Lateralised sleep spindles relate to false memory generation

Abstract

Sleep is known to enhance false memories: After presenting participants with lists of semantically related words, sleeping before recalling these words results in a greater acceptance of unseen "lure" words related in theme to previously seen words. Furthermore, the right hemisphere (RH) seems to be more prone to false memories than the left hemisphere (LH). In the current study, we investigated the sleep architecture associated with these false memory and lateralisation effects in a nap study. Participants viewed lists of related words, then stayed awake or slept for approximately 90min, and were then tested for recognition of previously seen-old, unseen-new, or unseen-lure words presented either to the LH or RH. Sleep increased acceptance of unseen-lure words as previously seen compared to the wake group, particularly for RH presentations of word lists. RH lateralised stage 2 sleep spindle density relative to the LH correlated with this increase in false memories, suggesting that RH sleep spindles enhanced false memories in the RH.

Higher sleep spindle activity is associated with fewer false memories in adolescent girls

“…In our study, higher stage 2 spindle activity in the slow range was consistently associated with fewer false memories. This is inconsistent with the theory proposed by Shaw and Monaghan (Shaw & Monaghan, 2017) whereby spindle activity facilitates the consolidation of studied DRM lists into semantic memory. However, their study involved a sample of adult participants, and did not examine overnight spindles, suggesting a potential difference between the impact of a full night of spindle activity and a brief daytime nap, and a difference between adult and adolescent sleep.…”

“…While spindle activity is thought to be a marker of neural plasticity, it is unknown whether the morphological parameters of individual spindles or overall overnight spindle activity is a more prominent marker of said plasticity. The only previous spindle study reporting false memory recollection using the DRM protocol focused on an experimental nap setting (Shaw & Monaghan, 2017), thus not being comparable to overnight spindle studies. Based on our results, it would seem that higher overnight spindle density and frequency, but not amplitude, is associated with a more accurate memory.…”

“…A recent study using a daytime-nap setting and the DRM paradigm found that the degree to which spindles were lateralised to the right hemisphere, but not the raw number of spindles, predicted the number of false memories generated after sleep (Shaw & Monaghan, 2017). This led the authors to propose that false memories are generated in the right hemisphere, and that sleep spindles facilitate this process by consolidating the studied word lists in semantic memory.…”

“…Sleep has been shown to be one such condition. In studies with adult participants, sleep (relative to wake) after exposure to the study lists in the DRM paradigm has been shown to increase false recall of critical lures both when tested in free recall (Payne et al, 2009) and in recognition memory tasks (Fenn, Gallo, Margoliash, Roediger, & Nusbaum, 2009;Shaw & Monaghan, 2017). Recent studies have begun to shed light on the aspects of sleep architecture that are involved with the generation of false memories.…”

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

“…The effect of sleep on semantic false memory is also under-researched using ERPs, despite decades of accumulated evidence for the influence of sleep on memory consolidation (Diekelmann, et al, 2009; Rasch & Born, 2008). Previous DRM and sleep literature has employed naps, which are effective in investigating sleep functions as they have similar characteristics to a full night of sleep (Durrant et al, 2011; Shaw & Monaghan, 2017). The few studies conducted to date have associated daytime naps with an increased number of DRM false memories, compared to wake conditions (Payne et al, 2009; Shaw & Monaghan, 2017).…”