scholarly journals P143 Sleep-dependent declarative memory consolidation and NREM sleep EEG oscillations in older adults with obstructive sleep apnea

2021 ◽  
Vol 2 (Supplement_1) ◽  
pp. A68-A68
Author(s):  
J Teh ◽  
L Grummit ◽  
C Haroutonian ◽  
N Cross ◽  
D Bartlett ◽  
...  
Keyword(s):  
Older Adults ◽  
Memory Consolidation ◽  
Declarative Memory ◽  
Memory Task ◽  
Nrem Sleep ◽  
Sleep Eeg ◽  
Control Group ◽  
Sleep Spindles ◽  
Targeted Interventions ◽  
Obstructive Sleep

Abstract Objectives To compare overnight declarative memory consolidation and NREM sleep EEG oscillations in older adults with OSA to an age-matched control group, and to assess the quantitative sleep EEG features as correlates of memory consolidation. Methods 46 participants (24 without OSA and 22 patients with OSA) were recruited. Participants completed a word-paired associates declarative memory task before and after an 8-hour sleep opportunity with full polysomnography. Power spectral analysis was performed on all-night EEG recorded at frontal and central electrode sites. We calculated slow wave activity (slow oscillations absolute power 0.25–1 Hz; and delta EEG power (0.5–4.5 Hz) in NREM sleep. Slow spindle density (11–13 Hz, events p/min) and fast spindle density (13–16 Hz, events p/min) in stage N2 was derived using an automated spindle detection algorithm. Results Patients with OSA showed no significant differences in overnight memory recall and recognition compared to individuals without OSA. The OSA group showed reduced slow spindle density at the central region and fast spindle density at the frontal region relative to controls. No differences were observed in SWA. Within group correlations showed slow and fast spindle density were correlated to percent recognition in the control group. Conclusion Older adults with OSA had deficits in slow and fast sleep spindles compared to controls. OSA patients showed preserved sleep-dependent declarative memory consolidation despite sleep fragmentation and intermittent hypoxemia. Sleep spindles were positively correlated with overnight memory consolidation in controls but not OSA patients. Targeted interventions to boost spindles may enhance memory consolidation in older adults.

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

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.

scholarly journals 0669 The Effects Of Continuous Positive Airway Pressure Therapy In Moderate To Severe Obstructive Sleep Apnea: A High-density EEG Study

SLEEP ◽  
2020 ◽  
Vol 43 (Supplement_1) ◽  
pp. A255-A255
Author(s):  
A L D’Rozario ◽  
C Kao ◽  
A E Mullins ◽  
N Memarian ◽  
B Yee ◽  
...  
Keyword(s):  
Memory Consolidation ◽  
Declarative Memory ◽  
Nrem Sleep ◽  
High Density ◽  
Sleep Eeg ◽  
Therapeutic Effects ◽  
Topographic Analysis ◽  
Pressure Therapy ◽  
Power Maps ◽  
Eeg Power

Abstract Introduction A previous high-density electroencephalography (EEG) investigation in asymptomatic OSA showed regional deficits in sleep EEG power particularly slow wave activity (SWA) during NREM sleep in the parietal region. It is unclear whether treatment with CPAP can reverse local sleep EEG abnormalities in OSA, and whether any recovery is related to improvement in sleep-dependent memory consolidation. Methods Fifteen male participants (age 50.4±6.5yrs, AHI 51.7±23.5/h) with moderate-severe OSA (AHI>15/h) underwent overnight polysomnography with 256-channel high-density EEG at baseline and following 3 months of CPAP therapy. A word paired associates declarative memory task was administered before and after sleep. After artefact removal, spectral analysis was performed for all channels. Topographical power maps were calculated for standard frequency ranges for NREM sleep (164 channels within a 0.57 radius from the vertex). Maps were compared using both absolute and normalized power (z-scores computed for each subject) and differences between baseline and treatment were determined by statistical nonparametric mapping. Results In 11 CPAP compliant patients (intolerant of CPAP [n=3]/high-density EEG [n=1]), analysis of polysomnographic variables showed that total sleep time did not differ but N1 (baseline vs. treatment: 66.9 vs. 39.5 mins,p=0.008) and N2 (195.0 vs. 150.6 mins,p=0.002) sleep was lower and N3 (89.8 vs. 128.7 mins,p=0.003) was higher after CPAP. Topographic analysis of high-density EEG data revealed a regional increase in SWA (1-4.5Hz) EEG power during N3 sleep in a cluster of electrodes overlying the centro-parietal cortex (cluster mean t-value=2.87,p=0.02). The change in overnight declarative memory consolidation (% recognition) after CPAP was significantly correlated with the change in slow spindle frequency activity in frontal regions (cluster mean r=0.875,p=0.003). Conclusion CPAP treatment may enhance localised deficits in sleep EEG activity in OSA, and specific regional recovery may translate to memory improvements in the short-term. These data also highlight the potential for long-term therapeutic effects on cognitive outcomes in OSA. Support  

scholarly journals Shining a Light on the Mechanisms of Sleep for Memory Consolidation

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.

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

2013 ◽  
Vol 25 (10) ◽  
pp. 1597-1610 ◽  
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.

scholarly journals 0086 Daytime Napping and Memory Consolidation of Novel Word Learning in Children and Adults

SLEEP ◽  
2020 ◽  
Vol 43 (Supplement_1) ◽  
pp. A35-A35
Author(s):  
E van Rijn ◽  
S A Walker ◽  
V C Knowland ◽  
S A Cairney ◽  
A D Gouws ◽  
...  
Keyword(s):  
White Matter ◽  
Memory Consolidation ◽  
Slow Wave Sleep ◽  
Diffusion Tensor ◽  
Brain Connectivity ◽  
Nrem Sleep ◽  
Sleep Spindles ◽  
Adults And Children ◽  
Structural Brain ◽  
Novel Words

Abstract Introduction Memory for novel words benefits from sleep, particularly non-rapid eye movement (NREM) sleep and its features, such as sleep spindles and slow oscillations. This is consistent with systems consolidation models, in which sleep supports transfer from hippocampal to neocortical memory networks. Larger amounts of slow wave sleep in children has been proposed to account for enhanced consolidation effects, but such studies have typically focused on nocturnal sleep. We examined whether daytime naps benefit word retention in adults and children aged 10–12 years, and whether this relationship in children is affected by differences in white matter pathway microstructure. We hypothesized that the link between memory consolidation and structural brain connectivity will be mediated by the degree of sleep spindles during the nap. Methods Adults (N = 31; mean age = 20.91, SD = 1.55) and children (N = 38; mean age = 11.95, SD = 0.88) learned spoken novel words, followed by a 90-minute nap opportunity monitored with polysomnography. Memory for the words was tested pre- and post-nap. Children’s structural brain connectivity was measured using diffusion tensor imaging (DTI). Results Word memory was preserved following sleep in adults, while an adult wake control condition showed deterioration. Similarly, in children memory performance was stable over the nap, with wake control data currently being collected. Analyses relating behavioral changes over the nap to NREM sleep features and structural brain connectivity will be presented. Conclusion In line with sleep-dependent memory consolidation models, daytime naps protect novel words from forgetting in adults and children. Examining potential relationships between nap-based consolidation and structural integrity has important theoretical implications, given the increase in brain connectivity in language areas during childhood, as well as white matter alterations in developmental populations. Support This research was supported by the UK Economic and Social Research Council, grant no. ES/N009924/1.

scholarly journals 0789 Decreased Sigma Band Power During NREM Sleep in REM Sleep Behavior Disorder

SLEEP ◽  
2020 ◽  
Vol 43 (Supplement_1) ◽  
pp. A300-A300
Author(s):  
Y Lee ◽  
B Lee
Keyword(s):  
Rem Sleep ◽  
Spectral Power ◽  
Rem Sleep Behavior Disorder ◽  
Behavior Disorder ◽  
Nrem Sleep ◽  
Control Group ◽  
Sleep Behavior ◽  
Band Power ◽  
Potential Biomarker ◽  
Obstructive Sleep

Abstract Introduction REM sleep Behavior Disorder (RBD) is characterized by dream enacting behaviors and a loss of atonia during REM sleep. Early detection of RBD is important because it is considered premonitory symptoms neurodegenerative disorders. In this study, we investigated the slow and fast sigma band power of patients with RBD using frequency analysis. Methods Twenty patients who were diagnosed as RBD according to the ICSD-3 criteria and 20 age-matched controls who underwent polysomnography (PSG) for other sleep disorders (insomnia, snoring) and showed normal to mild obstructive sleep apnea (OSA). NREM sleep EEG data was extracted and N1 sleep data was excluded to minimize arousal artifact. Fast Fourier transform-based spectral power analysis was used to compute the power spectral densities of the EEG in the MATLAB environment. The sigma bands were divided into 2 discrete bands: slow sigma (11 to 13 Hz) and- fast sigma (13 to 15 Hz). Mann-Whitney U test by SPSS was used. Results RBD patients (61.9 ± 7.1 years old; 12 men) had a significantly lower sigma band power than the control group (61.5 ± 1.1 years old; 11 men) in central region (p = 0.028). Particularly, the slow sigma band power showed a bigger difference in all regions except O1 (F3 = 0.017, F4 = 0.027, C3 = 0.004, C4 = 0.009, O2 = 0.017). Conclusion Sigma power was lower in the RBD patients than in the control. It suggests that RBD has impaired cortical activity. Thus, decreased spindle activity during NREM sleep may be a potential biomarker of RBD. Support  

scholarly journals Age-related changes in slow wave activity rise time and NREM sleep EEG with and without zolpidem in healthy young and older adults

2014 ◽  
Vol 15 (9) ◽  
pp. 1037-1045 ◽  
Author(s):  
Evan D. Chinoy ◽  
Danielle J. Frey ◽  
Daniel N. Kaslovsky ◽  
Francois G. Meyer ◽  
Kenneth P. Wright
Keyword(s):  
Older Adults ◽  
Slow Wave ◽  
Rise Time ◽  
Nrem Sleep ◽  
Wave Activity ◽  
Slow Wave Activity ◽  
Sleep Eeg ◽  
Age Related ◽  
Age Related Changes

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

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.

scholarly journals CPAP Treatment Partly Normalizes Sleep Spindle Features in Obstructive Sleep Apnea

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Tiia Saunamäki ◽  
Eero Huupponen ◽  
Juho Loponen ◽  
Sari-Leena Himanen
Keyword(s):  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Airway Pressure ◽  
Positive Airway Pressure ◽  
Control Group ◽  
Sleep Spindles ◽  
Sleep Spindle ◽  
Cpap Treatment ◽  
Automated Method ◽  
Obstructive Sleep

Objective. Obstructive sleep apnea (OSA) decreases sleep spindle density and frequency. We evaluated the effects of continuous positive airway pressure (CPAP) treatment on different features of sleep spindles.Methods. Twenty OSA patients underwent two night polysomnographies in a diagnostic phase and one night polysomnography after 6 months of CPAP treatment. The control group comprised 20 healthy controls. Sleep spindles were analyzed by a previously developed automated method. Unilateral and bilateral spindles were identified in central and frontopolar brain locations. Spindle density and frequency were determined for the first and last half of the NREM time.Results. The density of bilateral central spindles, which did not change in the untreated OSA patients, increased towards the morning hours during CPAP treatment and in the controls. Central spindles did not become faster with sleep in OSA patients and the central spindles remained slow in the left hemisphere even with CPAP.Conclusion. CPAP treatment normalized spindle features only partially. The changes may be associated with deficits in thalamocortical spindle generating loops.Significance. This study shows that some sleep spindle changes persist after CPAP treatment in OSA patients. The association of these changes to daytime symptoms in OSA patients needs to be further evaluated.

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