Neural activity patterns reinstatement, healthy aging, and memory for change in everyday activities

When encountering new events, memories of relevant past experiences can guide expectations about what will happen. When unexpected changes occur, this can lead to prediction errors with consequences for comprehension and subsequent memory. Current models of memory updating propose that people must first detect and register that features of the environment have changed, then encode the new event features and integrate them with relevant memories of past experiences to form configural memory representations. Aging could potentially impair each of these steps. Using fMRI pattern analysis, we investigated these mechanisms in healthy young and older adults. In the scanner, participants first saw a movie depicting a series of everyday events, as if following a day in the life of the actor. Later, they watched another movie of the day’s events where some scenes proceeded exactly as before, while others began similarly and then ended with a slightly different activity. Crucially, before watching the last part of each scene, the movie stopped, and participants were instructed to mentally replay its ending based on the previous movie. Three days later, participants were asked to retrieve the activity details. Individual differences in neural activity pattern reinstatement in posterior default network areas during mental replay were associated with better memory for changed features in young adults. This association was weaker in the older adults. This finding suggests posterior DN areas contribute to memory for changes by reinstating previous event features and that older adults are less able to use reinstatement to perform memory updating.