Feb. 27, 2008 -- The urge to cuddle and coo when presented with a baby turns out to be an innate response prompted, at least in part, by the structure of an infant's face, according to new research that actually shows how this baby love process works in adult brains.
The finding could explain many behaviors, including why adults connect with babies, why most parents immediately gravitate to their kids and why many men appear to be attracted to women with baby-like features.
All elicit an attraction and parental brain response beginning in the medial orbitofrontal cortex, which is at the front of the brain just over our eyeballs, the new study, published in this week's PLoS ONE, determined.
"The brain activity in the orbitofrontal cortex could help us pay more attention, protect and cuddle the infant," lead author Morten Kringelbach told Discovery News.
Kringelbach, a senior research fellow in the University of Oxford's Department of Psychiatry, and his colleagues compiled a database of infant photos pulled from digital videotapes of 27 infants who were filmed in their own homes. Ninety-five male and female adults rated the emotional expressions of the babies from "very negative" to "very positive" affects.
A neuroimaging technique called magnetoencephalography, which provides resolution of whole brain activity up to the millisecond at millimeter-level detail, was then used to monitor the brains of 12 of the adult participants. The dozen individuals focused on the changing color of a red cross on a computer screen while adult and infant faces flashed before them at 300 milliseconds apiece.
The red cross task was somewhat of a ruse because the scientists were really monitoring what was going on in the participants' brains as the photos flew by them at speeds too fast for the conscious mind to perceive them.
The imaging revealed that adult faces were registered toward the center and back of the viewers' brains, which was a very different area than the over-the-eyeballs region that lit up when viewers saw babies' faces.
That front part of the brain is a key region for emotions. According to the scientists, it appears to be related to continuous monitoring of prominent reward-related stimuli from the environment.
Babies, in other words, can give healthy adults a little happy buzz.
Prior research has even found that "men prefer female faces with baby-like features," said Kringelbach. "The data is more complex for women who, depending on their ovulation, tend to prefer either very masculine or baby-like faces."
Adults suffering from depression, however, may experience a malfunctioning of the baby love brain center, since another part of the brain that's been linked to depression is near the baby processing region. Mothers, in particular, can suffer from postnatal depression, which occurs in 13 percent of all new moms.
"Our study would not lead to better treatments, but it may help to identify those at risk much earlier and thus offer potential treatments," Kringelbach said.
Kent Berridge, a professor of psychology and neuroscience at the University of Michigan, told Discovery News that he was impressed by the way the new study "cleverly confirms Darwin's prediction that human brains are wired to respond with special emotional reactions to infant faces in a basic and immediate way."
"The beauty of Kringelbach and colleagues' paper is its use of new baby faces that the adults hadn't seen before, to rule out alternative explanations based solely on learning of social attachment," Berridge said.
In the future, Kringelbach and his team hope to address whether or not men or women show different brain responses to babies, and if infants from other species, such as puppies and kittens, also stimulate the human baby love center of the brain.
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Jennifer Viegas' blog: Born Animal