Top-down control of MEG alpha-band activity in children performing Categorical N-Back Task

Top-down cognitive control has been associated in adults with the prefrontal-parietal network. In children the brain mechanisms of top-down control have rarely been studied. We examined developmental differences in top-down cognitive control by monitoring event-related desynchronization (ERD) and event-related synchronization (ERS) of alpha-band oscillatory activity (8-13. Hz) during anticipation, target detection and post-response stages of a visual working memory task. Magnetoencephalography (MEG) was used to record brain oscillatory activity from healthy 10-year-old children and young adults performing the Categorical N-Back Task (CNBT). Neuropsychological measures assessing frontal lobe networks were also acquired. Whereas adults showed a modulation of the ERD at the anticipatory stages of CNBT and ERS at the post-response stage, children displayed only some anticipatory modulation of ERD but no ERS at the post-response stage, with alpha-band remaining at a desynchronized state. Since neuropsychological and prior neuroimaging findings indicate that the prefrontal-parietal networks are not fully developed in 10-year olds, and since the children performed as well as the adults on CNBT and yet displayed different patterns of ERD/ERS, we suggest that children may be using different top-down cognitive strategies and, hence, different, developmentally apt neuronal networks.