“Fluid Intelligence and the Locus Coeruleus-Norepinephrine System”, 2021-11-10 ():
To understand mind and behavior we must understand the biological basis of intelligence. Despite substantial progress, we lack a complete picture that integrates different levels of brain function and explains individual differences in cognitive ability. We propose that the locus coeruleus, the source of norepinephrine for the brain, plays a key role in this puzzle. It does so at all levels of brain function, regulating processes of learning, memory, and attention. We use baseline pupil size, which covaries with locus coeruleus activity, to anchor the present analyses of the role of the locus coeruleus in cognitive ability. This work provides a foundation for future research integrating different levels of brain function with individual differences in cognitive ability.
The last decade has seen substantial progress identifying genetic and brain differences related to intelligence. However, there remain considerable gaps in our understanding of how cognitive mechanisms that underpin intelligence map onto various brain functions.
In this article, we argue that the locus coeruleus-norepinephrine system is essential for understanding the biological basis of intelligence. We review evidence suggesting that the locus coeruleus-norepinephrine system plays a central role at all levels of brain function, from metabolic processes to the organization of large-scale brain networks.
We connect this evidence with our executive attention view of working-memory capacity and fluid intelligence and present analyses on baseline pupil size, an indicator of locus coeruleus activity. Using a latent variable approach, our analyses showed that a common executive attention factor predicted baseline pupil size. Additionally, the executive attention function of disengagement—not maintenance—uniquely predicted baseline pupil size.
These findings suggest that the ability to control attention may be important for understanding how cognitive mechanisms of fluid intelligence map onto the locus coeruleus-norepinephrine system. We discuss how further research is needed to better understand the relationships between fluid intelligence, the locus coeruleus-norepinephrine system, and functionally organized brain networks.