Visual Neuroscience Laboratory, International School for Advanced Studies, 34136 Trieste, Italy.
J Neurosci. 2013 Apr 3;33(14):5939-56. doi: 10.1523/JNEUROSCI.3629-12.2013.
The ability to recognize objects despite substantial variation in their appearance (e.g., because of position or size changes) represents such a formidable computational feat that it is widely assumed to be unique to primates. Such an assumption has restricted the investigation of its neuronal underpinnings to primate studies, which allow only a limited range of experimental approaches. In recent years, the increasingly powerful array of optical and molecular tools that has become available in rodents has spurred a renewed interest for rodent models of visual functions. However, evidence of primate-like visual object processing in rodents is still very limited and controversial. Here we show that rats are capable of an advanced recognition strategy, which relies on extracting the most informative object features across the variety of viewing conditions the animals may face. Rat visual strategy was uncovered by applying an image masking method that revealed the features used by the animals to discriminate two objects across a range of sizes, positions, in-depth, and in-plane rotations. Noticeably, rat recognition relied on a combination of multiple features that were mostly preserved across the transformations the objects underwent, and largely overlapped with the features that a simulated ideal observer deemed optimal to accomplish the discrimination task. These results indicate that rats are able to process and efficiently use shape information, in a way that is largely tolerant to variation in object appearance. This suggests that their visual system may serve as a powerful model to study the neuronal substrates of object recognition.
尽管物体的外观存在很大差异（例如，由于位置或大小的变化），但能够识别物体的能力代表了如此艰巨的计算壮举，以至于人们普遍认为这是灵长类动物所独有的。这种假设将其神经元基础的研究限制在灵长类动物研究中，而灵长类动物研究只允许采用有限的实验方法。近年来，在啮齿动物中越来越强大的光学和分子工具阵列激发了人们对视觉功能的啮齿动物模型的重新兴趣。然而，啮齿动物中类似于灵长类的视觉物体处理的证据仍然非常有限且存在争议。在这里，我们表明老鼠能够采用一种先进的识别策略，该策略依赖于提取在动物可能面临的各种观察条件下最具信息量的物体特征。通过应用图像掩蔽方法揭示了动物在一系列大小、位置、深度和平面旋转中区分两个物体所使用的特征，从而揭示了老鼠的视觉策略。值得注意的是，老鼠的识别依赖于多种特征的组合，这些特征在物体经历的变换中大部分得到保留，并且与模拟理想观察者认为完成识别任务的最佳特征基本重叠。这些结果表明，老鼠能够以对物体外观变化具有很大容忍度的方式处理和有效地利用形状信息。这表明它们的视觉系统可能成为研究物体识别的神经元基础的有力模型。
