Wednesday, March 29, 2006
The brains of high IQ children show a distinct pattern of development, according to a study from the National Institutes of Health (NIH) in Bethesda, Maryland.
The cortex, or outer mantle of the brain, starts out thinner and thickens more rapidly in very intelligent children, say the researchers. It then peaks at around 11 or 12 years old before thinning rapidly in the late teens.
This developmental pattern, rather than sheer brain size, may have more to do with intelligence said Philip Shaw, lead author of the NIH study. He said the changes are subtle and what is driving them is a mystery.
The scientists discovered the association between intelligence and brain development by taking MRI scans of 307 healthy children and teenagers, aged 5-19, over 2-year intervals as they grew up.
They compared the scans to see how they related to the children's IQ. Very intelligent youngsters had scores of 121-145 while high IQs were between 109-120 and average between 83-108.
The smartest youngsters showed the highest rate of change in the scans. The scientists believe the longer thickening time in the very brainy children might indicate a longer period for the development of high-level cognitive circuits in the brain.
The researchers added that the thinning phase could involve a "use it or lose it" pruning, or killing off, of brain cells and their connections as the brain matures and becomes more efficient.
"Brainy children are not cleverer solely by virtue of having more or less grey matter at any one age," said study co-author, Judith Rapoport.
"Rather IQ is related to the dynamics of cortex maturation."
The study appears in the journal, Nature.
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