White matter structure-function coupling in neonatal brain and its association with Autism-related traits in early childhood

The neonatal brain undergoes a rapid maturation of white matter pathways, yet how structural refinement within these tracts drives concurrent functional reorganization remains poorly understood. Using multimodal MRI data from 399 infants (348 term-born and 51 preterm-born) from the Developing Human Connectome Project, here we characterize the developmental trajectories of white matter structure-function coupling (SFC) and examine its associations with myelination (indexed by the T1w/T2w ratio), prematurity, and later autism-related traits. We find that SFC strength and its temporal variance develop heterogeneously across major fiber tracts, in which the inferior longitudinal and inferior fronto-occipital fasciculi exhibit a marked left-lateralized tendency, supporting the formation of nascent language and social cognition. The association between SFC and myelination is also dynamic, weakening over time in most tracts but strengthening selectively in the inferior longitudinal fasciculus. Preterm infants exhibit significantly reduced SFC across most tracts compared to term-born peers. Notably, reduced SFC in the right corticospinal tract partially mediates the association between prematurity and higher autism-related traits at 18 months. Furthermore, neonatal SFC predicts these traits only in preterm infants. These findings delineate a dynamic, tract-specific interplay between structure and function in early-life brain and establish neonatal SFC as a key link between prematurity and subsequent neurodevelopmental risk.