Age-dependent relationships between prefrontal cortex activation and processing efficiency

Functional magnetic resonance imaging (fMRI) was used in the present study to examine the neural basis for agerelated differences in processing efficiency, particularly targeting prefrontal cortex (PFC). During scanning, older and younger participants completed a processing efficiency task in which they determined on each trial whether a symbol-number pair appeared in a simultaneously presented array of nine symbol-number pairs. Estimates of task-related blood-oxygen-level-dependent (BOLD) signal-change were obtained for each participant. These estimates were then correlated with the participants' performance on the task. For younger participants, BOLD signalchange within PFC decreased with better performance, but for older participants, BOLD signal-change within PFC increased with better performance. The results support the hypothesis that the availability and use of PFC resources mediate age-related changes in processing efficiency.