Changes in Thickness and Surface Area of the Human Cortex and Their Relationship with Intelligence

Hugo G. Schnack*, Neeltje E M Van Haren, Rachel M. Brouwer, Alan Evans, Sarah Durston, Dorret I. Boomsma, René S. Kahn, Hilleke E. Hulshoff Pol

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Changes in cortical thickness over time have been related to intelligence, but whether changes in cortical surface area are related to general cognitive functioning is unknown. We therefore examined the relationship between intelligence quotient (IQ) and changes in cortical thickness and surface over time in 504 healthy subjects. At 10 years of age, more intelligent children have a slightly thinner cortex than children with a lower IQ. This relationship becomes more pronounced with increasing age: with higher IQ, a faster thinning of the cortex is found over time. In the more intelligent young adults, this relationship reverses so that by the age of 42 a thicker cortex is associated with higher intelligence. In contrast, cortical surface is larger in more intelligent children at the age of 10. The cortical surface is still expanding, reaching its maximum area during adolescence. With higher IQ, cortical expansion is completed at a younger age; and once completed, surface area decreases at a higher rate. These findings suggest that intelligence may be more related to the magnitude and timing of changes in brain structure during development than to brain structure per se, and that the cortex is never completed but shows continuing intelligence-dependent development.

Original languageEnglish
Pages (from-to)1608-1617
Number of pages10
JournalCerebral Cortex
Volume25
Issue number6
DOIs
Publication statusPublished - 1 Jan 2015

Keywords

  • brain development
  • cortex
  • intelligence
  • MRI
  • plasticity
  • QUANTITATIVE DENDRITIC ANALYSIS
  • HUMAN PREFRONTAL CORTEX
  • GENERAL INTELLIGENCE
  • GENETIC INFLUENCES
  • BRAIN-DEVELOPMENT
  • INTELLECTUAL ABILITY
  • CORTICAL DEVELOPMENT
  • CEREBRAL-CORTEX
  • WERNICKE AREA
  • GRAY-MATTER

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