Brain state before a memory probe and associative retrieval in older adults.

Older individuals' difficulty in remembering events from a particular time and place may be explained by changes in retrieval-related control processes. We investigated how aging affects neural activity leading up to a retrieval probe and how such activity relates to later performance. Electrical brain activity was recorded while healthy younger and older humans memorized visual word pairs consisting of an object word (e.g., doll) preceded by a location word (e.g., garden). Only object words were presented during the memory test, the task being to decide whether an object had been presented earlier and, if so, what location had been paired with it. A warning signal before each test probe alerted to an upcoming object. A sustained negative-going event-related potential deflection preceded objects whose associated location could be remembered, especially in older individuals. The poorer an older individual's associative memory, the bigger was this deflection. Aging thus seems accompanied by changes in anticipatory brain states that relate to recollection. Such states may serve to mobilize control processes that aid the recovery of contextual details.