Scientists report that sophisticated imaging showed that seeing a baby's face lit up a specific region of the adult brain associated with reward circuitry. This "Christmas tree" effect didn't occur when adults looked at another adult face, suggesting there's a neural basis for protective, nurturing feelings triggered by babies.
And the findings could also shed some light on postnatal depression, which affects some 13 percent of new mothers, the study authors said.
Using an imaging technique called magnetoencephalography, scientists led by researchers at the University of Oxford in England scanned the faces of 12 adults as they looked at images of 13 infant and 13 adult faces. The study participants had never seen the images before. The faces were matched for emotional content, attractiveness and other features.
Brain activity started in the medial orbitofrontal cortex region of the brain within one-seventh of a second after seeing infant faces, but not adult faces. The responses were considered too rapid to be consciously controlled.
This region of the brain has been implicated in reward behavior; it also appears to be involved in visual object recognition. And depression has been linked to another region of the brain -- the subgenual cingulate cortex -- that is connected to the medial orbitofrontal cortex.