Tamara Fisher at Unwrapping the Gifted recently pointed out this press release from the National Institute of Mental Health (NIMH) (citing a paper in the March 30, 2006* issue of Nature), which explains that for children with “superior” IQs:
“Magnetic resonance imaging (MRI) scans showed that their brain’s outer mantle, or cortex, thickens more rapidly during childhood, reaching its peak later than in their peers — perhaps reflecting a longer developmental window for high-level thinking circuitry. It also thins faster during the late teens, likely due to the withering of unused neural connections as the brain streamlines its operations.”
The effect was particularly true for the prefrontal cortex, which is responsible for executive functions such as planning and organizing. According to the NIMH:
“The smartest 7-year-olds tended to start out with a relatively thinner cortex that thickened rapidly, peaking by age 11 or 12 before thinning. In their peers with average IQ, an initially thicker cortex peaked by age 8, with gradual thinning thereafter.”
As Tamara notes, “[T]his might help explain why some of our brainy middle-schoolers can do algebra but can’t find the homework they know they did the night before!”
* An oldie but a goodie.