Babies are born with a strong interest in faces. This helps them form close bonds with the people who care for them. A new study from Yale now suggests that the brain system behind this interest starts to form well before birth.
Most brain networks primarily develop after a baby is born. This work is different. The final three months of pregnancy reveal the presence of a network that adults use to read moving, expressive faces. The results appeared in the journal Imaging Neuroscience. This pathway’s detection in the womb is the first proof of its existence.
The researchers believe that tracking this pathway before and just after birth could teach us a lot. It may help explain how some developmental conditions begin. One example is autism, which has been linked to differences in how people pay attention to others.
Dr Katarzyna Chawarska, a child psychiatry professor at Yale and the lead author, explained why this matters. A newborn who turns toward a smiling, talking face that makes eye contact is more likely to bond with a carer. She calls this an important survival skill. In older children and adults, the social perception pathway handles this job. She said the new results indicate that the pathway begins to take shape before a baby is born.
Earlier findings from the same team set the stage. Last year’s study revealed that the social perception pathway is observable at birth. This network helps the brain handle moving faces, eye gaze, and speech. Babies whose pathway was more strongly connected looked at faces more at four months of age. Those babies also had fewer social difficulties at 18 months.
Chawarska described the finding as a first. The pathway may exist in a simple form at birth, and it seems to act as a frame for building social skills in the first year of life.
The new study asked a simple question. Is this pathway also present before birth? Brains differ a lot from one person to the next. Because of these differences, the team needed a large group of babies to see clear patterns of growth. They used the Developing Human Connectome Project, a free, open database. It holds brain connection scans from foetuses and newborns aged 20 to 44 weeks after conception.
The team studied functional MRI scans from 167 foetuses and 477 newborns. They looked at two face-related pathways. The first was the social perception pathway, which deals with talking, moving faces. The second was the ventral pathway, which helps us recognise still faces.
Both pathways showed activity from about 30 weeks of pregnancy. That is when the third trimester begins. The social perception pathway stood out, though. It grew strongly as babies moved from the womb to the outside world. It also became highly connected soon after birth.
The third trimester is a time of rapid change. During these months, the weight of the foetal brain triples. Many key networks start to form then. Yet for most of them, the pattern only becomes clear after birth. Dr Laura Ment, a paediatrics professor and senior author, said it is striking that this pathway is already forming before babies are born.
The researchers plan to follow babies from birth into the toddler years. They want to check whether early features of the social perception pathway relate to later social and communication skills. Chawarska said the goal is to go beyond describing how these networks are arranged at birth. The team hopes to learn what early brain organisation reveals about how children come to engage with other people and respond to the world around them every day.
