Impulsive behavior during adolescence may stem from developmental imbalances between motivational and cognitive-control systems, producing greater urges to pursue reward and weakened capacities to inhibit such actions. Here, we developed a Pavlovian-instrumental transfer (PIT) protocol to assay rats’ ability to suppress cue-motivated reward seeking based on changes in reward expectancy. Traditionally, PIT studies focus on how reward-predictive cues motivate instrumental reward-seeking behavior (lever pressing). However, cues signaling imminent reward delivery also elicit countervailing focal-search responses (food-port entry). We first examined how reward expectancy (cue-reward probability) influences expression of these competing behaviors. Adult male rats increased rates of lever pressing when presented with cues signaling lower probabilities of reward but focused their activity at the food cup on trials with cues that signaled higher probabilities of reward. We then compared adolescent and adult male rats in their responsivity to cues signaling different reward probabilities. In contrast to adults, adolescent rats did not flexibly adjust patterns of responding based on the expected likelihood of reward delivery but increased their rate of lever pressing for both weak and strong cues. These findings indicate that control over cue-motivated behavior is fundamentally dysregulated during adolescence, providing a model for studying neurobiological mechanisms of adolescent impulsivity.

青春期的冲动行为可能源于动机和认知控制系统之间的发育不平衡，产生更大的追求奖励的冲动，并削弱了抑制此类行为的能力。在这里，我们开发了一种巴甫洛夫工具转移（PIT）方案来分析大鼠根据奖励预期的变化抑制线索驱动的奖励寻求的能力。传统上，PIT 研究的重点是奖励预测线索如何激发工具性寻求奖励的行为（按下杠杆）。然而，暗示即将发放奖励的线索也会引发相反的焦点搜索反应（进入食品港）。我们首先研究了奖励预期（提示奖励概率）如何影响这些竞争行为的表达。当出现表明奖励概率较低的线索时，成年雄性大鼠会增加按下杠杆的频率，但在出现表明奖励概率较高的线索时，它们将活动集中在食物杯上。然后，我们比较了青少年和成年雄性大鼠对不同奖励概率信号的反应。与成年人相比，青少年老鼠并没有根据预期的奖励提供可能性灵活地调整反应模式，而是增加了对弱和强线索的杠杆按下率。这些发现表明，青春期期间对线索驱动行为的控制从根本上失调，为研究青少年冲动的神经生物学机制提供了模型。