Isolating the neural mechanisms of age-related changes in human working memory

Working memory (WM), the process by which information is coded into memory, actively maintained and subsequently retrieved, declines with age. To test the hypothesis that age-related changes in prefrontal cortex (PFC) may med iate this WM decline, we used functional MRI to investigate age differences in PFC activity during separate WM task components (encoding, maintenance, retrieval). We found greater PFC activity in younger than older adults onl y in dorsolateral PFC during memory retrieval. Fast younger subjects showed less dorsolateral PFC activation during retrieval than slow younger subjec ts, whereas older adults showed the opposite pattern. Thus age-related chan ges in dorsolateral PFC and not ventrolateral PFC account for WM decline wi th normal aging.