Breakthrough in treating PND

In experiments using a neural scan, the researchers found that the medial orbitofrontal cortex lights up with activity within milliseconds of subjects seeing pictures of infants' faces.

But images of adult faces didn't elicit the same response, said co-principal investigator Morgen Kringelbach, noting that the reaction was the same for both men and women, and for people with and without children.

"This discovery helps answer the evolutionary question of why we view babies as special and could help doctors better identify people suffering from postnatal depression," the researchers said in the journal PLoS One.

"We think that the early response is guiding us to treat infants as special," Kringelbach said. "It happens so fast that almost without a doubt there is no conscious control over that."

The researchers suggest brain scans could provide a potentially predictive test for people prone to postnatal depression, a disease marked by an inability to bond with a newborn, which occurs in about 13% of mothers and 3% of fathers.

While there may be many reasons why postnatal depression occurs, Kringelbach said it may be that parents with the disorder don't have the "neural signature" that allows them to respond to their infant.

Kringelbach said it's important to identify and treat postnatal depression in a parent, not just for that individual but also for their child's long-term wellbeing.