Episodic memory and event construction in aging and amnesia

Construction of imaginative or fictitious events requires the flexible recombination of stored information into novel representations. How this process is accomplished is not understood fully. To address this problem, older adults (mean age = 74.2; Experiment 1) and younger patients with MTL lesions (mean age = 54.2; Experiment 2), both of whom have deficient LTM compared to their respective controls, were given a setting (e.g. jungle) and 3–6 words (e.g. tiger, tree, snake) and asked to imagine an event in that setting by relating the words to each other. Both older adults and patients showed deficits in forming coherent mental representations relative to younger adult and healthy control groups, respectively. Moreover, the ability to form coherent events was associated with subsequent memory for the items. These findings suggest that deficits in LTM, or processes mediating it, are one factor that affects event construction, which in turn leads to poorer encoding and/or retention of the studied materials. These results have implications for theories of the cognitive processes underlying the construction of imaginative events in the laboratory and everyday life.

► LTM encoding and retention are invoked during the construction of imagined events.
► The coherence of an imagined event affects later memory of that imagined event.
► These processes are dependent on the medial temporal lobes.
► Such a dynamic mechanism may underlie how memory systems are utilized in service of prospective actions/decisions.