The application of closed-loop targeted memory reactivation during slow wave sleep

Wadon, Megan 2025. The application of closed-loop targeted memory reactivation during slow wave sleep. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Sleep is essential, serving many functions including memory processing. Sleep engineering manipulates these processes to alter memory strength, integration and emotional tone. We do this using a technique called Targeted Memory Reactivation (TMR), inducing the reactivation of specific memory traces using sounds to bias these process. The timing of these sounds can alter the outcome, with different results seen in Rapid Eye Movement (REM) and non-REM sleep, as well as when sounds are targeted to specific phases of sleep oscillations – Closed-loop TMR (CL-TMR). Particularly promising results have been observed targeting sounds to the up-phase of the slow oscillation during slow wave sleep (SWS). This thesis explores the potential applications of this technique, looking at cognitive and emotional outcomes. Chapter 2 focuses on the effects of CL-TMR during SWS on memory integration. Utilising a transitive inference task over a three week study period we determine the effect of TMR is greatest for more distant inferences that require integration of multiple pieces of information. We also discover that CL-TMR enhances precuneus activation for inferences that have undergone TMR, suggesting a stronger memory representation – or engram – in this area. Chapter 3 investigates the impact of TMR on the processing of positive emotional memories in dysphoria. Emotional semantic memories and short novel videos were reactivated during SWS demonstrating different effects for the different types of information. We also found that depressive symptoms improved over the course of the study, although timelines differed for different symptoms. In conclusion, this thesis highlights the versatility of CL-TMR and it’s potential for not only enhancing cognition and strengthening memory engrams, but also augmenting emotional responses to positive stimuli. CL-TMR is effective not just in healthy individuals, but in individuals with sub-clinical depression – i.e. dysphoria – and may even contribute to alleviating depressive symptoms in this population.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Schools > Psychology
Date of First Compliant Deposit:	22 July 2026
Last Modified:	22 Jul 2026 08:20
URI:	https://orca.cardiff.ac.uk/id/eprint/188361

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