The average firing rates for three example units (recorded during control sessions) are plotted, with activity aligned to outcome delivery. The plots show the unit’s average firing rate for each of eight possible outcomes animals selected on forced-choice trials. The shaded region indicates the reward anticipation task epoch. The unit on the left discriminated the size of outcomes; dashed lines group all trials types in which the animal selected the large reward outcome, and solid lines indicate trial types when the rat selected the small outcome. Note that neurons can encode outcome size information with either increases or decreases in firing rate. The unit in the middle discriminated outcome flavor, firing more for trials in which chocolate was selected (solid lines) than trials in which vanilla (dashed lines) was chosen. The unit on the right distinguished response direction, firing faster when the animal chose the right fluid well (solid lines) than when it selected the left fluid well (dashed lines). The bin size used to compute firing rate was 45 ms. Outcome abbreviations: LLV = left, large, vanilla; LLC = left, large, chocolate; LSV = left, small, vanilla; LSC = left, small, chocolate; RLV = right, large, vanilla; RLC = right, large, chocolate; RSV = right, small, vanilla; RSC = right, small, chocolate.