Directions: Put parentheses ( ) around prepositional phrases. Underline all verbs with two lines and subjects with one line. Slashes / and words in [ ] separate clauses.
Dr. Jay Giedd has devoted the past 13 years to peering inside the heads of 1,800 kids and teenagers; / he uses high-powered magnetic resonance imaging (MRI).
For each volunteer, he has created a unique photo album by taking MRI snapshots every two years and building a record [as] the brain morphs and grows.
He discovered that little was known about the development of the normal brain / so it was impossible to figure out [where] things might be going wrong.
Giedd’s scanning studies have proved [that] the brain of the adolescent is far from mature, / and it undergoes extensive structural changes well past puberty.
Researchers are now looking at the physiological changes to see / how they might account for the adolescent behaviors familiar to parents: emotional outbursts, reckless risk taking and rule breaking, and the impassioned pursuit of sex, drugs and rock ‘n’ roll.
MRI has made it possible to study healthy kids because there is no radiation involved.
The machine does scan each teen brain for 10 minutes; / it can scan 124 slices, each as thin as a dime.
It will take 20 hours of computer time to process the images, / but the analysis is done by humans.
The teenage brain is growing very little over the course of childhood. By the time a child is 6, / the brain is 90% to 95% of it’s adult size.
10. During adolescence, you are getting fewer but faster connections in the brain. The brain is becoming a more efficient machine, / but it is losing some of its potential for learning and its ability to recover from trauma.
Page 2, Ticking Teens
11. Most scientists do believe [that] the pruning of neurons is guided both by genetics and by a use-it-or-lose-it principal. 12. The last part of the brain to mature is the prefrontal cortex; / this is the home of the executive functions – planning, setting priorities, organizing thoughts, suppressing impulses, weighing the consequences of one’s actions. 13. Once we were mapping brain changes, / we could say, / “Aha, one part of the brain makes teenagers more responsible, and that part is not finished maturing yet.” 14. Hormones are released during puberty, / and they are creating a tinderbox of emotions. 15. Adolescents are seeking situations [where] they can allow their emotions and passions to run wild. They are actively looking for experiences to create intense feelings. 16. The brain regions that can limit risky, impulsive behavior are under construction. 17.
Teens are wanting to take risks early in adolescence, / but part of the brain directs teens to think before acting. That brain part is still not mature, [and] it may continue to mature [until] a person is 25 years old.
18. It is like turning on the engine of a car with no skilled driver at the wheel.
Information from “What Makes Teens Tick,” Time, May 10, 2004.