Veterans Affairs San Diego Healthcare System, San Diego, CA 92161;
Department of Psychiatry, University of California San Diego, La Jolla, CA 92093.
Proc Natl Acad Sci U S A. 2021 May 11;118(19). doi: 10.1073/pnas.2104072118.
A degraded, black-and-white image of an object, which appears meaningless on first presentation, is easily identified after a single exposure to the original, intact image. This striking example of perceptual learning reflects a rapid (one-trial) change in performance, but the kind of learning that is involved is not known. We asked whether this learning depends on conscious (hippocampus-dependent) memory for the images that have been presented or on an unconscious (hippocampus-independent) change in the perception of images, independently of the ability to remember them. We tested five memory-impaired patients with hippocampal lesions or larger medial temporal lobe (MTL) lesions. In comparison to volunteers, the patients were fully intact at perceptual learning, and their improvement persisted without decrement from 1 d to more than 5 mo. Yet, the patients were impaired at remembering the test format and, even after 1 d, were impaired at remembering the images themselves. To compare perceptual learning and remembering directly, at 7 d after seeing degraded images and their solutions, patients and volunteers took either a naming test or a recognition memory test with these images. The patients improved as much as the volunteers at identifying the degraded images but were severely impaired at remembering them. Notably, the patient with the most severe memory impairment and the largest MTL lesions performed worse than the other patients on the memory tests but was the best at perceptual learning. The findings show that one-trial, long-lasting perceptual learning relies on hippocampus-independent (nondeclarative) memory, independent of any requirement to consciously remember.
一个对象的退化的、黑白的图像，在首次呈现时似乎毫无意义，但在单一暴露于原始完整图像后，很容易被识别。这种引人注目的感知学习的例子反映了一种快速（一次试验）的性能变化，但所涉及的学习类型尚不清楚。我们想知道这种学习是否依赖于对呈现的图像的有意识（海马体依赖的）记忆，或者依赖于对图像的无意识（海马体独立的）感知变化，而与记住它们的能力无关。我们测试了五名患有海马体损伤或更大的内侧颞叶（MTL）损伤的记忆受损患者。与志愿者相比，这些患者在感知学习方面完全正常，他们的改善在 1 天到 5 个月以上的时间内持续，没有减退。然而，患者在记忆测试格式方面存在障碍，甚至在 1 天后，他们在记忆图像本身方面也存在障碍。为了直接比较感知学习和记忆，在看到退化图像及其解决方案 7 天后，患者和志愿者要么接受命名测试，要么接受这些图像的识别记忆测试。患者在识别退化图像方面的提高与志愿者一样多，但在记忆方面严重受损。值得注意的是，记忆障碍最严重、MTL 损伤最大的患者在记忆测试中的表现比其他患者差，但在感知学习方面表现最好。研究结果表明，一次试验、长期的感知学习依赖于海马体独立（非陈述性）的记忆，而不需要有意识地记住。
