No Effect of Targeted Memory Reactivation during Slow-Wave Sleep on Emotional Recognition Memory

Recent work has suggested that the benefits of sleep for memory consolidation are enhanced for highly salient (vs. non-salient) memories. Using a technique known as targeted memory reactivation (TMR) it is possible to selectively strengthen newly learned memories by re-exposing the sleeping brain to auditory cues. The aim of the current study was to examine whether emotionally salient memories are also more responsive to TMR in slow-wave sleep (SWS) than neutral memories. In an initial training phase participants memorised emotionally negative and neutral pictures, which were each paired with a semantically related sound. Recognition for the pictures was assessed before and after a 90 minute nap opportunity, during which half the sounds were re-presented during SWS (as assessed via online polysomnographic sleep monitoring). We observed no effect of TMR on the recognition of emotionally negative or neutral memories. Our results highlight the importance of the memory paradigm used to assess TMR and suggest that the robust and durable nature of recognition memory may make it an insensitive measure of behavioural TMR benefits. To fully assess the impacts of TMR on emotional memory processing in sleep, future studies should adopt experimental paradigms that maximise the salience of emotional stimuli while also providing a sensitive index of memory accuracy.