1 Department of Psychological and Brain Sciences, Boston University.
2 Center for Systems Neuroscience, Boston University.
Psychol Sci. 2018 May;29(5):845-856. doi: 10.1177/0956797617747091. Epub 2018 Mar 29.
How distinct are visual memory representations from visual perception? Although evidence suggests that briefly remembered stimuli are represented within early visual cortices, the degree to which these memory traces resemble true visual representations remains something of a mystery. Here, we tested whether both visual memory and perception succumb to a seemingly ubiquitous neural computation: normalization. Observers were asked to remember the contrast of visual stimuli, which were pitted against each other to promote normalization either in perception or in visual memory. Our results revealed robust normalization between visual representations in perception, yet no signature of normalization occurring between working memory stores-neither between representations in memory nor between memory representations and visual inputs. These results provide unique insight into the nature of visual memory representations, illustrating that visual memory representations follow a different set of computational rules, bypassing normalization, a canonical visual computation.
视觉记忆表征与视觉感知有何不同？尽管有证据表明，短暂记忆的刺激会在早期视觉皮层中得到表示，但这些记忆痕迹与真实视觉表示的相似程度仍然是一个谜。在这里，我们测试了视觉记忆和感知是否都受到一种看似普遍的神经计算的影响：归一化。要求观察者记住视觉刺激的对比度，这些刺激相互竞争，以促进感知或视觉记忆中的归一化。我们的结果显示，在感知中，视觉表示之间存在强大的归一化，但在工作记忆存储中没有归一化的特征——无论是在记忆中的表示之间，还是在记忆表示和视觉输入之间。这些结果为视觉记忆表示的本质提供了独特的见解，表明视觉记忆表示遵循一组不同的计算规则，绕过了归一化，这是一种典型的视觉计算。
