Post-mortem histological and in vivo neuroimaging findings both reveal frontal lobe development that extends beyond the adolescent years. Few studies have examined whether this protracted neurodevelopment coincides with improvements in adolescent performance on putative frontal lobe tasks. An instrumental function supported by the frontal lobes is working memory, the ability to maintain and manipulate information "online." This study investigated the performance of typically developing children and adolescents on a battery of working memory tasks. Findings revealed an improvement in performance on most working memory tasks across the adolescent years. In contrast, no improvement was observed on tasks largely supported by more posterior neural substrates. Current findings indicate a similar unfolding of the executive aspects of verbal working memory as previously demonstrated with spatial working memory. Factor analysis revealed a grouping of working memory tasks based largely on task demands, irrespective of working memory domain, adding support for process-specific models of prefrontal organization. Important implications for typical and atypical frontal lobe development are discussed.
Bibliographical noteFunding Information:
This study was supported by a McKnight Land Grant Professorship awarded to Monica M. Luciana and by the Center for Neurobehavioral Development at the University of Minnesota, Minneapolis. Portions of this article were presented at the International Neuropsychological Society Meeting in Baltimore, MD February 4–7, 2004. We thank Kristina Johnson and Kristin Sullwold for assistance with data collection and the parents and adolescents who volunteered their time to participate in the study.