Cortical development occurs differently in extremely clever kids

Smarty Brains: High-IQ kids navigate notable neural shifts

Bruce Bower

The road to exceptional intelligence is paved with dramatic neural
alterations, a new brain-imaging study finds.

Critical parts of the brain's outer layer, or cortex, thicken more rapidly
during childhood and thin more drastically during adolescence in
individuals with extremely high IQ scores compared with peers of average or
moderately above-average intelligence, say neuroscientist Philip Shaw of
the National Institute of Mental Health in Bethesda, Md., and his colleagues.

The scientists propose that distinctive brain growth in superior-IQ youth
reflects prolonged development of neural circuits that contribute to
reasoning, planning, and other facets of analytical thinking.

"Cortical thickness at any one age tells you next to nothing about
intelligence," Shaw says. "What's important is that cortical development
occurs differently in extremely clever kids, possibly as a result of
particularly efficient sculpting of the brain." The report appears in the
March 30 Nature.

The researchers used a magnetic resonance imaging scanner to track brain
changes in 307 children and teenagers deemed free of psychiatric or
neurological disorders. Most volunteers submitted to two or more brain
scans at intervals averaging 2 years. Participants also completed a
verbal-and-nonverbal IQ test upon entering the study as children or teenagers.