WHEN it comes to the brain, bigger isn鈥檛 always better. Intelligence has more to do with when and how the brain grows than with its overall size.
The brain鈥檚 cortex thickens in childhood, reaches a peak, and then thins again in adolescence. To see how this pattern is related to intelligence, Philip Shaw and colleagues at the National Institute of Mental Health in Bethesda, Maryland, took brain scans of 307 children every two years on average from age 6 to 20. The children were divided on the basis of IQ tests into average, high and superior intelligence.
In the brightest, the thickness of the prefrontal cortex, a brain region thought to be responsible for many facets of intelligence, increased rapidly through the pre-teen years before thinning out again after the age of 11. The pattern was the same, but much less pronounced in children who were averagely intelligent (Nature, vol 440, p 676).
Advertisement
It is possible that a stimulating environment might encourage this thickening and thinning in the cortex. 鈥淚n a way, children with the most agile minds have the most agile cortex,鈥� says Shaw.
