Frontoparietal oscillatory dynamics support the development of fluid reasoning in children and adolescents

The neural basis of fluid intelligence (Gf) has been ascribed to a distinct network of parietal and frontal brain regions referred to as the P-FIT (parieto-frontal integration theory of intelligence) network. These neural substrates rapidly mature during adolescence, although the maturation of the oscillatory dynamics serving Gf has seldom been studied. Therefore, the present study utilized the largest sample to date to investigate the development of these neural dynamics in 104 youth ages 8 to 15 years old who completed an abstract reasoning task during magnetoencephalography (MEG), and behavioral matrix reasoning and vocabulary assessments. We detected multispectral age- and sex-related sensitivity across the P-FIT network, including oscillatory responses within the superior temporal gyrus, dorsolateral prefrontal cortex, and inferior frontal gyrus. Perhaps most notably, we found that changes in neural dynamics within the bilateral superior parietal lobules (βs = .157 to -.126) and right lingual gyrus (β = .068) significantly mediated age-related improvements in Gf abilities. These large-sample findings are consistent with the P-FIT model of fluid intelligence and serve to elucidate the neural dynamics supporting Gf development.