Early infant white matter tract microstructure predictors of subsequent change in emotionality and emotional regulation.

Abstract

There are rapid changes in negative and positive emotionality (NE, PE) and emotional regulation (e.g., soothability) during the first year of life. Understanding the neural basis of these changes during maturation can enhance the understanding of the etiology of early psychopathology. Our goal was to determine how measures of white matter (WM) microstructure in tracts connecting key emotion-related neural networks, including the forceps minor (FM), cingulum bundle (CB), and uncinate fasciculus (UF) interconnecting the default mode network (DMN), salience network (SN), and central executive network (CEN), can predict developmental change in infant emotionality and emotional regulation. We used Neurite Orientation Dispersion and Density Imaging (NODDI) measures together with conventional diffusion tensor metrics to examine WM tract microstructure and fiber collinearity in the primary sample (n=95), and modeled each WM feature with caregiver-reported infant NE, PE, and soothability, with infant and caregiver sociodemographic factors as covariates. In 3-month infants, higher neurite dispersion and lower longitudinal fiber alignment in the FM were associated with a larger increase in NE from 3 to 9 months of age, suggesting that greater integration of the DMN, SN, and CEN leads to a larger subsequent increase in NE; while higher neurite density and dispersion as well as lower WM longitudinal alignment in the left CB were associated with a larger increase in PE, suggesting that greater integration within the CEN leads to increasing PE over time. In addition, higher neurite dispersion and lower WM longitudinal alignment in the left CB were associated with a larger increase in soothability. Associations among diffusion tensor measures and changes in infant emotionality and emotional regulation measures were replicated in an independent test sample (n=44). These findings suggest that early infant WM microstructural features support infant emotionality and emotional regulation development and could represent early biomarkers of future emotional and behavioral disorders.