The extent to which human caregivers are biologically programmed to respond to their infants’ cries remains unclear. Researchers observed the behavior of 684 mothers, on average 27 years of age, with infants approximately 5 months old in 11 countries, and found that across all countries, mothers preferentially responded to their infants’ crying by picking up and holding the infant, and by talking to the infant. Based on these observations, the authors hypothesized that infants’ cries would elicit common responses in the brains of new mothers from different cultures.

The authors conducted fMRI experiments involving 43 mothers in the United States, on average 33 years of age, with 3.5-month-old infants, and 44 Chinese mothers, on average 30.5 years of age, with 7.6-month-old infants.

In both sets of mothers, the sound of infants’ cries activated the brain’s supplementary motor area associated with the intention to move and speak, Broca’s area and the superior temporal regions associated with processing speech and complex sounds, and midbrain and striatal regions associated with caregiving.

According to the authors, the results suggest a neurobiological and evolutionary basis for the human maternal response to infants’ cries.
http://www.pnas.org/content/early/2017/10/17/1712022114