photo of deborah yurgelun-toddinterview:  deborah yurgelun-todd

In a recent study mapping differences between the brains of adults and teens, Todd put teenage and adult volunteers through a MRI and monitored how their brains responded to a series of pictures. The volunteers were asked to discern the emotion a series of faces like this one. The results were surprising. All the adults identified the emotion as fear, but many of the teenagers saw something different, such as shock or anger. When she examined their brain scans, Todd found that the teenagers were using a different part of their brain when reading the images.

Do you notice a big difference between young teenagers and older teenagers, for instance, or adults?

Yes. Our data suggested that the younger teenagers were significantly different in how they responded compared to adults. And we did see an age-dependent or age-related change between the ages of 11 and 17, with the most dramatic difference being in the earlier teen years.

One aspect of our work has been to look at the frontal part of the brain, which has been known to underlie thought and anticipation and planning and goal-directed behavior, and try to understand the relationship of this part of the brain to the more inferior or lower part of the brain which has been associated with emotion and gut responses. It's quite well known that, in adults, there's a relationship between these two parts of the brain, and we wanted to understand what that relationship would be in adolescent subjects.

In adults, how are those two parts of the brain related? What do we see there?

In an adult, this anterior or prefrontal part of the brain carries out a lot of executive functions, or what we call more thinking functions: planning, goal-directed behavior, judgment, insight. And we think that that particular part of the brain influences this more emotional or gut part of the brain. Therefore this relationship is key to understanding behavior.

Yurgelun-Todd is the director of neuropsychology and cognitive neuroimaging at McLean Hospital in Belmont, Mass. Her recent work suggests that teens' brains actually work differently than adults' when processing emotional information from external stimuli.

brain (teen)brain (adult)
Teens (left) used less of the prefrontal (upper) region than adults (right) when reading emotion.

This is a really nice picture highlighting the fact that in an adolescent brain or a younger brain, the relative activation of the prefrontal region or this anterior front part of the brain is less it is in the adults. But in contrast to that, the more emotional region or that gut response region has more activation compared to the adult. So the relationship between these two regions is very different. And we think that that's been a very important finding in terms of understanding adolescent behavior.

So, confronted with a feeling, say, somebody looks at them with an expression of fear, how will the adolescent read it in relation to the adult?

... The adolescent will have a more of an emotional response. The part of the brain that has more of that gut reaction will respond to a greater extent than the adult brain will. And we think that that is due to the fact that this frontal region is not interacting with the emotional region in the same way.

How about this issue of misjudgment -- making mistakes about what they read on a person's face?

One of the things that we noticed in doing this experiment was, not only did the adolescents show this emotional response or this increased response, but they did this at the same time that they did not correctly identify the emotion. And that was very interesting to us, because it's clear that the brain was responding, but the way it was responding didn't have to do with the accuracy of the affect or the emotional expression. The adolescents typically said that they saw shock or confusion or sadness. But they did not correctly identify fear 100 percent of the time. This is in contrast to the adults, who did find that.

So 100 percent of the adults correctly identified the emotion of fear?

Right. In this pilot study, 100 percent of the adults did actually identify the emotion as fear.

And the teenagers?

Only about half.

What did they say instead?

They felt that the expression was sadness, confusion. Some said they didn't know; some said shock. But it was surprising to us that most fairly sophisticated adolescents did not correctly identify fear. ...

Is it possible that if you had interviewed ten more adults and ten more teens, the results would have changed?

This is a small pilot study, so clearly if we added a considerably larger sample, we may have very different results. So I want to be cautious and not over-interpret these findings.

The frontal lobe, that part of the executive region that we studied, is not always functioning fully in teenagers. That would suggest that therefore teenagers aren't thinking through the consequences of their behaviors

What does your work tell you about young teenagers?

One of the implications of this work is that the brain is responding differently to the outside world in teenagers compared to adults. And in particular, with emotional information, the teenager's brain may be responding with more of a gut reaction than an executive or more thinking kind of response. And if that's the case, then one of the things that you expect is that you'll have more of an impulsive behavioral response, instead of a necessarily thoughtful or measured kind of response.

Does this research go part of the way to explaining the miscues between adult and teenagers?

Yes, I do think this research goes to helping understand differences between adults and teenagers in terms of communications. And I think that it does for two reasons. One, we saw that adults can actually look at fearful faces and perceive them as fearful faces, and they label them as such, whereas teenagers ... don't label them the same way. So it means that they're reading external visual cues [differently], or they're looking at affect differently.

The second aspect of the findings are that the frontal region, or this executive region, is activating differentially in the teenagers compared to adults. And I think that has important implications in terms of modulating their own responses, or trying to inhibit their own gut responses.

Talk more about that in terms of the kind of risks that teenagers take. When they exhibit risky behavior, what is actually happening?

One thing that happens in the brain when we're going to get involved in any activity or initiate any activity is, we either have to decide what the consequences of that behavior are, or we're just going to behave impulsively. And to appreciate what the consequences of a behavior are, you have to really think through what the potential outcomes of a behavior are. I think the frontal lobe, that part of the executive region that we studied, is not always functioning fully in teenagers; or least our data suggests that perhaps it's not.

That would suggest that therefore teenagers aren't thinking through what the consequences of their behaviors are, which would lead us to believe that they'd be more impulsive, because they're not going to be so worried about whether or not what they're doing has a negative consequence. ...

Our findings suggest that what is coming into the brain, how it's being organized, and then ultimately the response -- all three of those may be different in our adolescents. So that attitude may be part of that, or may be related to that. But it's not simply a matter of teenagers feeling like they don't want to do something, or that they're just going to give you a hard time. ...

What does this mean for teens' relationship with their parents and teachers?

One of the interesting things about the findings are that they suggest that the teenagers are not able to correctly read all the feelings in the adult face. So that would suggest to us that when they're relating to their parents or to their friends' parents or to their teachers, they may be misperceiving or misunderstanding some of the feelings that we have as adults; that is, they see anger when there isn't anger, or sadness when there isn't sadness. And if that's the case, then clearly their own behavior is not going to match that of the adult. So you'll see miscommunication, both in terms of what they think the adult is feeling, but also what the response should then be to that.

Is there a difference between boys and girls?

Yes. Actually it's very interesting that in our study we found quite a bit of difference between males and females. And this really didn't surprise us. We found that females were somewhat more accurate than males, and also a little bit more subdued, relative to males. ... In general, the males in our studies showed more reaction from that gut region of the brain, and less frontal or executive reaction. The relationship between the gut response and that executive region was very striking for the males, and somewhat striking for the females, but was not as extreme for the teenage females compared to the teenage males. ....

So what does this mean about the kind of decisions that a teenager makes?

One of the interesting outcomes of this study suggests that perhaps decision-making in teenagers is not what we thought. That is, they may not be as mature as we had originally thought. Just because they're physically mature, they may not appreciate the consequences or weigh information the same way as adults do. So we may be mistaken if we think that [although] somebody looks physically mature, their brain may in fact not be mature, and not weigh in the same way. ...

Certainly the data from this study would suggest that one of the things that teenagers seem to do is to respond more strongly with gut response than they do with evaluating the consequences of what they're doing. This would result in a more impulsive, more gut-oriented response in terms of behavior, so that they would be different than adults. They would be more spontaneous, and less inhibited. ...

Do you think there should be things done for teenagers that are not done right now?

That's a really interesting point, because enrichment or special kinds of education during this period of time are very valuable; the brain is ready and responsive in a way that it's not later in life. And one of the questions is whether or not we can teach teenagers or adolescents to be more discriminating in interpersonal communication.

For example, many adults say that one of the things that they felt most limited by is the ability to have a really good relationship, a really intimate relationship with another person. And the basis of that really comes out of being able to read cues and being able to relate to others. So I think that the teenage years are important years for learning those skills. We assume that teenagers are getting those skills at home, or we think that they're getting them in groups that they participate in, such as Boy Scouts, Girl Scouts, clubs that they belong to. But for perhaps many of our teens, they're not getting these skills, and maybe we've just assumed they're getting them. ...

... Have the results of your work, and that of others studying adolescents changed you in your own dealings with teenagers?

Oh yes. I think that I also came to this research with the assumption that the teenager was going to look a lot like an adult. In fact, I assumed that the year-old brain would respond quite similarly to the adult brain in terms of the kinds of tasks that we were asking them to do when they were in the magnet. So I was quite surprised when we initially got these responses and found that there seemed to be a different pattern. And I was very reassured when other investigators such as Dr. Giedd had indicated that their findings also suggested ongoing structural changes in the brain. Of course, it makes sense that the behavior would be different through adolescence, in retrospect. But I was surprised. ...

What can your research tell parents?

One of the things I think that this research could help inform us about is the fact that the teenager is not going to take the information that is in the outside world, and organize it and understand it the same way we do. That's a very general statement. But when you think about it in terms of interactions at the dinner table or on the weekend or doing chores or doing homework, it means that whatever communication, whatever conversation you have with them, if you're assuming they understood everything you said -- they may not have. Or they may have understood it differently.

And if you think that their assignments are clear to them, they may not be. So it may be that we're putting them in a difficult situation, because we're assuming that our conversation is very clear, when in fact they may also think they've understood it clearly; but we're not saying the same things to each other.

... A good example of that is the typical Saturday morning conversation where there is a number of small things that a child or adolescent would be told to do. "Put your dish in the sink. Please get dressed now. We're going to get ready to go out." And ten minutes later, there seems to be no movement, the dish is not in the sink and they're not dressed. And the first response as an adult is that they're being difficult or confrontational or not wanting to do it.

But in fact, a lot of the time they're just not paying attention; either they heard that information, but they didn't really register it, or they heard it and they thought it was OK to do it later. Or they heard it, but whatever came on TV seemed more important. They somehow have reorganized that information, so they're not really trying to disappoint you or frustrate you. It's just that they saw it in a different light. ...

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