The Teenage Brain: Spock Vs. Captain Kirk

Mar 11, 2015
Originally published on March 12, 2015 5:43 pm

This story was written for the series, "Being 12: The Year Everything Changes," from member station WNYC.

If adolescence has a poster child, it's a teenager. In a car. Smoking, drinking, and driving badly while also, somehow, having sex in the back seat.

But changes in the brain that lead to the famously bad choices of adolescence don't start at 16 or 17 years old. They start around 11 or 12 and the beginning of puberty.

This is the dirty little secret of adolescence: The cloudy judgment and risky behavior may not last a year or two. Try a decade.

To understand why, let's start with an experiment. At Temple University, psychology professor Laurence Steinberg and his team put a bunch of adolescents into an FMRI machine — a brain scanner — and asked them to play a driving game.

"Your perspective is that of a person behind the wheel," Steinberg says, describing the set-up. "And you come to a series of intersections, and the lights turn yellow. And you have to decide whether to put the brakes on or not."

Now, what do you think the adolescents did in this situation?

Wrong.

They did not blow through the yellow every time.

"When adolescents are playing this game by themselves, they don't take any more chances than adults do when they're playing it by themselves," Steinberg says.

And that's a big deal. Because the adolescent brain gets a bad rep for being consistently impulsive. Steinberg hopes his latest book, Age of Opportunity, will help set the record straight: Being 12 (or 17) doesn't mean a kid's hard-wired to always make bad choices.

Why, then, do adolescents still make so many bad choices? To find out, Steinberg added a twist to his experiment.

He gave his subjects an adolescent crowd.

"This doubles the number of chances that adolescents take," Steinberg says, "but has no effect on the number of chances adults take."

In short, an adolescent's weakness is other adolescents. And we're not just talking about peer pressure. The mere presence of peers makes them less cautious.

One reason, says B.J. Casey, a neuroscientist at Weill Cornell Medical College, is that "the brain is being marinated in gonadal hormones" during adolescence. Another big reason: The prefrontal cortex is still a work-in-progress. And it serves a vital role in our decision-making.

The prefrontal cortex "helps to link past experiences to the current situation," Casey says, "and, at the same time, consider what the future consequences are of choices and actions that are made."

The prefrontal cortex is our voice of reason. Steinberg calls it the brain's CEO. Casey likens it to Mr. Spock from Star Trek, coldly calculating a life's worth of cost-benefit analyses.

Casey's analogy doesn't stop there. To her, Captain Kirk is the limbic system — the emotional center of the brain that's always on the lookout for threats and rewards. When it spots either, it sends a message to the prefrontal cortex. Because the limbic system can't make sense of these things on its own. It needs the prefrontal cortex.

Kirk needs Spock.

Here's the problem. For kids in adolescence, the prefrontal cortex is still developing, and it can't keep up with the limbic system as it goes into reward-seeking warp speed.

"It's as if these emotional regions hijack the prefrontal systems," Casey says, "and it leads to a choice that they make that's a bad one. And they even know it's a bad one."

Which brings us full-circle to Steinberg's driving experiment. The limbic system doesn't just flag rewards in things like alcohol and sex. A 12-year-old gets a kind of high simply by being around other adolescents. They're wired to seek each other out and develop the skills they'll need to leave their parents, feed and protect themselves, and raise children.

In the short-term, that means cloudy judgment and risky behavior.

But adolescence is all about the long view.

Copyright 2015 NPR. To see more, visit http://www.npr.org/.

Transcript

AUDIE CORNISH, HOST:

The reckless image of adolescence looks something like this - a teenager, say about 16, behind the wheel, smoking, drinking and driving dangerously. But now it's believed that the changes in the brain that lead to the famously bad choices of adolescence actually start earlier, around 11 or 12, along with puberty. This week, member station WNYC in New York is running a series on the beginning of adolescence. It's called Being 12. And Cory Turner of the NPR Ed team contributed this story, set inside the wilds of the adolescent brain.

CORY TURNER, BYLINE: Let's start with an experiment. At Temple University, psychology professor Laurence Steinberg and his team put a bunch of adolescents into an FMRI machine - a brain scanner - and asked them to play a driving game.

LAURENCE STEINBERG: And you come to a series of intersections and the lights turn yellow, and you have to decide whether to put the brakes on or not.

TURNER: Now, what do you think the adolescents did in this situation? Wrong. They did not blow through the yellow every time.

STEINBERG: When adolescents are playing this game by themselves, they don't take any more chances than adults do when they're playing it by themselves.

TURNER: And that's a big deal, Steinberg says, because the adolescent brain gets a bad rep for being consistently impulsive. His latest book, called "Age Of Opportunity," is an attempt to set the record straight. Being 12 or 17 doesn't mean you're hardwired to always make bad choices. Why, then, do adolescents make so many bad choices? To find out, Steinberg added a twist to his experiment - he gave his subjects an adolescent crowd.

STEINBERG: This doubles the number of chances that adolescents take, but has no effect on the number of chances that adults take.

TURNER: In short, an adolescent's weakness is other adolescents.

B.J. CASEY: Adolescence is a time, really, when the brain is being marinated in gonadal hormones.

TURNER: B.J. Casey is a neuroscientist at Weill Cornell Medical College and she says much of the turmoil in the 12-year-old brain comes from changes in two places. First - the frontal cortex, one of the last areas of the brain to mature.

CASEY: It helps to link past experiences to the current situation and consider what the future consequences are of choices and actions that are made.

TURNER: The prefrontal cortex is our voice of reason. Steinberg calls it the brain's CEO. Casey likens it to this guy...

(SOUNDBITE OF TV SHOW, "STAR TREK")

LEONARD NIMOY: (As Mr. Spock) The odds against you and I both being killed are 2,228.7.

TURNER: That is, of course, Spock from "Star Trek."

CASEY: The rational person on the starship Enterprise. And he often has to keep the passionate Captain Kirk at bay.

(SOUNDBITE OF TV SHOW, "STAR TREK")

WILLIAM SHATNER: (As Captain Kirk) Traitors. I'll hang you up by your Vulcan ears. I'll have you all executed.

NIMOY: (As Mr. Spock) I think not. Your authority on this ship is extremely limited, Captain.

TURNER: In Casey's analogy, Captain Kirk is the limbic system.

(SOUNDBITE OF TV SHOW, "STAR TREK")

SHATNER: (As Captain Kirk) There's only one thing I want to say to you, Commodore - get my ship out of there.

TURNER: The limbic system is the emotional center of the brain, always on the lookout for threats and rewards. When it spots either, it sends a message to the prefrontal cortex. See, the limbic system can't make sense of these things on its own. Kirk needs Spock. And here's the problem - for kids in adolescence, the prefrontal cortex is still developing. And it just can't keep up with the limbic system, which goes into reward-seeking hyper-drive, especially with other kids around.

CASEY: It's as if these emotional regions hijack the prefrontal systems and it leads to a choice that they make that's a bad one, and that they even know is a bad one.

TURNER: The limbic system doesn't just flag rewards in things like alcohol and sex. A 12-year-old gets a kind of high simply by being around other adolescents. They're wired to seek each other out, developing the skills they'll need to leave their parents, feed and protect themselves and raise children. In the short term, that means cloudy judgment and potentially risky behavior. But adolescence is all about the long view. Cory Turner, NPR News, Washington. Transcript provided by NPR, Copyright NPR.