Absorbing lessons, brain gets bigger. Having mastered lessons, smaller

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.