Is bigger always better? The importance of cortical configuration with respect to cognitive ability

Abstract

General cognitive ability (GCA) has substantial explanatory power for behavioral and health outcomes, but its cortical substrate is still not fully established. GCA is highly polygenic and research to date strongly suggests that its cortical substrate is highly polyregional. We show in map-based and region-of-interest-based analyses of adult twins that a complex cortical configuration underlies GCA. Having relatively greater surface area in evolutionary and developmentally high-expanded prefrontal, lateral temporal, and inferior parietal regions is positively correlated with GCA, whereas relatively greater surface area in low-expanded occipital, medial temporal, and motor cortices is negatively correlated with GCA. Essentially the opposite pattern holds for relative cortical thickness. The phenotypic positive-to-negative gradients in our cortical-GCA association maps were largely driven by a similar pattern of genetic associations. The patterns are consistent with regional cortical stretching whereby relatively greater surface area is related to relatively thinner cortex in high-expanded regions. Thus, the typical “bigger is better” view does not adequately capture cortical-GCA associations. Rather, cognitive ability is influenced by complex configurations of cortical development patterns that are strongly influenced by genetic factors. Optimal cognitive ability appears to be driven both by the absolute size and the polyregional configuration of the entire cortex rather than by small, circumscribed regions.

Neurodevelopmental origins of lifespan changes in brain and cognition

“…36). However, cognitive ability appears to have a highly polyregional substrate (36). In line with this finding, regardless of age, in the present study children with higher GCA had larger cortical area in relatively broad regions.…”

“…Surface maps were smoothed using a circularly symmetric Gaussian kernel with a full-width at half maximum (FWHM) of 15 mm. The smoothing level was chosen both to improve signal-to-noise ratio for the vertex-wise comparisons and based on an expectation of relatively broad effects, in line with previous observations of a polyregional substrate for GCA (36). However, the initial analysis on the relationship of GCA and cortical area in subsample 1 was rerun also with less smoothing (i.e., a kernel with FWHM of 10 mm) and this yielded similar, yet as expected somewhat smaller effect areas (Fig.…”

Personality Traits Are Associated With Cortical Development Across Adolescence: A Longitudinal Structural MRI Study

“…Past studies have identified negative associations between agreeableness and gray matter volume in occipital areas; this may reflect the role of visual regions in processing of social stimuli although it is unlikely that occipital areas alone are implicated in benevolence (Coutinho et al., ; Kapogiannis et al., ). Overall, these findings correspond with work (Vuoksimaa et al., ) demonstrating that relatively greater SA in evolutionally and developmentally high‐expanded areas are associated with positive developmental outcomes, whereas the opposite holds for low‐expanded areas. In our study, relatively larger SA in lateral temporal cortices (high‐expanded area) was associated with higher emotional stability, whereas relatively smaller SA in occipital cortices (low‐expanded area) was related to higher benevolence.…”

“…Indeed timing, for example, delays rather than complete deviation from normal cortical development may be crucial for developmental outcomes (Ducharme et al., ). Moreover, these associations may depend on the brain area in question (Vuoksimaa et al., ); changes in one direction may be adaptive in some regions, but the opposite may be true for other regions. Finally, individual differences in size of particular brain structures at young ages may be predictive of later development (Cheetham et al., ).…”

Brain structure mediates the association between height and cognitive ability

“…Using the same sample, we have previously reported that GCA is positively correlated with total cortical CSA but not with mean CT and that total CSA is much more strongly related to cortical, whole brain, and intracranial volumes in comparison to mean CT (Vuoksimaa et al 2015). Further, we have also shown that both GCA and height are associated with greater CSA in regions that are relatively high-expanded across evolution and human development whereas CT in these regions was not related to height (Vuoksimaa et al 2016). These observations, together with other studies including brain structure, cognition and height (e.g., (Andreasen et al 1993; Taki et al 2012), led us to hypothesize that the height-GCA association would be accounted for by cortical CSA, rather than CT.…”