Economic “Activity-Silent” Synaptic Mechanisms of Working Memory

Illustration of the “Activity-silent” synaptic mechanisms of working memory. Neural representations are activated when the novel “to-be-remembered” items are first encoded. After the first cue, neural representations of the attended memory item (AMI) are sustained, with elevated activation. Neural representations of the unattended memory item (UMI) enter a “drop-to-baseline” pattern. The transcranial magnetic stimulation (TMS) could reactivate the representations of the AMI and UMI, including the elevated and latent representations, suggesting that the UMI is still at a state of “easy to activate” priority, and that information held in working memory (WM) is interconnected (in the solid circle). If the same AMI is cued again in the second phase, the representations of the uncued item drop to baseline and maintain there, and TMS is unable to activate them. After the second cue, the uncued item becomes task-irrelevant, and the connectivity between the representations of different items is broken (solid circle disappear). Before this model, the traditional state-based model proposes that memory representations of information held in WM are maintained in an elevated state of activation until the information is no longer relevant to the current target. The traditional theory does not isolate the role of attention from WM and suggests that the items held in working memory are at the same priorit