Pharmacologically Increasing Sleep Spindles Enhances Recognition for Negative and High-arousal Memories

Sleep affects declarative memory for emotional stimuli differently than it affects declarative memory for nonemotional stimuli. However, the interaction between specific sleep characteristics and emotional memory is not well understood. Recent studies on how sleep affects emotional memory have focused on rapid eye movement sleep (REM) but have not addressed non-REM sleep, particularly sleep spindles. This is despite the fact that sleep spindles are implicated in declarative memory as well as neural models of memory consolidation (e.g., hippocampal neural replay). Additionally, many studies examine a limited range of emotional stimuli and fail to disentangle differences in memory performance because of variance in valence and arousal. Here, we experimentally increase non-REM sleep features, sleep spindle density, and SWS, with pharmacological interventions using zolpidem (Ambien) and sodium oxybate (Xyrem) during daytime naps. We use a full spread of emotional stimuli to test all levels of valence and arousal. We find that increasing sleep spindle density increases memory discrimination (da) for highly arousing and negative stimuli without altering measures of bias (ca). These results indicate a broader role for sleep in the processing of emotional stimuli with differing effects based on arousal and valence, and they raise the possibility that sleep spindles causally facilitate emotional memory consolidation. These findings are discussed in terms of the known use of hypnotics in individuals with emotional mood disorders.

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Dysfunctional Overnight Memory Consolidation in Patients with Schizophrenia in Comparison to Healthy Controls: Disturbed Slow-Wave Sleep as Contributing Factor?

Neuropsychobiology ◽

10.1159/000517858 ◽

2021 ◽

pp. 1-12

Author(s):

Sara Lena Weinhold ◽

Julia Lechinger ◽

Jasper Ittel ◽

Romina Ritzenhoff ◽

Henning Johannes Drews ◽

...

Keyword(s):

Linear Relationship ◽

Slow Wave ◽

Memory Consolidation ◽

Slow Wave Sleep ◽

Declarative Memory ◽

Sleep Spindles ◽

Sleep Spindle ◽

Delta Power ◽

Sleep Parameters ◽

Spindle Power

Introduction: Memory deficiency has been shown in schizophrenia patients, but results on the role of sleep parameters in overnight consolidation of associative verbal memory are still missing. Therefore, the aim of our study was to elucidate underlying processes of impaired sleep-related consolidation of associative word pairs in schizophrenia including standard sleep parameters as well as sleep spindle counts and spectral analysis. Methods: Eighteen stably medicated schizophrenia patients and 24 healthy age-matched controls performed an associative declarative memory task before and after polysomnographic recordings. Part of the participants expected verbal associative memory testing in the morning, while the others did not. Furthermore, participants filled in self-rating questionnaires of schizophrenia-typical experiences (Eppendorf Schizophrenia Inventory [ESI] and Psychotic Symptom Rating Scale). Results: Schizophrenia patients performed worse in verbal declarative memory in the evening as well as in overnight consolidation (morning compared to evening performance). While duration of slow-wave sleep was nearly comparable between groups, schizophrenia patients showed lower sleep spindle count, reduced delta power during slow-wave sleep, and reduced spindle power during the slow oscillation (SO) up-state. In healthy but not in schizophrenia patients, a linear relationship between overnight memory consolidation and slow-wave sleep duration as well as delta power was evident. No significant effect with respect to the expectation of memory retrieval was evident in our data. Additionally, we observed a negative linear relationship between total number of sleep spindles and ESI score in healthy participants. Discussion/Conclusion: As expected, schizophrenia patients showed deficient overnight verbal declarative memory consolidation as compared to healthy controls. Reduced sleep spindles, delta power, and spindle power during the SO up-state may link sleep and memory deficiency in schizophrenia. Additionally, the absence of a linear relationship between sleep-related memory consolidation and slow-wave sleep as well as delta power suggests further functional impairments in schizophrenia. Note that this conclusion is based on observational data. Future studies should investigate if stimulation of delta waves during sleep could improve memory performance and thereby quality of life in schizophrenia.

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0100 Effect of Naps on Preschoolers’ Consolidation of an Emotional Storybook

SLEEP ◽

10.1093/sleep/zsaa056.098 ◽

2020 ◽

Vol 43 (Supplement_1) ◽

pp. A40-A40

Author(s):

J F Holmes ◽

M K Deighan ◽

N W Miranda ◽

G M Mason ◽

R M Spencer

Keyword(s):

Preschool Children ◽

Memory Consolidation ◽

Declarative Memory ◽

Memory Performance ◽

Emotional Memory ◽

Multiple Choice Questions ◽

Time Points ◽

Sleep Physiology ◽

Emotional Events ◽

Time Point

Abstract Introduction Naps are known to benefit emotional memory consolidation in preschoolers, though improvement is not evident until the following day. The mechanisms by which naps aid emotional memory, and how they differ from those facilitating more neutral declarative memory consolidation, are currently unknown. In this study, we used an emotional storybook task to assess change in memory for emotionally salient vs. neutral events across a nap and overnight sleep. PSG was included to explore sleep physiology correlates. Methods Preschool children (n = 9; Mage= 43.2 months) were read a novel storybook featuring negative and neutral events. Memory of story events was probed through sets of multiple-choice questions and assessed at three time points: immediately following the story, following a nap or equivalent wake period (within-subject; counterbalanced; separated by ~1 week), and 24h post-encoding. PSG was recorded during the nap period and both subsequent overnight sleep bouts. Results Memory performance across time points was assessed via change scores. Recall of story events did not differ between conditions from immediate to post-nap/wake assessment. When probed the following morning, children better remembered events when a nap took place the day prior (F(1,7) = 8.848, p=.021). This delayed nap benefit correlated with time spent in NREM2 during the nap (r=.91, p=.017). No differences were found between recall of negative vs. neutral events at any time point or between conditions. Conclusion Our results show a delayed benefit of napping on recall of a storybook, though at present no preference for emotional events is seen. Time spent in NREM2 during the nap was strongly associated with our finding, likely reflecting the declarative memory benefits conferred from this stage. Further analyses will include overnight sleep physiology to explore differential enhancement between event types, and possible interactions with nap microstructure. Support This work was supported by NIH R01 HL111695.

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Sleep spindles and cognition in depression

10.31219/osf.io/waz3d ◽

2017 ◽

Author(s):

Leonore Bovy ◽

Martin Dresler ◽

Frederik D Weber

Keyword(s):

Memory Consolidation ◽

Cognitive Abilities ◽

Declarative Memory ◽

Critical Role ◽

Antidepressant Medication ◽

Sleep Spindles ◽

Sleep Spindle ◽

Preliminary Model ◽

Patient Groups ◽

Medication Selection

Sleep plays a critical role in orchestrating several cognitive functions. Sleep spindles are particularly at the forefront of studies on the consolidation of cognitive abilities, such as procedural and declarative memory. Despite that major depressive disorder (MDD) has been linked to sleep spindle alterations, their role in MDD pathogenesis and symptomatology (including memory deficits) is still scarcely investigated. Here, we first provide an overview of sleep and sleep spindle alterations in MDD and their potential effects on memory and cognition. Secondly, limited data suggest that sleep spindles deficits in severe MDD might not only lead to cognitive impairments but primarily affect memory consolidation processes during sleep. Furthermore, it seems likely that many sleep spindle related effects are masked by interacting (antidepressant) medication, selection of mixed patient groups with mild symptomatology as well as use of incomprehensive methodology in analyzing sleep. We propose a preliminary model predicting that impairments in sleep spindle related activity during sleep are mainly responsible for memory consolidation deficits in depressed patients, but that medication augmenting sleep spindle activity can enhance and restore sleep-mediated consolidation. Future studies thus need to scrutinize previous findings on sleep spindle effects in MDD.

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Electrophysiological Indicators of Sleep-associated Memory Consolidation in 5- to 6-year-old Children

10.1101/2020.09.04.283606 ◽

2020 ◽

Author(s):

Ann-Kathrin Joechner ◽

Sarah Wehmeier ◽

Markus Werkle-Bergner

Keyword(s):

Young Adults ◽

School Children ◽

Memory Consolidation ◽

Declarative Memory ◽

Slow Oscillation ◽

Sleep Spindles ◽

Sleep Spindle ◽

Slow Oscillations ◽

Slow Sleep ◽

Temporal Coupling

ABSTRACTIn young adults, memory consolidation during sleep is supported by a time-coordinated interplay of sleep spindles and slow oscillations. However, given tremendous developmental changes in sleep spindle and slow oscillation morphology, it remains elusive whether the same mechanisms as identified in young adults are comparably functional across childhood. Here, we characterise slow and fast sleep spindles and their temporal coupling to slow oscillations in 24 pre-school children. Further, we ask whether slow and fast sleep spindles and their modulation during slow oscillations are similarly associated with behavioural indicators of declarative memory consolidation as suggested from adult literature. Employing a development-sensitive, individualised approach, we reliably identify an inherent, development-specific fast sleep spindle type, though nested in the adult-like slow sleep spindle frequency range, along with a dominant slow sleep spindle type. Further, we provide evidence for the modulation of fast sleep spindles during slow oscillations, already in pre-school children. However, the temporal coordination between fast sleep spindles and slow oscillations is weaker and less precise than expected from adult research. While we do not find evidence for a critical contribution of the pattern of fast sleep spindle modulation during slow oscillations for memory consolidation, crucially, both inherent slow and fast sleep spindles separately are differentially related to sleep-associated consolidation of items of varying quality. While a higher number of slow sleep spindles is associated with stronger maintenance of medium-quality memories, more fast sleep spindles are linked to higher gain of low-quality items. Our results provide evidence for two functionally relevant inherent sleep spindle types in pre-school children despite not fully matured sleep spindle – slow oscillation coupling.

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Shining a Light on the Mechanisms of Sleep for Memory Consolidation

Current Sleep Medicine Reports ◽

10.1007/s40675-021-00204-3 ◽

2021 ◽

Author(s):

Michelle A. Frazer ◽

Yesenia Cabrera ◽

Rockelle S. Guthrie ◽

Gina R. Poe

Keyword(s):

Rem Sleep ◽

Neural Activity ◽

Memory Consolidation ◽

Strong Support ◽

Nrem Sleep ◽

Future Research ◽

Sleep Spindles ◽

Slow Oscillations ◽

Theta Waves ◽

Learning Tasks

Abstract Purpose of review This paper reviews all optogenetic studies that directly test various sleep states, traits, and circuit-level activity profiles for the consolidation of different learning tasks. Recent findings Inhibiting or exciting neurons involved either in the production of sleep states or in the encoding and consolidation of memories reveals sleep states and traits that are essential for memory. REM sleep, NREM sleep, and the N2 transition to REM (characterized by sleep spindles) are integral to memory consolidation. Neural activity during sharp-wave ripples, slow oscillations, theta waves, and spindles are the mediators of this process. Summary These studies lend strong support to the hypothesis that sleep is essential to the consolidation of memories from the hippocampus and the consolidation of motor learning which does not necessarily involve the hippocampus. Future research can further probe the types of memory dependent on sleep-related traits and on the neurotransmitters and neuromodulators required.

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0084 Sleep Consolidates Incidentally Encoded Information After Deep but Not Shallow Encoding

SLEEP ◽

10.1093/sleep/zsaa056.082 ◽

2020 ◽

Vol 43 (Supplement_1) ◽

pp. A34-A34

Author(s):

E M Wernette ◽

K M Fenn

Keyword(s):

Slow Wave ◽

Memory Consolidation ◽

Slow Wave Sleep ◽

Declarative Memory ◽

Memory Performance ◽

Memory Test ◽

Memory Traces ◽

Incidental Encoding ◽

The Relationship ◽

With Memory

Abstract Introduction Slow wave sleep (SWS) strengthens declarative memory for information studied for a later test. However, research on the effect of sleep on information that is not intentionally remembered is scare. Previous research from our lab suggests sleep consolidates some, but not all, information that has been encoded incidentally, meaning that it has been acted on but not intentionally remembered. It remains unclear what determines which information benefits from sleep-dependent consolidation processes and what aspects of sleep are related to these mnemonic benefits. In two experiments, we test the hypothesis that sleep consolidates strong but not weak memory traces following incidental encoding, and assess the relationship between memory performance and objective sleep characteristics. Methods In Experiment 1, participants rated words one (weak traces) or three times (strong traces) in a deep or shallow incidental encoding task. Participants either rated words on a scale from ‘concrete’ to ‘abstract’ (deep) or counted the vowels in the words (shallow). Following a 12-hour period containing sleep or wakefulness, participants took a surprise memory test. In Experiment 2, participants rated words one or three times in the deep encoding task, received an 8-hour sleep opportunity with polysomnography, and took the surprise memory test. Results In Experiment 1, participants remembered words better after sleep than wake regardless of whether words were encoded one or three times, but only after deep encoding. Sleep did not consolidate information following shallow encoding. Experiment 2 is ongoing, but we predict that the amount of SWS will correlate positively with memory. Conclusion Results thus far suggest sleep may have consolidated information based on the strength of memory traces. Because deep encoding results in stronger memory traces than shallow encoding, this work is broadly consistent with theories of memory consolidation that predict sleep is more beneficial for strong memory traces than weak, such as the synaptic downscaling hypothesis. Support N/A

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The influence of REM sleep and SWS on emotional memory consolidation in participants reporting depressive symptoms

Cortex ◽

10.1016/j.cortex.2017.12.004 ◽

2018 ◽

Vol 99 ◽

pp. 281-295 ◽

Cited By ~ 8

Author(s):

Marcus O. Harrington ◽

Jennifer M. Johnson ◽

Harriet E. Croom ◽

Kyla Pennington ◽

Simon J. Durrant

Keyword(s):

Depressive Symptoms ◽

Rem Sleep ◽

Memory Consolidation ◽

Emotional Memory

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Sleep-Related Declarative Memory Consolidation and Verbal Replay during Sleep Talking in Patients with REM Sleep Behavior Disorder

PLoS ONE ◽

10.1371/journal.pone.0083352 ◽

2013 ◽

Vol 8 (12) ◽

pp. e83352 ◽

Cited By ~ 8

Author(s):

Ginevra Uguccioni ◽

Olivier Pallanca ◽

Jean-Louis Golmard ◽

Pauline Dodet ◽

Bastien Herlin ◽

...

Keyword(s):

Rem Sleep ◽

Memory Consolidation ◽

Declarative Memory ◽

Rem Sleep Behavior Disorder ◽

Behavior Disorder ◽

Sleep Behavior ◽

Sleep Talking

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Coupling of autonomic and central events during sleep benefits declarative memory consolidation

10.1101/195586 ◽

2017 ◽

Author(s):

Mohsen Naji ◽

Giri P. Krishnan ◽

Elizabeth A McDevitt ◽

Maxim Bazhenov ◽

Sara C. Mednick

Keyword(s):

Memory Consolidation ◽

Declarative Memory ◽

Memory Performance ◽

Memory Task ◽

Nrem Sleep ◽

Heart Beat ◽

Vagal Activity ◽

Rr Intervals ◽

Slow Oscillations ◽

Event Based

AbstractWhile anatomical pathways between forebrain cognitive and brainstem autonomic nervous centers are well defined, autonomic–central interactions during sleep and their contribution to waking performance are not understood. Here, we analyzed simultaneous central activity via electroencephalography (EEG) and autonomic heart beat-to-beat intervals (RR intervals) from electrocardiography (ECG) during wake and daytime sleep. We identified bursts of ECG activity that lasted 4-5 seconds and predominated in non-rapid-eye-movement sleep (NREM). Using event-based analysis of NREM sleep, we found an increase in delta (0.5-4Hz) and sigma (12-15Hz) power and an elevated density of slow oscillations (0.5-1Hz) about 5 secs prior to peak of the heart rate burst, as well as a surge in vagal activity, assessed by high-frequency (HF) component of RR intervals. Using regression framework, we show that these Autonomic/Central Events (ACE) positively predicted post-nap improvement in a declarative memory task after controlling for the effects of spindles and slow oscillations from sleep periods without ACE. No such relation was found between memory performance and a control nap. Additionally, NREM ACE negatively correlated with REM sleep and learning in a non-declarative memory task. These results provide the first evidence that coordinated autonomic and central events play a significant role in declarative memory consolidation.

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Contribution of REM sleep and N2 sleep spindles to procedural memory consolidation in Vipassana meditators and non-meditating controls.

10.31231/osf.io/e4zr2 ◽

2017 ◽

Author(s):

Elizaveta Solomonova ◽

Simon Dubé ◽

Cloé Blanchette-Carrière ◽

Arnaud Samson-Richer ◽

Michelle Carr ◽

...

Keyword(s):

Eye Movement ◽

Rem Sleep ◽

Memory Consolidation ◽

Nrem Sleep ◽

Procedural Memory ◽

Sleep Stages ◽

Sleep Spindles ◽

Meditation Practice ◽

Rapid Eye Movement ◽

Vipassana Meditation

Study objectives: Rapid eye movement (REM) sleep, non-rapid eye movement (NREM) sleep, and sleep spindles are all implicated in the consolidation of procedural memories. The relative contributions of sleep stages and sleep spindles was previously shown to depend on individual differences in task processing. Experience with Vipassana meditation is one such individual difference that has not been investigated in relation to sleep. Vipassana meditation is a form of mental training that enhances proprioceptive and somatic awareness and alters attentional style. The goal was thus to examine a potential moderating role for Vipassana meditation experience on sleep-dependent procedural memory consolidation.Methods: Groups of Vipassana meditation practitioners (N=20) and matched meditation-naïve controls (N=20) slept for a single daytime nap in the laboratory. Before and after the nap they completed a procedural task on the Wii Fit balance platform.Results: Meditators performed slightly better on the task before the nap, but the two groups improved similarly after sleep. The groups showed different patterns of sleep-dependent procedural memory consolidation: in meditators task learning was negatively correlated with density of fast and positively correlated with density of slow occipital spindles, while in controls task improvement was associated with increases in REM sleep. Meditation practitioners had a lower density of sleep spindles, especially in occipital regions.Conclusions: Results suggest that neuroplastic changes associated with sustained meditation practice may alter overall sleep architecture and reorganize sleep-dependent patterns of memory consolidation. The lower density of spindles in meditators may mean that meditation practice compensates for some of the memory functions of sleep.

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