Linking the Supplementary Motor Network and Executive Function in Developing Brain.

Objective: Essential development of the frontal lobe occurs during childhood and adolescence, affecting various executive function (EF) domains. Of the frontal areas, the supplementary motor area (SMA) located in the medial frontal cortex, is involved in various high-order EFs which include inhibition, working memory, and cognitive flexibility. However, it remains unclear how the functional network of the SMA is associated with EF development. Methods: We assessed Wisconsin Card Sorting Test (WCST) score and resting state functional magnetic resonance imaging data from 6- to 17-year-old children and adolescents to identify age differences in SMA functional connectivity (FC) associated with EF. Results: A total of 112 children and adolescents (62 males; mean [standard deviation] age, 12.21 [2.98] years) were included. After adjusting for sex, we discovered significant evidence in the older group that 300 FCs between the SMA and numerous regions of the brain, including the frontal, occipital, parietal, temporal, limbic, and cerebellar areas, were negatively correlated with the WCST subcategories (false discovery rate < 0.05). Conclusion: This finding underscores the SMA's pivotal role in executive dysfunction during developmental stages. Interestingly, this significant connectivity was absent in younger participants, highlighting the age range of 11-12 as a critical turning point for brain functional alterations involved in EF development. Since the crucial role of SMA in refining EF development has been underappreciated, this work has the potential to provide insight into both the nature of the functional alteration of SMA and the differences in individuals' EF development trajectories.