The young brain is remarkably plastic and flexible

I have already alluded to Alison Gopnik's article in Your Baby is Smarter Than You Think in the August 16, 2009 New York Times. Read the whole thing.

Part of the explanation for these differing approaches can be found in the brain. The young brain is remarkably plastic and flexible. Brains work because neurons are connected to one another, allowing them to communicate. Baby brains have many more neural connections than adult brains. But they are much less efficient. Over time, we prune away the connections we don't use, and the remaining ones become faster and more automatic. Moreover, the prefrontal cortex, the part of the brain that controls the directed, planned, focused kind of intelligence, is exceptionally late to mature, and may not take its final shape until our early 20s.

It is worth noting that Gopnik's research supports the importance that Through the Magic Door places on creating an early reading environment. If much of a child's exploration is occurring pre-five years old, it explains why Head Start and other programs are already playing catch-up when children join their programs.