Cultural Variation in Behavioral Correlates of Cortical Thickness among 9-10-Year-Old Children
Authors:   Minorities’ Diminished Returns (MDRs), Los Angeles, CA, USA, Assari Shervin , Najand Babak ,   Minorities’ Diminished Returns (MDRs), Los Angeles, CA, USA
Published: April 2024

Background: One of the main characteristics that differentiate Asian and European cultures is self-construal, the former has a higher tendency to have interdependent, and the latter tends to have an independent self. Recent structural brain imaging studies have shown that the Prefrontal Cortex (PFC) is thinner in Asian than European individuals, attributed to a need for reduction of reward relevant to self to maximize the reward relevant to the group. There is more to find out about differential cortical thickness and behavioral correlates across these cultural groups Aim: This study was performed to investigate the associations between cultural group membership, age, cortical thickness, and two sets of reward-related behaviors (e.g., reward responsiveness and prosocial behaviors) in a national sample of 9/10-year-old children in the U.S. Materials and Methods: For this cross-sectional study, we used demographic, socioeconomic, structural, and behavioral data from the Adolescent Brain Cognitive Development (ABCD) study. Our analytical sample included 5942 American children between the ages of 9 and 10 who were either European (n=5741) or Asian (n=201). The cortical thickness for various Regions Of Interest (ROIs) was measured using Structural Magnetic Resonance Imaging (sMRI). Two aspects of the behavioral profile, reward sensitivity, and prosocial behaviors, were also measured using self-report data. As a proxy of self-construal, culture was the independent variable or the moderator variable, depending on the model. Mixed-effects regression models were used for data analysis to adjust for nested data across families and study sites. Results: In the overall sample, asian children had a smaller thickness of cortical regions across all ROIs than European children. Age did not interact with culture on cortical thickness, suggesting a similar rate of pruning across cultures. Culture showed statistically significant interactions with cortical thickness across ROIs within and beyond PFC on children’s reward responsiveness and prosocial behaviors, indicating stronger associations for Asian than European children. Conclusion: Compared to European children, Asian children show lower cortical thickness across ROIs, a phenomenon that is not limited to PFC and is not due to a differential rate of age-related pruning. There are stronger associations between the thickness of several cortical areas with prosocial behaviors and reward responsiveness in Asian children relative to European children, extending the existing literature on culture, cerebral cortex, and reward salience. Our findings support the hypothesis that Asian children’s cortical volume changes are a cultural adaptation to maximize conformity and harmony with the group in Asian culture by reducing the relevance of reward salience of self and maximizing it for the community. More research is needed on cultural differences in behavioral correlates of structural and functional measures of cortical regions among European and Asian children.