Secrets of The Teen Brain

1. Secrets of The Teen Brain • Tom Sewell, summary of article in Time: May 10, 2004

2. 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.

3. 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.

4. 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.

5. 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

6. 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)

7. 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.

8. 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.

9. Synapses

10. Brain Regions • Practicing piano: thickens neurons that control the fingers. • Study of London cab drivers: found larger hippocampus: structure involved in memory.

11. 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.

12. Functions of Prefrontal Cortex • Planning • Setting priorities • Organizing thoughts • Suppressing impulses • Weighing the consequences of one’s actions

13. 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.

14. Web Resources • Brain Basics: http://faculty.washington.edu/chudler/phylo.html • Nervous System: http://faculty.washington.edu/chudler/nsdivide.html • 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

15. Resource • Park, Alice. “The Teen Brain." Time May 10 2004: 56-65.