Temporal costs influence reward-based decisions. This is commonly studied in temporal discounting tasks that involve choosing between cues signaling an imminent reward option or a delayed reward option. However, it is unclear whether the temporal delay before a reward can alter the value of that option. To address this, we identified the relative preference between different flavored rewards during a free-feeding test using male and female rats. Animals underwent training where either the initial preferred or the initial less preferred reward was delivered noncontingently. By manipulating the intertrial interval during training sessions, we could determine whether temporal delays impact reward preference in a subsequent free-feeding test. Rats maintained their initial preference if the same delays were used across all training sessions. When the initial less preferred option was delivered after short delays (high reward rate) and the initial preferred option was delivered after long delays (low reward rate), rats expectedly increased their preference for the initial less desirable option. However, rats also increased their preference for the initial less desirable option under the opposite training contingencies: delivering the initial less preferred reward after long delays and the initial preferred reward after short delays. These data suggest that sunk temporal costs enhance the preference for a less desirable reward option. Pharmacological and lesion experiments were performed to identify the neural systems responsible for this behavioral phenomenon. Our findings demonstrate the basolateral amygdala and retrosplenial cortex are required for temporal delays to enhance the preference for an initially less desirable reward.

SIGNIFICANCE STATEMENT The goal of this study was to determine how temporal delays influence reward preference. We demonstrate that delivering an initially less desirable reward after long delays subsequently increases the consumption and preference for that reward. Furthermore, we identified the basolateral amygdala and the retrosplenial cortex as essential nuclei for mediating the change in reward preference elicited by sunk temporal costs.

时间成本影响基于奖励的决策。这通常在时间折扣任务中进行研究，这些任务涉及在提示即将奖励选项或延迟奖励选项的提示之间进行选择。然而，目前尚不清楚奖励之前的时间延迟是否会改变该选项的价值。为了解决这个问题，我们在使用雄性和雌性大鼠的自由喂养测试中确定了不同口味奖励之间的相对偏好。动物接受了训练，其中最初首选或最初不太喜欢的奖励是非偶然地提供的。通过在训练期间操纵试验间隔，我们可以确定时间延迟是否会影响后续自由喂养测试中的奖励偏好。如果在所有训练课程中使用相同的延迟，大鼠将保持其最初的偏好。当最初的不太喜欢的选项在短时间延迟（高奖励率）后交付，而最初的首选选项在长时间延迟（低奖励率）后交付时，老鼠预期会增加他们对最初不太理想的选项的偏好。然而，在相反的训练意外情况下，大鼠也增加了对最初不太理想的选择的偏好：在长时间延迟后提供最初不太喜欢的奖励，在短时间延迟后提供最初的首选奖励。这些数据表明沉没的时间成本增强了对不太理想的奖励选项的偏好。进行了药理学和损伤实验，以确定导致这种行为现象的神经系统。

重要性陈述本研究的目的是确定时间延迟如何影响奖励偏好。我们证明，在长时间延迟后提供最初不太理想的奖励会增加对该奖励的消费和偏好。此外，我们将基底外侧杏仁核和脾后皮层确定为调节沉没时间成本引起的奖励偏好变化的重要细胞核。