title: Using IQ discrepancy scores to examine the neural correlates of specific cognitive abilities.
abstract: 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 a much smaller but statistically significant portion of variance in VIQ-PIQ discrepancy.
authors.affiliation: Center for Developmental Neuropsychiatry, Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: Margolis
authors.forename: Ravi
authors.initials: R
authors.lastname: Bansal
authors.forename: Xuejun
authors.initials: X
authors.lastname: Hao
authors.forename: Molly
authors.initials: M
authors.lastname: Algermissen
authors.forename: Cole
authors.initials: C
authors.lastname: Erickson
authors.forename: Kristin W
authors.initials: KW
authors.lastname: Klahr
authors.forename: Jack A
authors.initials: JA
authors.lastname: Naglieri
authors.forename: Bradley S
authors.initials: BS
authors.lastname: Peterson
mesh_terms: D000328:Adult; D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D003071:Cognition / Q000502:physiology*; D005260:Female; D006801:Humans; D007361:Intelligence Tests; D008297:Male; D008875:Middle Aged