Intellect as distinct from Openness: differences revealed by fMRI of working memory.

Relatively little is known about the neural bases of the Big Five personality trait Openness/Intellect. This trait is composed of 2 related but separable aspects, Openness to Experience and Intellect. On the basis of previous behavioral research (C. G. DeYoung, J. B. Peterson, & D. M. Higgins, 2005), the authors hypothesized that brain activity supporting working memory (WM) would be related to Intellect but not to Openness. To test this hypothesis, the authors used functional magnetic resonance imaging (fMRI) to scan a sample of 104 healthy adults as they performed a difficult WM task. Intellect (and not Openness) was found to correlate with WM accuracy and with accuracy-related brain activity, in left lateral anterior prefrontal cortex and posterior medial frontal cortex. Neural activity in these regions mediated the association between Intellect and WM performance, implicating these regions in the neural substrate of Intellect. Intellect was also correlated significantly with scores on tests of intelligence and WM capacity, but the association of Intellect with brain activity could not be entirely explained by cognitive ability.

Individual differences in delay discounting: relation to intelligence, working memory, and anterior prefrontal cortex.

Lower delay discounting (better self-control) is linked to higher intelligence, but the basis of this relation is uncertain. To investigate the potential role of working memory (WM) processes, we assessed delay discounting, intelligence (g), WM (span tasks, 3-back task), and WM-related neural activity (using functional magnetic resonance imaging) in 103 healthy adults. Delay discounting was negatively correlated with g and WM. WM explained no variance in delay discounting beyond that explained by g, which suggests that processes through which WM relates to delay discounting are shared by g. WM-related neural activity in left anterior prefrontal cortex (Brodmann's area 10) covaried with g, r= .26, and delay discounting, r=-.40, and partially mediated the relation between g and delay discounting. Overall, the results suggest that delay discounting is associated with intelligence in part because of processes instantiated in anterior prefrontal cortex, a region known to support the integration of diverse information.

Multiple bases of human intelligence revealed by cortical thickness and neural activation.

We hypothesized that individual differences in intelligence (Spearman's g) are supported by multiple brain regions, and in particular that fluid (gF) and crystallized (gC) components of intelligence are related to brain function and structure with a distinct profile of association across brain regions. In 225 healthy young adults scanned with structural and functional magnetic resonance imaging sequences, regions of interest (ROIs) were defined on the basis of a correlation between g and either brain structure or brain function. In these ROIs, gC was more strongly related to structure (cortical thickness) than function, whereas gF was more strongly related to function (blood oxygenation level-dependent signal during reasoning) than structure. We further validated this finding by generating a neurometric prediction model of intelligence quotient (IQ) that explained 50% of variance in IQ in an independent sample. The data compel a nuanced view of the neurobiology of intelligence, providing the most persuasive evidence to date for theories emphasizing multiple distributed brain regions differing in function.

Emotional Intelligence predicts individual differences in social exchange reasoning.

When assessed with performance measures, Emotional Intelligence (EI) correlates positively with the quality of social relationships. However, the bases of such correlations are not understood in terms of cognitive and neural information processing mechanisms. We investigated whether a performance measure of EI is related to reasoning about social situations (specifically social exchange reasoning) using versions of the Wason Card Selection Task. In an fMRI study (N=16), higher EI predicted hemodynamic responses during social reasoning in the left frontal polar and left anterior temporal brain regions, even when controlling for responses on a very closely matched task (precautionary reasoning). In a larger behavioral study (N=48), higher EI predicted faster social exchange reasoning, after controlling for precautionary reasoning. The results are the first to directly suggest that EI is mediated in part by mechanisms supporting social reasoning and validate a new approach to investigating EI in terms of more basic information processing mechanisms.

Frontopolar cortex mediates abstract integration in analogy.

Integration of abstractly similar relations during analogical reasoning was investigated using functional magnetic resonance imaging. Activation elicited by an analogical reasoning task that required both complex working memory and integration of abstractly similar relations was compared to activation elicited by a non-analogical task that required complex working memory in the absence of abstract relational integration. A left-sided region of the frontal pole of the brain (BA 9/10) was selectively active for the abstract relational integration component of analogical reasoning. Analogical reasoning also engaged a left-sided network of parieto-frontal regions. Activity in this network during analogical reasoning is hypothesized to reflect categorical alignment of individual component terms that make up analogies. This parieto-frontal network was also engaged by the complex control task, which involved explicit categorization, but not by a simpler control task, which did not involve categorization. We hypothesize that frontopolar cortex mediates abstract relational integration in complex reasoning while parieto-frontal regions mediate working memory processes, including manipulation of terms for the purpose of categorical alignment, that facilitate this integration.