Lead researcher Dr. Pilyoung Kim, of the National Institute of Mental Health, part of the National Institutes of Health, and colleagues used functional magnetic resonance imaging to map the brain's responses when the mothers were breastfeeding.
The breastfeeding mothers showed greater responses to their infant's cry in brain regions related to caregiving behavior and empathy than mothers who relied upon formula as the baby's main food source.
The findings suggest breastfeeding and its high levels of hormones such as oxytocin, prolactin, as well as stress and culture, may all play an important role for mothers' brain activity and parenting behaviors during the early postpartum period, Kim said.
The research, published in the Journal of Child Psychology and Psychiatry, shows that up to three or four months after delivery some of the brain regions originally observed at one month postpartum -- amygdala, putamen, globus pallidus and superior frontal gyrus -- continued to activate and were correlated with maternal, sensitive behavior among the same group of mothers.
"It is important for loved ones to support mothers and help them cope with challenges related to breastfeeding and parenting during this period," Kim said in a statement.