A possible neural basis for the parental instincts was revealed by Researchers from the University of Oxford. Lead author Morten Kringelbach and Alan Stein from the University of Oxford demonstrated that a region of the human brain called the medial orbitofrontal cortex is highly specifically active within a seventh of a second in response to (unfamiliar) infant faces but not to adult faces.
For the study, the researchers used a neuroimaging method called magnetoencephalography (MEG) - an advanced neuroscientific tool that offers both excellent temporal and spatial resolution of whole brain activity - at Aston University, UK.
Since the researchers were primarily interested in the highly automatized processing of faces, they used an implicit task, in which participants were required to monitor the colour of a small red cross and to press a button as soon as the colour changed.
This was interspersed by adult and infant faces that were shown for 300 ms, but which were not important to solve the task.
The researchers found a key difference in the early brain activity of normal adults when they viewed infant faces compared to adult faces.
Besides the well-documented brain activity in the visual areas of the brain in response to faces, the researchers found early activity in the medial orbitofrontal cortex to infant faces but not adult faces.
This wave of activity begins around a seventh of a second after presentation of an infant face. These responses are almost certainly too fast to be consciously controlled and are therefore perhaps instinctive.
The medial orbitofrontal cortex, located in the front of the brain, just over the eyeballs, is a key region of the emotional brain and appears to be related to the ongoing monitoring of salient reward-related stimuli in the environment.
In the context of the study, the medial orbitofrontal cortex might provide the necessary emotional tagging of infant faces that predisposes us to treat infant faces as special and plays a key role in establishing a parental bond.
The finding of this study has potentially important clinical application in relation to postnatal depression, which is common, occurring in approximately 13 percent of mothers after birth and often within six weeks.
The study could eventually provide opportunities for early identification of families at risk.
The study is published in the scientific journal PLoS ONE.