Moms get high on smiles
2008-07-14 21:27
New York - A baby's smile does more than
warm a mother's heart - it also lights up the reward centres
of her brain, according to the results of a brain imaging
study.
The finding, investigators say, could go a long way in
helping researchers dissect the unique bond between mother and
infant and how it sometimes goes wrong.
"The relationship between mothers and infants is critical
for child development," Dr Lane Strathearn, of the Human
Neuroimaging Laboratory at Baylor College of Medicine, Houston
noted in a statement.
"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," Strathearn
explained.
Strathearn and colleagues used magnetic resonance imaging
(MRI) to scan the brains of 28 first-time mothers of 5- to
10-month-old infants while they looked at photos of their own
babies and other infants.
Happy-baby addiction
In some of the photos babies were smiling or happy. In
others, the infants were sad and in some they had neutral
expressions.
The investigators found that when the mothers saw their own
infants' faces, key areas of the brain associated with reward
lit up during the scans, suggesting increased blood flow to
that area.
The areas stimulated by the sight of their own babies were
those involved in thinking, movement, behaviour and emotion.
"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 investigator added.
Smiles give strongest reactions
The strength of mom's reaction depended on her baby's
facial expression.
"The strongest activation was with smiling
faces," Strathearn said. There was less effect from pictures of
their babies with sad or neutral expressions.
"We were expecting a different reaction with sad faces,"
the researcher explained. In fact, the team found little
difference in the reaction of the mothers' brains to their own
babies' crying face compared to that of an unknown child.
Overall, the mothers responded much more strongly to their
own infants' faces than to those of an unknown baby.
"Understanding how a mother responds uniquely to her own
infant, when smiling or crying," Strathearn said, may be the
first step in understanding the neural basis of mother-infant
attachment.