Current Trends in
Understanding the
Adolescent Brain
Shirley Shen, Ph.D
Clark County Juvenile Court
Maturation of the teen brain
Something more organized that
looks like this..
Like a remote control
Cross section of brain
Neuron
Stages of brain development

The infant is born
with an
overproduction of
neuron, much
more than the
adult brain.


Neural connections,
however, are not
established during birth.
Experiences in the child’s
environment leads to
either reinforcement
(wiring) of the neural
connections or elimination
of the neural connection
(pruning)
NIMH Study


Dr. Jay Giedd—National Institute of Mental
Health
Began studying the brain of normal
children and teenagers every two years
with a fMRI
Implications of Dr. Giedd’s findings
of the adolescent brain


Dr. Giedd found that
prior to adolescence,
there is a thickening
in the grey areas of
the frontal lobe.
There are also
profound changes in
the amygdala and
also in the nucleus
accumbens
Frontal Grey Matter Development
in the Adolescent Brain
Frontal Lobe
Function of Frontal Lobe
Responsible for:
Executive functioning tasks such
as:
planning
strategizing
organizing
Attention functioning:
maintaining attention
shifting attention
Examples of Functional Impairments
in Frontal Lobe Lesions


Short term memory is impaired with
easy distraction.
Impairments in divergent thinking
(when there are multiple correct
answers).
Examples of Functional Impairments
in Frontal Lobe Lesions



Impaired strategy formation and planning,
especially in unfamiliar situations.
There is inappropriate behavior with
difficulty using social cues and information
to direct, control, or change personal
behavior.
Inhibition impaired.


The frontal lobe functions as the CEO.
The adolescent is just learning how to use
the prefrontal cortex.
However, it is not always very successful
at it.
When the frontal lobe is
vulnerable


When emotions are called on first to solve
a problem
During times of peer influence.
What is the anatomical reason
for this


The brain is being reorganized during
adolescene
The more primitive portions of the brain,
such as the sensorimotor region and the
emotional regions are already developed
Beatrice Luna-University of
Pittsburg


Adolescent risk taking
Design- Asked both adults and adolescent
to not look at a light placed in a brain
scanner.
Findings of Study



Adults
Able to not look at
the light
Used several parts
of brain to manage
the task



Teens
Able to not look at
the light
Solely used the
frontal lobe to
complete this task
MRI Study by Dr. Yurgelun-Todd


N=19
Suggestive that the prefrontal cortex
attenuates or monitors what happens in
the amygdala
Implications




Teens can use their frontal lobe.
However, as they are learning to use it,
they are using it even to do very easy
tasks
Teens are not good managers of their
frontal lobe.
It is as if the manager makes himself take
on the role of all his employees.
Amygdala
Function of the Amygdala



Emotional center of the brain
It has been suggested that the amygdala
functions to associate sensation with
reward or punishment.
The amygdala does seem to be closely
associated with the feeling of fear
Amygdala and the Adolescent
Brain


Adolescents tend to use their Limbic
System more often in the decision making
process, since their Frontal Lobes are not
fully developed.
The Amygdala, part of the Limbic
System, is responsible for impulse
reactions, emotional reactions, fear, and is
also used in the decision-making process
of adolescents.
Implications of Amygdala on
Adolescent Behaviors



Results in adolescents making more decisions
based on emotional reactions rather than
reasoning.
Less capable ability to weigh long term
consequences.
Developing adolescents tend to use their
Amygdala when responding to other people’s
emotions, yielding more reactionary, less
reasoned perceptions of situations than
adults.
Teen brain
Adult brain
Nucleus Accumbens
Mortality Rates in Adolescents in
the U.S. 1979-1988

Approximately three fourths of the more
than 40,000 deaths each year among
persons aged 10-24 years in the United
States are related to preventable causes




motor-vehicle crashes (37%),
homicide (14%),
suicide (12%), and
other injuries (e.g., drowning, poisoning, and
burns) (12%).
Function of Nucleus Accumbens




Directs motivation
Responsible for how much effort an
organism will expend in order to seek
reward
Also often referred to as the brain’s
reward system
Has significant implications in the reward
system for drugs in the brain
Studies of adolescent response
in risk takingWheel of fortune task



Adolescents took significantly more risks than
did adults and were
Adolescents were happier when they won
money, but were less upset than adults when
they lost.
In response to feedback, adolescents
activated the nucleus accumbens more than
did adults, while adults engaged the
amygdala and PFC more than did adolescents.
Teens Perception of Self
Also a function of brain
development
Who Am I ?????
Who
I am
depends on who
my friends think I
am….
My Friends tell me who
I am socially
Social Influences
Who Am I ?????
Who
I am
depends on who
my parents think I
am……
My parents tell me who I am
academically
Dr. Jennifer Pfeifer-University of
Oregon
Study
Group
Method
• 12 (11-13 year olds)
• 12 (22-30 year olds)
• MRI Images of the brain in response to
questions of individuals’ perception of
themselves

Two separate types of questions were
asked while subjects were put in an fMRI
scan.


What do I think of myself……(direct self apprasial)
What others think of me……..(reflected self
apprasial)
Study Findings

When asked what others thought of you,
both teens and adults used the medial
prefrontal cortex and also the temporal
parietal areas of the brain.
However
When asked how adults and teens think of
themselves, teens continued to use the
same region of the brain, suggesting that
teen’s self appraisal is tied into what they
believe others think of them.
Studies on brain vulnerability to
drugs and alcohol as it relates
to risk taking

Susan Anderson-Harvard Medical School
Placed juvenile and adult rats in situation where
they were able to have access to cocaine.
 Young and old rats opted not to be in that
environment, but adolescent rats tended to be
immensely attracted to the situation.


Scott Swartzwelder-Duke University



7 million youngsters binge drink once a month
Effects of alcohol has lasting impact on the
adolescent brain, particularly in the area of
the hippocampus which is responsible for
memory.
Teen brains do not recover as quickly after
drinking as adults-demonstrated in memory
tests 3-weeks post last binge episode.


While their brains are much more vulnerable to
alcohol, it has less sedating effects. Teens don’t
get tired after drinking the same way that adults
do.
Teens are also less vulnerable to balance
problems and hangovers from drinking
Alcohol’s affect on the
hippocampus

Receptors are activated by the
neurotransmitter glutamate and allow
calcium to enter neurons, setting off a
cascade of changes that strengthen
synapses, by helping to create repeated
connections between cells, aiding in the
efficient formation of new memories.

But at the equivalent of one or two
alcoholic drinks, the receptors' activity
slowed, and at higher doses, they shut
down almost entirely.
What Do We Know




Drinking during the teen years significantly
increases a youngster’s chances of
becoming alcoholic in adult life.
Drinking, even moderately in teen years
significantly damage the hippocampus.
The long term damage of drinking in
adolescence is significantly more than in
the adult.
These damages are long term
How brain research affects legal
ruling for adolescents
Jackson v. Hobbs
mandatory life-without-parole sentences for all
children 17 or younger convicted of homicide are
unconstitutional
“Mandatory life without parole for a juvenile precludes
consideration of his chronological age and its hallmark features
— among them, immaturity, impetuosity, and failure to
appreciate risks and consequences,” Justice Kagan
Relationship
Relationship
Relationship



Have concrete specific goals and tools that
will work for one or two days.
Don’t make goals so long that it is not
salient
Make sure that kids are appropriately
diagnosed.
Most youths in detention have contributing
academic, learning, mental health or a
combination of all of them



Make doing well more exciting than the
crime.
Encourage exercise-exercise increased
plasticity to brain development.
With increased opportunities, the brain will
learn to do it better and quicker.
References



1 Giedd JN, Blumenthal J, Jeffries NO, et al. Brain
development during childhood and adolescence: a
longitudinal MRI study. Nature Neuroscience, 1999;
2(10): 861-3.
2 Rapoport JL, Giedd JN, Blumenthal J, et al. Progressive
cortical change during adolescence in childhood-onset
schizophrenia. A longitudinal magnetic resonance
imaging study. Archives of General Psychiatry, 1999;
56(7): 649-54.
3 Thompson PM, Giedd JN, Woods RP, et al. Growth
patterns in the developing brain detected by using
continuum mechanical tensor maps. Nature, 2000;
404(6774): 190-3.


4 Sowell ER, Thompson PM, Holmes CJ, et al. In
vivo evidence for post-adolescent brain
maturation in frontal and striatal regions. Nature
Neuroscience, 1999; 2(10): 859-61.
5 Baird AA, Gruber SA, Fein DA, et al. Functional
magnetic resonance imaging of facial affect
recognition in children and adolescents. Journal
of the American Academy of Child and
Adolescent Psychiatry, 1999; 38(2): 195-9.