Working memory (WkM) is a fundamental cognitive process that serves as a building block for higher order cognitive functions. While studies have shown that children and adolescents utilize similar brain regions during verbal WkM, there have been few studies that evaluate the developmental differences in brain connectivity. Our goal was to study the development of brain connectivity related to verbal WkM in typically developing children and adolescents.
Thirty-five healthy children and adolescents, divided into three groups: 9–12 (children), 13–16 (young adolescents) and 17–19 (older adolescents) years, were included in this fMRI study. The verbal WkM task involved a modified Sternberg item recognition paradigm using three different loads. Brain connectivity analysis was performed using independent component analyses and regressing the components with the design matrix to determine task-related networks.
Connectivity analyses resulted in four components associated solely with encoding, four solely with recognition and two with both. Two networks demonstrated age-related differences with respect to load, 1) the left motor area and right cerebellum, and 2) the left prefrontal cortex, left parietal lobe, and right cerebellum. Post hoc analyses revealed that the first network showed significant effects of age between children and the two older groups. There was increasing connectivity with increasing load for adolescents. The second network demonstrated age-related differences between children and older adolescents. Children have higher task-related connectivity at lower loads, but they tend to equalize with the adolescents with higher loads. Finally, a non-load related network involving the orbital frontal and anterior cingulate cortices showed less connectivity in children.