Does Cue Focality Modulate Age-related Performance in Prospective Memory? An fMRI Investigation

How prospective memory (PM) weakens with increasing age has been largely debated. We hypothesized that automatic and strategic PM processes, respectively mediated by focal and non-focal cues, are differently affected by aging, even starting from 50-60 years of age. We investigated this issue using a 2 x 2 design in which focal and non-focal experimental conditions were created by varying the conjoint nature of the ongoing task (lexical decision vs. syllable matching tasks) and the PM cue (words vs. syllables). In the whole-brain analysis we found that the left inferior frontal gyrus and the middle cingulate cortex were more activated when young compared to older individuals performed a PM task; moreover, the anterior cingulate cortex was selectively activated during non-focal PM when the cues were words. In a region-of-interest analysis we observed that the medial and the lateral portions of the rostral prefrontal cortex were associated with the focal and non-focal conditions respectively, more in young than in older adults. Our findings provide evidence in support of early age-related differences in automatic/strategic PM functioning.