Many people, at one time or another, have witnessed this ritual: a beaming new mother enters with baby pictures. A group of genuinely excited women gather around the new mother admiring the pictures as they are passed around. The new mother is oblivious to the fact that she has showed dozens of pictures at different angles of “Little Johnny” smiling. In her eyes, the baby is adorable and all she wants to do is hold and cuddle him. The mother, who cannot wait until she returns home to her baby, is in a celebratory mood and returns to her desk, which is now decorated with favorite pictures of her smiling bundle of joy.

It turns out that pictures of the smiling babies may be more than just decorative pieces. An interesting study at the Baylor College of Medicine suggests that a baby’s smile may be providing a natural high to the mother. This natural high, as with some foods or drugs, may even be addictive. Recently released in the journal, Pediatrics, the study shows that the brain responds to the facial cues of babies. Specifically, functional MRI scans revealed that the reward- processing areas of the brain associated with dopamine were activated when first time mothers saw their own infants’ happy faces. These dopamine sensitive areas include the substantia nigra/midbrain ventral tegmental area and primary motor cortex. Dopamine is an important neurotransmitter and hormone produced in several areas of the brain but especially the nuclei of the substantia nigra and ventral tegmentum. Among the many important functions of dopamine is its role in motivation, pleasure, and attachment.

Some research scientists believe that there is an association between the limbic system (emotions), associative system (cognition) and motor system (behavior) of the brain that is set into motion when a new mother observes her happy, smiling baby. A cascade of reactions is initiated with that smile, activating important dopamine-associated reward processing areas of the brain, which motivates maternal care and contributes to maternal-fetal attachment. The brain responses to neutral or sad faces from the baby were also recorded and showed a graded response with the least response coming from sad faces and the highest response from smiling faces. More dopamine sensitive areas were activated with happy faces than with sad or neutral faces. However, sad or neutral faces activated a different area of the brain involved in conflict resolution, which prompts an empathetic response from the mother to soothe the baby.

The findings of this study may shed some light on why some new mothers find it extremely difficult to cope with their new baby or why there is a high incidence of child neglect in mothers who are depressed or who are substance abusers. Past studies show that depressed people display decreased emotional responses to happy faces and have more difficulty recognizing facial expressions. Also, cocaine activates dopamine receptors and may compete with reward-processing areas of the brain that respond to infant cues.

More studies are needed to test fathers’ and grandparents’ neural responses to a child. It would be interesting to see if this natural, addictive high is elicited in them as strongly as the new mother.

Reference

L. Strathearn, J. Li, P. Fonagy, P. R. Montague (2008). What’s in a Smile? Maternal Brain Responses to Infant Facial Cues PEDIATRICS, 122 (1), 40-51 DOI: 10.1542/peds.2007-1566

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