Reward expectation alters learning and memory: the impact of the amygdala on appetitive-driven behaviors.

The capacity to seek and obtain rewards is essential for survival. Pavlovian conditioning is one mechanism by which organisms develop predictions about rewards and such anticipatory or expectancy states enable successful behavioral adaptations to environmental demands. Reward expectancies have both affective/motivational and discriminative properties that allow for the modulation of instrumental goal-directed behavior. Recent data provide evidence that different cognitive strategies (cue-outcome associations) and neural systems (amygdala) are used when subjects are trained under conditions that allow Pavlovian-induced reward expectancies to guide instrumental behavioral choices. Furthermore, it has been demonstrated that impairments typically observed in a number of brain-damaged models are alleviated or eliminated by embedding unique reward expectancies into learning/memory tasks. These results suggest that Pavlovian-induced reward expectancies can change both behavioral and brain processes.