Posted on 03/30/2006 12:04:14 PM PST by LibWhacker
A large-scale study of brain development pinpoints the anatomical changes that are linked to IQ.
The brains of more intelligent children appear to develop in a characteristic way, growing quickly over an extended period between the ages of 5 and 12. These findings -- some of the most detailed research on brain development and IQ -- resulted from a 15-year study done by the National Institutes of Mental Health (NIMH.)
The study, which used magnetic resonance imaging (MRI) to gain a detailed picture of how the brains of children change over time, found that in kids who did better on standard IQ tests, the cortex grew thicker and faster and its growth peaked later than among their average peers.
[To view images from the study, click here.]
Researchers say the findings could help scientists pinpoint genes involved in brain development and IQ levels. It could also give scientists a better picture of normal brain development and shed light on childhood developmental and psychiatric diseases, such as Attention Deficit Hyperactivity Disorder (ADHD.)
"The study shows that there are clear features in brain images that are different for smart children versus average children," says Paul Thompson, a brain-imaging expert at the University of California, Los Angeles (who was not involved in the project). "Now it should become extremely fast to identify some of the main factors that make the brain develop in a healthy way...such as how kids are taught, their diet, their parental upbringing, or...genetics."
Most previous studies of brain development have compared children's brains at a single time in their lives. The new study, published today in the journal Nature, took a broader look, by studying children as they grew. The researchers followed more than 300 children, ages 5 to 19, for a total of 15 years, taking MRI images of their brains at several different times in their development.
The cortex, which is made up of nerve-cell bodies covering the outer layer of the brain, is largely responsible for higher-order brain functions, such as reasoning and perception. All children show the same basic pattern of cortical development: the cortex grows during childhood, and thins in adolescence, as unused neural connections are pruned away.
According to this new study, children with the highest IQs start out with a thinner cortex, which undergoes rapid growth, peaking at around age 12, instead of age 8 or 9 for children who got average scores on IQ tests. "Children with the most agile minds have the most rapidly changing cortex," says Philip Shaw, a child psychiatrist at NIMH who led the research.
The greatest correlation was seen in the prefrontal cortex, which mediates planning and complex reasoning. "Intelligent children have a prolonged period of thickening in the prefrontal cortex. We wonder if this gives them an extended period to develop the complex circuitry to support high-level thought," says Shaw.
John Gabrieli, a neuroscientist at MIT, says the long-term duration of the study allowed scientists to uncover patterns not observable in previous studies, such as the delayed developmental trajectory for people who go on to score high on IQ. "If you tested just at age 7 or 14, you would have come to opposite conclusions," he says.
"It would be interesting to see how those trajectories evolve in kids with dyslexia or other learning disorders," Gabrieli adds. "Perhaps you could identify children at risk for learning disorders much earlier than we now do."
Shaw's team recently finished a similar study of children with ADHD, in which researchers looked for the brain changes that accompany spontaneous remission of the learning disorder. Shaw says the database of normal brain development helped interpret those findings, which they expect to release in a few months.
Richard Haier, a neuroscientist at the University of California, Irvine, who studies IQ, says the findings also raise the question: "What influences the development of this brain area to give some people a thicker cortex than others? Is it based on genetics or some interactions or experience that a young person has that may foster a thicker cortex?"
Shaw and his colleagues now plan to search for genetic variants that are linked to the pattern of cortical development, and hence IQ. Many studies have demonstrated that IQ has a strong genetic component, yet it's still unclear how those genetic differences manifest in the brain.
While this area of research has been contentious -- critics worry that knowing genetic determinants of IQ could lead to a deterministic attitude toward education -- experts say that IQ is most likely linked to a complex interaction of genetics and environment.
Shaw says it's still too soon to tell how much of the growth pattern is due to genetics and how much to the environment, or both. His team plans to investigate this question in future studies.
"'It would be interesting to see how those trajectories evolve in kids with dyslexia or other learning disorders,' Gabrieli adds. 'Perhaps you could identify children at risk for learning disorders much earlier than we now do.'"
And garner additional state and federal funding "much earlier than we do now" for special needs kids, while the average kids are dumbed down and medicated into complacancy.
Smart, talented, handsome people tend to have smart, telented, handsome kids, while stupid, untalented, ugly people tend to have stupid, untalented, ugly kids, and THE LIBERALS CAN'T STAND THAT! Nya-Nya-Na-NYA-Nya!
Carefully selected on the basis of performance... exactly. You're making my point in an obverse sort of way. Everyone at Oxford is selected on the basis of high performance - those whose innate abilities, developed habits, parental expectations, reward structure (and a long list of other "et ceteras") have resulted in their achieve admission. No inferences about the race-innate ability connection can be inferred, because of all the other factors.
Applying the same logic, groups of persons perform, on average, worse or better on IQ tests in public schools, than others. A whole bunch of other factors are thrown in the mix, with no attempt to factor them out separately: preparation, home stability, behavior habits, early childhood malnutrition/trauma, cultural and parental expectations, emotional state (another long list of et ceteras).
Part of science is to draw out cause and effect. Every item in the list above needed to be studied and factored out carefully before any "analysis" could be done. And the quantity "IQ" is still an ill-defined measure of innate ability.
A very good book on this subject is Stephen Jay Gould's "The Mismeasure of Man", in which he explores in depth the fallacy of making "linear" extrapolations from a multidimensional system such as human intelligence.
Both of you are wrong! I assume that what you mean to say is the Normal curve not "the bell curve". It is EXTREMELY useful just so many people don't understand and misuse it. Like "the relationship...is .8 of a standard deviation" makes absolutely NO sense. Perhaps you meant a .8 correlation? Perhaps you'd like to join my students in stats class so you can sound smarter too.
I sincerely hope you're not teaching kids statistics.
Welcome to FR!
Right, which is why I put "racial differences" in quotes. He argues that because those who have a social agenda which mandates equal results between races, use statistics like this to measure racial differences, their goals are invalid.
I never read the "Bell Curve", so I wont pass judgement on it, but this particular defense of it (I don't know how much of the criticism of his book he answered, however) was very convincing.
The whole concept of racial grouping is pretty weak these days anyway, but then thats exactly what social liberals do. That sword can cut many ways...
And I suppose they are good lookin for the same reason ? ;-)
Lol! Flattery will get you everywhere! P.S get those eyes checked, Pronto!
They compare identical twins raised apart with fraternal twins raised apart. IIRC, about half of the difference between people's IQs is due to genes.
That opinion is getting harder and harder to defend with studies coming fast and thick like the instant one. No matter how much the lefties don't like it, if IQ correlates to definite, measurable, objective biological differences then it is stupid to maintain it's not a real phenomenon.
Thousands of identical twin studies. Raised together, raised apart, they have the same IQ +/- 5 points. When there is a significant deviation, the problem is usually correlated with a lower birth weight in the twin with the lower IQ. A shared placenta can lead to one of the twins getting less nutrition and oxygen. The lighter twin sometimes gets the "used" blood and waste by-products as well.
What does an IQ point measure? What definite, measurable, objective biological quantity does it represent?
Synapse speed?
Neurons firing/second?
Brain current?
What does it measure? Well, in the case at hand, it is a statistical measure of the growth function of the cerebral cortex in children.
The import of your post is that we must have a reductionist explanation of IQ or it isn't real. That is a misconception. If we were to accept your requirement, temperature wasn't real until we had a reductionist explanation in terms of the atomic theories of matter and all those guys with their thermometers were deluded.
In fact, if we were to accept your requirement of reductionist explanations, there could be no science. Every scientific theory must have undefined terms.
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