Brain development patterns differ in smartest kids
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A new study ties intelligence to the speed of brain changes in childhood and the teen years, rather than the size of the brain itself.
During childhood and adolescence, the cerebral cortex—the outer layer of the brain, which is involved in learning, language, attention and other higher-order skills, and is also known as the gray matter—gets thicker and thicker until it reaches a peak, and then thins out again. In the current study of 629 brain scans from 307 healthy young people, Dr. Philip Shaw of the National Institutes of Mental Health in Bethesda, Maryland and his colleagues found this process happened more rapidly and dramatically in the most intelligent individuals.
It’s not clear why the cortex shrinks after it thickens, but this may represent a pruning of brain cells that “sculpts and fine-tunes the cortex to make it more effective,” Shaw told Reuters Health. “We wonder if that process is maybe particularly efficient in the most intelligent children.”
Shaw and his team found the children who ranked highest on IQ tests started out with the thinnest cortexes, which then thickened more rapidly, reached a peak of thickness at about age 11, and then rapidly thinned. Children of average intelligence showed a similar pattern, but their cortical thickness peaked earlier, so they had a less prolonged period of cortical growth. “What differed with intelligence was the rate of these changes,” Shaw explained.
Changes were most pronounced in the front portion of the cortex, “the seat of reasoning, planning and other very complex thought processes,” he added.
The current study has no implications for how to promote intelligence in children with normal abilities, Shaw said, but the findings are very valuable for helping to understand what goes wrong in learning disabilities or psychological illnesses that may be related to brain development, such as attention deficit hyperactivity disorder or schizophrenia.
“We can use that to help kids who really do need a lot of help,” he said.
SOURCE: Nature, March 30, 2004.
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