Until recently, it was assumed that once a brain was mature (at the end of adolescence) it was an unchanging organ. Cognitive scientists have found that the human brain is actually quite plastic—cognitive functions that were assigned to one neural pathway can be reassigned to a different neural pathway. Early in life (through early adolescence) there is a period (lasting several years) during which many, many connections between neurons are established. This is followed by a period of pruning, during which those connections that are not strengthened through repetition and practice are lost (Willis 2006). Later in life, pathways can be rewired, although the rewiring can be more difficult than the wiring that occurs early in life.
The rewiring of one’s brain is something with which I have some personal experience. I suffered a stroke when I was 42. Doctors were able to remove most of the clot from an artery in the base of my brain, but when they did, a piece of it broke off and entered “a very forgiving part of the brain.” Those words were used by the brain surgeon to explain my condition to my family and were his description of a very plastic part of my brain. When I regained consciousness, my left side was quite disabled; I could not walk. With the help of some very talented therapists, I was able to regain the ability to walk, and my therapy became a lesson in brain function and plasticity.
My therapists gave me a long list of actions to follow when talking my first steps: “keep your toes up,” “land heal first,” “kick that leg forward,” “head up,” “back straight,” “don’t lean too far forward.” It was hard work to keep all of those things in mind and I became thoroughly confused as I tried to perform each in the correct order during my first tentative steps. Taking steps, which had been managed by pathways that did not require conscious control, now required much effort and concentration (but still were slow, deliberate, and very clumsy). The pathways and synapses in my brain controlling the muscles for walking had been damaged, but by working with my therapists, I rebuilt them.
For several weeks, my therapists had me perform what seemed quite silly exercises, (standing on one foot on a pillow with my eyes closed was a favorite), and they directed me to pay attention to how my body was reacting (for example when standing on a pillow with eyes closed, I attended to my ankles). I could sense my brain rewiring the pathways to control the muscles in my body, and by repeating the exercises I strengthened the connections. When my therapists took me to walk on gravel and grass, I could sense the same muscles and pathways working in my ankles that I had sensed when standing on a pillow. (My experiences led me to the conclusion that the exercises alone would never have been sufficient for me to become a walker again; but without the exercises, my journey back to walking would have been longer and more frustrating.)
References
Willis, Judy. 2006. Research-Based Strategies to Ignite Student Learning: Insights from a Neurologist and Classroom Teacher. Alexandria, VA: Association for Supervision & Curriculum Development.