Medio-lateral functional dissociation of the rostral prefrontal cortex with focal/non-focal cues during a prospective memory task.

The rostral prefrontal cortex (rPFC) is crucial in prospective memory (PM) behavior. Several functional magnetic resonance imaging studies showed that its medial (mrPFC) and lateral (lrPFC) portions dissociate during PM tasks. In light of the Multiprocess theory (McDaniel and Einstein 2000), here we tested whether the two portions of the rPFC are dissociable by modulating strategic vs. spontaneous processes during a PM task. We investigated these two processes by means of a 2 × 2 experimental design in which focal vs. non-focal conditions were modulated by varying the conjoint nature of the ongoing task (i.e., lexical decision vs. syllable matching) and the PM cue (words vs. syllables). Using the two portions of the rPFC as regions of interest, we found an effect of the non-focal condition in the lrPFC and, conversely, an effect of the focal condition in the mrPFC. In the whole-brain analysis we found an effect of the non-focal condition in the bilateral intraparietal sulcus, the bilateral middle frontal gyrus, the supplementary motor areas and the vermis of the cerebellum, whereas we found an effect of the focal condition in the ventromedial PFC. Overall, our results show that different brain regions are involved when multiple processes underlying PM behavior are modulated.