Transcript Secrets of the Teen Brain

Secrets of The Teen Brain
• Tom Sewell, summary of article in Time:
May 10, 2004
Article based on research by
Dr. Jay Giedd,
National Inst. Of Mental Health
• Researched 1800 teens
• MRI snapshots every 2 years
• Research started 13 years ago and will continue
until subjects are 25.
• Subjects also included twins: both identical and
fraternal.
• Prior to MRI: Cadavers were primary source for
brain research
• MRI shows that both gray and white matter
undergo extensive structural changes well past
puberty.
Previously Held Brain Information
• Most scientists thought brain was
developed by 12 years of age.
• Piaget research in cognitive development,
stages and ~12 years was start of formal
operations.
• Adolescence behavior influenced by
hormones and needed cognitive control to
develop mature behavior.
Nature vs Nuture
• Brain preprogrammed by Genes
• Brain influenced by environment and
external forces.
• Pruning in brain is guided by genetics and
or Neural Darwinism.
• Neural Darwinism: use-it-or-lose-it
principle.
Children Brain Development
• Age 6: Brain is 90-95% of adult size
• Age 6-12: Neurons grow brushier making more
connections to other neurons = creating new
paths
• Gray matter is thickening: Neurons and
branching of dendrites
• Peak of thickening is ~11 for girls and ~12.5 for
boys
• Gray matter: thins ~0.7% a year tapering off in
early 20’s
Some New Facts
• Pruning takes place in waves to eliminate
unneeded cells
• 1st pruning is in final months before birth
• 2nd wave of pruning starts in childhood
with a final pruning in late teens
• This final pruning alters not the # of nerve
cells by the # of connections (synapses)
Gray Matter
• Gray matter thickens:
Neurons and branching of
dendrites
• Peak of thickening is ~11
for girls and ~12.5 for
boys
• Gray matter: thins ~0.7%
a year tapering off in
early 20’s
• Practicing piano: thickens
neurons that control the
fingers.
White Matter
• White matter is fatty
myelin sheaths that
encase axons and act
like insulations. This
helps speed nerve
signals faster and
more efficiently.
• Up to age 40 the
myelin continues to
thicken.
Synapses
Brain Regions
• Practicing piano:
thickens neurons that
control the fingers.
• Study of London cab
drivers: found larger
hippocampus:
structure involved in
memory.
Research Outcomes
• The Cerebellum which
coordinates both physical
and mental activities
maybe responsive to
experience.
• Development of brain
generally proceeds from
back to front.
• 1st sensory functions, 2nd
coordination of those
sensory functions, 3rd
prefrontal cortex.
Functions of Prefrontal Cortex
•
•
•
•
•
Planning
Setting priorities
Organizing thoughts
Suppressing impulses
Weighing the consequences of one’s
actions
Thoughts
• During the final stage of pruning the
hormones are at their peak.
• Sex hormones are very active in limbic
system of the brain.
• The parts of the brain responsible for
sensation seeking are working overtime
while the judgment section of the brain
have not fully developed.
Web Resources
• Brain Basics:
http://faculty.washington.edu/chudler/phylo.html
• Nervous System:
http://faculty.washington.edu/chudler/nsdivide.ht
ml
• Synapses: http://synapses.mcg.edu/about.asp
• Neurotransmitters:
http://www.psy.plym.ac.uk/year1/neurotr.htm
• Limbic System:
http://www.brainplace.com/bp/brainsystem
/limbic.asp
Resource
• Park, Alice. “The Teen Brain." Time May
10 2004: 56-65.