Our brain’s maturation follows an intriguing 20-year rhythmic trajectory that helps to explain child and adolescent behavior. To simplify a complex process, this development encompasses two distinct 10-year periods—a childhood acceptance of dependence, and an adolescent reach for independence.

Each 10-year developmental period begins slowly and awkwardly with a four-year initial activation of the brain systems that process the focus of that period, followed by a six-year developmental drive towards confident competence. Think of the four preschool years followed by the six K-5 years, followed by the four middle school years followed by the six high school and early college years.

Our brain is basically a social system. Even a simple task involves the collaboration of many of our brain’s hundreds of systems and subsystems. For example, separate subsystems within our visual system process quantity, color, shape, location, and movement. Their collaborative activity can lead to the perception of a red ball rolling across a table—which may spark our brain’s decision-making systems to grasp the ball, and our motor system to carry out the action.

These hundreds of cognitive systems don’t mature simultaneously. Children can grasp before they can walk, and talk before they can read. Similarly, the early adolescent brain can successfully carry out many but not all the functions of a mature brain.

This pair of columns will focus principally on the brain development that occurs during late childhood and early adolescence (the tween years), perhaps our brain’s most important developmental period—but it’s important to have at least a functional understanding of the entire organization and development of our brain to understand any of it. This month’s column will provide that background, and the next will focus on parental and educational implications. Regular readers of this column will note that some key brain organization and development elements were introduced in earlier columns, but this discussion will place such elements into the context of early adolescence.

Brain Organization and Development
Our brain is organized and develops from bottom to top, back to front, and right to left.

Bottom to Top Organization. Our brain is composed of (1) the relatively small subcortical systems such as the brainstem and cerebellum that are located at the base of our brain, and (2) the cerebrum, a large deeply folded overlying sheet of neuronal processing tissue called the cortex, and its dense underlying connective network. The subcortical systems regulate such innate subconscious survival functions as circulation, respiration, and automatic movements; and the cerebrum processes learned conscious thought and behavior. Childhood and adolescent brain development occurs principally within the cerebrum.

The cortex is a quadrant. An ear-to-ear fissure separates the occipital (vision), temporal (sound), and parietal (touch) sensory lobes at the back of the cortex from the frontal lobes; and a back-to-front fissure separates the two hemispheres. Each hemisphere contains a complete set of sensory and frontal lobes, and all major systems are highly interconnected. Our brain’s principal tasks are to recognize and respond to the novel and familiar challenges we confront. The four major cortical regions identified above process key elements of these four tasks, and early adolescence initiates their integration into a functional unit.

Back to Front Organization. The paired sets of hemispheric sensory lobes receive and process information about our body and the external environment. They transform such sensory data into a comprehensive perceptual map of the current environment and its challenges. They thus recognize (or interpret) the nature of the current challenges as they identify, locate, and integrate the individual elements (as in the rolling ball illustration above).

The sensory lobes mature during childhood. For example, children initially master verbal language and then the greater complexities of written language. Language provides efficient memory pegs for the increasing amount of complex natural and cultural concepts we confront, and it enhances social interaction. Children similarly master increasingly complex mathematical concepts and skills over time because knowing the magnitude and space/time relationships of the dangers and opportunities we confront is also central to survival.

By the time children reach the age of ten, most will have mastered the basic language and mathematical skills and the cultural information they will need during adolescence. The elementary school has a major responsibility to develop such factual knowledge and skills to the automatic level required in social interaction and frontal lobe problem solving.

Our frontal lobe processing systems receive the sensory lobes’ interpretation of the current challenge, determine whether and how best to respond, and execute the appropriate behavior. Our frontal lobes can also shift us from reactive to proactive thought and behavior—to imagine, and then consciously predict and prepare for potential challenges.

It’s important to quickly and accurately recognize the dynamics of a looming challenge, but it’s often equally important to delay a decision in order to reflectively consider various alternatives before we respond to the challenge. For example, our sensory lobes’ ability to rapidly read and interpret a menu’s information is cognitively different from our frontal lobes’ decision about what to order.

Our frontal lobes mature during adolescence and early adulthood. Since our frontal lobes develop the solutions we need to survive, one might think that they should mature first, but then we would be trying to solve problems that we don’t understand (something governments frequently and unsuccessfully attempt to do).

The cultural strategy for rearing children with immature frontal lobes is to expect the adults in their lives to make major frontal lobe decisions for them—where to live, what to wear, when to go to bed, etc. When children do make decisions, an adult is usually nearby to veto it if it’s inappropriate. If no adult is nearby, children will typically do what they think an adult would do in that situation—and they usually know since they spend a lot of time observing adults making such decisions. Further we explicitly teach them how to make the important decisions they need to make—how to cross a street or ride a bus, how to use a phone to call for help, how to identify and respond to potential predators.

Children with immature frontal lobes are willing to let adults make many decisions for them. Infants who can’t walk are similarly willing to let adults carry them. But just as young children generally don’t want to be carried while they’re learning to walk, early adolescents don’t want adults to make frontal lobe decisions for them while their frontal lobes are maturing.

The only way we can learn to walk is to practice walking on various surfaces, and the only way our frontal lobes can mature is to practice the reflective problem solving and advanced social skills that our frontal lobes process—even though early adolescents aren’t very successful initially.

Home and school should thus provide a non-threatening exploratory venue for a tween brain that is reasonably competent at recognizing the dynamics of a problem but is only beginning to develop reflective response capabilities. Infants insist on exploring independent movement, and early adolescents insist on exploring independent problem solving strategies—a significant shift from their childhood acceptance and use of adult-imposed rules, procedures, and algorithms.

Individual and collaborative home and classroom projects focused on budding interests, and the informal assessment of such enterprises provides excellent opportunities for exploration and feedback. The tween fascination with games, hobbies, and extended conversations with friends also demonstrate the seemingly innate exploratory drive tweens exhibit as they begin their cognitive shift from a sensory to a frontal lobe focus. Family activities and school extracurricular programs provide further exploratory possibilities.

Right to Left Organization. The fundamental organizing principle for the right and left hemispheres emerges out of an important question a brain must ask whenever danger or opportunity looms: Have I confronted this challenge before?

The right hemisphere (in most humans) is organized to process novel challenges and creative solutions, and the left hemisphere familiar problems and established routines. For example we process strange faces principally in our right hemisphere, and familiar faces in the left.

Although both hemispheres are active in processing most cognitive functions, the relative level of activation shifts from the right to the left hemisphere with increased experience. The right hemisphere is thus organized to rapidly and creatively recognize and respond to a novel challenge, but the more stable left hemisphere processing systems eventually translate the successful initial responses into an efficient established routine that is activated whenever the challenge reoccurs.

The arts are unique, creative, aesthetic expressions of a phenomenon, and so draw heavily on right hemisphere processing. Crafts are reproducible artistic expressions and so draw heavily on established left hemisphere routines. Similarly, body language communicates creatively, while articulate speech provides a more efficient reproducible communication vehicle. Both hemispheric systems are thus critical to successful behavior, but the maturation of cognition requires initial right hemisphere exploration.

What occurs within the sensory and frontal lobes of one brain that’s confronting a novel challenge parallels the brainstorming that occurs within a committee of brains confronting a novel challenge. The process begins with the identification of all possible explanations and proposals, and eventually converges on a single acceptable explanation and decision. It doesn’t have to be the best possible explanation and solution—just something that gains general agreement. The committee then saves its decision in the minutes, just as a single brain saves it in memory (or saves it to disk).

When a similar problem emerges later, the record is retrieved and edited to meet any different circumstances, and that decision is then saved. The process continues until the committee (or the individual) creates a policy or routine to automatically follow whenever this problem or a close variant occurs.

As we individually and corporately age we tend to develop an increasingly large repertoire of such routines and policies that we incorporate into the resolution of a wide variety of challenges. We may even come to resent novel challenges because we lack the energy they require for resolution. We thus become set in our ways. We further seek to impose our solutions to life’s problems on young people who need to explore and resolve such challenges within the context of their own maturation and generation. We thus teach them our answers to questions they haven’t yet asked.

Next month’s column will explore the resolution of this major parental and school dilemma—when to regulate, when to advise, and when to back off.