From affective value to decision-making in the prefrontal cortex.

Representing the affective value of a reward on a continuous scale may occur separately from making a binary, for example yes vs no, decision about whether to choose the reward. To investigate whether these are separable processes, we used functional magnetic resonance imaging to measure activations produced by pleasant warm, unpleasant cold, and affectively complex combinations of these stimuli applied to the hand. On some trials the affective value was rated on a continuous scale, and on different trials a yes-no decision was made about whether the stimulus should be repeated in future. Decision-making contrasted with just rating the affective stimuli revealed activations in the medial prefrontal cortex area 10, implicating this area in binary decision-making. Activations related to the pleasantness ratings and which were not influenced when a binary decision was made were found in the pregenual cingulate and parts of the orbitofrontal cortex, implicating these regions in the continuous representation of affective value. When a decision was yes vs. no, effects were found in the dorsal cingulate cortex, agranular (anterior) insula and ventral tegmental area, implicating these areas in initiating actions to obtain goals.