Looking to the future: automatic regulation of attention between current performance and future plans.

We investigated neuro-cognitive mechanisms involved with coordination of attention between current task performance and future action plans in prospective memory. We developed a novel task paradigm with continuous performance of a prospective memory task, where trial intervals of prospective memory targets were systematically manipulated in a periodic cycle of expanding and contracting target intervals. We found that subjects' behaviour was significantly modulated without awareness of this temporal sequence of the targets: remembering to perform a prospective memory response to target events was more successful and faster in the expanding target interval phase, at the cost of lower and slower performance of ongoing tasks, while an opposite direction of this trade-off effect was observed in the contracting target interval phase. By using functional magnetic resonance imaging (fMRI), we identified the similar trade-off effect in activations in the anterior medial prefrontal cortices (activation elevation at the target responses as well as deactivation at the ongoing responses in the expanding phase as compared with the contracting phase). The opposite direction of the trade-off was observed in the anterior cingulate cortex. These results show a clear case in which attention between current task performance and future action plans in prospective memory tasks is automatically regulated without particular task instructions or strategic control processes initiated by subjects. We suggest that medial areas of the frontal cortex specifically mediate the automatic coordination of attentional resources between current task performance and future action plans.