Due to their unique characteristics, the zebrafish plays a key role in the comprehension of neurobiology of cognition and its pathologies, such as neurodegenerative diseases. More and more molecular tools for this aim are being developed, but our knowledge about the cognitive abilities of zebrafish remains extremely scarce compared to other teleost fish. We aimed to investigate the complex cognitive abilities of zebrafish using a tracking-based automated conditioning chamber that allowed precise experimental control, avoided potential cueing provided by the observer (Clever Hans phenomenon), and was shown to considerably improve learning in other teleosts. A computer presented two visual stimuli in two sectors of the chamber, and zebrafish had to enter the correct sector to obtain a food reward. Zebrafish quickly learned to use the conditioning device and easily performed up to 80 trials per day. In Experiment 1, zebrafish efficiently discriminated between two differently coloured sides, reaching a 75% accuracy in only 10 training sessions. Surprisingly, zebrafish failed to choose the correct chamber when the stimuli were two shapes, a small circle and a small triangle, even when, in Experiment 2, training on shape discrimination was prolonged for up to 30 sessions. In Experiment 3, we tested the hypothesis that simultaneously learning to use the conditioning chamber and learning discrimination imposes a too-high cognitive load. However, zebrafish that first successfully learned how the conditioning chamber functioned (in the colour discrimination) subsequently failed in the shape discrimination. Conversely, zebrafish that firstly failed the shape discrimination subsequently learned colour discrimination. In Experiment 4, zebrafish showed some evidence of learning when the stimuli were two large shapes, suggesting that zebrafish did not discriminate between the shapes of the previous experiments because they were not salient enough. Altogether, results suggest constraints in the discrimination learning abilities of zebrafish, which should be taken into account when developing cognitive tasks for this species.

中文翻译：

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细节决定成败：斑马鱼只有在突出的情况下才能学会区分视觉刺激

由于其独特的特性，斑马鱼在理解认知神经生物学及其病理学方面发挥着关键作用，例如神经退行性疾病。正在为此目的开发越来越多的分子工具，但与其他硬骨鱼相比，我们对斑马鱼认知能力的了解仍然极为匮乏。我们旨在使用基于跟踪的自动调节室来研究斑马鱼的复杂认知能力，该室允许精确的实验控制，避免观察者提供的潜在提示（聪明的汉斯现象），并被证明可以显着改善其他硬骨鱼的学习。一台计算机在房间的两个部分呈现两个视觉刺激，斑马鱼必须进入正确的部分才能获得食物奖励。斑马鱼很快学会了使用调节装置，并且每天轻松进行多达 80 次试验。在实验 1 中，斑马鱼有效区分了两个不同颜色的边，仅在 10 次训练中就达到了 75% 的准确率。令人惊讶的是，当刺激是两种形状时，斑马鱼未能选择正确的腔室，一个小圆圈和一个小三角形，即使在实验 2 中，形状辨别训练延长了 30 次。在实验 3 中，我们测试了这样一个假设，即同时学习使用调节室和学习辨别会带来过高的认知负荷。然而，首先成功了解调节室如何运作（在颜色辨别中）的斑马鱼随后在形状辨别中失败。反过来，最初未能通过形状辨别的斑马鱼随后学会了颜色辨别。在实验 4 中，当刺激是两个大的形状时，斑马鱼表现出一些学习的证据，这表明斑马鱼没有区分之前实验的形状，因为它们不够显着。总之，结果表明斑马鱼的辨别学习能力受到限制，在为该物种开发认知任务时应考虑到这一点。