Passive working memory relies on episodic mechanisms for maintenance

Recent studies have suggested that working memory (WM) representations can be retained through transient changes in synaptic weights, introducing the concept of activity-silent passive memory. This concept has been hypothesized to reflect mechanisms of episodic memory. However, there was no empirical evidence to delineate the role of episodic memory system in the passive memory functioning. To investigate this, we explored whether the passive memory suffered deficits similarly to the episodic memory system when disrupting the episodic memory functioning. It has shown that episodic memory system was damaged near in time to intentional suppression on unwanted events (i.e., amnesic shadow) in a Think/No-Think task, referred to as an amnesic shadow effect. In this study, participants completed Think/No-Think to induce amnesic shadow, and immediately performing a sequential WM task in which the first array was later probed as passive and the second as active. In this task, both active and passive memory representations in WM tasks were exposed to the amnesic shadow. The results showed that only passive memory suffered the amnesic shadow effect, while active memory was not affected. These findings provide the evidence that episodic memory processes contribute to the maintenance of activity-silent passive memory in working memory.