Princeton Neuroscience Institute and Department of Psychology, Princeton University, Princeton, New Jersey 08544 and
Department of Psychology, Yale University, New Haven, Connecticut 06520.
J Neurosci. 2018 Aug 1;38(31):6888-6899. doi: 10.1523/JNEUROSCI.0163-18.2018. Epub 2018 Jul 9.
Perception can be cast as a process of inference, in which bottom-up signals are combined with top-down predictions in sensory systems. In line with this, neural activity in sensory cortex is strongly modulated by prior expectations. Such top-down predictions often arise from cross-modal associations, such as when a sound (e.g., bell or bark) leads to an expectation of the visual appearance of the corresponding object (e.g., bicycle or dog). We hypothesized that the hippocampus, which rapidly learns arbitrary relationships between stimuli over space and time, may be involved in forming such associative predictions. We exposed male and female human participants to auditory cues predicting visual shapes, while measuring high-resolution fMRI signals in visual cortex and the hippocampus. Using multivariate reconstruction methods, we discovered a dissociation between these regions: representations in visual cortex were dominated by whichever shape was presented, whereas representations in the hippocampus reflected only which shape was predicted by the cue. The strength of hippocampal predictions correlated across participants with the amount of expectation-related facilitation in visual cortex. These findings help bridge the gap between memory and sensory systems in the human brain. The way we perceive the world is to a great extent determined by our prior knowledge. Despite this intimate link between perception and memory, these two aspects of cognition have mostly been studied in isolation. Here we investigate their interaction by asking how memory systems that encode and retrieve associations can inform perception. We find that upon hearing a familiar auditory cue, the hippocampus represents visual information that had previously co-occurred with the cue, even when this expectation differs from what is currently visible. Furthermore, the strength of this hippocampal expectation correlates with facilitation of perceptual processing in visual cortex. These findings help bridge the gap between memory and sensory systems in the human brain.
感知可以被视为一种推理过程，在这个过程中，来自底部的信号与来自顶部的预测在感觉系统中结合在一起。与此一致的是，感觉皮层中的神经活动受到先前期望的强烈调节。这种自上而下的预测通常来自跨模态关联，例如，当一个声音（例如，钟声或狗叫声）引起对相应物体的视觉外观的期望（例如，自行车或狗）。我们假设，海马体，它可以快速学习空间和时间上刺激之间的任意关系，可能参与形成这种联想预测。我们让男性和女性人类参与者接触预测视觉形状的听觉线索，同时测量视觉皮层和海马体的高分辨率 fMRI 信号。使用多元重建方法，我们发现这些区域之间存在差异：视觉皮层中的表示主要取决于呈现的形状，而海马体中的表示仅反映了线索预测的形状。海马体预测的强度与视觉皮层中与期望相关的促进作用的量在参与者之间相关。这些发现有助于弥合人类大脑中记忆和感觉系统之间的差距。我们感知世界的方式在很大程度上取决于我们的先验知识。尽管感知和记忆之间存在这种密切联系，但这两个认知方面在很大程度上是分开研究的。在这里，我们通过询问编码和检索关联的记忆系统如何为感知提供信息来研究它们的相互作用。我们发现，当听到熟悉的听觉线索时，即使与当前可见的内容不同，海马体也会表示先前与该线索共同出现的视觉信息。此外，这种海马体预期的强度与视觉皮层中感知处理的促进作用相关。这些发现有助于弥合人类大脑中记忆和感觉系统之间的差距。
