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

Relatively little is known regarding the interaction between encoding-related neural activity and sleep-based memory consolidation. One suggestion is that a function of encoding-related theta power may be to 'tag' memories for subsequent processing during sleep. This study aimed to extend previous work on the relationships between sleep spindles, slow oscillation-spindle coupling and task-related theta activity with a combined Deese-Roediger-McDermott (DRM) and nap paradigm. This allowed us to examine the influence of task- and sleep-related oscillatory activity on the recognition of both encoded list words and associative theme words. Thirty-three participants (29 females, mean age = 23.2 years) learned and recognised DRM lists separated by either a 2hr wake or sleep period. Mixed-effects modelling revealed the sleep condition endorsed more associative theme words and fewer list words in comparison to the wake group. Encoding related theta power was also found to influence sleep spindle density, and this interaction was predictive of memory outcomes. The influence of encoding-related theta was specific to sleep spindle density, and did not appear to influence the strength of slow oscillation-spindle coupling as it relates to memory outcomes. The finding of interactions between wakeful and sleep oscillatory-related activity in promoting memory and learning has important implications for theoretical models of sleep-based memory consolidation.

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Bidirectional Interaction of Hippocampal Ripples and Cortical Slow Waves Leads to Coordinated Spiking Activity During NREM Sleep

Cerebral Cortex ◽

10.1093/cercor/bhaa228 ◽

2020 ◽

Vol 31 (1) ◽

pp. 324-340

Author(s):

Pavel Sanda ◽

Paola Malerba ◽

Xi Jiang ◽

Giri P Krishnan ◽

Jorge Gonzalez-Martinez ◽

...

Keyword(s):

Slow Wave ◽

Memory Consolidation ◽

Slow Wave Sleep ◽

Nrem Sleep ◽

Slow Waves ◽

Slow Oscillation ◽

Cortical Input ◽

Sharp Wave ◽

Up States ◽

Intracranial Recordings

Abstract The dialogue between cortex and hippocampus is known to be crucial for sleep-dependent memory consolidation. During slow wave sleep, memory replay depends on slow oscillation (SO) and spindles in the (neo)cortex and sharp wave-ripples (SWRs) in the hippocampus. The mechanisms underlying interaction of these rhythms are poorly understood. We examined the interaction between cortical SO and hippocampal SWRs in a model of the hippocampo–cortico–thalamic network and compared the results with human intracranial recordings during sleep. We observed that ripple occurrence peaked following the onset of an Up-state of SO and that cortical input to hippocampus was crucial to maintain this relationship. A small fraction of ripples occurred during the Down-state and controlled initiation of the next Up-state. We observed that the effect of ripple depends on its precise timing, which supports the idea that ripples occurring at different phases of SO might serve different functions, particularly in the context of encoding the new and reactivation of the old memories during memory consolidation. The study revealed complex bidirectional interaction of SWRs and SO in which early hippocampal ripples influence transitions to Up-state, while cortical Up-states control occurrence of the later ripples, which in turn influence transition to Down-state.

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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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Positive Arousal Enhances the Consolidation of Item Memory

Swiss Journal of Psychology ◽

10.1024/1421-0185/a000151 ◽

2015 ◽

Vol 74 (2) ◽

pp. 91-104 ◽

Cited By ~ 1

Author(s):

Bo Wang

Keyword(s):

Episodic Memory ◽

Memory Consolidation ◽

Source Memory ◽

Emotional Arousal ◽

Theoretical Models ◽

Memory Test ◽

Learning Phase ◽

Item Memory ◽

Memory Tests ◽

Immediate Memory

Emotional arousal induced after learning has been shown to modulate memory consolidation. However, it is unclear whether the effect of postlearning arousal can extend to different aspects of memory. This study examined the effect of postlearning positive arousal on both item memory and source memory. Participants learned a list of neutral words and took an immediate memory test. Then they watched a positive or a neutral videoclip and took delayed memory tests after either 25 minutes or 1 week had elapsed after the learning phase. In both delay conditions, positive arousal enhanced consolidation of item memory as measured by overall recognition. Furthermore, positive arousal enhanced consolidation of familiarity but not recollection. However, positive arousal appeared to have no effect on consolidation of source memory. These findings have implications for building theoretical models of the effect of emotional arousal on consolidation of episodic memory and for applying postlearning emotional arousal as a technique of memory intervention.

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Hippocampus-retrosplenial cortex interaction is increased during phasic REM and contributes to memory consolidation

Scientific Reports ◽

10.1038/s41598-021-91659-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Daniel Gomes de Almeida-Filho ◽

Bruna Del Vechio Koike ◽

Francesca Billwiller ◽

Kelly Soares Farias ◽

Igor Rafael Praxedes de Sales ◽

...

Keyword(s):

Rem Sleep ◽

Memory Consolidation ◽

Retrosplenial Cortex ◽

Contextual Fear Conditioning ◽

Oscillatory Activity ◽

Theta Oscillation ◽

Contextual Fear ◽

Before And After ◽

Freely Behaving ◽

Phasic Rem Sleep

AbstractHippocampal (HPC) theta oscillation during post-training rapid eye movement (REM) sleep supports spatial learning. Theta also modulates neuronal and oscillatory activity in the retrosplenial cortex (RSC) during REM sleep. To investigate the relevance of theta-driven interaction between these two regions to memory consolidation, we computed the Granger causality within theta range on electrophysiological data recorded in freely behaving rats during REM sleep, both before and after contextual fear conditioning. We found a training-induced modulation of causality between HPC and RSC that was correlated with memory retrieval 24 h later. Retrieval was proportional to the change in the relative influence RSC exerted upon HPC theta oscillation. Importantly, causality peaked during theta acceleration, in synchrony with phasic REM sleep. Altogether, these results support a role for phasic REM sleep in hippocampo-cortical memory consolidation and suggest that causality modulation between RSC and HPC during REM sleep plays a functional role in that phenomenon.

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072 Sleep Spindle Harmonics in Insomnia

SLEEP ◽

10.1093/sleep/zsab072.071 ◽

2021 ◽

Vol 44 (Supplement_2) ◽

pp. A29-A30

Author(s):

Michael Goldstein ◽

Monika Haack ◽

Janet Mullington

Keyword(s):

Spectral Power ◽

Nrem Sleep ◽

Sleep Time ◽

Sleep Spindle ◽

Time Frequency ◽

Insomnia Disorder ◽

Spectral Peaks ◽

Limited Application ◽

Thalamic Relay Nuclei ◽

Restorative Sleep

Abstract Introduction Prior research has reported NREM spectral EEG differences between individuals with insomnia and good-sleeper controls, including elevated high-frequency EEG power (beta/gamma bands, ~16-50Hz) and, to a lesser extent, elevations in sleep spindle parameters. However, the mechanisms driving these differences remain unclear. Harmonics have been observed in EEG data as spectral peaks at multiples of a fundamental frequency associated with an event (e.g., for a 14Hz spindle, the 2nd harmonic is expected to be a peak at 28Hz). Thus far, there has been very limited application of this idea of spectral harmonics to sleep spindles, even though these patterns can indeed be seen in some existing literature. We sought to build on this literature to apply spectral harmonic analysis to better understand differences between insomnia and good sleepers. Methods 15 individuals with insomnia disorder (DSM-5 criteria, 13 female, age 18–32 years) and 15 good-sleeper controls (matched for sex, age, and BMI) completed an overnight polysomnography recording in the laboratory and subsequent daytime testing. Insomnia diagnosis was determined by a board-certified sleep specialist, and exclusion criteria included psychiatric history within past 6 months, other sleep disorders, significant medical conditions, and medications with significant effects on inflammation, autonomic function, or other psychotropic effects. Results Consistent with prior studies, we found elevated sleep spindle density and fast sigma power (14-16Hz). Despite no difference in beta or gamma band power when averaged across NREM sleep, time-frequency analysis centered on the peaks of detected spindles revealed a phasic elevation in spectral power surrounding the 28Hz harmonic peak in the insomnia group, especially for spindles coupled with slow waves. We also observed an overall pattern of time-locked delay in the 28Hz harmonic peak, occurring approximately 40 msec after spindle peaks. Furthermore, we observed a 42Hz ‘3rd harmonic’ peak, not yet predicted by the existing modeling work, which was also elevated for insomnia. Conclusion In conjunction with existing mathematical modeling work that has linked sleep spindle harmonic peaks with thalamic relay nuclei as the primary generators of this EEG signature, these findings may enable novel insights into specific thalamocortical mechanisms of insomnia and non-restorative sleep. Support (if any) NIH 5T32HL007901-22

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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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Manipulating neural activity and sleep-dependent memory consolidation

Neuroforum ◽

10.1515/nf-2020-0002 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Maryam Ghorbani ◽

Lisa Marshall

Keyword(s):

Eye Movement ◽

Neural Activity ◽

Memory Consolidation ◽

Nrem Sleep ◽

Neural Oscillations ◽

Rapid Eye Movement ◽

Hippocampus Dependent Memory

AbstractSleep contributes actively to the consolidation of many forms of memory. This review describes the neural oscillations of non-rapid eye movement (NREM) sleep, the structures underlying these oscillations and their relation to hippocampus-dependent memory consolidation. A main focus lies on the relation between inter- and intraregional interactions and their electrophysiological representation. Methods for modulating neural oscillations with the intent of affecting memory consolidation are presented.

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0327 NREM Sleep EEG in Typically Developing and Drug-Naïve ADHD Adolescents: Data from a Longitudinal Study

SLEEP ◽

10.1093/sleep/zsaa056.324 ◽

2020 ◽

Vol 43 (Supplement_1) ◽

pp. A124-A124

Author(s):

T Basishvili ◽

M Eliozishvili ◽

T Oniani ◽

T Tchintcharauli ◽

I Sakhelashvili ◽

...

Keyword(s):

Longitudinal Study ◽

Nrem Sleep ◽

Sleep Eeg ◽

Brain Maturation ◽

Adhd Group ◽

Typically Developing ◽

Eeg Activity ◽

Theta Power ◽

Delta Power ◽

Drug Naïve

Abstract Introduction Structural MRI studies suggest delayed brain maturation in children with attention deficit hyperactivity disorder (ADHD). The steep adolescent decline in sleep slow wave EEG activity provides an opportunity to investigate brain electrophysiological evidence for this maturational delay. Most ADHD sleep EEG studies have been cross-sectional. Here we present data from an ongoing longitudinal study of the maturational trajectories of sleep EEG in drug-naïve ADHD and typically developing adolescents. Methods Nine children diagnosed with ADHD (combined subtype, DSM-V criteria, mean age 12.39±0.61 years), and nine typically developing controls (12.07±0.35 years) were recruited. Subjects underwent an adaptation night and all night polysomnography twice yearly at the Laboratory. Sleep EEG was analyzed using fast Fourier transform. NREM delta and theta EEG activity were compared across first two recordings. Results Group effects (ADHD vs. control) on all night delta and theta energy, and delta power were not significant (p>0.2 for all). All night theta power was lower (p=0.035) for the ADHD group, and all night NREM sleep duration trended (p=0.060) toward being lower for the ADHD group. Controlling for sleep duration differences by examining only the first 5 h of NREM sleep showed no group effect on delta power (p=0.77) and a trend toward lower theta power (p=0.057) for the ADHD group. Conclusion At age 12 to 13 years, NREM sleep delta EEG did not differ between ADHD and control subjects. Theta power, which declines at a younger age than delta, was lower in control subjects. The two recordings thus far differ only by 6 months. The entire study will provide 5 semiannual recordings and allow us to determine if the higher theta power in the ADHD group will hold and if delta power will be greater as well, and thus provide electrophysiological support for the delayed brain maturation suggested by MRI findings. Support Shota Rustaveli National Science Foundation Grant FR17_94; Subjects Recruitment Support - Mental Health Service in Tbilisi “Kamara”.

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

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_00433 ◽

2013 ◽

Vol 25 (10) ◽

pp. 1597-1610 ◽

Cited By ~ 65

Author(s):

Erik J. Kaestner ◽

John T. Wixted ◽

Sara C. Mednick

Keyword(s):

Rem Sleep ◽

Memory Consolidation ◽

Declarative Memory ◽

Memory Performance ◽

Emotional Memory ◽

Limited Range ◽

Sleep Spindles ◽

Sleep Spindle ◽

Emotional Stimuli ◽

Valence And Arousal

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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