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Genetically Clever 2006-04-02

Posted by clype in Intolerance, Science.

Clever people outsmart their peers — not because they have more grey matter — but because part of their brain develops differently, a 'Nature' study suggests.

The US American 'National Institute of Mental Health' used scans to study development of the 'cortex', which is responsible for thinking, in 307 children.

They found smarter youngsters tended to have a thin 'cortex' aged seven, but this thickened rapidly by the age of 12.

Average children had an initially thick 'cortex' which peaked in size aged eight. In both cases, the 'cortex' thinned after reaching this peak but this was more gradual in children of average 'IQ' as their 'cortex' had reached peak thickness at an earlier age.

The researchers believe the extended period of thickening during the early years of the brighter children may give the brain more time to develop high-level thinking 'circuitry'. Then, the rapid thinning out of the 'cortex' later on may be due to withering of unused 'neural' connections as the brain 'streamlines' its operations. Researcher Mr.Elias Zerhouni MD said:


'Studies of brains have taught us that people with higher "IQs" do not have larger brains.

'Thanks to brain imaging technology, we can now see that the difference may be in the way the brain develops.'

Long-term study:

Ms.Judith Rapoport MD, who also worked on the study, said:

'Brainy children are not cleverer solely by virtue of having more or less "grey matter" at any one age.

'Rather, IQ is related to the dynamics of "cortex" maturation.'

The researchers are now searching for genetic variations which might be linked to differential brain maturation rates. In a commentary piece on the study, Professor Mr.Richard Passingham, of 'The University of Oxford', said variations in general intelligence were thought to depend to a great extent on 'genetic' differences.

'It is tempting to assume that this developmental change in brain structure is determined by a person's "genes",' he said.

'But one should be very wary of such a conclusion.

'The body's development is intimately linked to interactions with its environment.

'It could be that people with superior intelligence also live in a richer social and linguistic environment, and that it is this that accounts for the sharp increase in the thickness of their "prefrontal cortex" in late childhood.'



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