Cueing memory reactivation during NREM sleep engenders long-term plasticity in both brain and behaviour

Memory reactivation during Non-Rapid Eye Movement (NREM) sleep is important for memory consolidation but it remains unclear exactly how such activity promotes the development of a stable memory representation. We used Targeted Memory Reactivation (TMR) in combination with longitudinal structural and functional MRI to track the impact of reactivating memories in one night of sleep over the next 20 days. Our exploratory analysis showed that such cued reactivation leads to increased precuneus activation 24 h post-TMR. Furthermore, the behavioural impact of cueing, which only emerged 20 days later, was predicted by both functional and structural TMR related changes in sensorimotor cortex. These preliminary findings demonstrate that TMR leads to neuroplasticity, starting as early as 24 hours after the manipulation, and evolving over the next few weeks

Targeted memory reactivation in REM but not SWS selectively reduces arousal responses

A growing body of evidence suggests that sleep can help to decouple the memory of emotional experiences from their associated affective charge. This process is thought to rely on the spontaneous reactivation of emotional memories during sleep, though it is still unclear which sleep stage is optimal for such reactivation. We examined this question by explicitly manipulating memory reactivation in both rapid-eye movement sleep (REM) and slow-wave sleep (SWS) using targeted memory reactivation (TMR) and testing the impact of this manipulation on habituation of subjective arousal responses across a night. Our results show that TMR during REM, but not SWS significantly decreased subjective arousal, and this effect is driven by the more negative stimuli. These results support one aspect of the sleep to forget, sleep to remember (SFSR) hypothesis which proposes that emotional memory reactivation during REM sleep underlies sleep-dependent habituation