Stimuli in our environment are not always associated with an outcome. Some of these stimuli, depending on how they are presented, may gain inhibitory value or simply be ignored. If experienced in the presence of other cues predictive of appetitive or aversive outcomes, they typically gain inhibitory value and become predictive cues indicating the absence of appetitive or aversive outcomes. In this case, these cues are referred to as conditioned inhibitors. Here, male and female Long Evans rats underwent cue discrimination training where a reward cue was paired with sucrose, a fear cue with footshock, and an inhibitor cue resulted in neither sucrose or footshock. During a subsequent summation test for conditioned inhibition of fear and reward, the inhibitor cue was presented concurrently with the reward and fear cues without any outcome, intermixed with trials of reinforced reward and fear trials. Males showed significant conditioned inhibition of freezing, while females did not, which was not dependent on estrous. Both males and females showed significant conditioned inhibition of reward. During a retardation of fear acquisition test, the inhibitor was paired with footshock and both males and females showed delayed acquisition of fear. During a retardation of reward acquisition test, the inhibitor was paired with sucrose, and females showed delayed acquisition of reward, while males did not. In summary, males and females showed significant reward-fear-inhibitor cue discrimination, conditioned inhibition of reward, and retardation of fear acquisition. The main sex difference, which was not estrous-dependent, was the lack of conditioned inhibition of freezing in females. These data imply that while the inhibitor cue gained some inhibitory value in the females, the strength of this inhibitory value may not have been great enough to effectively downregulate freezing elicited by the fear cue.

我们环境中的刺激并不总是与结果相关。其中一些刺激，取决于它们的呈现方式，可能会获得抑制价值或干脆被忽略。如果在存在预测食欲或厌恶结果的其他线索的情况下经历，它们通常会获得抑制价值并成为指示不存在食欲或厌恶结果的预测线索。在这种情况下，这些线索被称为条件抑制剂。在这里，雄性和雌性 Long Evans 大鼠接受了提示辨别训练，其中奖励提示与蔗糖配对，恐惧提示与足部电击配对，抑制剂提示既不导致蔗糖也不电击。在随后对恐惧和奖励的条件抑制的总结测试中，抑制剂线索与奖励和恐惧线索同时呈现，但没有任何结果，与强化奖励和恐惧试验混合在一起。雄性表现出显着的条件性冻结抑制，而雌性则没有，这不依赖于发情。男性和女性都表现出显着的奖赏条件抑制。在恐惧获得延迟测试中，抑制剂与足部电击配对，男性和女性都表现出恐惧获得延迟。在奖励获得延迟测试中，抑制剂与蔗糖配对，雌性表现出奖励获得延迟，而雄性则没有。总之，男性和女性表现出显着的奖赏-恐惧-抑制线索辨别、奖赏的条件性抑制和恐惧获得的延迟。主要的性别差异不依赖于发情期，而是雌性缺乏条件性冻结抑制。这些数据表明，虽然抑制剂线索在雌性中获得了一些抑制价值，但这种抑制价值的强度可能不足以有效地下调恐惧线索引起的冻结。