Thursday, June 21, 2007

The Brain, Part 2: The Adolescent Brain On Stress

Here is some information that may help some of the current or future parents who stumble across this entry understand how to deal with their teenagers. This portion takes place in the linked area from yesterday's post.
This anatomical fact may also shed light on why teens can be model citizens of the world one moment and impetuous children the next. "Under ideal conditions, teens function very much like adults," says Beatriz Luna, director of the Laboratory of Neurocognitive Development at the University of Pittsburgh. "But when the going gets tough, they may become quickly overwhelmed." Adolescents, Luna has found, exert a great deal more mental effort to do what's relatively easy for adults. A simple experiment she designed vividly illustrates this point. Teens and adults were instructed to avoid looking at lights that popped up on a computer screen as an MRI scanner recorded their brain's activity. "Since it's natural to look toward lights," says Luna, "the challenge was to suppress this impulse."

As she discovered, both age groups are equally adept at diverting their gaze from the lights. But teens rely much more heavily on the frontal cortex. In contrast, adults use that part of the brain to a much lesser degree during the task and instead distribute the workload among different specialized centers. ... "What this tells us is that teens are using up their most valuable resource — the frontal cortex — to do a relatively simple task," says Luna." So if they're under emotional stress from peer pressure or in a situation that requires them to multitask, their performance is likely to deteriorate. Translation: They're liable to fall apart or throw a tantrum if too many demands are placed on them.

To add to the many strains of teenagers, some are much less accurate at reading faces than adults. Teens were shown pictures of faces portraying emotions from happiness and sadness to anger and fear at the laboratory of Deborah Yurgelun-Todd, director of cognitive neuroimaging at McLean Hospital outside of Boston. ... Yurgelun-Todd asks a teenage boy, "What are those faces feeling?" "A lot of them are shocked or angry," he replies, reflecting the less discriminating ability he and other teens have when asked to identify expressions of anger, sadness, or fear. By contrast, the adults were 100 percent accurate in making such discriminations.


The limbic system, predominantly a part of the lower brain involved in primal responses to frightening or threatening situations, reigns supreme in teens when they are processing negative emotions. But in adults, the more developed prefrontal cortex exerts a moderating influence on this response, amplified by the sobering effects of life experience. ... Adults are able to make more nuanced discriminations of expressions than teens.


"The teen years are a time when we are still refining our ability to distinguish emotions and accurately assess people's motives," says Yurgelun-Todd. "A teen looking at his teacher's face, parent's face, or the expressions of his peers may be assuming people are reacting to him one way when that's not the way the other party perceived the interaction. That can lead to a lot of miscommunication."
(Apologies to Kathleen McAuliffe and Discover magazine. Discover is a scientific journal, and I'm using it in the context of a research project source. No more or less harmful than reprinting an AP article in a blog, but I implore you once more to buy this issue. It's as fascinating as it is important if you care about understanding why people think the way they do.)


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