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Weassessed the correlations of age, sex, and cognitive performance with measures of asymmetry in cortical thickness on high-resolution MRIs in 215 healthy human children and adults, 7-59 years of age. A left> right asymmetry in thickness of the cortical mantle was present throughout the entire lateral, dorsal, and mesial surfaces of the frontal lobe, extending into primary sensory, superior parietal, and anterior superior temporal cortices. A right left asymmetry was present in the lateral, mesial, and dorsal surfaces of the posterior temporal, parietal, and occipital cortices, as well as in the entire inferior surface of the brain. An exaggerated left right asymmetry was detected in females in anterior brain regions, and an exaggerated right> left asymmetry was detected in males in the orbitofrontal, inferior parietal, and inferior occipital cortices. Weaker moderating effects of sex were scattered along the mesial surface of the brain. Age significantly moderated asymmetry measures in the inferior sensorimotor, inferior parietal, posterior temporal, and inferior occipital cortices. The age asymmetry interaction derived from a steeper decline in cortical thickness with age in the right hemisphere than in the left on the lateral surface, whereas it derived from a steeper decline with age in the left hemisphere than in the right on the mesial surface. Finally, measures of performance on working memory and vocabulary tasks improved with increasing magnitudes of normal asymmetries in regions thought to support these cognitive capacities. [ABSTRACT FROM AUTHOR]

The underlying neural determinants of general intelligence have been studied intensively, and seem to derive from the anatomical and functional characteristics of a frontoparietal network. Little is known, however, about the underlying neural correlates of domain-specific cognitive abilities, the other factors hypothesized to explain individual performance on intelligence tests. Previous preliminary studies have suggested that spatially distinct neural structures do not support domain-specific cognitive abilities. To test whether differences between abilities that affect performance on verbal and performance tasks derive instead from the morphological features of a single anatomical network, we assessed in two independent samples of healthy human participants (N=83 and N=58; age range, 5-57 years) the correlation of cortical thickness with the magnitude of the verbal intelligence quotient (VIQ)-performance intelligence quotient (PIQ) discrepancy. We operationalized the VIQ-PIQ discrepancy by regressing VIQ onto PIQ (VIQ-regressed-on-PIQ score), and by regressing PIQ onto VIQ (PIQ-regressed-on-VIQ score). In both samples, a progressively thinner cortical mantle in anterior and posterior regions bilaterally was associated with progressively greater (more positive) VIQ-regressed-on-PIQ scores. A progressively thicker cortical mantle in anterior and posterior regions bilaterally was associated with progressively greater (more positive) PIQ-regressed-on-VIQ scores. Variation in cortical thickness in these regions accounted for a large portion of the overall variance in magnitude of the VIQ-PIQ discrepancy. The degree of hemispheric asymmetry in cortical thickness accounted for amuchsmaller but statistically significant portion of variance in VIQ-PIQ discrepancy. [ABSTRACT FROM AUTHOR]