Sleep Enhances Neural Representations of True and False Memories: An Event-Related Potential Study

Abstract

Episodic memory is reconstructive and is thus prone to false memory formation. Although false memories are proposed to develop via associative processes, the nature of their neural representations, and the effect of sleep on false memory processing is currently under debate. The present research employed the Deese-Roediger-McDermott (DRM) paradigm and a daytime nap to determine whether semantic false memories and true memories could be differentiated using event-related potentials (ERPs). We also sought to illuminate the role of sleep in memory formation and learning, with a daytime nap. Healthy participants (N = 34, 28F, mean age = 23.23, range = 18-33) completed the DRM task with the learning and recognition phases separated by either a 2hr daytime nap or an equivalent wake period. Linear mixed modelling revealed larger LPC amplitudes for true memories in contrast to false memories, and larger P300 amplitudes for false compared to true memories. Those in the nap group also exhibited larger LPC and P300 amplitudes than participants in the wake group. Additionally, larger P300 amplitudes at delayed recognition (following a consolidation opportunity) were associated with increased true memory accuracy. These findings are argued to be reflective of sleeps ability to promote pattern separation and pattern completion, with true memories arising from distinct memory traces, and false memories arising from thematic extraction and overlap in neural representations. The present research supports the perspective that both true and false memories are reflective of adaptive memory processes, whilst also suggesting that P300 amplitude affects episodic memory accuracy.

Theta activity during encoding interacts with NREM sleep oscillations to predict memory generalization

“…d' was calculated using the package Psycho (Makowski, 2018) implemented in R version 3.6.1 (R Core Team, 2018). As per the methods used in Jano et al (2021), d' was calculated (Zhits -Zfa) for both list words and associative lures, in order to reflect our viewpoint that 'false memory' measured in the DRM reflects associative processes, as opposed to memory errors.…”