Neonatal Amygdala Mean Diffusivity: A Potential Predictor of Emotional Face Perception

The ability to differentiate between different facial expressions is an important part of human social and emotional development that begins in infancy. Studies have shown that within the first year of life, infants develop a distinctive attentional bias towards fearful facial expressions. Investigations into the neural basis for this bias have highlighted the significance of the amygdala. The amygdalas role in directing attention towards fearful facial expressions underscores its importance in early emotional development, significantly influencing how infants interpret and react to facial expressions. To date, no studies have been conducted to investigate the associations between the amygdala microstructure and infants perception of emotional faces. This study aimed to elucidate this relationship while also investigating whether this association is sex specific. We measured the amygdala microstructural properties using diffusion tensor imaging mean diffusivity (MD) measurements in 40 healthy infants aged 2 to 5 weeks. Eye tracking was used to assess attention disengagement from fearful vs. non-fearful (happy and neutral) facial expressions as well as scrambled non-face control picture at 8 months. Generally, infants were age-typically less likely to disengage from fearful faces than from non-fearful faces towards salient distractors. A significant negative association was observed between the right amygdala MD measures and disengagement probability from fearful faces in the overall sample. Moreover, there was a positive association between the bilateral amygdala MD measures and the disengagement probability from scrambled non-face control picture in girls. These results indicate that the amygdala MD is associated with attention disengagement processes already in infancy, both in fear processing and in non-emotional conditions. Specifically, these findings highlight the role of the amygdala microstructure in modulating attentional processes, which may have implications for emotional regulation and susceptibility to emotional dysregulation later in life.