Part II

So let's review: the teenage brain undergoes an enormous amount of change around the onset of puberty. The limbic, or emotional-memory-rewards-impulse, system is effecting every aspect of mental life. The frontal lobe, which is growing thicker and denser, is not quite able to moderate all the force of the limbic. Meanwhile, the cerebellum is also undergoing something of a revolution, as it is coordinating a kind of circuit between the frontal and the limbic.
It seems any description of the brain is overly simplistic, but for our purposes, this three part system is enough. This is where a consensus on the teenager's brain is forming, for now.

Whatever we do during this period may well form enduring patterns: this is one of the real dangers and ironies of adolescent drug use. The brain, with its limbic sensitivity to rewards and pleasure, establishes patterns fairly firmly. Meanwhile, self-perception and forward thinking are patchy at best.

Interestingly, I have not come across any significant right brain-left brain studies on teenagers other than ones regarding certain abilities, like mathematics and music. What I have read, however, is that where the left brain is oriented towards analysis, the right brain is the hemisphere of autobiography, maps of the self, self-awareness, empathy, holistic thought, the recognition of emotion, and stress. Some speculation is in order, but not now.

Another interesting frontal factoid is that this frontal-limbic-cerebellar "circuit" develops later in girls due to the presence of estrogen. Perhaps this is not really the case- but I've read it several times without chasing down the actual studies. What intrigues me is that, generally, in girls, the frontal lobe is more developed, that impulse is more readily suppressed than in boys. Yet this "circuit" develops later.

Lastly, but of some significance, is the construct of "hot and cold cognition". The limbic lends itself to emotional, "hot" thinking. The frontal may be more detached and abstract. In a sense, your average teenager is wending his or her way through a novel, ever-changing, and complex social world with little ability to step back and analyze. The thinking "just happens" and the solutions "just pop up".

One final note: the effects of chronic stress on children and teenagers. I wonder: young people need to have good academic and emotional practices, as the brain is setting down some deep patterns. But what if the added stress undermines those very processes? Perhaps modern schooling for many children negates its own efforts.

Citations Will Come Later...

Now that we have postponed those workshops until after the spring break, I thought I might share the nickel version of my presentation.

Why is adolescent behavior different than adult behavior? It used to be thought that the brain was largely developed by the time the teenage years are over. Now it is thought that at the very least, the frontal lobe is not fully developed until one's twenties. The frontal lobe (the outer layer of the brain more or less behind the forehead) is the seat of much of what we consider to be human: damage to this area makes concentration difficult and self-awareness very sketchy.

What makes this a nickel version is my avoidance of the big issue of oversimplifying the brain. We are leaving that aside.

The answer to the question "why are teenagers different" seems to be rooted in some newly understood relationships within the brain, that is, between the limbic system, the frontal lobe, and the cerebellum. Rather than it being a matter of the frontal lobe being underdeveloped per se, it is how these areas interact that may give rise to the risk taking, moodiness, and general lability of this time of life. My guess is that now that there MRI's everywhere researchers have access to healthy subjects and their brains in a way never before possible. There is a lot of information coming in.

Around age three there ends a period of extraordinary growth and change in the brain and nervous system. By age six, the brain is nearly its adult size. The rate of growth quiets down, and the brain, as the child plays, learns, and socializes, begins "pruning" back the unused connections. This is when we become expert television watchers and carbohydrate consumers. This is when we learn so much about what to expect from others. The connections that remain- trillions of them- are anticipating the world ahead.

There is a time- months, perhaps a couple of years- around the onset of puberty that the brain undergoes another enormous cascade of changes. The limbic system- that seat of arousal, dreaming, aggression, and love (and the first stages of memory encoding)- fires up. Attention is driven by emotion as every boring teacher doesn't know; to get someone's attention you must stir him up. A young person is pretty stirred up at this point, but the brain's counter-balance to this- the frontal lobe, which inhibits, analyzes, defers, and strategizes- is only beginning to take on the kind of neural density that the adult brain is characterized by.

In short, the accelerator works great, but the brakes are untested.

The frontal lobe (or cortex) manages attention. But it is constantly changing. It is also somewhat larger in girls, usually, which allows them to inhibits impulses a little more effectively. The frontal lobe looks ahead, as it were, to consequences and penalties. But sometimes it doesn't. This can be a real problem when the limbic, generating emotion, gut instinct, general outlines of experience, and full on embrace of life's pleasures, is so dominant. This sounds an awful lot like the Id and Superego of psychoanalysis. Maybe it is. But it is more complex than that.

A major role for the frontal lobe (more specifically, the pre-frontal cortex or PFC) is maintaining "cognitive flexibility". Imagining alternatives, projecting outcomes, considering counter-factuals, changing variables, and so on. A major role for the limbic system is memory, but more specifically for our purposes, rewards. The limbic system is very, very sensitive to being rewarded. Whatever feels good is readily stored as memory.

Let's think about this for a moment. The teenage brain is very sensitive to reward/reinforcement/pleasure. But it is somewhat numb to consequences, penalties, and imagining alternatives. Ouch.

Plant bad habits here. This is very fertile ground.

The third member of this simplified arrangement is the cerebellum. It used to be thought that this rather primitive part of the brain merely arranged coordination of voluntary, semi-voluntary (like breathing), and involuntary movement. Now it appears that this erstwhile hindmost region plays a part in coordinating all mental phenomena. Go figure, it seems that every part of the brain is really complex.

Stay tuned for part two

Workshops Postponed

The workshops on teenage brain development and mindfulness are postponed until May 7th.