Abstract Mathematics is a complex skill requiring the coordination of distributed gray matter brain regions connected by white matter tracts. Diffusion tensor imaging (DTI) studies have revealed a network of white matter tracts that support math processing, but the specific microstructural features driving this relationship remain unclear. Other magnetic resonance imaging (MRI) methods—neurite orientation dispersion and density imaging (NODDI), inhomogeneous magnetization transfer (ihMT), multicomponent driven-equilibrium single-pulse observation of T1 and T2 (mcDESPOT), and g-ratio imaging—can probe microstructural features like axon packing, fiber orientation, and myelin more specifically than DTI. We applied these methods alongside DTI to evaluate links between white matter microstructure and math in a longitudinal cohort of 33 6–16 year olds (66 datasets total). Partial correlations between metrics of white matter microstructure and math skill, controlling for age and gender, were carried out in the left superior longitudinal and inferior longitudinal fasciculi, corticospinal tract, and the splenium. Cross-sectionally, fiber coherence of the corticospinal tract and superior longitudinal fasciculus correlated to mathematics performance. Longitudinally, change in markers of axonal packing and myelin were linked to changes in both math skill and fluency in a regionally-specific manner, with links to myelin-sensitive metrics most prevalent. Notably, decreases in myelin were linked to improvements in mathematics over time, suggesting ongoing refinement of the math network. Findings presented here did not survive multiple comparisons corrections, but provide insight for future work elaborating upon these associations in larger samples.
Bryce L. Geeraert, Kiara Kunimoto, R. Lebel et al.· ASN Neuro· 0 citations
BACKGROUND
Prenatal alcohol exposure (PAE) occurs in ~10% of pregnancies in North America and can alter brain development. Prior research on brain morphology in children with PAE shows mixed findings for cortical thickness, and only a few studies have investigated more complex morphological features, showing decreased gyrification with PAE. Here, we use four anatomical measures to provide a comprehensive characterization of cortical morphology in youth with PAE compared to unexposed youth.
METHODS
T1-weighted Magnetic Resonance Imaging (MRI) was used to examine cortical morphology metrics in 163 scans from 121 youth (56 with PAE) aged 7-21 years. Each participant had between 1 and 3 scans. Images were processed to segment 98 cortical brain regions. Linear mixed-effects models were used to test the effects of PAE on cortical gyrification index, thickness, sulcal depth, and shape complexity index, as well as their relationships with age.
RESULTS
Individuals with PAE had significantly lower gyrification (β=-0.17, q = 0.028) and sulcal depth (β=-0.60, q = 0.013) in the right pars triangularis, lower shape complexity in the right occipital pole (β=-0.019, q = 0.012), and higher shape complexity in the right medial orbital gyrus (β=0.017, q = 0.012), compared to unexposed youth. PAE moderated the relationship between age and both gyrification and sulcal depth in several regions such that sulcal depth and gyrification decreased with age in the PAE group but slightly increased with age (or remained stable) in the unexposed group.
CONCLUSION
These findings build upon previous reports of structural and developmental differences in youth with PAE, suggesting that gyrification may be more sensitive to the effects of PAE than cortical thickness.
Chloe Scholten, Courtney P. Gilchrist, Bryce L. Geeraert et al.· Drug and Alcohol Dependence· 0 citations
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