Sulcal Polymorphisms of the IFC and ACC Contribute to Inhibitory Control Variability in Children and Adults.

Inhibitory control (IC) is a core executive function that enables humans to resist habits, temptations, or distractions. IC efficiency in childhood is a strong predictor of academic and professional success later in life. Based on analysis of the sulcal pattern, a qualitative feature of cortex anatomy determined during fetal life and stable during development, we searched for evidence that interindividual differences in IC partly trace back to prenatal processes. Using anatomical magnetic resonance imaging (MRI), we analyzed the sulcal pattern of two key regions of the IC neural network, the dorsal anterior cingulate cortex (ACC) and the inferior frontal cortex (IFC), which limits the inferior frontal gyrus. We found that the sulcal pattern asymmetry of both the ACC and IFC contributes to IC (Stroop score) in children and adults: participants with asymmetrical ACC or IFC sulcal patterns had better IC efficiency than participants with symmetrical ACC or IFC sulcal patterns. Such additive effects of IFC and ACC sulcal patterns on IC efficiency suggest that distinct early neurodevelopmental mechanisms targeting different brain regions likely contribute to IC efficiency. This view shares some analogies with the "common variant-small effect" model in genetics, which states that frequent genetic polymorphisms have small effects but collectively account for a large portion of the variance. Similarly, each sulcal polymorphism has a small but additive effect: IFC and ACC sulcal patterns, respectively, explained 3% and 14% of the variance of the Stroop interference scores.

Adolescents' inhibitory control: keep it cool or lose control.

Inhibitory control (i.e., the ability to resist automatisms, temptations, distractions, or interference and to adapt to conflicting situations) is a determinant of cognitive and socio-emotional development. In light of the discrepancies of previous findings on the development of inhibitory control in affectively charged contexts, two important issues need to be addressed. We need to determine (a) whether cool inhibitory control (in affectively neutral contexts) and hot inhibitory control (in affectively charged contexts) follow the same developmental pattern and (b) the degree of specificity of these two types of inhibitory control at different ages. Thus, in the present study, we investigated the developmental patterns of cool and hot inhibitory control and the degree of specificity of these abilities in children, adolescents and adults. Typically developing children, adolescents, and adults performed two Stroop-like tasks: an affectively neutral one (Cool Stroop task) and an affectively charged one (Hot Stroop task). In the Cool Stroop task, the participants were asked to identify the ink color of the words independent of color that the words named; in the Hot Stroop task, the participants were asked to identify the emotional expression of a face independent of the emotion named by a simultaneously displayed written word. We found that cool inhibitory control abilities develop linearly with age, whereas hot inhibitory control abilities follow a quadratic developmental pattern, with adolescents displaying worse hot inhibitory control abilities than children and adults. In addition, cool and hot inhibitory control abilities were correlated in children but not in adolescents and adults. The present study suggests (a) that cool and hot inhibitory control abilities develop differently from childhood to adulthood - i.e., that cool inhibition follows a linear developmental pattern and hot inhibition follows an adolescent-specific pattern - and (b) that they become progressively more domain-specific with age.