Action Sequences Structure Human Memory Reactivation

Abstract

Episodic memory formation is not a passive process but emerges from sequences of actions through which we engage with our environment. Yet, how these action sequences interact with the neural dynamics underlying human memory formation and retrieval remains poorly understood. Here, we investigated whether coordinated gaze shifts, one of the major exploratory actions in humans, structure the reactivation of memories. Participants learned multiple action sequences by pairing images with distinct real-world gaze shifts while we simultaneously recorded EEG and motion tracking data. During subsequent retrieval, the recalled gaze sequences acted as a direct behavioral readout of memory performance. Representational similarity analyses revealed that the reactivation of image memories was precisely timed to recalled gaze shifts within each sequence. Crucially, only correctly executed, but not incorrectly executed gaze shifts elicited significant reactivation of the corresponding image class, directly linking neural reactivation to retrieval success. These findings suggest that exploratory actions are fundamental components of episodic memories, not incidental accompaniments: self-initiated movements can serve as temporal anchors of memory reactivation that predict retrieval success. By investigating memory through natural behavior, our work provides an ecologically grounded perspective on human cognition, revealing that species-typical actions such as gaze shifts are essential to, rather than obstacles for, understanding memorys neural basis.