How the Brain Constructs and Maintains Coherent Episodic Memories through Eye Movements

The process of constructing, maintaining, and reconstructing episodic memories is closely linked to the temporal dynamics of visual exploration through sequences of eye movements (Johansson et al., 2022; Nikolaev et al., 2023). However, the neural mechanisms that mediate relational memory across eye movements are not yet fully understood.

This study presented participants with a series of visuospatial events, each consisting of six distinct elements (faces, places, objects) positioned in different screen locations. This setup allowed for the identification and analysis of various types of inter-element associations. During a 10-second encoding phase, participants visually explored each event. Following this, the visual stimuli were removed, leaving participants with a 10-second “looking-at-nothing”-phase, where they had to retain the event and continue forming and recalling the visuospatial relationships among the elements. EEG and eye movement data were collected during the intervals with and without visual information. Finally, an associative memory test assessed memory for event-specific inter-element relationships.

The results showed that the vividness of memory during the interval without visual information correlated with the amount of inter-element gaze transitions. These specific gaze transitions predicted subsequent memory for the corresponding inter-element associations and were related to changes in fixation-related neural activity observed in the desynchronization of alpha and synchronization of theta. This study is the first, to our knowledge, to identify at a fixation level the neural signatures subserving the inter-element linking process of dynamically constructing and maintaining coherent episodic memories across eye movements in the absence of visual input.