The Teen Brain

Recent research explains risky behavior with brain scans

Posted Jul 09, 2015

How we think about ourselves changes with time. Renaissance painters depicted babies as miniature adults. And, in fact, these young humans were expected to fulfill adult roles of work and marriage at puberty. For example, Shakespeare’s Juliet, from Romeo and Juliet, was just 13 years old when she became Romeo’s lover.  Writing in the 1600s, John Locke believed that children were born a tabula rasa, or blank slate, and shaped by their experiences. Similarly, B. F. Skinner conducted experiments demonstrating that rewards and punishments shaped behavior.

The very concept of childhood is a relatively new idea. It was the Industrial Revolution that dramatically changed the lives of children and families. Children who had once been apprenticed to their fathers and mothers on farms, moved to cities and were employed in factories. This led to long hours and poor working conditions and eventually the idea that children needed to be protected with child labor laws. Still, the idea that childhood was a time of innocence came much later with kindergartens. And, Stanley Hall, in 1904, was the first to write about the storm and stress of adolescence. The birth of childhood and adolescence as social phenomena and fields of scholarship are twentieth century novelties.

It has been observed that tools and technology often guide scholarship. This is certainly the case with the flood of neuro-psychological research in the past two decades. The advent of MRI machines has expanded the way psychologists study the brain. Prior to the MRI, much psychological research was observational and experimental, like Skinner or neurological research depended on brain trauma, surgery, or electrodes. The MRI has allowed detailed images of the brain and this has expanded the way we understand ourselves.

Since the time of Aristotle, it has been observed that adolescents were impulsive. They fluctuated rapidly between controlled reason and impulse. But, only recently has the technology been sophisticated enough to suggest reasons with images of the brain. In the June 2015 issue of Scientific American, Jay Giedd, from UC San Diego, explains the teenage brain “is a unique entity characterized by changeability and an increase in networking among brain regions.” The adolescent brain is neither a big child nor an incomplete adult. It is unique to itself.

Giedd (2015) further explains that there is a mismatch in growth rate between the limbic portion of the brain, which is the center of emotion, and the prefrontal cortex, which controls logic and reasoning. This mismatch explains the adolescent proclivity for risky behavior. Teenagers are impulsive because the emotional part of their brain develops faster than the logical part. Support for this comes from the brain imaging research of Dennis et al. (2013). Dennis et al. scanned the brains of 439 subjects between the ages of 12 and 30.  Using graph theory as a model, she says it is neural connectivity or communication between brain regions, not simply brain maturation rate, that improves with development. Some neural connections are pruned and others strengthen with development

The flood of recent brain imaging research is fun and fascinating. Certainly, it contributes to our understanding of ourselves in new ways. But, how helpful is this knowledge? Can it be applied in ways that will prevent teens from having car accidents or developing heroin habits? That teens are impulsive has been known for centuries. Does this expensive, new tool for self-observation add sufficient new and practical information to justify the enormous expense? These are all questions that remain to be answered.