The Benefits of Targeted Memory Reactivation for Consolidation in Sleep are Contingent on Memory Accuracy and Direct Cue-Memory Associations

To investigate how the effects of targeted memory reactivation (TMR) are influenced by memory accuracy prior to sleep and the presence or absence of direct cue-memory associations. 30 participants associated each of 50 pictures with an unrelated word and then with a screen location in two separate tasks. During picture-location training, each picture was also presented with a semantically related sound. The sounds were therefore directly associated with the picture locations but indirectly associated with the words. During a subsequent nap, half of the sounds were replayed in slow wave sleep (SWS). The effect of TMR on memory for the picture locations (direct cue-memory associations) and picture-word pairs (indirect cue-memory associations) was then examined. TMR reduced overall memory decay for recall of picture locations. Further analyses revealed a benefit of TMR for picture locations recalled with a low degree of accuracy prior to sleep, but not those recalled with a high degree of accuracy. The benefit of TMR for low accuracy memories was predicted by time spent in SWS. There was no benefit of TMR for memory of the picture-word pairs, irrespective of memory accuracy prior to sleep. TMR provides the greatest benefit to memories recalled with a low degree of accuracy prior to sleep. The memory benefits of TMR may also be contingent on direct cue-memory associations. Research has demonstrated that memory reactivations in the sleeping brain can be triggered by re-exposing individuals in slow-wave sleep to sound cues previously associated with the newly-learned materials; a technique known as targeted memory reactivation (TMR). In this study, we examined how the success of TMR is influenced by (1) the presence or absence of direct cue-memory associations and (2) the accuracy with which newly-learned memories are recalled prior to sleep. Our findings suggest that low accuracy memories are more responsive to TMR and that the benefits of TMR for consolidation are contingent on the presence of direct cue-memory associations. These data have important implications for the potential educational applications of TMR.