Animal responses were registered at two lateralized water spouts (situated at the arena periphery at a bearing of ±30° relative to center), with correct responses rewarded by a fixed amount of water.
Following the response, reward feedback was provided.
For this reason, we used a task that allowed for the dissociation of responses during reward selection, reward anticipation, and reward outcome phases of reward responding.
Still, their direct, instantaneous response rewards, and so encourages, exploration and persistence.
Because successful performance on acquisition of a new response for conditioned reinforcement does not depend on inhibition of established response-reward associations, we hypothesized that DA, rather than 5-HT depletions of the OFC would disrupt responding for conditioned reinforcement.
Second, the magnitudes of responses following reward delivery covaried with the instantaneous reward probabilities, reflecting the influence of temporal reward structures at the moment of reward delivery.
We investigated the coding of marginal utility by dopamine responses to reward prediction errors, defined as reward − prediction.
Elevated responses to reward could presumably reflect higher subjective values of the reward, and this interpretation is consistent with the biological needs of an animal.
To examine age differences in neural responses during reward learning (even in the face of preserved responses to reward outcomes), 39 healthy adults of varying ages (age range 22 85) completed a probabilistic-learning task while undergoing fMRI.
These data suggest that temporal delays affect dopamine responses to reward predicting stimuli in a similar manner as they affect subjective reward value assessed by intertemporal choices.
