Hippocampal-guided reconstruction of an event's prior temporal context

Abstract

Leading theories of episodic memory argue that when events from the past are remembered, temporally-adjacent events are also reinstated ( temporal context reinstatement). However, direct evidence for temporal context reinstatement is surprisingly limited. Here, we tested for temporal context reinstatement in a human fMRI continuous recognition memory experiment in which natural scene images were repeatedly encountered. For the original encounter with each scene, we defined its temporal context as the visual content of temporally-adjacent scenes. Using voxelwise encoding models, we tested whether fMRI activity patterns evoked when a scene was re-encountered carried information about the original encounters temporal context. Indeed, we found robust temporal context reinstatement within high-level visual cortex (lateral occipitotemporal cortex; LOTC), despite the fact that reinstated content was entirely incidental to task demands. However, temporal context reinstatement only occurred when stimuli were successfully recognized, indicating that reinstatement was behaviorally-relevant, even if incidental. Finally, the strength of temporal context reinstatement in LOTC was predicted by the similarity of hippocampal activity patterns across encounters, demonstrating distinct, but complimentary, roles for the hippocampus and neocortex in reinstating temporal context information.