Emotional tone of the maternal voice may stimulate infant brain

Infants, even while sleeping, exhibit heightened brain function when exposed to their mothers' infant-directed speech, compared with their brain function in response to maternal speech that is adult-directed, according to a report in the March issue of the Archives of Disease in Childhood––Fetal and Neonatal Edition.

Yuri Saito, of Hiroshima University in Hiroshima, Japan, and colleagues conducted a study of 20 full-term newborns while they slept in a silent room. Brain activity in the form of relative oxygenated hemoglobin values was measured using probes on the left and right sides of the forehead. The subjects were exposed to two types of auditory stimuli: a recording of their mothers' speech directed at infants, and directed at adults.

Exposure to infant-directed speech caused a significantly greater increase in brain function compared with adult-directed speech, suggesting that the emotional tone of the mother's voice may play a role in activating newborns' brains even during sleep.

Saito Y, Aoyama S, Kondo T, et al. Frontal cerebral blood flow change associated with infant-directed speech. Arch Dis Child Fetal Neonatal Ed. 2007;92:F113-F116.