A Baby's Smile is Like a Natural High

"The relationship between mothers and infants is critical for child development," said Doctor Lane Strathearn of the research team. "For whatever reason, in some cases, that relationship doesn't develop normally. Neglect and abuse can result, with devastating effects on a child's development."

To study this relationship, the scientists asked 28 first-time mothers with infants aged five to ten months to watch photos of their own babies and other infants while they were in a functional magnetic resonance imaging scanner. The machine measures blood flow in the brain. In the scans, areas of increased blood flow "light up," giving researchers a clue as to where brain activity takes place.

In some of the photos, babies were smiling. In others they were sad, and in some with neutral expressions. They found that when the mothers saw their own infants' faces, key areas of the brain associated with reward lit up during the scans.

The areas stimulated by the sight of their own babies were those associated with the neurotransmitter dopamine. Specifically, the areas associated included the ventral tegmental area and substantia nigra regions, the striatum, and frontal lobe regions involved in emotion processing, cognition and motor and behavioral outputs. "These are areas that have been activated in other experiments associated with drug addiction," said Strathearn. "It may be that seeing your own baby's smiling face is like a 'natural high'."

The strength of the reaction depended on the baby's facial expression. "The strongest activation was with smiling faces," he said. There was less effect from pictures of their babies with sad or neutral expressions. "We were expecting a different reaction with sad faces," he adds. In fact, the researchers found little difference in the reaction of the mothers' brains to their own babies' crying face compared to that of an unknown child.

MEDICA.de; Source: Baylor College of Medicine