Patterns of Early Myelination Identify Functionally Relevant Brain Networks

Abstract Myelination of the brain’s white and cortical gray matter is a critical neurodevelopmental process that underpins efficient brain messaging and communication and, accordingly, contributes to the development and refinement of cognitive skills and abilities. While this is conceptually supported by the concurrent timelines of myelination derived from histological assays and cognitive development from behavioral studies, in vivo demonstration of myelin-cognitive associations across human infancy and childhood is limited. From histological studies, myelination proceeds in a known and characteristic caudal-cranial and posterior-to-anterior arc, driven by the increasingly coherent synaptic activity associated with emerging cognitive and behavioral functions. Patterns of myelination, therefore, may intrinsically inform on the rate and sequence of these developing skills and abilities, as well as the brain regions that contribute to them. In this work, we used longitudinal and myelin-sensitive MRI measures from a large cohort of neurotypical children to examine patterns of myelination throughout the brain and link these patterns to concurrently evolving motor, visual, and language skills. Results revealed a core system of central brain regions that contributed broadly across cognitive domains as well as individual and domain-specific regions that align with known functional specialization. These results provide important new insight into the sequence of emerging skills and the underlying myeloarchitectural changes that support them. This information provides context and reference for how early alterations may affect cognitive outcomes depending on their timing and anatomical location.