A new study showed yesterday the way the brains of very intelligent children develop, as opposed to those of less intelligent children, differences being found in the cortex, the outer layer of the brain that is involved in complex thinking. The team of American and Canadian scientists did several brain scans on 309 healthy children between the ages of 6 and 19 to see how brain development is linked to intelligence. According to the scans, children with the highest IQs have a thin cortex at the beginning, which rapidly grows thicker before reaching a peak and then again, rapidly becomes thinner. For the children with average intelligence, they had a thicker cortex at 6 years of age, but which, by the age of 13, became thinner than in children of superior intelligence. "Studies of brains have taught us that people with higher IQs do not have larger brains, but thanks to brain imaging technology, we can now see that the difference may be in the way the brain develops," said National Institutes of Health Director Elias A. Zerhouni. "In early childhood, the smartest children had a thinner cortex -- this is the opposite of what you'd expect. By late childhood, the pattern had changed completely," he added. The study also suggests that experience and environmental cues may have a serious role in shaping intelligence. "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," stated Richard E. Passingham, a psychologist at the University of Oxford.