To test the hypothesis that infant cortical regions activated by a head-up tilt also exhibit increased functional electrocortical connectivity, prone sleeping newborn and 2- to 4-month-old infants were tilted head-up to 30°. Electroencephalogram (EEG) data were collected with 128 electrodes and coherence calculated to quantify electrocortical synchrony. Local coherence, defined as the average of coherence measurements between the EEG at each electrode site and neighboring sites (1 cm electrode spacing), was found in activated cortical regions that had previously shown increased high-frequency power with tilt. Long-distance coherence was computed between the regions. Newborn infants had significant increases in local coherence in the activated left frontal, right frontal-temporal, and occipital cortical regions; long-distance coherence increased between the right frontal-temporal and occipital regions. In contrast, infants at 2 to 4 months old, the age of maximum risk for sudden infant death syndrome, had no significant changes in coherence. Newborn and 2- to 4-month-old infants thus have different electrocortical responses to a classic cardiovascular challenge.