The brain supports adaptive behavior by generating predictions, learning from errors, and updating memories. Prediction error, or surprise, is a known trigger for memory updating; however, the mechanisms that link prediction error, neural representations, and naturalistic memory updating remain unknown. In an fMRI study, we elicited prediction errors by interrupting familiar narrative videos immediately before an expected conclusion. We found that prediction errors reversed the effect of post-video univariate hippocampal activation on subsequent memory: hippocampal activation predicted false memories after prediction errors, but protected memories from distortion after expected events. Tracking second-by-second neural patterns revealed that prediction errors disrupted the temporal continuity of hippocampal representations. This disruption of signal history led to memory updating after prediction error. We conclude that prediction errors during memory reactivation prompt the hippocampus to abandon ongoing predictions and neural representations. Following prediction error, the hippocampus switches to an externally-oriented processing mode that supports memory updating.
bioRxiv Subject Collection: Neuroscience