It is, by now, axiomatic, that there is a developmental increase in performance on episodic or explicit tests of memory, such as free recall, cued recall, and recognition, tests which require conscious access to previously experienced events. However, the causes of improvement in episodic memory remain elusive. This proposal's major aim, therefore, is to test the hypothesis that alterations in executive, or cognitive control processes, presumably mediated by the prefrontal cortex, can explain at least some of the improvement in memory function throughout the childhood years. ERP, EEG, and behavioral data will be obtained from children (9-11), adolescents (14-16) and young adults (20-30) during a series of working and episodic memory tasks and independent assessments of executive processing. The first experiment is aimed at determining the physiological correlates of developmental improvements in working memory during n-back tasks, which have a strong prefrontally based executive component. The second experiment assesses differences in source and item memory (i.e., recollection- and familiarity-based, respectively) to test the hypothesis that familiarity-based processes are in place before recollection-based processes. The third experiment uses the directed forgetting paradigm to assess the effect of inhibitory control on episodic memory performance and whether knowledge of source information can overcome the younger child's difficulty in inhibiting the retrieval of no longer relevant mnemonic information. The independent executive tasks, which will be administered to all subjects, assess working memory spans, the ability to task switch, the ability to ignore task-irrelevant flankers, and verbal and category fluency, all quintessential, prefrontally based tasks that tap cognitive control mechanisms. ERPs will be recorded from 62 scalp sites to enable good spatial resolution for current source density and EEG coherence analyses. The latter will enable a better understanding of the possible developmental changes in the neural networks underpinning episodic memory performance. The data will be relevant to developmental improvements in cognitive control mechanisms, prefrontal functioning, and episodic memory, and their physiological underpinnings.
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