When making a turn at a familiar intersection, we know what items and landmarks will come into view. These perceptual expectations, or predictions, come from our knowledge of the context; however, it is unclear how memory and perceptual systems interact to support the prediction and reactivation of sensory details in cortex. To address this, human participants learned the spatial layout of animals positioned in a cross maze. During fMRI, participants of both sexes navigated between animals to reach a target, and in the process saw a predictable sequence of five animal images. Critically, to isolate activity patterns related to item predictions, rather than bottom-up inputs, one-fourth of trials ended early, with a blank screen presented instead. Using multivariate pattern similarity analysis, we reveal that activity patterns in early visual cortex, posterior medial regions, and the posterior hippocampus showed greater similarity when seeing the same item compared with different items. Further, item effects in posterior hippocampus were specific to the sequence context. Critically, activity patterns associated with seeing an item in visual cortex and posterior medial cortex, were also related to activity patterns when an item was expected, but omitted, suggesting sequence predictions were reinstated in these regions. Finally, multivariate connectivity showed that patterns in the posterior hippocampus at one position in the sequence were related to patterns in early visual cortex and posterior medial cortex at a later position. Together, our results support the idea that hippocampal representations facilitate sensory processing by modulating visual cortical activity in anticipation of expected items.

SIGNIFICANCE STATEMENT Our visual world is a series of connected events, where we can predict what we might see next based on our recent past. Understanding the neural circuitry and mechanisms of the perceptual and memory systems that support these expectations is fundamental to revealing how we perceive and act in our world. Using brain imaging, we studied what happens when we expect to see specific visual items, and how such expectations relate to top-down memory signals. We find both visual and memory systems reflect item predictions, and moreover, we show that hippocampal activity supports predictions of future expected items. This demonstrates that the hippocampus acts to predict upcoming items, and reinstates such predictions in cortex.

当在熟悉的十字路口转弯时，我们知道会看到哪些物品和地标。这些感知期望或预测来自我们对上下文的了解；然而，目前尚不清楚记忆和感知系统如何相互作用以支持皮层感觉细节的预测和重新激活。为了解决这个问题，人类参与者学习了位于十字迷宫中的动物的空间布局。在功能磁共振成像期间，男女参与者在动物之间导航以到达目标，并在此过程中看到了可预测的五张动物图像序列。至关重要的是，为了隔离与项目预测相关的活动模式，而不是自下而上的输入，四分之一的试验提前结束，取而代之的是空白屏幕。通过多变量模式相似性分析，我们发现，与不同项目相比，看到相同项目时，早期视觉皮层、后内侧区域和后海马的活动模式表现出更大的相似性。此外，后海马体中的项目效应特定于序列背景。至关重要的是，与视觉皮层和后内侧皮层中看到某个项目相关的活动模式也与预期某个项目但被忽略时的活动模式相关，这表明序列预测在这些区域中得到了恢复。最后，多变量连通性表明，序列中某一位置的后海马体模式与较晚位置的早期视觉皮层和后内侧皮层的模式相关。总之，我们的结果支持这样的观点：海马表征通过调节视觉皮层活动来预测预期项目，从而促进感觉处理。

意义声明我们的视觉世界是一系列相互关联的事件，我们可以根据最近的过去来预测我们接下来可能会看到什么。了解支持这些期望的感知和记忆系统的神经回路和机制对于揭示我们如何在世界中感知和行动至关重要。利用大脑成像，我们研究了当我们期望看到特定的视觉项目时会发生什么，以及这种期望与自上而下的记忆信号之间的关系。我们发现视觉和记忆系统都反映了项目预测，此外，我们表明海马活动支持对未来预期项目的预测。这表明海马体可以预测即将发生的事情，并在皮层中恢复这种预测。