Peeking inside the human brain to find out how it absorbs lessons, science finds out that the human brain first gets bigger - then smaller. At question is why brain tissue responds in that manner. Scientific American:
Still, there’s a big question lurking here. If a newly learned skill, in the end, has only a tiny footprint in the brain, why not tread more lightly during the learning process? Why go through the trouble of having large functional regions [of the brain], only to arrive at the few small neural differences that make a perceptual difference?
It might be because your brain is no smarter than you are. Just as you don’t know how to move from novice to expert in a few optimal and wisely chosen moves (how could you?), your brain doesn’t either. In a provocative theory that describes his findings, Kilgard speculates that the expanding cortical map is like a search committee. It’s generating a huge range of candidate solutions to a problem the brain has been tasked with, but doesn’t yet know how to solve. (How do I discriminate these tones? How do I get the ball in the basket? How do I solve that tricky calculus problem?) Once a good solution is found, the search committee is disbanded. Efficient changes that impart skill are retained, and the non-meaningful changes are winnowed away as the map shrinks.
The find is part of a remarkable string of discoveries that show just how physically elastic the mind really is.