FIGURE 8-17 Frontal Lobe Development and IQ Score The trajectory of frontal lobe development from ages 7 to 16 years correlates with dynamic changes in cortical thickness. Colors on the scans scale to the magnitude of differences between individuals with average and superior intelligence. Purple shows thinner cortex in the individuals with higher IQ scores; red, yellow, and green show progressively increasing cortical thickness in those individuals. At age 7, they have a thinner frontal cortex that rapidly thickens to peak at age 13, then wanes later in adolescence.

P. Shaw, D. Greenstein, J. Lerch, L. Clasen, R. Lenroot et al. Intellectual ability and cortical development in children and adolescents, Nature, 440, pp. 676–679 Mar 30, 2006, permission conveyed through Copyright Clearance Center, Inc.