Demystifying the
Adolescents can be mature one moment
and frustratingly immature the next.
The nature of brain development helps explain why.
Laurence Steinberg
In addition to being a transitional time in physical, intellectual, emotional, and social development, adolescence is a time of important changes in the structure and function of the brain.
and our understanding of brain maturation
has grown at breathtaking speed. Major
contributions to our understanding have
come from studies using functional magnetic
resonance imaging (fMRI). This technique
Scientists are beginning to understand how
enables researchers to take pictures of indi-
the psychological changes of adolescence are viduals’ brains and compare anatomy (brain
linked to brain maturation.
structure) and activity (brain function).
Before the development of brain imaging
Some aspects of brain development in
technology, scientists could only speculate
adolescence are reflected in changes in brain
about the workings of the adolescent brain.
structure (for instance, certain parts of the
Now, however, with the same scanners that
brain are relatively smaller in childhood
are used to identify tumors and torn liga-
than in adolescence, whereas other parts
ments, researchers can see inside the adoles-
are relatively larger). Other aspects of brain
cent’s brain and watch what happens when
development are reflected in changes in brain
teenagers think. We now know that, other
function (for instance, adolescents may use
than the first three years of life, no period of
different parts of the brain than children do
development is characterized by more dra-
when performing the same task).
matic brain changes than adolescence.
In addition, greater interconnectedness
among various regions of the brain allows for
What We’ve Learned from fMRI
better communication between parts asso-
It used to be thought that improved intel-
ciated with different functions. For example,
lectual functioning in adolescence would be
connections between regions of the brain
reflected in larger brain size. However, the
responsible for logical reasoning become
brain has reached its adult size by age 10,
better connected with those responsible for
making it impossible that changes in thinking experiencing intense emotions; “cross-talk”
during adolescence are the result of sheer
increases in the brain’s size or volume.
Since 2000, there’s been an explosion in
research on adolescent brain development,
between these regions enables better impulse
control and self-regulation. That’s one reason
that older teenagers are so much better than
younger ones at controlling their emotions.
