Learning & the Brain – Frances Jensen, second part (teen brain)

[July 28, 2008 Update: I just came upon this wonderful interview with Frances Jensen on the teen brain. She responds to ten questions, and you can watch the brief video clips for each response or read the corresponding text.]

My previous post provided a primer in cellular learning as a beginning to understanding how the teen brain develops. As part of this process Frances Jensen describes:

The Paradox of the Teen Brain

Cell (neuronal) based learning is at its height in the teen brain
but
the network coordination is not fully connected up yet.

What does this mean? Essentially, teenagers – who, Jensen stressed, are not small adults – have superior learning skills to adults but their prefrontal cortex is still developing. As a result, then tend to have difficulty with impulse control and are not the best at making informed decisions.

As the brain develops, it matures from back to front, so the prefrontal cortex is the last to develop, becoming fully developed around age twenty-four. This explains why teenagers do not always act in what adults would consider a rational manner. Jensen also explained that the “excitation system peaks in early childhood, which is also when many affective disorders begin, while the inhibitory system continues to develop into adulthood.

Long term potentiation, described in my previous post, peaks two to three years earlier with girls (ages 10 to 14) than with boys (ages 12 to 17). Thus, “adolescent synaptic plasticity is “way better” than adults.” Because LTP is widely influenced by the environment, teenagers may be wired for optimal learning but also have the highest susceptibility to negative influences.

If you recall from the previous post, LTP is why repetition works. Imagine a fertile brain, still developing, and highly attuned to learning. Now expose this brain to drugs or alcohol or addiction or sleep deprivation or stress or multitasking. The teen brain is primed to learn and not primed to make informed decisions. With repetitive exposure to these negative influences, the teen brain learns to want continued exposure to these influences. Jensen states it succinctly: the “Adolescent brain responds too robustly to addiction, much more so than the adult brain.”

Jensen touched on some of the specifics of these negative influences. For instance, marijuana negatively impacts the sending and receiving of neuronal signals. “The effects may linger for days, so if you get high on Saturday this may impact your test taking four days later.” (I’ll bet that’s a surprise to any teenage readers!)

She shared a story about stress: Consider a mouse in a cage, with a cat hovering just outside the cage, and imagine the stress level of the mouse. Now simply replace the mouse with a student in a classroom, and replace the cat with either a teacher or a parent, and imagine the stress level of the student. Perhaps it will not surprise you to learn that high levels of stress in adolescence can cause depression later on in adulthood.

Lastly, Jensen talked about chronic sleep deprivation. According to her, two days of deprivation can lead to no LTP taking place; that means no real learning being consolidated over night. The simple solution is to get to sleep early and be sure to get sufficient amounts of sleep. Reviewing information at night, just before falling asleep, leads to sleep-induced replay which facilitates LTP. I have read about this many times and, while not testing it out in terms of preparing for a test, have done my own experiment for remembering. Instead of writing myself a note before bed, I have repeated to myself out loud what I want to remember in the morning. And guess what, in the morning I have remembered my message to myself from the night before.

At the National Institute for Health site you can view a time lapse movie of consolidated brain MRI scans showing 15 years of normal brain development from ages 5 through 20.

“Red indicates more gray matter, blue less gray matter. Gray matter wanes in a back-to-front wave as the brain matures and neural connections are pruned. Areas performing more basic functions mature earlier; areas for higher order functions mature later. The prefrontal cortex, which handles reasoning and other “executive” functions, emerged late in evolution and is among the last to mature. Studies in twins are showing that development of such late-maturing areas is less influenced by heredity than areas that mature earlier.”

What does all of this mean in terms of teenage brains and their education? As Jensen summarized:

  • Teenagers have exceptional skill for cellular learning (better than an adult, not as good as a young child).
  • Connectivity is a work in progress (better than a young child, not as good as an adult).
  • There is a paradoxical state in the teen brain (impulsive, enhanced susceptibility to environmental effects).
  • Schools and teachers should take genetic differences and school hours into consideration (girls develop two years sooner than boys, and all teens tend to have circadian rhythms that have them most alert and awake by ten o’clock in the morning).
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One thought on “Learning & the Brain – Frances Jensen, second part (teen brain)

  1. John Reilly

    Excellent insights into the functioning of the goo between our ears. Perhaps we could assign our adolescents to Risk Control Centers where they get exposed to just the right amount of risk without the exposure to fatal risk. Goodness knows the streets of America are not the best learning facility.

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