Reactivation of latent working memories with transcranial magnetic stimulation

TLDR

Working memory, the capacity to hold information temporarily, is essential for cognition. The study challenges the sustained‑activity view of working memory by showing that it can be maintained through activity‑silent synaptic mechanisms. Multivariate pattern analyses revealed that when attention shifts away, the active representation of an item falls to baseline, but a targeted TMS pulse briefly reactivates the item in brain activity and improves memory performance only when the item is potentially relevant later, supporting a synaptic theory of working memory.

Abstract

The ability to hold information in working memory is fundamental for cognition. Contrary to the long-standing view that working memory depends on sustained, elevated activity, we present evidence suggesting that humans can hold information in working memory via "activity-silent" synaptic mechanisms. Using multivariate pattern analyses to decode brain activity patterns, we found that the active representation of an item in working memory drops to baseline when attention shifts away. A targeted pulse of transcranial magnetic stimulation produced a brief reemergence of the item in concurrently measured brain activity. This reactivation effect occurred and influenced memory performance only when the item was potentially relevant later in the trial, which suggests that the representation is dynamic and modifiable via cognitive control. The results support a synaptic theory of working memory.