Manual dexterity in late childhood is associated with maturation of the corticospinal tract

Despite the important role of manual dexterity in child development, neurobiological mechanisms associated with childhood remain unclear. We leveraged fixel-based analysis (FBA) to examine longitudinal association between and development white matter structural properties corticospinal tract (CST). High angular diffusion weighted imaging (HARDI) data were acquired for 44 right-handed typically developing children (22 female) aged 9-13 across two timepoints (timepoint 1: mean age 10.5 years ± 0.5 years, timepoint 2: 11.8 years). Manual was assessed using Grooved Pegboard Test, a widely used measure dexterity. FBA-derived measures fiber density morphology generated CST at each timepoint. Connectivity-based fixel enhancement mixed linear modelling CST. Longitudinal effects models showed that greater dominant hand increased cross-section contralateral Analyses further demonstrated rate improvement increase timepoints. Our suggest late is maturation These findings significantly enhance our understanding systems subserve fine motor provide an step toward mapping normative trajectories function against microstructural morphological childhood.