Abstract

Objective: As executive functions (EF) involve complex and integrated white matter (WM) networks, performance may be strongly modulated by the myelin content along these WM pathways. In neuropsychological evaluations, EF is routinely evaluated via performance measures and also by collateral report questionnaires. Elucidating their relationship may help understanding of EF emergence during typical development. Method: Twenty-four children (mean age = 8.2 years (SD = 1.8), 66.7% Male, 66.7% Caucasian) participated in a longitudinal study of brain development (R01 MH087510). Myelin content was estimated throughout the brain using an MRI-based multicomponent relaxometry approach (mcDESPOT). Within 7 days of MRI, children received Digit Span from the Wechsler Intelligence Scale for Children - Fourth Edition (WISC-IV) and the Inhibition subtest from the Developmental Neuropsychological Assessment (NEPSY). Parents also completed the Behavior Rating Inventory of Executive Functioning (BRIEF). Non-parametric correlations, corrected for multiple comparisons, were examined between myelin content and neurocognitive measures throughout the brain, with age included as a covariate. Results: Mean scores on the performance measures as well as BRIEF Indices all emerged in the average range for age (range T = 35−84). Statistically significant correlations (p < 0.05 to p < .001) were identified between myelin and performance on Digit Span, Digits Forward, NEPSY Naming and Inhibition, and BRIEF Working Memory and Inhibition Indices, particularly in bilateral frontal and parietal WM and corpus callosum. Conclusion(s): Myelination plays an important role in EF emergence in children. While we identified overlapping brain regions across functions (in particular, anterior frontal WM), discrete areas also emerged for some functions, which warrant further study.