Targeted memory reactivation during slow wave sleep facilitates emotional memory consolidation

Abstract

Study objectives: To investigate the mechanisms by which auditory targeted memory reactivation (TMR) during slow wave sleep (SWS) influences the consolidation of emotionally negative and neutral memories.

Design: Each of 72 (36 negative, 36 neutral) picture-location associations were encoded with a semantically related sound. During a subsequent nap, half of the sounds were replayed in SWS, before picture-location recall was examined in a final test.

Setting: Manchester Sleep Laboratory, University of Manchester.

Participants: 15 adults (3 male) mean age = 20.40 (standard deviation ± 3.07).

Interventions: TMR with auditory cues during SWS.

Measurements and results: Performance was assessed by memory accuracy and recall response times (RTs). Data were analyzed with a 2 (sound: replayed/not replayed) × 2 (emotion: negative/neutral) repeated measures analysis of covariance with SWS duration, and then SWS spindles, as the mean-centered covariate. Both analyses revealed a significant three-way interaction for RTs but not memory accuracy. Critically, SWS duration and SWS spindles predicted faster memory judgments for negative, relative to neutral, picture locations that were cued with TMR.

Conclusions: TMR initiates an enhanced consolidation process during subsequent SWS, wherein sleep spindles mediate the selective enhancement of reactivated emotional memories.

Keywords: Emotional memory; memory consolidation; reactivation; sleep spindles; slow wave sleep.

Figure 1

(A) Session one (12:00): encoding and retrieval tasks. (B) Targeted memory reactivation (02:00): half of the sounds were replayed during slow wave sleep (SWS). (C) Session two (04:00): retrieval task.

Figure 2

The influence of targeted memory reactivation (TMR) on the relationship between slow wave sleep and the emotion effect (neutral response time – negative response time).