Sleep enhances reconsolidation-based strengthening of visuospatial memories

Abstract

Consolidated memories can be returned to a labile state upon reactivation. The re-stabilization of reactivated memories, or reconsolidation, can allow for change in previously established memories. Given the role of sleep in the initial consolidation of memories, sleep may be important for reconsolidation as well. However, effects of sleep on reconsolidation and specific aspects of sleep that may contribute are unclear. Here, participants learned 30 picture-location pairs. After overnight sleep, initial consolidation was tested. Following either one day (Experiment 1) or one week (Experiment 2), participants were tested again to reactivate their memory and then learned 30 novel picture-location pairs. Control groups (Experiment 1) received no reactivation prior to new learning. Twelve hours later, after daytime wakefulness or overnight sleep, participants completed a final memory test. Sleep participants underwent polysomnography between reactivation and final tests. In Experiment 1, reactivation led to preservation of memory compared to no reactivation. Sleep was associated with less post-reactivation memory decline than waking, with memory preservation positively related to time spent in non-rapid-eye movement sleep. In Experiment 2, sleep was associated with greater post-reactivation memory improvement than waking, with improvement positively related to sigma activity. These results suggest sleep enhances reconsolidation-based strengthening of episodic memories.

Modulation of memory reconsolidation by adjacent novel tasks: timing defines the nature of change

“…Most of them focused on understanding the effects of reconsolidation on established memories and showed, in different cases, that the sole reactivation could serve as a memory enhancer. This type of effect was found in rodents and humans 32 – 37 . Instead of focusing on the effect of reconsolidation on memory, we studied how experiences occurring close to a reactivating event act on the reconsolidation process to affect previously stored memories.…”