Scientists once thought the brain's key development ended within the first few years of life. Now, thanks to advanced brain imaging technology and adolescent research, scientists are learning more about the teenage brain both in health and in disease. (Raleigh Philp in Amy Standen interview "Understanding How Adolescents Think," www.edutopia.org, 2010)
New brain imaging studies are revealing—for the first time—patterns of brain development that extend into (and beyond) the teenage years. Studies continue to demonstrate that the teen brain is not fully developed until the mid-twenties (possibly even 30), prompting educators to assess new ways to teach adolescents and young adults. (Michael Streich, "Teen Brain Research In Education," educationalissues.suite101.com, February 24 2009)
Scientists don't know all the reasons for the observed changes; however, they are becoming convinced the patterns parallel a pruning process that occurs early in life following the principle of "use-it-or-lose-it." It seems neural connections, or synapses, that get exercised are retained, while those that don't are lost. (J. Giedd, J. Blumenthal, N. Jeffries, et al, "Brain Development During Childhood and Adolescence: A Longitudinal MRI Study," Nature Neuroscience, 1999)
At least, this is what studies of animals' developing visual systems suggest. While it's known that both genes and environment play major roles in shaping early brain development, science still has much to learn about the relative influence of experience versus genes on the later maturation of the brain.
Jay Giedd neuroscientist at the National Institute of Mental Health reported around puberty and on into the adult years is a particularly critical time for the brain sculpting to take place. He compared the human brain in the years of puberty to an unformed block of granite ready for the artist's hand. The art is created by removing pieces of the granite, and that is the way the brain also sculpts itself. Bigger isn't necessarily better, or else the peak in brain function would occur at age 11 or 12. ... The advances come from actually taking away and pruning down of certain connections themselves. ("Inside the Teenage Brain," Frontline, www.pbs.org, January 2002)
The gray matter of the human brain peaks just before puberty (overproduction). After that peak, the gray matter thins as the excess connections are eliminated or pruned back down throughout adolescence. Enter the "use-it- or-lose-it" phase.
So, in the teen years, the part of the brain that is helping organization, planning and strategizing is not done being built. Then, some of the most dramatic development happens in the frontal lobes, the seat of judgment and decision-making, and the development has the potential to have lasting positive or negative effects. (Jay Giedd, "Inside the Teenage Brain," Frontline, www.pbs.org, January 2002)
The cerebellum, in the back of the brain -- is not very genetically controlled. Identical twins' cerebellum are no more alike than non-identical twins. So, Giedd and others think this part of the brain is very susceptible to the environment. And interestingly, it's a part of the brain that changes most during the teen years. This part of the brain has not finished growing well into the early 20s, even.
The cerebellum used to be thought to be primarily involved in the coordination of the muscles. So if their cerebellum was working well, people were apt to be graceful individuals, good dancers, or good athletes.
But now researchers believe the cerebellum also sub-serves changes in behaviors. It's involved in coordination of cognitive (thinking) processes. "Just like one can be physically clumsy, one can be kind of mentally clumsy. And this ability to smooth out all the different intellectual processes to navigate the complicated social life of the teen and to get through these things smoothly and gracefully instead of lurching ... seems to be a function of the cerebellum," claimed Giedd. ("Inside the Teenage Brain," Frontline, www.pbs.org, January 2002)
Effects On Youth
So, if a teen is doing music or sports or academics, those are the cells and connections that will be hard-wired. If they're lying on the couch or playing video games or MTV, those are the cells and connections that are going to survive.
A 2005 study published in the journal Child Development found that the parts of the brain responsible for multitasking don't even fully mature until people are 16 or 17 years old. According to USA Today in an article entitled, "So Much Media, So Little Attention Span," (Marian Elias, March 30 2005) children that are exposed to 8½ hours of TV, video games, computers and other media a day — often at once — may be losing the ability to concentrate.
Are these students developing brains that are becoming hard-wired to “multi-task lite” rather than learning focused critical thinking? This is a critical question. Children are becoming more attuned to distractions around them. Studies with college students and adults have confirmed that the brain doesn’t work as well when it focuses on more than one task.
And, research presented at the BA Festival of Science in 2006 revealed that teens also have a neural excuse for self-centeredness. For example, when considering an action that would affect others, teens are less likely than adults to use the medial prefrontal cortex, an area associated with higher-level thinking, empathy and guilt.
The crucial difference is that the distribution of those brain activities shifts from the back of the brain (as a teenager) to the front (as an adult). Teens' judgment of what they would do in a given situation is driven by the simple question: "What would I do?" according to Sarah-Jayne Blakemore of the University College London Institute of Cognitive Neuroscience. (Sara Goudarzi, "Study: Teen Brain Lacks Empathy," LiveScience, www.msnbc.msn.com, September 8 2006)
Teens learn empathy by practicing socializing, the researchers said. So much for grounding them until they're 20? Should parents let teens go to find their own experiences? Of course not -- parents have known for a long time if they let their teens do their own things, they'll first seek out adult role models, but if those are not available for them, they'll seek out teen role models.
Naturally, some of the teen role models youth find are negative influences. Raleigh Philp stated that teenagers, dealing with physical and emotional changes, sexual development, and a host of other things are undertaking socialization with brains that aren't capable of functioning like adult brains. (Raleigh Philp in Amy Standen's interview "Understanding How Adolescents Think," www.edutopia.org, 2010)
Parents of stubborn teenagers may take some consolation in the belief that an adolescent attitude, stems, in part, from lack of frontal brain development. Dr. Ken C. Winters' research concluded that, “The teenage brain is quite capable of demonstrating plenty of mental ability. But the teenager…is more likely to act impulsively and with gut instinct when confronted with stressful or emotional decisions…” (Adolescent Brain Development and Drug Abuse, Department of Psychiatry, University of Minnesota, June 2008)
Teenagers and adults often don't see eye to eye, but this new brain research is shedding light on why. Although adolescence is often characterized by increased independence and a desire for knowledge and exploration, it is also a time when brain changes can result in high-risk behaviors, addiction vulnerability, and mental illness, as different parts of the brain mature at different rates. Some teens never recover from such behaviors.
In reference to his findings, Geidd lamented, "It's also a particularly cruel irony of nature, I think, that right at this time when the brain is most vulnerable is also the time when teens are most likely to experiment with drugs or alcohol. Sometimes when I'm working with teens, I actually show them these brain development curves, how they peak at puberty and then prune down and try to reason with them that if they're doing drugs or alcohol that evening, it may not just be affecting their brains for that night or even for that weekend, but for the next 80 years of their life...." ("Inside the Teenage Brain," Frontline, www.pbs.org, January 2002)
This research may help explain why many top tier students who excel in upper level academic classes and who also engage in innumerable extra curricular activities and service projects often make poor choices in other parts of their lives. Why does a student making straight A’s get caught using illegal substances? Why is a star athlete cited for excessive speeding? Why do the best students frequently make poor choices? Understanding the teen brain and applying that knowledge benefits all members of the extended school community.
All too often, however, teachers, parents, counselors, and school administrators are apt to use the “frontal lobe” disconnect as a blanket excuse for every teenage failure or meltdown, so caution is needed in every evaluation.
What Would Influence the Development of the Cerebellum?
1. Actual physical activity, not with thumbs and video games, may have an effect on the development of the cerebellum.
2. Recess, play, and physical education in school need to be emphasized, not cut out of the school curriculum.
3. Computer people use the analogy that the cerebellum is like a math co-processor. It's not essential for any activity. People can get by quite well without large chunks of it. But it makes many activities better. The more complicated the activity, the more people call upon the cerebellum to help them solve the problem. And so almost anything that one can think of as higher thought -- mathematics, music, philosophy, decision making, social skills -- seems to draw upon the cerebellum. ...