Implications of Brain Plasticity Part 2


Comments   |   Blog, Substance Abuse

Erich Engelhardt M.A.

Joseph Shrand, MD

The Oxford English dictionary defines plasticity as the ability to be easily molded or to undergo a permanent change in shape.  The biological definition describes plasticity as the adaptability of an organism to changes in its environment; specifically the ability to alter the neural connections of the brain as a result of experience, in the process of learning. Neuroplasticity thus holds promise for many people who previously existed in a rigid world without options. Victims of traumatic brain injury, and people who suffer from mental illnesses including anxiety, depression, and addictions, now have the hope that treatments and therapies can change their brain. However, the promise intrinsic in neuro-plasticity also creates the perils our young people incur when they decide to abuse substances. The actions we take can and do influence and create sustainable change in our neural nets, and the changes we create are not always positive.

The adolescent human brain is at a pinnacle of plasticity, creating downright danger even in the promise of possibility. According to Dr. Frances Jensen, senior assistant in Neurology at Children’s Hospital Boston and professor at Harvard Medical School, the teenage brain had been thought to be just a young adult brain.  New research has shown that is an enormous misrepresentation. The adolescent brain is not like the adult brain at all.  In fact, because of the rapid changes and re-organization of neural pathways, according to Dr. Jensen (2009) “teen brains can get addicted faster and stronger than adult brains and teenagers can have a lifelong problem with trying to shed an addiction that has been acquired as a teenager.”

To understand this process, one has to first understand how the brain “matures.” Neurons, or brain cells, are basically electrical wires that transmit signals from one cell to another.  Like any wire, having a sheath around the wire enhances its ability to conduct that signal.  The sheath around a neuron is actually composed of specialized glial cells (oligodendrocytes.  I love that word!) that create a fatty coating called myelin.  Maturation is measured, in part, by the amount of myelin around the neuron.

For example, you may have seen a baby wiggling around.  As it grows the baby begins to crawl, to pull itself up, to walk with a wobble, then walk with more balance, and eventually be able to run a sprint.  This development is due to the progressive myelination of that part of the brain, the motor neurons, that controls the muscles of the legs.  Myelination is the general process of development and maturation of the brain.  (Multiple Sclerosis, a devastating disease that slowly results in people losing the ability to walk or talk or see, is a progressive de-myelination of motor neurons due to the death of those oligodendrocyetes.  Myelin is really important.)

Research has demonstrated that the brain undergoes a prolonged process of development and refinement. Myelination occurs from birth to early adulthood. However, during the teenage years a developmental shift occurs. Adolescent behavior transforms from more impulsive to more reasoned and reflective. In fact, the brain areas most closely associated with aspects of responsible behaviors such as decision making, judgment, planning, and self-control undergoes a period of rapid development during adolescence.