A new study in Nature magazine has shown that clever children have thicker brains rather than bigger brains. For less intelligent children, cortical thickness peaks at age 8, at which time it is thicker than smarter children. But then thickness decreases for average kids, and increases in smarter kids up to age 12.
The brain is a network of neurons. Implicit in the study is that the network is getting more complex when the cortex thickens. The number of neurons doesn’t change, but the number of connections between neurons does.
The researcher said the thinning was thought to be due to a “use-it-or-lose-it” strategy, where connections were pruned as the brain streamlined its operations. So exercising the brain stimulates the number of connections.
Children need stimulating, otherwise their brains “dumb down”.
The same is true at the other end. A New Scientist article (“Use it don’t lose it”, 17 December 2005) said exactly the same thing about older people. It described a retired university lecturer who was “intolerably good” at chess. He found he could no longer think eight moves ahead, only five. Tests designed to spot early dimentia didn’t reveal any problem. Yet after he died two years later, his brain was found to be “riddled with plaques and tangles, the hallmark of Alzheimer’s disease”. This is an example of “cognitive reserve”, where people who lead intellectually stimulating lives are more protected from degeneration of the mind. They also recover better from “stroke, head injury, intoxication, and … neurotoxins”. Sounds like common sense, but it’s certainly surprising to hear someone can be riddled with Alzheimer’s and function well.
I guess you’re lucky if you’re the kind of person who enjoys being intellectually stimulated.