Abstract
How do we encode our continuous life experiences for later retrieval? Theories of event segmentation and integration suggest that the hippocampus binds separately represented events into an ordered narrative. Using an open-access functional Magnetic Resonance Imaging (fMRI) movie watching-recall dataset, we quantified neural similarities between separate events during movie watching and related them to subsequent retrieval of events as well as retrieval of sequential order. We demonstrate that distinct activation patterns of the hippocampus and medial prefrontal cortex form event memories. By contrast, similar within-region connectivity patterns between events facilitate memory formation and are critical for the retention of events in the correct sequential order. We propose that distinct activation patterns represent neural segmentation of events while similar connectivity patterns act as the ‘chunking code’ for integration across events. Our results provide novel evidence for the role of hippocampal-medial prefrontal event segmentation and integration in episodic memory formation of real-life experience.
Significance How do our brains encode continuous life experience? Prior work suggests that the hippocampus represents information with dissimilar patterns to separate them, but it remains unclear how events could be both separated and integrated into the sequenced narrative that characterizes episodic memory. We used functional MRI during movie watching to identify complementary patterns of brain activity in the hippocampus and medial prefrontal cortex that perform these dual operations. Successful encoding was dependent on events being represented with dissimilar activity patterns, while a similar connectivity pattern linked events and preserved the order they were encoded. These findings reveal a network that simultaneously separates and integrates event memories, and highlights the potential of connectivity patterns to examine dynamic memory processes in brains.