Mechanistic Link between Executive Functions and Higher Cognition: Evidence from Psychometric Modeling and Brain Stimulation

Human cognitive abilities depend on flexible coordination across distributed cognitive control systems within the frontoparietal network, yet the causal architecture linking executive functions (EFs) to higher cognition remains debated. We combined psychometric modeling and neuromodulation to test causal contributions of EFs to distinct cognitive abilities. In a psychometric study, we modeled Unity-Diversity EF components (updating, inhibition, shifting) against four Cattell-Horn-Carroll (CHC) group factors. Fluid reasoning (Gf) was uniquely related to both Common EF and Updating-specific variance, whereas visual processing (Gv) and processing speed (Gs) were primarily linked to Common EF; crystallized ability (Gc) proved to be largely independent of EFs. To causally probe this architecture, in neuromodulatory study we applied anodal transcranial direct current stimulation (tDCS) over prefrontal and parietal hubs of the frontoparietal network. tDCS selectively enhanced working memory updating, with right-hemisphere stimulation improving Gv but reducing Gf performance. Mediation analyses revealed that working memory updating mediated tDCS effects on higher cognition, yet the direction of effects varied across hemispheres and ability domains, exposing indirect, updating-driven facilitative and compensatory mechanisms within the frontoparietal network. Together, these findings bridge psychometric and neuromodulatory approaches to advance mechanistic understanding of how EFs support higher cognition.