Probing the role of reward expectancy in Pavlovian-instrumental transfer

Abstract

Reward-paired cues acquire motivational properties which allow them to invigorate instrumental reward-seeking behavior — termed Pavlovian-instrumental transfer. Somewhat surprisingly, this motivational influence is greatest for cues that serve as unreliable or otherwise weak predictors of reward. In this review, we delve into the ongoing debate about why weak and strong reward-predictive cues differ in their motivational effects. We outline evidence that, when presented with a strong reward predictor, rats exert cognitive control over their motivation to seek out new rewards to allow for efficient reward retrieval, an effect modulated by the expected probability, timing, and magnitude of reward. We also review recent research applying this approach to study how cue-motivated behavior becomes dysregulated in drug addiction and adolescent development.