National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA.
National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA.
Curr Biol. 2021 Jun 21;31(12):2652-2657.e3. doi: 10.1016/j.cub.2021.03.045. Epub 2021 Apr 12.
Animals learn not only what is potentially useful but also what is meaningless and should be disregarded. How this is accomplished is a key but seldom explored question in psychology and neuroscience. Learning to ignore irrelevant cues is evident in latent inhibition-the ubiquitous phenomenon where presenting a cue several times without consequences leads to retardation of subsequent conditioning to that cue. Does learning to ignore these cues, because they predict nothing, involve the same neural circuits that are critical to learning to make predictions about other "real world" impending events? If so, the orbitofrontal cortex (OFC), as a key node in such networks, should be important. Specifically, the OFC has been hypothesized to participate in the recognition of hidden task states, which are not directly signaled by explicit outcomes. Evaluating its involvement in pre-exposure learning during latent inhibition would be an acid test for this hypothesis. Here, we report that selective chemogenetic inactivation of rat orbitofrontal cortex principal neurons during stimulus pre-exposure markedly reduces latent inhibition in subsequent conditioning. Inactivation only during pre-exposure ensured that the observed effects were due to an impact on the acquisition of information prior to its use in any sort of behavior, i.e., during latent learning. Further behavioral tests confirmed this, showing that the impact of OFC inactivation during pre-exposure was limited to the latent inhibition effect. These results demonstrate that the OFC is important for latent learning and the formation of associations even in the absence of explicit outcomes.
动物不仅可以学习潜在有用的东西，还可以学习那些无意义且应该被忽视的东西。这是心理学和神经科学中一个关键但很少被探索的问题。在潜伏抑制中可以明显观察到这种学习忽略不相关线索的能力，即呈现线索多次而没有后果会导致随后对该线索的条件反射减缓。学习忽略这些线索，因为它们什么也预测不到，是否涉及到对其他“现实世界”即将发生的事件进行预测的关键神经回路？如果是这样，眶额皮层（OFC）作为这些网络中的关键节点，应该很重要。具体来说，OFC 被假设参与识别隐藏的任务状态，这些状态不是由明确的结果直接信号传递的。评估其在潜伏抑制前暴露学习中的参与度将是对该假设的一个严峻考验。在这里，我们报告说，在刺激前暴露期间选择性地化学遗传学失活大鼠眶额皮层主神经元会显著减少随后的条件反射中的潜伏抑制。仅在前暴露期间失活可以确保观察到的效果是由于在任何行为之前获取信息之前对信息的获取产生了影响，即在潜伏学习期间。进一步的行为测试证实了这一点，表明在潜伏期暴露期间 OFC 失活的影响仅限于潜伏抑制效应。这些结果表明，即使没有明确的结果，OFC 对于潜伏学习和联想的形成也很重要。
