Teenage exploration and risk taking could be explained by dramatic changes
in the brain that allow elaborate planning and are driven by the need for
immediate reward, according to a University of Pittsburgh neuroscientist who
will be talking about her research in a panel discussion and press briefing at
the American Association for the Advancement of Science annual meeting, Feb. 13
to 16, in San Jose, Calif.
Using an elegant model in which eye movements, or saccades, reveal insight
into executive brain function, Beatriz Luna, Ph.D., Staunton Professor of
Psychiatry and Pediatrics, Pitt School of Medicine, has studied hundreds of
young volunteers to examine brain development during the transition between
childhood and adulthood.
"Our studies are beginning to challenge the traditional concept that
the teenage brain can't plan because of an immature prefrontal cortex,"
Dr. Luna said. "Our findings indicate that the teen prefrontal cortex is
not much different than in the adult, but it can be easily overruled by
heightened motivation centers in the brain. You have this mixture of newly
gained executive control plus extra reward that is pulling the teenager toward
In the experiments, volunteers are instructed to immediately look away from
a small light that randomly appears on a screen in front of them. This
"anti-saccade" test shows if the brain is able to engage the planning
centers of the prefrontal cortex to overcome the impulse to look toward the
light rather than away from it. Dr. Luna's team has found in previous studies
that children succeed in about half their tries, teens in about 70 percent of
tries and adults in about 90 percent of tries. People with mental illnesses
typically struggle with the task.
The study team had volunteers do the same tasks while scanning their brains
with functional MRI. They found that much of the architecture of mature brain
is in place by adolescence, but the ability of the networks to talk to one
another and integrate information is still a work in progress.
"Further enhancement of this network integration is likely why adults
can switch and very quickly adapt their behavior to changing circumstances,
which is more difficult for adolescents," Dr. Luna explained.
She added that while parents and teachers sometimes find bewildering the
choices teens might make, their brains are perfectly adapted to explore and
take some chances as they become independent adults.
"Across societies and species, we know that adolescence is a period of
increased sensation seeking that can lead to risk taking, which increases
mortality rate," Dr. Luna said. "Also, we often see during this
period the first signs of mental illnesses such as schizophrenia, depression
and eating disorders. All of these have a neurobiological basis, so if we know
how the brain is changing, we might be able to figure out a way to intervene
earlier in life."
Dr. Luna and researchers from the Children's National Medical Center,
Washington, D.C.; Columbia University Medical Center; and University of
California, Berkeley, will present their work from 1:30 to 4:30 p.m., Saturday,
Feb. 14, during a AAAS session called "From Womb to Tomb."