Data from Time-dependent latent inhibition of predator-recognition learning

To optimally manage an environment with predators, prey must correctly distinguish between cues that are risky and cues that are safe. Even a specific cue that is safe in one area or at a certain time may be dangerous in other situations, and vice versa. Latent inhibition is a cognitive mechanism by which animals fail to learn a stimulus as risky because they have already learned it as non-threatening via previous encounters with the stimulus in the absence of negative consequences. Here, we demonstrate that latent inhibition of predator-recognition learning in wood frog tadpoles, <i>Lithobates sylvaticus</i>, depends on the timing of their learning opportunities. For 6 days, tadpoles were exposed daily to an initially novel stimulus (salamander odour), either in the morning (11.00–13.00 h) or evening (16.00–18.00 h). The following day, we conditioned tadpoles to recognize the salamander odour as a predator by pairing it with injured tadpole cues, either at the same time as their previous experience or at the opposite time. When tested the following day, latent inhibition occurred under each scenario where the timing of conditioning matched the timing of the pre-exposure. However, tadpoles tested in the morning showed learned fright responses when conditioned in the morning if their pre-exposure had occurred in the evening, whereas individuals tested in the evening showed learned fright responses when conditioned in the evening if their pre-exposure had occurred in the morning. This is the first report of time-dependent latent inhibition of predator-recognition learning, which is likely an important mechanism for correctly managing predation risk and safety.

为最优管理存在捕食者的环境，猎物需准确区分风险线索与安全线索。即便某一特定线索在某一区域或特定时段安全，在其他情境下也可能变得危险，反之亦然。潜伏抑制（latent inhibition）是一种认知机制，指动物因此前在无负面后果的情况下接触过某一刺激，已将其认知为无威胁，因此无法再将该刺激学习为风险线索。本研究证实，林蛙蝌蚪（*Lithobates sylvaticus*）的捕食识别学习潜伏抑制，取决于其学习机会的时机。研究人员将蝌蚪每日暴露于初始陌生的刺激（蝾螈气味）中，持续6天，暴露时段分为晨间（11:00–13:00）与晚间（16:00–18:00）两组。次日，研究人员通过将该蝾螈气味与受伤蝌蚪线索配对，对蝌蚪进行捕食识别条件化训练，训练时机要么与此前的暴露时段一致，要么相反。次日开展测试时，当条件化训练的时机与预暴露时机相匹配时，两组蝌蚪均出现了潜伏抑制效应。不过，晨间接受测试的蝌蚪，若此前预暴露发生在晚间，则在晨间条件化训练后会表现出习得的惊恐反应；而晚间接受测试的蝌蚪，若此前预暴露发生在晨间，则在晚间条件化训练后会表现出习得的惊恐反应。本研究首次报道了捕食识别学习的时间依赖性潜伏抑制，该机制可能是猎物准确权衡捕食风险与安全的重要生理基础。