Gyrification increases brain surface area through what mechanism?

• A. Folding of the cerebral cortex.
• B. Growth of neural networks without changing surface area.
• C. Expansion of the skull.
• D. Increase in muscle mass in the brain.

Answer: (A)

Gyrification increases brain surface area by folding the cerebral cortex, creating ridges (gyri) and grooves (sulci) that pack more cortical surface into a fixed skull volume. The cortex is relatively thin, so folding allows a much larger area for neurons and connections without enlarging the brain’s overall size. Developmentally, differential growth and the interconnected white matter help drive these folds, effectively expanding processing capacity within the same cranial space. So the mechanism is folding of the cortex, not growth in surface area without folding, skull expansion, or increases in muscle mass.