Mind Matters

EVER WONDER WHY A SEEMINGLY SMART TEENAGER MAKES DUMB DECISIONS? RESEARCH BY BRAIN SCIENCES PROFESSOR ABIGAIL BAIRD MAY OFFER A COMPELLING EXPLANATION.

ANYONE WHO'S RAISED TEENAGERS HAS STORIES TO TELL and tells them over and over again, eyes rolling, voice incredulous even years later:

About the son who lent the family car to a friend saying, "Don't worry, Mom, he's really responsible..." but, whoops, didn't know how to drive a stick shift.

About the mall trip that ended at the police station because, well, "She dared me to take the cigarettes—I didn't think I'd get caught!"

About the unsanctioned party for "a few friends" that attracted most of the high school:" Honest, I didn't invite them. I have no idea how they found out!"

Wouldn't it be nice to get inside those kids' heads and figure out why they do what they do—and how parents, teachers, employers and others might help them stay on track?

These are the questions that drive Abigail A. Baird, an assistant professor in Dartmouth's department of psychological and brain sciences.

Baird, 36, is one of a handful of neuroscientists in the United States using functional magnetic resonance imaging, or fMRI, to study adolescent brain development. Specifically, she is helping to map the parts of the brain that teenagers use to solve problems or respond to emotionally charged situations. Early findings are that when confronted with identical scenarios, teenagers and adults use different parts of the brain to arrive at solutions. Taken together, Baird's experiments and those of other neuroscientists studying age-related brain differences suggest that this final stage of neurological development may not be complete until the early 20s.

To scientists this is exciting stuff, even if it comes as no surprise to the aforementioned parents. Baird acknowledges a wide range of reactions, depending on her audience. "Whenever I present this to a group of parents or high school teachers, they're really disappointed," she laughs.' The response is like Duh, tell us something we don't know.'" Nevertheless, fMRI studies are adding a new dimension to the conventional wisdom, enabling scientists to "see" at the physiological level evidence of what previously had to be deduced from behavior.

In 2001, after completing a doctorate in developmental psychology at Harvard University, Baird arrived at Dartmouth to spend one year as a post-doctoral fellow at the Colleges Center for Cognitive Neuroscience. In 2002, however, she accepted a dual appointment as assistant professor in the neuroscience center and in the department of psychological and brain sciences.

Baird says her explorations of the adolescent brain are energized by classroom discussions, as well as by interactions with undergraduate and graduate students using the brain science center for experiments of their own.

She recalls the classroom debate stimulated by the senior honorsproject of Jane C.Viner '05, which focused on the notoriously fractious peer relationships of middle school students. Could the brains of these teens get a jump on maturity if theyoungsters were drilled in how to get along? Working with BBaird, Viner designed a mentoring program for 10 seventh-grade girls,then compared them—and their brainsto 10 girls of the same age who did not attend the mentoring sessions. The results showed increased frontal lobe activity in the mentored girls, Viner reported, specifically in the dorsolateral prefrontal cortex, or DLPFC, which is involved in perception and the regulation of emotion.

"What Jane's results basically tell you is that there are some brain regions that are more active in girls who handle relationships better," says Baird. What were their frontal lobes actually working on? This is where the discussion took off in Baird's undergraduate course "Adolescence," yielding a wide range of theories to explain greater DLPFC activityand generating new ideas for Baird and Viner to investigate.

"One of my students said, 'That's probably because they're planning what they're going to do later in the day,' " Baird recalls. 'Another student said, 'No, that's because they're planning their revenge.'"

Such exchanges are invaluable to a researcher. "What Dartmouth has is incredibly bright students who come up with novel insights, and they also ask really tough questions," says Baird. "I have piles of notes from the class discussions, and I keep the students' questions in mind as I go over my data sets. Very often we have other pieces of data that we initially did not consider essential to the original question of the experiment, but on reexamination they might be useful."

For undergraduate students thinking about research careers, the opportunity to work on an original theory alongside a scientist is equally stimulating, according to Viner.

"Dr. Baird's research is complicated but, the way she explained it, I could understand it and it helped me design my honors thesis project," says Viner, who graduated last June with a psychological and brain sciences major and French minor. She also completed Dartmouth's premedical curriculum, with hopes of earning both M.D. and Ph.D. degrees in the neurosciences.

So what is going on, or not, in teenagers' heads? How can a 17-year-old who successfully juggles a parental A-list of responsibilities—honor roll, after-school job, community service, team captain—suddenly display the judgment of a 10-year-old? And to what degree can scans charting brain function yield insight into these sometimes sullen, sometimes exuberant, often impulsive and very unpredictable near-adults?

Baird, exuberant herself when talking about the adolescent brain, says the evidence so far is that teenagers' thinking processes simply aren't as streamlined as they will be in adulthood, leading to misfires and gaps in perception and response. "Children are incredibly resilient," she says. "Their brains have tremendous plasticity and share a drive with the body to take care of the child. The adolescent brain is doing that, too. The thinking process is just not as coordinated as it will be."

Baird says she was drawn to this relatively neglected branch of neuroscience partly because of lingering questions from her own teenage years. The oldest of three growing up in a close-knit family in Amesbury, Massachusetts, she was struck by personality and other differences among members of her own family, never mind the kids at school. "What hurt my feelings didn't hurt other peoples' feelings," Baird says. "And there were people who were even more emotional than I was. Why was that?"

Baird's undergraduate years were spent at Vassar College, where she planned to major in one of the basic sciences while completing prerequisites for medical school. Her long-range goal was to be a surgeon. Then she happened upon Vassars psychology department, through an entry-level course needed to fill out course distribution requirements.

"I was already taking biology courses, but with psychology it was love at first sight," Baird recalls. 'And if you combine the two fields, you get psychological brain science. I was, like, 'Perfect!

Baird graduated as a bio-psychology major, then shelved medical school plans in order to pursue her doctorate in developmental psychology. While the opportunities to both teach and undertake fMRI research attracted her to Dartmouth, Baird also credits her undergraduate experience with her decision to accept a faculty appointment in Hanover. "Vassar is a huge amount of what brought me to Dartmouth, because I strongly believe in liberal arts education," she says. "Small classrooms, getting to know one's students and teachers, it is tremendously exciting."

first five years of life—from helpless newborns unable to pick their mothers from a crowd of faces to walking, talking, emotionally com- plex individuals already making sense of symbolic language such as ABCs and 1, 2, 3s. Culturally and legally, the age of adulthood in most Western societies is 18, reflecting the long-held belief that the brain matures at the same pace as the body, with puberty defining the threshold of adulthood. Indeed, until recently the best available evidence—gleaned from cadaver dissection and later via early scanning devices—showed little difference between the brains of post pubescent teens and adults. Baird's interest in teenagers puts her decidedly in the minority among developmental psychologists. Historically, the field has focused on early childhood. It's an understandable choice when one considers the enormous neurological distance humans travel in the

Then, in the 1990s, fMRI debuted. Suddenly scientists had the ability not just to visualize gray matter but also to watch this brain material in action. The technology makes it possible to measure changes in blood flow within the tissue; increased blood flow to a particular brain region means greater neural activity. These active regions light up on the fMRI computer screen, creating, quite literally, the picture of thought as it forms.

Baird's fMRI explorations take place in the Dartmouth Brain Imaging Center, located in the basement of Moore Hall. Constructed and equipped by the College at a cost of $3.5 million, the 6-year-old center is part of the evolution of Dartmouth's psychology department into a science-driven and research-oriented faculty and major. The department underscored this orientation in 1999, when it changed its name to psychological and brain sciences.

"There had been a growing discontent between what students believed psychology was all about and what our faculty actually taught," says Todd F.Heatherton, department chairman. "Students thought couches and Freud, and nothing could be further from the truth."

The misconception was irksome to faculty in the department, most of whom were more focused on behavioral science than applied research or clinical psychology. In fact, brain science has been Dartmouth's signature orientation for close to 50 years. In the 1960s faculty members were conducting studies on animals to explore the physical and behavioral consequences of sensory deprivation and stress. In the 1970s and 1980s they built on the work of geneticists to investigate the influence of genes on human psychology. "All of this culminated in the name change of the department, " says Heatherton. Since then, the number of undergraduates declaring psychological and brain sciences majors has risen (20 percent since 2003) as has campus-wide demand for use of the imaging center.

The center makes Dartmouth unique among Ivy Leagueschools, according to Heatherton, because it provides hands-on re- search opportunities for undergraduates in addition to faculty and graduate students. Equipped with a powerful 3.0 Tesla fMRI scanner, the center has hosted more than 4,500 human brain imaging experiments, supporting the research of more than 40 faculty members from a wide range of academic departments, including psychological and brain sciences, biology, physics, education, engineering, philosophy, economics, mathematics and computer science. Nearly two dozen undergraduates have used the fMRI equipment for experiments related to senior honors theses.

The imagining center also has turned out to be a powerful tool in faculty recruiting, says Michael S. Gazzaniga '61, former director of Dartmouth's graduate program in cognitive neuroscience. In fact, it helped land Baird.

"If you want a first-class institution, you have to be a little ahead of the curve," Gazzaniga says. "To get the kind of faculty you want, you have to entice them with equipment that makes high-quality research possible as well as opportunities for teaching."

Baird's experiments involve giving adult and teenage test subjects a thinking task as they lie in the fMRI tube, then analyzing the neural activity required to solve the question. It's not just a mat- ter of whether the lights are on, but of the specific brain regions activated by the problem. Scans are then compared to see if the location and amount of neural activity differ between adults and adolescents.

Baird and other neuroscientists have found that teenagers have less going on in the frontal lobes, the part of the brain responsible for analysis of multiple factors, anticipation of consequences and long-range planning, but that this activity increases through the teen years into the early2os.This correlates with anecdotal accounts of adolescent behavior, a physiological explanation for how an otherwise stellar kid can lend the family car on impulse without a thought to parental, mechanical or other consequences.

Researchers also have found what they consider to be significant structural differences between adult and adolescent brains. For example, a team at the University of California, Los Angeles, reported in 1999 that myelin, the fatty tissue that surrounds nerve fibers and helps transmit messages from one part of the brain to another, does not appear to have fully accumulated in teenagers' frontal lobes. At the University of Pennsylvania, adolescent frontal lobes were found to have an excess of nerve cells. Researchers there describe a pruning process that continues into the early 20s, enabling the brain to function more efficiently.

The sum of these disparate findings fuels neuroscientists' belief that brain development lags behind physical maturity.

"There is so much going on during the teenage years," Baird says, not the least of which is the struggle for emotional balance. "You can be walking down the hall in middle school and someone says, 'I hate your shirt,' and your day is over!" Baird says. "Why is that? How do emotion and cognition work together? How do we integrate how we feel and how we think?"

The task of the adolescent years is this integration of complex neurological processes—to tame emotion with reason and put a rein on wild impulse. In other words, act adult. Many forces besides biology press on children to achieve this, including family, society and culture. And vast fields of scholarship are devoted to their examination, including sociology, anthropology and most of the liberal arts. Baird and her fellow neuroscientists hope to contribute the neurophysiological part of the story, using fMRI to build the roadmap.

The mapping task is a daunting one, even with technology as razzle-dazzle as fMRI and computers that can turn subtle physiologic activity into bright dancing lights on a screen. Forget Map Quest, think cartography in the Middle Ages. With rudimentary measuring tools and the math and science of their day, early mapmakers set out on no less ambitious a mission than to rough out the contours of lands they'd never seen and a world newly defined as round. They relied on sketches and reports of travelers, then revised, revised, revised as new information became available.

Todays neuroscientists approach their task with comparable tools—and similar uncertainties.

Baird and her research colleagues, for instance, wanted to take a look at how adolescent brains deal with "counterfactual idea gen eration," which involves imagining what might have been, given different circumstances or actions. They suspected the task would result in measurable functional differences between teens and adults because counterfactual idea generation is neurologically complex, challenging the brains capacity to analyze and anticipate consequences—not the strong suit of teenagers. For comparison purposes, a second type of thinking task was added to the experiment, calling for "simple idea generation," at which adolescents and adults were expected to perform similarly.

Baird recruited two sets of test subjects, adults and 14-year-olds. The 14-year-olds, accompanied by their parents, came from two Hanover-area middle schools where Baird teaches on a volunteer basis in the science curriculum. Adult subjects were recruited from Dartmouth's medical and business schools, as well as surrounding communities.

The simple and counterfactual tasks were presented in the form of scenarios, displayed on a computer screen inside the fMRI tube. As the subjects considered problems posed by each scenario, the machine tracked blood flow to identify the brain areas being used to generate solutions. Baird and her team also collected the solutions in order to evaluate the quality of each group's problem solving skills.

Here's one of the scenarios calling for simple idea generation: Daniel is a candidate for student council president. He is well known to students involved in sports, but not to students involved with other extracurricular activities. Come up with a list of things Daniel could do to improve his chances of winning the election.

In their responses, adult and teen subjects listed similar strategies, including putting up campaign posters, making speeches and generally glad-handing around the school. There was no remarkable difference in their responses, according to Baird.

Here's one of the scenarios calling for counterfactual idea generation: Jason is babysitting his little brother, Rex. Jason decides he wants to have an adventure and climb on the garage roof. Rex insists on coming along, and even though Jason knows it is not safe, he gives in. Rex falls off the roof and breaks his arm. What could Jason have done differently?

As expected, the adults and 14-year-olds responded differently They also had notably different brain function, according to Baird. All of the subjects came up with alternatives they thought would keep Rex from harm. But the adults' answers showed better judgment, a frontal lobe function. This was backed up by the fMRI scans. "There's activity you don't see in the kids going on in the adults frontal lobes," says Baird. The as-yet-unpublished data suggest that while generating ideas, the adults simultaneously evaluated them, picking and choosing among various options to hone in on the best course of action.

Besides having less activity in their frontal lobes, the 14-yearolds also took longer to solve the problem. "It's almost as if they get stuck on what they have been presented with and do a lot of 'I dunno' type answers," Baird says. "Then they come up with less practical solutions."

That's putting it mildly.

One young test subject said the boys should have donned parachutes. Another suggested dragging mattresses outside to place them around the house so falls would be less likely to result in broken bones. A third suggested putting a rope around Rex.

As for the adults, they crisply nixed the roof, then moved on to strategies Jason could use to distract Rex or deal with his disappointment in being denied the adventure. Baird says adult brains seem able to instantaneously picture consequences, then seamlessly switch to analysis of alternatives. By contrast, the teens in her ex- periment seemed to blow by the key decision point of the scenario—whether or not to go on the roof—because they were transfixed by the scenarios most dramatic moment, Rex's fall.

Even as Baird throws out these potential links between the fMRI images and the answers of her test subjects, she falls back on the language of scientists taking their first steps on new terrain: Clue, theory, hint, possibility.

"There is no absolute truth in these images," Baird says emphatically. "There are so many other influential factors, including individual temperament. Is the child shy by nature? Risk averse? What has been their life experience so far? How does a teenager or anyone manage their core neurological inheritance in the context of their lives?"

Bairds early work was with teenagers hospitalized for psychiatricillnesses. "These were children with depression, anxiety disorders, the beginnings of severe mental illness such as schizophrenia," says Baird. She recalls being impressed by parents' accounts of these children, just as today she eagerly absorbs the antic stories told by parents of healthy teenagers.

"I kept hearing the same thing over and over again from the parents: 'We always knew something was wrong,'" Baird says. "They described the kids as always a bit off; 'Johnny's my third child,' a mother would tell me, 'and he's the one who never learned to tie his shoes. Then it all blew up in adolescence.'"

These encounters with the instinctive wisdom of parents made a strong impression on Baird, as did their frustration that medical science had neither diagnosis nor intervention to offer their children before catastrophic symptoms forced hospitalization. Baird's ongoing brain mapping projects are part of a larger goal to define the parameters of normal and aberrant brain function, potentially leading to earlier diagnosis and treatment of psychiatric and neurological disorders.

Brain Trust Although Bairdlogs plenty oftime with imaging equipment,she most enjoysinteracting withsubjects—andher students.

IRENE M. WIELAWSKI is an award-winning freelance journalist wholives in Pound Ridge, New York. Her story on pediatric sports orthopedistSally Harris 'BO appeared in the July/Aug2004 issue of DAM.

"THERE IS SO MUCH GOING ON DURING THE TEENAGE YEARS" BAIRD SAYS. "YOU CAN BE WALKING DOWN THE HALL IN MIDDLE SCHOOL AND SOMEONE SAYS 'I HATE YOUR SHIRT,' AND YOUR DAY IS OVER! WHY IS THAT? HOW DO EMOTION AND COGNITION WORK TOGETHER? "