AEA 267 R4

Adolescent Brain

"As it turns out, teenagers may, indeed, be a bit crazy. But they are crazy according to a primal blueprint; they are crazy by design." Barbara Strauch,  (The Primal Teen)  

Crazy by design. Educators across the ages have known that teenagers act differently than younger children.  They also act differently than most adults- even though many teenage bodies are adult-sized.  We've always known that hormones play a large role in the unique behavior of adolescents, but it is only recently that we have come to understand that hormones are only one piece of a bigger picture.  Newly developed brain-imaging technologies, employed by neuroscientists interested in studying the structures and functions of the adolescent brain, have led to amazing discoveries!  For years, it had been assumed that because the brain of an adolescent was the same physical size as the brain of an adult, that it must be fully-formed.  It was assumed that if there were any structural changes at all in the teen brain, that they were subtle ones.  What we now know is that these adolescent brains are far from being "fully-cooked." On the contrary, the adolescent brain undergoes a dramatic transformation between the ages of about 10 and the mid-twenties, rivaled only by the changes that occur in early childhood. 

• Throughout childhood, there is a thickening of "gray matter" in the brain.  This thickening is caused by an overproduction of connections between brain cells (neurons).  This "exuberance", as it is called, seems to be nature's way of ensuring that the brain is prepared to survive and flourish in any environment and through any circumstance that it encounters.  At about the age of 10 in girls (11 in boys), this exuberance gives way to a systematic "pruning" of these connections. Neural connections that are used remain intact and strengthen.  Those connections that are not used are "pruned", essentially eliminating pathways that could have been utilized, but were deemed unnecessary.  The phrase "use it, or lose it" is particularly applicable to the adolescent brain.  Utilizing certain neural pathways through life (and school) experiences, results in a strengthening of some connections, and an elimination of others.  The final product is a brain that is highly efficient and effective- perfectly "sculpted" by its environment and its experiences.
  
  
• Beginning before birth and continuing into the mid-twenties, a process called Myelination occurs in the brain.  Following a pre-set developmental pattern, neurons (brain cells) are coated with a fatty, waxy substance called Myelin.  Once coated, these myelinated cells become more efficient in the way they carry messages throughout the brain.  The myelin provides insulation for each neuron and enables messages to travel much more quickly than in cells that have not been myelinated.  It is only when all of the neurons in the brain are equipped with their myelin sheath, that it becomes efficient and effective in its functioning.  Some neurons are fully-myelinated at birth- such as those in the motor cortex that control the ability of an infant to suck.  Other neurons become myelinated early in life, and provide ever-increasing efficiency for infants as they fine-tune their vision, hearing, language, emotions, and physical capabilities.  The last areas of the brain to receive their full coating of myelin are the frontal lobes.  It is these frontal lobes that (when fully developed) allow us to plan for the future, accurately assess risk, control our impulses, reason, set goals and priorities, make sound judgments, plan and organize multiple tasks, and exhibit emotional control.  Adults who have spent time with adolescents may recognize this as a veritable laundry list of tasks that are often difficult for them.  Knowing about the late Myelination pattern in adolescents provides valuable information for caring adults regarding the types of experiences needed in order to maximize this critical wiring phase of brain development.
  
  
• Though the adolescent brain's frontal lobes are still under construction, its emotional center is fully-functional.  This group of structures, located in the center of the brain and often referred to as the limbic system, has been developing since infancy and is, for the most part, complete.  (Like the rest of the brain, the emotional center's development is  dependent upon a combination of genes and environment- nature and nurture.)  Because the frontal lobes- those that govern many of the behaviors associated with "adulthood"- are not fully developed until the mid-twenties, adolescents rely upon their fully-functional emotional centers more heavily than most adults must.  Most adults are able to "temper" their brain's emotional center- exhibiting the more complex thinking and reasoning behaviors that are governed by their fully-functional frontal lobes.  They are able to "over-ride" the more primitive area of the brain and utilize the more fully evolved and complex frontal lobes as they move through their daily lives.  Adolescents often find this difficult, reacting emotionally to experiences and events, rather than rationally and thoughtfully.
  
  

• The ability to hold information in working memory -an area of the prefrontal lobes located directly behind the forehead- develops with age.  Children with a mental age of 5, for instance, can typically hold 2 (plus or minus 2) bits of information at any one time.  From the mental age of 15 and throughout the rest of our lives, humans typically have the ability to work with 7 (plus or minus 2) bits of information at a time.  The capacity of working memory does not typically grow as we age.  However, by grouping and chunking bits of information, we are able to hold larger and larger amounts at any one time.  It has been said that the difference between a novice and an expert in any field is his/her ability to chunk information. Chunking information is the process of combining multiple bits- to form larger coherent chunks- each of which carries meaning.