Cortical Expansion
Noted neuroscientist Alvaro Pascual-Leone of the Harvard Medical School conducted a deceptively simple experiment. He instructed volunteers to learn a five-finger piano exercise and try to play it as fluidly as possible while keeping up to a metronome’s constant sixty beats per minute. They were asked to practice two hours a day, every day, for five days. Then it was test time.
Only this was not the proficiency test to which Harvard medical students were accustomed. Over the course of the five days, subjects underwent "transcranial-magnetic-stimulation" (TMS) testing to infer functions of neurons in specific locations in the brain. Scientists tested every day after practice to map how much of each volunteer's cortex controlled finger movements.
The part of the cortex dedicated to these finger movements expanded and “took over” surrounding areas of the brain “like dandelions on a suburban lawn,” a result well beyond just strengthening connections.[i] The brains of these students were recruiting new neurons for the musical task at hand, neurons presumably previously dedicated to other, less-often-used functions. Other studies have confirmed the results—providing proof that greater use of muscles causes more cortex tissue to be devoted to that specific task.
This expansion of recruited cortex was contrary to prior genetic coded disposition theory. But it wasn't difficult to imagine, nor was it especially surprising.
But the next step was.
Pascual-Leone and his team continued the study but added a group that merely thought about the piano exercise. They imagined their fingers playing the piano part while keeping their hands still. Results were unexpected, to say the least: Volunteers who only mentally practiced recorded similar physical reorganization of their cortex.
Let's restate that.
Volunteers who did zero physical rehearsing, and only mentally imagined the practice, had physical reorganization of their cortex similar to participants who practiced physically!
This concept is used extensively today by athletes, musicians, and even people giving speeches. When you can't practice physically, a mental rehearsal can still be of great benefit.
[i] Sharon Begley, "How the Brain Rewires Itself," Time Magazine, January 29, 2007, 73.