Working memory demands modulate memory brain state engagement

The extent to which attention and memory processes rely on shared as opposed to distinct mechanisms is critical for understanding the role of both processes in cognition. As working memory sits at the intersection of external, perceptual input and long-term internal storage, it provides the ideal testbed for investigating overlaps between attention and memory. We hypothesize that memory brain states, whole-brain activity patterns that support long-term memory encoding and retrieval, map onto the external/internal axis of attention. Specifically, we hypothesize that external attention, focusing on sensory information, recruits the encoding state and internal attention, focusing on stored information, recruits the retrieval state. To test this hypothesis, we conducted a scalp electroencephalography study in which participants engaged in a working memory paradigm with and without maintenance demands. We used an independently validated cross-study multivariate pattern classifier to measure memory brain state engagement during change and target detection tasks. We find that the encoding state is recruited for stimulus presentation during both tasks, whereas the retrieval state is selectively recruited during the delay of the change detection task. Together, these results suggest that memory states map onto the external/internal axis of attention to support working memory, long-term memory, and cognition more broadly.