independence and learning from experience are important steps toward adulthood. From an evolutionary perspective, youthful willingness to take risks may help a newly independent person discover opportunities and expand horizons.
Funding: Gina Rippon has previously received support from the Medical Research Council and the Wellcome Trust.
Source: Gina Rippon – The Conversation
Publisher: Organized by NeuroscienceNews.com
Image Source: NeuroscienceNews.com image adapted from The Conversation news release.
MLA: The Conversation. “Brain Scans Reveal Why Rewards and Punishments Don’t Seem to Work on Teens.” NeuroscienceNews, 30 November 2017.
APA: The Conversation (2017, November 30). Brain Scans Reveal Why Rewards and Punishments Don’t Seem to Work on Teens. NeuroscienceNews.
Chicago: The Conversation. “Brain Scans Reveal Why Rewards and Punishments Don’t Seem to Work on Teens.” NeuroscienceNews. (accessed November 30, 2017).