To determine developmental changes of activity-related metabolism in human visual cortex, we performed functional magnetic resonance imaging (fMRI) from the neonatal period. A rapid metabolic changing pattern accompanying normal human brain maturation was revealed by fMRI with photic stimulation. Infants older than 8 weeks of age showed a stimulus-related signal decrease in the visual cortex, whereas younger neonates showed a signal increase. This inversion of response in infants suggests a change in oxygen consumption during neuronal activation, which is related to rapid synapse formation and accompanying increased metabolism. fMRI can detect dynamic metabolic changes during the brain maturation, and provides a new clue in the detection of abnormal brain development or CNS plasticity.