In the study, Dr. Madoka Noriuchi, of Graduate School of Tokyo Metropolitan University, senior author on the paper, and colleagues used functional magnetic resonance imaging (fMRI), a tool that allows to study the function of brain circuits in people, to examine patterns of maternal brain activation. The researchers asked healthy mothers to watch video clips, which showed either their own infant - approximate age of 16 months - or an unknown infant in two emotional conditions, either happy or upset/crying.
"We found that a limited number of mother's brain areas were specifically related to maternal love, and the specific pattern of mother's response was observed for her infant's attachment behaviors evoking mother's care-taking behaviors for vigilant protectiveness," Dr. Madoka Noriuchi. They found that particular circuits in the brain, involving several regions in the cerebral cortex and limbic system, are distinctively activated when mothers distinguish the smiles and cries of their own infants from those of other infants.
The researchers also found that a mother reacts more strongly to the crying than the smiling of her own infant, which authors believe, seems 'to be biologically meaningful in terms of adaptation to specific demands associated with successful infant care.'
John H. Krystal, M.D., Editor of Biological Psychiatry and affiliated with both Yale University School of Medicine and the VA Connecticut Healthcare System, said: "This type of knowledge provides the beginnings of a scientific understanding of human maternal behavior. This knowledge could be helpful some day in developing treatments for the many problems and diseases that may adversely affect the mother-infant relationship."
The study is published in the February 15th issue of Biological Psychiatry.