September 8, 2023

The Influence of Social Status on Early Social Development: Insights from Maturing Visual Pathways

 Forming infant-caregiver bonds is critical to social and neural development during infancy. However, the underlying brain pathways supporting infant attention to others’ eyes have remained largely unknown. Recent groundbreaking research conducted at the Emory National Primate Research Center (EPC) and the Marcus Autism Center sheds light on the development of eye contact behaviors in infant rhesus macaques and their influence on brain growth. This research not only has the potential to reveal early neurobehavioral markers of social disability but also provides insights into the impact of social status on these developmental processes.


“For both humans and macaques, learning to engage with the eyes of others during infancy is a critical social skill in typical neurodevelopment,” says senior author Mar Sanchez, Ph.D. Exploring the brain regions and environmental factors that contribute to this behavior can enhance our understanding of its emergence and role in primates’ social development.


Studying Infant Macaques

The research team conducted a study involving male infant macaques, measuring their eye contact behaviors through eye-tracking tools while showing them videos of other macaques. Resting-state functional MRI (rs-fMRI) scans were also taken to analyze connectivity within the occipital and temporal cortices, which are involved in visual perception and social processing.


The researchers collected data from two weeks to six months old at regular intervals. This unique longitudinal dataset allowed them to observe changes in the connectivity patterns between the occipital and temporal cortices over time. They discovered that the most significant changes occurred during the first three months of life, which is analogous to humans’ first year of life.


Importance of Brain Connectivity and Influence of Social Status

Infants with stronger connections between the brain areas responsible for visual processing (primary visual areas) showed a greater tendency to make eye contact with other monkeys earlier than infants with weaker connections. The study also revealed that social status impacted the relationship between brain maturation and eye contact. Low-ranking infants displayed a stronger association between the development of visual pathways and eye contact compared to their high-ranking counterparts. This suggests that low-ranking infants may have adapted brains that facilitate early identification of faces and expressions, enabling them to navigate social interactions more effectively.


Implications for Human Development

Aiden Ford, the first author and a Ph.D. candidate in Neuroscience at Emory, highlights the influence of social status on the development of the social brain, even in the earliest postnatal months. This research provides unique insights into brain and behavior development dynamics at both the group and individual levels. It also raises the possibility that early exposure to adversity may accelerate biological, brain, and social development.


The research group plans to conduct further studies mapping the development of social behaviors and social brain regions in infant macaques. The amygdala, a critical part of emotional processing, will be a particular focus. Additionally, the effects of infant social status will continue to be investigated, providing a deeper understanding of how social factors shape neural development.


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