Parents say a baby lights up their life. A new study proves they’re right - literally, because an image of a smiling baby “lights up” the reward centres of the mother’s brain.
A report from the Baylor College of Medicine researchers recently appeared in the journal Pediatrics and the findings could help scientists demystify the special mother-infant bond and how it sometimes go wrong.
“The relationship between mothers and infants is critical for child development,” said Strathearn. “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, Strathearn and his colleagues asked 28 first-time mothers with infants aged 5 to 10 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.
The subjects were shown photos of babies with different expressions: smiling or happy, sad and some expressions.
Strathearn said the women in his study spent about 20 minutes in the MRI machine.
“It was interesting, some of the mothers when they did come out of the scanner told me that they felt like reaching out to their baby when they saw their baby on the screen — for some of these mothers at least, it was really a very strong stimulus for them, even being in the noisy scanner, lying completely still.”
“The most important thing is that this response that mothers have to their babies is biologically driven. That there are particular brain systems in place to help forge this important relationship between a mother and baby. I think where it leads now is to look at where those systems aren’t working normally, aren’t functioning as we’d hope they would, and how that may be associated with difficulties in the relationship between mothers and their babies.”
Dr. Jean Wittenberg, head of the Infant Psychiatry Program at the Toronto Hospital for Sick Children, said it’s an important and interesting study.
“It’s part of a general development in psychiatry and neuropsychology looking at finding the areas of the brain related to specific behaviours,” he said. “It’s a way of helping us understand more about the psychosomatic continuum.”
Maternal responses are both psychological and physical and “each one has influence and impact on the other,” he said.
Wittenberg noted that what happens in the first couple of years sets down patterns that can be lifelong.
Caring for an infant can be tedious and frustrating, he said, but if the mother is rewarded, it becomes worthwhile.
“Mothers are responding very specifically to their own babies in a physiological way,” he said.
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/substantia nigra regions, the striatum, and frontal lobe regions involved in emotion processing, cognition and motor/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 said. In fact, they 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, may be the first step in understanding the neural basis of mother–infant attachment,” said Strathearn.
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Based on the news release from http://www.eurekalert.org and an article from the Calgary Sun: http://calsun.canoe.ca/Lifestyle/2008/07/07/6088751.html
