Human intelligence has often been associated with structural and functional features of the brain. Two recent studies explore how changes in cortical thickness and area, as well as nodal efficiency of specific brain regions, are related to intelligence. This article aims to summarize the main findings and sample sizes of these studies to clarify their contributions to cognitive neuroscience.
Study 1: Changes in Cortical Thickness and Area
The study by Schnack et al. (2015) investigated the relationships between intelligence quotient (IQ) and changes in cortical thickness and area across development. Using a sample of 504 healthy individuals, the authors found that more intelligent children at age 10 had slightly thinner cortices, but that this relationship was reversed in young adults, where a thicker cortex was associated with greater intelligence. Furthermore, the cortical area in more intelligent children was larger, peaking earlier during adolescence. These results suggest that intelligence is more related to the magnitude and timing of changes in brain development than to fixed features of cortical structure.
Study 2: Nodal Efficiency in Key Regions of the Salience Network
Hilger et al. (2017) examined the nodal efficiency of key regions of the salience network, such as the right anterior insula and the dorsal anterior cingulate cortex, in relation to IQ. Using a sample of 54 healthy adults, the study demonstrated that higher intelligence is associated with greater nodal efficiency in these areas, which play crucial roles in filtering out irrelevant information and processing salience. The study also found an inverse association between IQ and nodal efficiency in the left temporoparietal junction, possibly due to this region’s role in distraction by non-essential information.
Conclusion
These studies highlight how different structural and functional features of the brain relate to human intelligence. While the study by Schnack et al. (2015) emphasizes the dynamics of cortical development, Hilger et al. (2017) focuses on the functional efficiency of specific regions of the brain network. Together, they provide a comprehensive overview of the complex relationships between brain structure and function and cognitive abilities.
References
• Schnack, HG, van Haren, NEM, Brouwer, RM, Evans, AC, Durston, S., Boomsma, D., Kahn, RS, & Hulshoff Pol, HE (2015). Changes in Thickness and Surface Area of the Human Cortex and Their Relationship with Intelligence. Cerebral Cortex, 25(6), 1608–1617. https://doi.org/10.1093/cercor/bht357
• Hilger, K., Ekman, M., Fiebach, C., & Basten, U. (2017). Efficient hubs in the intelligent brain: Nodal efficiency of hub regions in the salience network is associated with general intelligence. Intelligence, 60, 10–25. https://doi.org/10.1016/j.intell.2016.11.001
