Figure 17.

Reward prediction error at the end of a trial. (A) Average reward prediction (TD) error at the end of correct trials for the 60% coherence case (left) and the 8% coherence case (right). The vertical line denotes the time of reward delivery. Right after reward delivery, TD error is larger for the 8% coherence case due to its smaller expected value (see Figure 13). (B) Population dopamine responses of SNc neurons in the same monkey as in Figure 16 but after the monkey has made a decision and a feedback tone indicating reward or no reward is presented. (Plots adapted from Nomoto et al., 2010). The black and red traces show dopamine response for correct and error trials respectively. The gray traces show the case where the amount of reward was reduced (see (Nomoto et al., 2010) for details). (C) Average reward prediction (TD) error at the end of error trials for the 60% coherence case (left) and the 8% coherence case (right). The absence of reward (or negative reward/penalty in the current model) causes a negative reward prediction error, with a slightly larger error for the higher coherence case due to its higher expected value (see Figure 13).