Reward-predicting and reward-detecting neuronal activity in the primate supplementary eye field

In addition to cells specifically active with visual stimuli, saccades, or fixation, the supplementary eye field contains cells that fire in precise t emporal relationship with the occurrence of reward. We studied reward-relat ed activity in two monkeys performing a prosaccade/antisaccade task and in one monkey trained in memory prosaccades only. Two types of neurons were di stinguished by their reciprocal firing pattern: reward-predicting (RP) and reward-detecting (RD). RP neurons linearly increased their firing as early as 150 ms before saccade onset until the occurrence of reward, at which tim e they abruptly ceased firing. In contrast, RD neurons fired in phase with reward delivery, even when its duration was varied and when it was repeated at different frequencies. RD discharges were little affected or unaffected by the position of a visual cue that briefly anchored the goal at the onse t of reward. The complementary firing patterns of the RP and RD neurons cou ld provide a feedback mechanism necessary for learning and performing the t ask.