Analysis of slow-wave activity and slow-wave oscillations prior to somnambulism.

PubMed

Jaar, Olivier; Pilon, Mathieu; Carrier, Julie; Montplaisir, Jacques; Zadra, Antonio

2010-11-01

STUDY OBJECTIVIES: several studies have investigated slow wave sleep EEG parameters, including slow-wave activity (SWA) in relation to somnambulism, but results have been both inconsistent and contradictory. The first goal of the present study was to conduct a quantitative analysis of sleepwalkers' sleep EEG by studying fluctuations in spectral power for delta (1-4 Hz) and slow delta (0.5-1 Hz) before the onset of somnambulistic episodes. A secondary aim was to detect slow-wave oscillations to examine changes in their amplitude and density prior to behavioral episodes. twenty-two adult sleepwalkers were investigated polysomnographically following 25 h of sleep deprivation. analysis of patients' sleep EEG over the 200 sec prior to the episodes' onset revealed that the episodes were not preceded by a gradual increase in spectral power for either delta or slow delta over frontal, central, or parietal leads. However, time course comparisons revealed significant changes in the density of slow-wave oscillations as well as in very slow oscillations with significant increases occurring during the final 20 sec immediately preceding episode onset. the specificity of these sleep EEG parameters for the occurrence and diagnosis of NREM parasomnias remains to be determined.

Enhancing Slow Wave Sleep with Sodium Oxybate Reduces the Behavioral and Physiological Impact of Sleep Loss

PubMed Central

Walsh, James K.; Hall-Porter, Janine M.; Griffin, Kara S.; Dodson, Ehren R.; Forst, Elizabeth H.; Curry, Denise T.; Eisenstein, Rhody D.; Schweitzer, Paula K.

2010-01-01

Study Objectives: To investigate whether enhancement of slow wave sleep (SWS) with sodium oxybate reduces the impact of sleep deprivation. Design: Double-blind, parallel group, placebo-controlled design Setting: Sleep research laboratory Participants: Fifty-eight healthy adults (28 placebo, 30 sodium oxybate), ages 18-50 years. Interventions: A 5-day protocol included 2 screening/baseline nights and days, 2 sleep deprivation nights, each followed by a 3-h daytime (08:00-11:00) sleep opportunity and a recovery night. Sodium oxybate or placebo was administered prior to each daytime sleep period. Multiple sleep latency test (MSLT), psychomotor vigilance test (PVT), Karolinska Sleepiness Scale (KSS), and Profile of Mood States were administered during waking hours. Measurements and Results: During daytime sleep, the sodium oxybate group had more SWS, more EEG spectral power in the 1-9 Hz range, and less REM. Mean MSLT latency was longer for the sodium oxybate group on the night following the first daytime sleep period and on the day following the second day sleep period. Median PVT reaction time was faster in the sodium oxybate group following the second day sleep period. The change from baseline in SWS was positively correlated with the change in MSLT and KSS. During recovery sleep the sodium oxybate group had less TST, SWS, REM, and slow wave activity (SWA) than the placebo group. Conclusions: Pharmacological enhancement of SWS with sodium oxybate resulted in a reduced response to sleep loss on measures of alertness and attention. In addition, SWS enhancement during sleep restriction appears to result in a reduced homeostatic response to sleep loss. Citation: Walsh JK; Hall-Porter JM; Griffin KS; Dodson ER; Forst EH; Curry DT; Eisenstein RD; Schweitzer PK. Enhancing slow wave sleep with sodium oxybate reduces the behavioral and physiological impact of sleep loss. SLEEP 2010;33(9):1217-1225. PMID:20857869

Medical management with diazepam for electrical status epilepticus during slow wave sleep in children.

PubMed

Francois, Densley; Roberts, Jessica; Hess, Stephany; Probst, Luke; Eksioglu, Yaman

2014-03-01

Oral diazepam, administered in varying doses, is among the few proposed treatment options for electrical status epilepticus during slow wave sleep in children. We sought to retrospectively evaluate the long-term efficacy of high-dose oral diazepam in reducing electrographic and clinical evidence of electrical status epilepticus during slow wave sleep in children. Additionally, we surveyed caregivers to assess safety and behavioral outcomes related to ongoing therapy. We collected demographic and clinical data on children treated for electrical status epilepticus during slow wave sleep between October 2010 and March 2013. We sought to identify the number of patients who achieved at least a 50% reduction in spike wave index on electroencephalograph after receiving high-dose oral diazepam. We also administered a questionnaire to caregivers to assess for behavioral problems and side effects. We identified 42 evaluable patients who received high-dose diazepam (range 0.23-2.02 mg/kg per day) to treat electrical status epilepticus during slow wave sleep. Twenty-six patients had spike reduction data and 18/26 (69.2%) children achieved a greater than 50% reduction in spike wave count from an average of 15.54 to 5.05 (P = 0.001). We received 28 responses to the questionnaire. Some patients experienced new onset of difficulties with problem-solving and speech and writing development. Sleep disturbances (50%) and irritability (57.1%) were the most frequent side effects reported. There did not appear to be a dose-related effect with electroencephalograph changes, behavioral effects, or side effects. High-dose oral diazepam significantly reduces the spike wave count on electroencephalograph in children with electrical status epilepticus during slow wave sleep. Although this therapy improves electroencephalograph-related findings, it can be associated with concerning neurological and behavioral side effects in some individuals, so further study is warranted. Copyright © 2014

Slow Wave Sleep and Long Duration Spaceflight

NASA Technical Reports Server (NTRS)

Orr, M.; Whitmire, A.; Arias, D.; Leveton, L.

2011-01-01

To review the literature on slow wave sleep (SWS) in long duration space flight, and place this within the context of the broader literature on SWS particularly with respect to analogous environments such as the Antarctic. Explore how SWS could be measured within the International Space Station (ISS) context with the aim to utilize the ISS as an analog for future extra-orbital long duration missions. Discuss the potential use of emergent minimally intrusive wireless technologies like ZEO for integrated prelaunch, flight, and return to Earth analysis and optimization of SWS (and general quality of sleep).

Old Brains Come Uncoupled in Sleep: Slow Wave-Spindle Synchrony, Brain Atrophy, and Forgetting.

PubMed

Helfrich, Randolph F; Mander, Bryce A; Jagust, William J; Knight, Robert T; Walker, Matthew P

2018-01-03

The coupled interaction between slow-wave oscillations and sleep spindles during non-rapid-eye-movement (NREM) sleep has been proposed to support memory consolidation. However, little evidence in humans supports this theory. Moreover, whether such dynamic coupling is impaired as a consequence of brain aging in later life, contributing to cognitive and memory decline, is unknown. Combining electroencephalography (EEG), structural MRI, and sleep-dependent memory assessment, we addressed these questions in cognitively normal young and older adults. Directional cross-frequency coupling analyses demonstrated that the slow wave governs a precise temporal coordination of sleep spindles, the quality of which predicts overnight memory retention. Moreover, selective atrophy within the medial frontal cortex in older adults predicted a temporal dispersion of this slow wave-spindle coupling, impairing overnight memory consolidation and leading to forgetting. Prefrontal-dependent deficits in the spatiotemporal coordination of NREM sleep oscillations therefore represent one pathway explaining age-related memory decline. Copyright © 2017 Elsevier Inc. All rights reserved.

Slow Wave Sleep Enhancement with Gaboxadol Reduces Daytime Sleepiness During Sleep Restriction

PubMed Central

Walsh, James K.; Snyder, Ellen; Hall, Janine; Randazzo, Angela C.; Griffin, Kara; Groeger, John; Eisenstein, Rhody; Feren, Stephen D.; Dickey, Pam; Schweitzer, Paula K.

2008-01-01

Study Objectives: To evaluate the impact of enhanced slow wave sleep (SWS) on behavioral, psychological, and physiological changes resulting from sleep restriction. Design: A double-blind, parallel group, placebo-controlled design was used to compare gaboxadol (GBX) 15 mg, a SWS-enhancing drug, to placebo during 4 nights of sleep restriction (5 h/night). Behavioral, psychological, and physiological measures of the impact of sleep restriction were assessed in both groups at baseline, during sleep restriction and following recovery sleep. Setting: Sleep research laboratory. Participants: Forty-one healthy adults; 9 males and 12 females (mean age: 32.0 ± 9.9 y) in the placebo group and 10 males and 10 females (mean age: 31.9 ± 10.2 y) in the GBX group. Interventions: Both experimental groups underwent 4 nights of sleep restriction. Each group received either GBX 15 mg or placebo on all sleep restriction nights, and both groups received placebo on baseline and recovery nights. Measurements and Results: Polysomnography documented a SWS-enhancing effect of GBX with no group difference in total sleep time during sleep restriction. The placebo group displayed the predicted deficits due to sleep restriction on the multiple sleep latency test (MSLT) and on introspective measures of sleepiness and fatigue. Compared to placebo, the GBX group showed significantly less physiological sleepiness on the MSLT and lower levels of introspective sleepiness and fatigue during sleep restriction. There were no differences between groups on the psychomotor vigilance task (PVT) and a cognitive test battery, but these measures were minimally affected by sleep restriction in this study. The correlation between change from baseline in MSLT on Day 6 and change from baseline in SWS on Night 6 was significant in the GBX group and in both groups combined. Conclusions: The results of this study are consistent with the hypothesis that enhanced SWS, in this study produced by GBX, reduces

Circadian regulation of slow waves in human sleep: Topographical aspects

PubMed Central

Lazar, Alpar S.; Lazar, Zsolt I.; Dijk, Derk-Jan

2015-01-01

Slow waves (SWs, 0.5–4 Hz) in field potentials during sleep reflect synchronized alternations between bursts of action potentials and periods of membrane hyperpolarization of cortical neurons. SWs decline during sleep and this is thought to be related to a reduction of synaptic strength in cortical networks and to be central to sleep's role in maintaining brain function. A central assumption in current concepts of sleep function is that SWs during sleep, and associated recovery processes, are independent of circadian rhythmicity. We tested this hypothesis by quantifying all SWs from 12 EEG derivations in 34 participants in whom 231 sleep periods were scheduled across the circadian cycle in a 10-day forced-desynchrony protocol which allowed estimation of the separate circadian and sleep-dependent modulation of SWs. Circadian rhythmicity significantly modulated the incidence, amplitude, frequency and the slope of the SWs such that the peaks of the circadian rhythms in these slow-wave parameters were located during the biological day. Topographical analyses demonstrated that the sleep-dependent modulation of SW characteristics was most prominent in frontal brain areas whereas the circadian effect was similar to or greater than the sleep-dependent modulation over the central and posterior brain regions. The data demonstrate that circadian rhythmicity directly modulates characteristics of SWs thought to be related to synaptic plasticity and that this modulation depends on topography. These findings have implications for the understanding of local sleep regulation and conditions such as ageing, depression, and neurodegeneration which are associated with changes in SWs, neural plasticity and circadian rhythmicity. PMID:25979664

Temporal coordination of olfactory cortex sharp-wave activity with up- and downstates in the orbitofrontal cortex during slow-wave sleep.

PubMed

Onisawa, Naomi; Manabe, Hiroyuki; Mori, Kensaku

2017-01-01

During slow-wave sleep, interareal communications via coordinated, slow oscillatory activities occur in the large-scale networks of the mammalian neocortex. Because olfactory cortex (OC) areas, which belong to paleocortex, show characteristic sharp-wave (SPW) activity during slow-wave sleep, we examined whether OC SPWs in freely behaving rats occur in temporal coordination with up- and downstates of the orbitofrontal cortex (OFC) slow oscillation. Simultaneous recordings of local field potentials and spike activities in the OC and OFC showed that during the downstate in the OFC, the OC also exhibited downstate with greatly reduced neuronal activity and suppression of SPW generation. OC SPWs occurred during two distinct phases of the upstate of the OFC: early-phase SPWs occurred at the start of upstate shortly after the down-to-up transition in the OFC, whereas late-phase SPWs were generated at the end of upstate shortly before the up-to-down transition. Such temporal coordination between neocortical up- and downstates and olfactory system SPWs was observed between the prefrontal cortex areas (OFC and medial prefrontal cortex) and the OC areas (anterior piriform cortex and posterior piriform cortex). These results suggest that during slow-wave sleep, OC and OFC areas communicate preferentially in specific time windows shortly after the down-to-up transition and shortly before the up-to-down transition. Simultaneous recordings of local field potentials and spike activities in the anterior piriform cortex (APC) and orbitofrontal cortex (OFC) during slow-wave sleep showed that APC sharp waves tended to occur during two distinct phases of OFC upstate: early phase, shortly after the down-to-up transition, and late phase, shortly before the up-to-down transition, suggesting that during slow-wave sleep, olfactory cortex and OFC areas communicate preferentially in the specific time windows. Copyright © 2017 the American Physiological Society.

Temporal coordination of olfactory cortex sharp-wave activity with up- and downstates in the orbitofrontal cortex during slow-wave sleep

PubMed Central

Onisawa, Naomi; Mori, Kensaku

2016-01-01

During slow-wave sleep, interareal communications via coordinated, slow oscillatory activities occur in the large-scale networks of the mammalian neocortex. Because olfactory cortex (OC) areas, which belong to paleocortex, show characteristic sharp-wave (SPW) activity during slow-wave sleep, we examined whether OC SPWs in freely behaving rats occur in temporal coordination with up- and downstates of the orbitofrontal cortex (OFC) slow oscillation. Simultaneous recordings of local field potentials and spike activities in the OC and OFC showed that during the downstate in the OFC, the OC also exhibited downstate with greatly reduced neuronal activity and suppression of SPW generation. OC SPWs occurred during two distinct phases of the upstate of the OFC: early-phase SPWs occurred at the start of upstate shortly after the down-to-up transition in the OFC, whereas late-phase SPWs were generated at the end of upstate shortly before the up-to-down transition. Such temporal coordination between neocortical up- and downstates and olfactory system SPWs was observed between the prefrontal cortex areas (OFC and medial prefrontal cortex) and the OC areas (anterior piriform cortex and posterior piriform cortex). These results suggest that during slow-wave sleep, OC and OFC areas communicate preferentially in specific time windows shortly after the down-to-up transition and shortly before the up-to-down transition. NEW & NOTEWORTHY Simultaneous recordings of local field potentials and spike activities in the anterior piriform cortex (APC) and orbitofrontal cortex (OFC) during slow-wave sleep showed that APC sharp waves tended to occur during two distinct phases of OFC upstate: early phase, shortly after the down-to-up transition, and late phase, shortly before the up-to-down transition, suggesting that during slow-wave sleep, olfactory cortex and OFC areas communicate preferentially in the specific time windows. PMID:27733591

How do children fall asleep? A high-density EEG study of slow waves in the transition from wake to sleep.

PubMed

Spiess, Mathilde; Bernardi, Giulio; Kurth, Salome; Ringli, Maya; Wehrle, Flavia M; Jenni, Oskar G; Huber, Reto; Siclari, Francesca

2018-05-17

Slow waves, the hallmarks of non-rapid eye-movement (NREM) sleep, are thought to reflect maturational changes that occur in the cerebral cortex throughout childhood and adolescence. Recent work in adults has revealed evidence for two distinct synchronization processes involved in the generation of slow waves, which sequentially come into play in the transition to sleep. In order to understand how these two processes are affected by developmental changes, we compared slow waves between children and young adults in the falling asleep period. The sleep onset period (starting 30s before end of alpha activity and ending at the first slow wave sequence) was extracted from 72 sleep onset high-density EEG recordings (128 electrodes) of 49 healthy subjects (age 8-25). Using an automatic slow wave detection algorithm, the number, amplitude and slope of slow waves were analyzed and compared between children (age 8-11) and young adults (age 20-25). Slow wave number and amplitude increased linearly in the falling asleep period in children, while in young adults, isolated high-amplitude slow waves (type I) dominated initially and numerous smaller slow waves (type II) with progressively increasing amplitude occurred later. Compared to young adults, children displayed faster increases in slow wave amplitude and number across the falling asleep period in central and posterior brain regions, respectively, and also showed larger slow waves during wakefulness immediately prior to sleep. Children do not display the two temporally dissociated slow wave synchronization processes in the falling asleep period observed in adults, suggesting that maturational factors underlie the temporal segregation of these two processes. Our findings provide novel perspectives for studying how sleep-related behaviors and dreaming differ between children and adults. Copyright © 2018 Elsevier Inc. All rights reserved.

Neuronal Networks in Children with Continuous Spikes and Waves during Slow Sleep

ERIC Educational Resources Information Center

Siniatchkin, Michael; Groening, Kristina; Moehring, Jan; Moeller, Friederike; Boor, Rainer; Brodbeck, Verena; Michel, Christoph M.; Rodionov, Roman; Lemieux, Louis; Stephani, Ulrich

2010-01-01

Epileptic encephalopathy with continuous spikes and waves during slow sleep is an age-related disorder characterized by the presence of interictal epileptiform discharges during at least greater than 85% of sleep and cognitive deficits associated with this electroencephalography pattern. The pathophysiological mechanisms of continuous spikes and…

Slow waves, sharp waves, ripples, and REM in sleeping dragons.

PubMed

Shein-Idelson, Mark; Ondracek, Janie M; Liaw, Hua-Peng; Reiter, Sam; Laurent, Gilles

2016-04-29

Sleep has been described in animals ranging from worms to humans. Yet the electrophysiological characteristics of brain sleep, such as slow-wave (SW) and rapid eye movement (REM) activities, are thought to be restricted to mammals and birds. Recording from the brain of a lizard, the Australian dragon Pogona vitticeps, we identified SW and REM sleep patterns, thus pushing back the probable evolution of these dynamics at least to the emergence of amniotes. The SW and REM sleep patterns that we observed in lizards oscillated continuously for 6 to 10 hours with a period of ~80 seconds. The networks controlling SW-REM antagonism in amniotes may thus originate from a common, ancient oscillator circuit. Lizard SW dynamics closely resemble those observed in rodent hippocampal CA1, yet they originate from a brain area, the dorsal ventricular ridge, that has no obvious hodological similarity with the mammalian hippocampus. Copyright © 2016, American Association for the Advancement of Science.

Effects of oral temazepam on slow waves during non-rapid eye movement sleep in healthy young adults: A high-density EEG investigation.

PubMed

Plante, D T; Goldstein, M R; Cook, J D; Smith, R; Riedner, B A; Rumble, M E; Jelenchick, L; Roth, A; Tononi, G; Benca, R M; Peterson, M J

2016-03-01

Slow waves are characteristic waveforms that occur during non-rapid eye movement (NREM) sleep that play an integral role in sleep quality and brain plasticity. Benzodiazepines are commonly used medications that alter slow waves, however, their effects may depend on the time of night and measure used to characterize slow waves. Prior investigations have utilized minimal scalp derivations to evaluate the effects of benzodiazepines on slow waves, and thus the topography of changes to slow waves induced by benzodiazepines has yet to be fully elucidated. This study used high-density electroencephalography (hdEEG) to evaluate the effects of oral temazepam on slow wave activity, incidence, and morphology during NREM sleep in 18 healthy adults relative to placebo. Temazepam was associated with significant decreases in slow wave activity and incidence, which were most prominent in the latter portions of the sleep period. However, temazepam was also associated with a decrease in the magnitude of high-amplitude slow waves and their slopes in the first NREM sleep episode, which was most prominent in frontal derivations. These findings suggest that benzodiazepines produce changes in slow waves throughout the night that vary depending on cortical topography and measures used to characterize slow waves. Further research that explores the relationships between benzodiazepine-induced changes to slow waves and the functional effects of these waveforms is indicated. Copyright © 2016 Elsevier B.V. All rights reserved.

Optimizing detection and analysis of slow waves in sleep EEG.

PubMed

Mensen, Armand; Riedner, Brady; Tononi, Giulio

2016-12-01

Analysis of individual slow waves in EEG recording during sleep provides both greater sensitivity and specificity compared to spectral power measures. However, parameters for detection and analysis have not been widely explored and validated. We present a new, open-source, Matlab based, toolbox for the automatic detection and analysis of slow waves; with adjustable parameter settings, as well as manual correction and exploration of the results using a multi-faceted visualization tool. We explore a large search space of parameter settings for slow wave detection and measure their effects on a selection of outcome parameters. Every choice of parameter setting had some effect on at least one outcome parameter. In general, the largest effect sizes were found when choosing the EEG reference, type of canonical waveform, and amplitude thresholding. Previously published methods accurately detect large, global waves but are conservative and miss the detection of smaller amplitude, local slow waves. The toolbox has additional benefits in terms of speed, user-interface, and visualization options to compare and contrast slow waves. The exploration of parameter settings in the toolbox highlights the importance of careful selection of detection METHODS: The sensitivity and specificity of the automated detection can be improved by manually adding or deleting entire waves and or specific channels using the toolbox visualization functions. The toolbox standardizes the detection procedure, sets the stage for reliable results and comparisons and is easy to use without previous programming experience. Copyright © 2016 Elsevier B.V. All rights reserved.

Blindfolding during wakefulness causes decrease in sleep slow wave activity.

PubMed

Korf, Eva Magdalena; Mölle, Matthias; Born, Jan; Ngo, Hong-Viet V

2017-04-01

Slow wave activity (SWA, 0.5-4 Hz) represents the predominant EEG oscillatory activity during slow wave sleep (SWS). Its amplitude is considered in part a reflection of synaptic potentiation in cortical networks due to encoding of information during prior waking, with higher amplitude indicating stronger potentiation. Previous studies showed that increasing and diminishing specific motor behaviors produced corresponding changes in SWA in the respective motor cortical areas during subsequent SWS Here, we tested whether this relationship can be generalized to the visual system, that is, whether diminishing encoding of visual information likewise leads to a localized decrease in SWA over the visual cortex. Experiments were performed in healthy men whose eyes on two different days were or were not covered for 10.5 h before bedtime. The subject's EEG was recorded during sleep and, after sleep, visual evoked potentials (VEPs) were recorded. SWA during nonrapid eye movement sleep (NonREM sleep) was lower after blindfolding than after eyes open ( P  < 0.01). The decrease in SWA that was most consistent during the first 20 min of NonREM sleep, did not remain restricted to visual cortex regions, with changes over frontal and parietal cortical regions being even more pronounced. In the morning after sleep, the N75-P100 peak-to-peak-amplitude of the VEP was significantly diminished in the blindfolded condition. Our findings confirm a link between reduced wake encoding and diminished SWA during ensuing NonREM sleep, although this link appears not to be restricted to sensory cortical areas. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

A Mechanism for Upper Airway Stability during Slow Wave Sleep

PubMed Central

McSharry, David G.; Saboisky, Julian P.; DeYoung, Pam; Matteis, Paul; Jordan, Amy S.; Trinder, John; Smales, Erik; Hess, Lauren; Guo, Mengshuang; Malhotra, Atul

2013-01-01

Study Objectives: The severity of obstructive sleep apnea is diminished (sometimes markedly) during slow wave sleep (SWS). We sought to understand why SWS stabilizes the upper airway. Increased single motor unit (SMU) activity of the major upper airway dilating muscle (genioglossus) should improve upper airway stability. Therefore, we hypothesized that genioglossus SMUs would increase their activity during SWS in comparison with Stage N2 sleep. Design: The activity of genioglossus SMUs was studied on both sides of the transition between Stage N2 sleep and SWS. Setting: Sleep laboratory. Participants: Twenty-nine subjects (age 38 ± 13 yr, 17 males) were studied. Intervention: SWS. Measurement and Results: Subjects slept overnight with fine-wire electrodes in their genioglossus muscles and with full polysomnographic and end tidal carbon dioxide monitors. Fifteen inspiratory phasic (IP) and 11 inspiratory tonic (IT) units were identified from seven subjects and these units exhibited significantly increased inspiratory discharge frequencies during SWS compared with Stage N2 sleep. The peak discharge frequency of the inspiratory units (IP and IT) was 22.7 ± 4.1 Hz in SWS versus 20.3 ± 4.5 Hz in Stage N2 (P < 0.001). The IP units also fired for a longer duration (expressed as a percentage of inspiratory time) during SWS (104.6 ± 39.5 %TI) versus Stage N2 sleep (82.6 ± 39.5 %TI, P < 0.001). The IT units fired faster during expiration in SWS (14.2 ± 1.8 Hz) versus Stage N2 sleep (12.6 ± 3.1 Hz, P = 0.035). There was minimal recruitment or derecruitment of units between SWS and Stage N2 sleep. Conclusion: Increased genioglossus SMU activity likely makes the airway more stable and resistant to collapse throughout the respiratory cycle during SWS. Citation: McSharry DG; Saboisky JP; DeYoung P; Matteis P; Jordan AS; Trinder J; Smales E; Hess L; Guo M; Malhotra A. A mechanism for upper airway stability during slow wave sleep. SLEEP 2013;36(4):555-563. PMID:23565001

Automated selective disruption of slow wave sleep.

PubMed

Ooms, Sharon J; Zempel, John M; Holtzman, David M; Ju, Yo-El S

2017-04-01

Slow wave sleep (SWS) plays an important role in neurophysiologic restoration. Experimentally testing the effect of SWS disruption previously required highly time-intensive and subjective methods. Our goal was to develop an automated and objective protocol to reduce SWS without affecting sleep architecture. We developed a custom Matlab™ protocol to calculate electroencephalogram spectral power every 10s live during a polysomnogram, exclude artifact, and, if measurements met criteria for SWS, deliver increasingly louder tones through earphones. Middle-aged healthy volunteers (n=10) each underwent 2 polysomnograms, one with the SWS disruption protocol and one with sham condition. The SWS disruption protocol reduced SWS compared to sham condition, as measured by spectral power in the delta (0.5-4Hz) band, particularly in the 0.5-2Hz range (mean 20% decrease). A compensatory increase in the proportion of total spectral power in the theta (4-8Hz) and alpha (8-12Hz) bands was seen, but otherwise normal sleep features were preserved. N3 sleep decreased from 20±34 to 3±6min, otherwise there were no significant changes in total sleep time, sleep efficiency, or other macrostructural sleep characteristics. This novel SWS disruption protocol produces specific reductions in delta band power similar to existing methods, but has the advantage of being automated, such that SWS disruption can be performed easily in a highly standardized and operator-independent manner. This automated SWS disruption protocol effectively reduces SWS without impacting overall sleep architecture. Copyright © 2017 Elsevier B.V. All rights reserved.

Automated selective disruption of slow wave sleep

PubMed Central

Ooms, Sharon J.; Zempel, John M.; Holtzman, David M.; Ju, Yo-El S.

2017-01-01

Background Slow wave sleep (SWS) plays an important role in neurophysiologic restoration. Experimentally testing the effect of SWS disruption previously required highly time-intensive and subjective methods. Our goal was to develop an automated and objective protocol to reduce SWS without affecting sleep architecture. New Method We developed a custom Matlab™ protocol to calculate electroencephalogram spectral power every 10 seconds live during a polysomnogram, exclude artifact, and, if measurements met criteria for SWS, deliver increasingly louder tones through earphones. Middle-aged healthy volunteers (n=10) each underwent 2 polysomnograms, one with the SWS disruption protocol and one with sham condition. Results The SWS disruption protocol reduced SWS compared to sham condition, as measured by spectral power in the delta (0.5–4 Hz) band, particularly in the 0.5–2 Hz range (mean 20% decrease). A compensatory increase in the proportion of total spectral power in the theta (4–8 Hz) and alpha (8–12 Hz) bands was seen, but otherwise normal sleep features were preserved. N3 sleep decreased from 20±34 to 3±6 minutes, otherwise there were no significant changes in total sleep time, sleep efficiency, or other macrostructural sleep characteristics. Comparison with existing method This novel SWS disruption protocol produces specific reductions in delta band power similar to existing methods, but has the advantage of being automated, such that SWS disruption can be performed easily in a highly standardized and operator-independent manner. Conclusion This automated SWS disruption protocol effectively reduces SWS without impacting overall sleep architecture. PMID:28238859

Slow eye movements distribution during nocturnal sleep.

PubMed

Pizza, Fabio; Fabbri, Margherita; Magosso, Elisa; Ursino, Mauro; Provini, Federica; Ferri, Raffaele; Montagna, Pasquale

2011-08-01

To assess the distribution across nocturnal sleep of slow eye movements (SEMs). We evaluated SEMs distribution in the different sleep stages, and across sleep cycles in nocturnal recordings of 10 healthy women. Sleep was scored according to standard criteria, and the percentage of time occupied by the SEMs was automatically detected. SEMs were differently represented during sleep stages with the following order: wakefulness after sleep onset (WASO): 61%, NREM sleep stage 1: 54%, REM sleep: 43%, NREM sleep stage 2: 21%, NREM sleep stage 3: 7%, and NREM sleep stage 4: 3% (p<0.0001). There was no difference between phasic and tonic REM sleep. SEMs progressively decreased across the NREM sleep cycles (38%, 15%, 13% during NREM sleep stage 2 in the first three sleep cycles, p=0.006), whereas no significant difference was found for REM, NREM sleep stage 1, slow-wave sleep and WASO. Our findings confirm that SEMs are a phenomenon typical of the sleep onset period, but are also found in REM sleep. The nocturnal evolution of SEMs during NREM sleep stage 2 parallels the homeostatic process underlying slow-wave sleep. SEMs are a marker of sleepiness and, potentially, of sleep homeostasis. Copyright © 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Mechanisms of Memory Retrieval in Slow-Wave Sleep.

PubMed

Cairney, Scott A; Sobczak, Justyna M; Lindsay, Shane; Gaskell, M Gareth

2017-09-01

Memories are strengthened during sleep. The benefits of sleep for memory can be enhanced by re-exposing the sleeping brain to auditory cues; a technique known as targeted memory reactivation (TMR). Prior studies have not assessed the nature of the retrieval mechanisms underpinning TMR: the matching process between auditory stimuli encountered during sleep and previously encoded memories. We carried out two experiments to address this issue. In Experiment 1, participants associated words with verbal and nonverbal auditory stimuli before an overnight interval in which subsets of these stimuli were replayed in slow-wave sleep. We repeated this paradigm in Experiment 2 with the single difference that the gender of the verbal auditory stimuli was switched between learning and sleep. In Experiment 1, forgetting of cued (vs. noncued) associations was reduced by TMR with verbal and nonverbal cues to similar extents. In Experiment 2, TMR with identical nonverbal cues reduced forgetting of cued (vs. noncued) associations, replicating Experiment 1. However, TMR with nonidentical verbal cues reduced forgetting of both cued and noncued associations. These experiments suggest that the memory effects of TMR are influenced by the acoustic overlap between stimuli delivered at training and sleep. Our findings hint at the existence of two processing routes for memory retrieval during sleep. Whereas TMR with acoustically identical cues may reactivate individual associations via simple episodic matching, TMR with nonidentical verbal cues may utilize linguistic decoding mechanisms, resulting in widespread reactivation across a broad category of memories. © Sleep Research Society 2017. Published by Oxford University Press [on behalf of the Sleep Research Society].

Long-term history and immediate preceding state affect EEG slow wave characteristics at NREM sleep onset in C57BL/6 mice.

PubMed

Cui, N; Mckillop, L E; Fisher, S P; Oliver, P L; Vyazovskiy, V V

2014-01-01

The dynamics of cortical activity across the 24-h day and at vigilance state transitions is regulated by an interaction between global subcortical neuromodulatory influences and local shifts in network synchrony and excitability. To address the role of long-term and immediate preceding history in local and global cortical dynamics, we investigated cortical EEG recorded from both frontal and occipital regions during an undisturbed 24-h recording in mice. As expected, at the beginning of the light period, under physiologically increased sleep pressure, EEG slow waves were more frequent and had higher amplitude and slopes, compared to the rest of the light period. Within discrete NREM sleep episodes, the incidence, amplitude and slopes of individual slow waves increased progressively after episode onset in both derivations by approximately 10-30%. Interestingly, at the beginning of NREM sleep episodes slow waves in the frontal and occipital derivations frequently occurred in isolation, as quantified by longer latencies between consecutive slow waves in the two regions. Notably, slow waves during the initial period of NREM sleep following REM sleep episodes were significantly less frequent, lower in amplitude and exhibited shallower slopes, compared to those that occurred in NREM episodes after prolonged waking. Moreover, the latencies between consecutive frontal and occipital NREM slow waves were substantially longer when they occurred directly after REM sleep compared to following consolidated wakefulness. Overall these data reveal a complex picture, where both time of day and preceding state contribute to the characteristics and dynamics of slow waves within NREM sleep. These findings suggest that NREM sleep initiates in a more "local" fashion when it occurs following REM sleep episodes as opposed to sustained waking bouts. While the mechanisms and functional significance of such a re-setting of brain state after individual REM sleep episodes remains to be

Why Does Sleep Slow-Wave Activity Increase After Extended Wake? Assessing the Effects of Increased Cortical Firing During Wake and Sleep

PubMed Central

Rodriguez, Alexander V.; Funk, Chadd M.; Vyazovskiy, Vladyslav V.; Nir, Yuval; Tononi, Giulio

2016-01-01

During non-rapid eye movement (NREM) sleep, cortical neurons alternate between ON periods of firing and OFF periods of silence. This bi-stability, which is largely synchronous across neurons, is reflected in the EEG as slow waves. Slow-wave activity (SWA) increases with wake duration and declines homeostatically during sleep, but the underlying mechanisms remain unclear. One possibility is neuronal “fatigue”: high, sustained firing in wake would force neurons to recover with more frequent and longer OFF periods during sleep. Another possibility is net synaptic potentiation during wake: stronger coupling among neurons would lead to greater synchrony and therefore higher SWA. Here, we obtained a comparable increase in sustained firing (6 h) in cortex by: (1) keeping mice awake by exposure to novel objects to promote plasticity and (2) optogenetically activating a local population of cortical neurons at wake-like levels during sleep. Sleep after extended wake led to increased SWA, higher synchrony, and more time spent OFF, with a positive correlation between SWA, synchrony, and OFF periods. Moreover, time spent OFF was correlated with cortical firing during prior wake. After local optogenetic stimulation, SWA and cortical synchrony decreased locally, time spent OFF did not change, and local SWA was not correlated with either measure. Moreover, laser-induced cortical firing was not correlated with time spent OFF afterward. Overall, these results suggest that high sustained firing per se may not be the primary determinant of SWA increases observed after extended wake. SIGNIFICANCE STATEMENT A long-standing hypothesis is that neurons fire less during slow-wave sleep to recover from the “fatigue” accrued during wake, when overall synaptic activity is higher than in sleep. This idea, however, has rarely been tested and other factors, namely increased cortical synchrony, could explain why sleep slow-wave activity (SWA) is higher after extended wake. We forced

Why Does Sleep Slow-Wave Activity Increase After Extended Wake? Assessing the Effects of Increased Cortical Firing During Wake and Sleep.

PubMed

Rodriguez, Alexander V; Funk, Chadd M; Vyazovskiy, Vladyslav V; Nir, Yuval; Tononi, Giulio; Cirelli, Chiara

2016-12-07

During non-rapid eye movement (NREM) sleep, cortical neurons alternate between ON periods of firing and OFF periods of silence. This bi-stability, which is largely synchronous across neurons, is reflected in the EEG as slow waves. Slow-wave activity (SWA) increases with wake duration and declines homeostatically during sleep, but the underlying mechanisms remain unclear. One possibility is neuronal "fatigue": high, sustained firing in wake would force neurons to recover with more frequent and longer OFF periods during sleep. Another possibility is net synaptic potentiation during wake: stronger coupling among neurons would lead to greater synchrony and therefore higher SWA. Here, we obtained a comparable increase in sustained firing (6 h) in cortex by: (1) keeping mice awake by exposure to novel objects to promote plasticity and (2) optogenetically activating a local population of cortical neurons at wake-like levels during sleep. Sleep after extended wake led to increased SWA, higher synchrony, and more time spent OFF, with a positive correlation between SWA, synchrony, and OFF periods. Moreover, time spent OFF was correlated with cortical firing during prior wake. After local optogenetic stimulation, SWA and cortical synchrony decreased locally, time spent OFF did not change, and local SWA was not correlated with either measure. Moreover, laser-induced cortical firing was not correlated with time spent OFF afterward. Overall, these results suggest that high sustained firing per se may not be the primary determinant of SWA increases observed after extended wake. A long-standing hypothesis is that neurons fire less during slow-wave sleep to recover from the "fatigue" accrued during wake, when overall synaptic activity is higher than in sleep. This idea, however, has rarely been tested and other factors, namely increased cortical synchrony, could explain why sleep slow-wave activity (SWA) is higher after extended wake. We forced neurons in the mouse cortex to fire

Role of slow oscillatory activity and slow wave sleep in consolidation of episodic-like memory in rats.

PubMed

Oyanedel, Carlos N; Binder, Sonja; Kelemen, Eduard; Petersen, Kimberley; Born, Jan; Inostroza, Marion

2014-12-15

Our previous experiments showed that sleep in rats enhances consolidation of hippocampus dependent episodic-like memory, i.e. the ability to remember an event bound into specific spatio-temporal context. Here we tested the hypothesis that this enhancing effect of sleep is linked to the occurrence of slow oscillatory and spindle activity during slow wave sleep (SWS). Rats were tested on an episodic-like memory task and on three additional tasks covering separately the where (object place recognition), when (temporal memory), and what (novel object recognition) components of episodic memory. In each task, the sample phase (encoding) was followed by an 80-min retention interval that covered either a period of regular morning sleep or sleep deprivation. Memory during retrieval was tested using preferential exploration of novelty vs. familiarity. Consistent with previous findings, the rats which had slept during the retention interval showed significantly stronger episodic-like memory and spatial memory, and a trend of improved temporal memory (although not significant). Object recognition memory was similarly retained across sleep and sleep deprivation retention intervals. Recall of episodic-like memory was associated with increased slow oscillatory activity (0.85-2.0Hz) during SWS in the retention interval. Spatial memory was associated with increased proportions of SWS. Against our hypothesis, a relationship between spindle activity and episodic-like memory performance was not detected, but spindle activity was associated with object recognition memory. The results provide support for the role of SWS and slow oscillatory activity in consolidating hippocampus-dependent memory, the role of spindles in this process needs to be further examined. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Memory improvement via slow-oscillatory stimulation during sleep in older adults.

PubMed

Westerberg, Carmen E; Florczak, Susan M; Weintraub, Sandra; Mesulam, M-Marsel; Marshall, Lisa; Zee, Phyllis C; Paller, Ken A

2015-09-01

We examined the intriguing but controversial idea that disrupted sleep-dependent consolidation contributes to age-related memory decline. Slow-wave activity during sleep may help strengthen neural connections and provide memories with long-term stability, in which case decreased slow-wave activity in older adults could contribute to their weaker memories. One prediction from this account is that age-related memory deficits should be reduced by artificially enhancing slow-wave activity. In young adults, applying transcranial current oscillating at a slow frequency (0.75 Hz) during sleep improves memory. Here, we tested whether this procedure can improve memory in older adults. In 2 sessions separated by 1 week, we applied either slow-oscillatory stimulation or sham stimulation during an afternoon nap in a double-blind, crossover design. Memory tests were administered before and after sleep. A larger improvement in word-pair recall and higher slow-wave activity was observed with slow-oscillatory stimulation than with sham stimulation. This is the first demonstration that this procedure can improve memory in older adults, suggesting that declarative memory performance in older adults is partly dependent on slow-wave activity during sleep. Copyright © 2015 Elsevier Inc. All rights reserved.

Effect of Conditioned Stimulus Exposure during Slow Wave Sleep on Fear Memory Extinction in Humans

PubMed Central

He, Jia; Sun, Hong-Qiang; Li, Su-Xia; Zhang, Wei-Hua; Shi, Jie; Ai, Si-Zhi; Li, Yun; Li, Xiao-Jun; Tang, Xiang-Dong; Lu, Lin

2015-01-01

Study Objectives: Repeated exposure to a neutral conditioned stimulus (CS) in the absence of a noxious unconditioned stimulus (US) elicits fear memory extinction. The aim of the current study was to investigate the effects of mild tone exposure (CS) during slow wave sleep (SWS) on fear memory extinction in humans. Design: The healthy volunteers underwent an auditory fear conditioning paradigm on the experimental night, during which tones served as the CS, and a mild shock served as the US. They were then randomly assigned to four groups. Three groups were exposed to the CS for 3 or 10 min or an irrelevant tone (control stimulus, CtrS) for 10 min during SWS. The fourth group served as controls and was not subjected to any interventions. All of the subjects completed a memory test 4 h after SWS-rich stage to evaluate the effect on fear extinction. Moreover, we conducted similar experiments using an independent group of subjects during the daytime to test whether the memory extinction effect was specific to the sleep condition. Participants: Ninety-six healthy volunteers (44 males) aged 18–28 y. Measurements and Results: Participants exhibited undisturbed sleep during 2 consecutive nights, as assessed by sleep variables (all P > 0.05) from polysomnographic recordings and power spectral analysis. Participants who were re-exposed to the 10 min CS either during SWS and wakefulness exhibited attenuated fear responses (wake-10 min CS, P < 0.05; SWS-10 min CS, P < 0.01). Conclusions: Conditioned stimulus re-exposure during slow wave sleep promoted fear memory extinction without altering sleep profiles. Citation: He J, Sun HQ, Li SX, Zhang WH, Shi J, Ai SZ, Li Y, Li XJ, Tang XD, Lu L. Effect of conditioned stimulus exposure during slow wave sleep on fear memory extinction in humans. SLEEP 2015;38(3):423–431. PMID:25348121

Mechanisms of Memory Retrieval in Slow-Wave Sleep

PubMed Central

Cairney, Scott A; Sobczak, Justyna M; Lindsay, Shane

2017-01-01

Abstract Study Objectives Memories are strengthened during sleep. The benefits of sleep for memory can be enhanced by re-exposing the sleeping brain to auditory cues; a technique known as targeted memory reactivation (TMR). Prior studies have not assessed the nature of the retrieval mechanisms underpinning TMR: the matching process between auditory stimuli encountered during sleep and previously encoded memories. We carried out two experiments to address this issue. Methods In Experiment 1, participants associated words with verbal and nonverbal auditory stimuli before an overnight interval in which subsets of these stimuli were replayed in slow-wave sleep. We repeated this paradigm in Experiment 2 with the single difference that the gender of the verbal auditory stimuli was switched between learning and sleep. Results In Experiment 1, forgetting of cued (vs. noncued) associations was reduced by TMR with verbal and nonverbal cues to similar extents. In Experiment 2, TMR with identical nonverbal cues reduced forgetting of cued (vs. noncued) associations, replicating Experiment 1. However, TMR with nonidentical verbal cues reduced forgetting of both cued and noncued associations. Conclusions These experiments suggest that the memory effects of TMR are influenced by the acoustic overlap between stimuli delivered at training and sleep. Our findings hint at the existence of two processing routes for memory retrieval during sleep. Whereas TMR with acoustically identical cues may reactivate individual associations via simple episodic matching, TMR with nonidentical verbal cues may utilize linguistic decoding mechanisms, resulting in widespread reactivation across a broad category of memories. PMID:28934526

Effects of Tiagabine on Slow Wave Sleep and Arousal Threshold in Patients With Obstructive Sleep Apnea.

PubMed

Taranto-Montemurro, Luigi; Sands, Scott A; Edwards, Bradley A; Azarbarzin, Ali; Marques, Melania; de Melo, Camila; Eckert, Danny J; White, David P; Wellman, Andrew

2017-02-01

Obstructive sleep apnea (OSA) severity is markedly reduced during slow-wave sleep (SWS) even in patients with a severe disease. The reason for this improvement is uncertain but likely relates to non-anatomical factors (i.e. reduced arousability, chemosensitivity, and increased dilator muscle activity). The anticonvulsant tiagabine produces a dose-dependent increase in SWS in subjects without OSA. This study aimed to test the hypothesis that tiagabine would reduce OSA severity by raising the overall arousal threshold during sleep. After a baseline physiology night to assess patients' OSA phenotypic traits, a placebo-controlled, double-blind, crossover trial of tiagabine 12 mg administered before sleep was performed in 14 OSA patients. Under each condition, we assessed the effects on sleep and OSA severity using standard clinical polysomnography. Tiagabine increased slow-wave activity (SWA) of the electroencephalogram (1-4 Hz) compared to placebo (1.8 [0.4] vs. 2.0 [0.5] LogμV2, p = .04) but did not reduce OSA severity (apnea-hypopnea index [AHI] 41.5 [20.3] vs. 39.1 [16.5], p > .5). SWS duration (25 [20] vs. 26 [43] mins, p > .5) and arousal threshold (-26.5 [5.0] vs. -27.6 [5.1] cmH2O, p = .26) were also unchanged between nights. Tiagabine modified sleep microstructure (increase in SWA) but did not change the duration of SWS, OSA severity, or arousal threshold in this group of OSA patients. Based on these findings, tiagabine should not be considered as a therapeutic option for OSA treatment. © Sleep Research Society 2016. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

Age-Dependency of Location of Epileptic Foci in "Continuous Spike-and-Waves during Sleep": A Parallel to the Posterior-Anterior Trajectory of Slow Wave Activity.

PubMed

Bölsterli Heinzle, Bigna Katrin; Bast, Thomas; Critelli, Hanne; Huber, Reto; Schmitt, Bernhard

2017-02-01

Epileptic encephalopathy with continuous spike-and-waves during sleep (CSWS) occurs during childhood and is characterized by an activation of spike wave complexes during slow wave sleep. The location of epileptic foci is variable, as is etiology. A relationship between the epileptic focus and age has been shown in various focal epilepsies following a posterior-anterior trajectory, and a link to brain maturation has been proposed. We hypothesize that in CSWS, maximal spike wave activity, corresponding to the epileptic focus, is related to age and shows a posterior-anterior evolution. In a retrospective cross-sectional study on CSWS (22 EEGs of 22 patients aged 3.1–13.5 years), the location of the epileptic focus is related to age and follows a posterior-anterior course. Younger patients are more likely to have posterior foci than older ones. We propose that the posterior-anterior trajectory of maximal spike waves in CSWS might reflect maturational changes of maximal expression of sleep slow waves, which follow a comparable course. Epileptic spike waves, that is, “hyper-synchronized slow waves” may occur at the place where the highest and therefore most synchronized slow waves meet brain tissue with an increased susceptibility to synchronization. Georg Thieme Verlag KG Stuttgart · New York.

Electroencephalographic slow waves prior to sleepwalking episodes.

PubMed

Perrault, Rosemarie; Carrier, Julie; Desautels, Alex; Montplaisir, Jacques; Zadra, Antonio

2014-12-01

Recent studies have suggested that the onset of sleepwalking episodes may be preceded by fluctuations in slow-wave sleep electroencephalographic characteristics. However, whether or not such fluctuations are specific to sleepwalking episodes or generalized to all sleep-wake transitions in sleepwalkers remains unknown. The goal of this study was to compare spectral power for delta (1-4 Hz) and slow delta (0.5-1 Hz) as well as slow oscillation density before the onset of somnambulistic episodes versus non-behavioral awakenings recorded from the same group of sleepwalkers. A secondary aim was to describe the time course of observed changes in slow-wave activity and slow oscillations during the 3 min immediately preceding the occurrence of somnambulistic episodes. Twelve adult sleepwalkers were investigated polysomnographically during the course of one night. Slow-wave activity and slow oscillation density were significantly greater prior to patients' somnambulistic episodes as compared with non-behavioral awakenings. However, there was no evidence for a gradual increase over the 3 min preceding the episodes. Increased slow-wave activity and slow oscillation density appear to be specific to sleepwalking episodes rather than generalized to all sleep-wake transitions in sleepwalkers. Copyright © 2014 Elsevier B.V. All rights reserved.

Landau-Kleffner Syndrome, Electrical Status Epilepticus in Slow Wave Sleep, and Language Regression in Children

ERIC Educational Resources Information Center

McVicar, Kathryn A.; Shinnar, Shlomo

2004-01-01

The Landau-Kleffner syndrome (LKS) and electrical status epilepticus in slow wave sleep (ESES) are rare childhood-onset epileptic encephalopathies in which loss of language skills occurs in the context of an epileptiform EEG activated in sleep. Although in LKS the loss of function is limited to language, in ESES there is a wider spectrum of…

Slow oscillating transcranial direct current stimulation during sleep has a sleep-stabilizing effect in chronic insomnia: a pilot study.

PubMed

Saebipour, Mohammad R; Joghataei, Mohammad T; Yoonessi, Ali; Sadeghniiat-Haghighi, Khosro; Khalighinejad, Nima; Khademi, Soroush

2015-10-01

Recent evidence suggests that lack of slow-wave activity may play a fundamental role in the pathogenesis of insomnia. Pharmacological approaches and brain stimulation techniques have recently offered solutions for increasing slow-wave activity during sleep. We used slow (0.75 Hz) oscillatory transcranial direct current stimulation during stage 2 of non-rapid eye movement sleeping insomnia patients for resonating their brain waves to the frequency of sleep slow-wave. Six patients diagnosed with either sleep maintenance or non-restorative sleep insomnia entered the study. After 1 night of adaptation and 1 night of baseline polysomnography, patients randomly received sham or real stimulation on the third and fourth night of the experiment. Our preliminary results show that after termination of stimulations (sham or real), slow oscillatory transcranial direct current stimulation increased the duration of stage 3 of non-rapid eye movement sleep by 33 ± 26 min (P = 0.026), and decreased stage 1 of non-rapid eye movement sleep duration by 22 ± 17.7 min (P = 0.028), compared with sham. Slow oscillatory transcranial direct current stimulation decreased stage 1 of non-rapid eye movement sleep and wake time after sleep-onset durations, together, by 55.4 ± 51 min (P = 0.045). Slow oscillatory transcranial direct current stimulation also increased sleep efficiency by 9 ± 7% (P = 0.026), and probability of transition from stage 2 to stage 3 of non-rapid eye movement sleep by 20 ± 17.8% (P = 0.04). Meanwhile, slow oscillatory transcranial direct current stimulation decreased transitions from stage 2 of non-rapid eye movement sleep to wake by 12 ± 6.7% (P = 0.007). Our preliminary results suggest a sleep-stabilizing role for the intervention, which may mimic the effect of sleep slow-wave-enhancing drugs. © 2015 European Sleep Research Society.

Involvement of Spindles in Memory Consolidation Is Slow Wave Sleep-Specific

ERIC Educational Resources Information Center

Cox, Roy; Hofman, Winni F.; Talamini, Lucia M.

2012-01-01

Both sleep spindles and slow oscillations have been implicated in sleep-dependent memory consolidation. Whereas spindles occur during both light and deep sleep, slow oscillations are restricted to deep sleep, raising the possibility of greater consolidation-related spindle involvement during deep sleep. We assessed declarative memory retention…

Age-Related Reduction in Daytime Sleep Propensity and Nocturnal Slow Wave Sleep

PubMed Central

Dijk, Derk-Jan; Groeger, John A.; Stanley, Neil; Deacon, Stephen

2010-01-01

Objective: To investigate whether age-related and experimental reductions in SWS and sleep continuity are associated with increased daytime sleep propensity. Methods: Assessment of daytime sleep propensity under baseline conditions and following experimental disruption of SWS. Healthy young (20-30 y, n = 44), middle-aged (40-55 y, n = 35) and older (66-83 y, n = 31) men and women, completed a 2-way parallel group study. After an 8-h baseline sleep episode, subjects were randomized to 2 nights with selective SWS disruption by acoustic stimuli, or without disruption, followed by 1 recovery night. Objective and subjective sleep propensity were assessed using the Multiple Sleep Latency Test (MSLT) and the Karolinska Sleepiness Scale (KSS). Findings: During baseline sleep, SWS decreased (P < 0.001) and the number of awakenings increased (P < 0.001) across the 3 age groups. During the baseline day, MSLT values increased across the three age groups (P < 0.0001) with mean values of 8.7min (SD: 4.5), 11.7 (5.1) and 14.2 (4.1) in the young, middle-aged, and older adults, respectively. KSS values were 3.7 (1.0), 3.2 (0.9), and 3.4 (0.6) (age-group: P = 0.031). Two nights of SWS disruption led to a reduction in MSLT and increase in KSS in all 3 age groups (SWS disruption vs. control: P < 0.05 in all cases). Conclusions: Healthy aging is associated with a reduction in daytime sleep propensity, sleep continuity, and SWS. In contrast, experimental disruption of SWS leads to an increase in daytime sleep propensity. The age-related decline in SWS and reduction in daytime sleep propensity may reflect a lessening in homeostatic sleep requirement. Healthy older adults without sleep disorders can expect to be less sleepy during the daytime than young adults. Citation: Dijk DJ; Groeger JA; Stanley N; Deacon S. Age-related reduction in daytime sleep propensity and nocturnal slow wave sleep. SLEEP 2010;33(2):211-223. PMID:20175405

Polysomnographic measures of sleep in cocaine dependence and alcohol dependence: Implications for age‐related loss of slow wave, stage 3 sleep

PubMed Central

Bjurstrom, Martin F.; Olmstead, Richard

2016-01-01

Abstract Background and aims Sleep disturbance is a prominent complaint in cocaine and alcohol dependence. This controlled study evaluated differences of polysomnographic (PSG) sleep in cocaine‐ and alcohol‐dependent subjects, and examined whether substance dependence interacts with age to alter slow wave sleep and rapid eye movement (REM) sleep. Design Cross‐sectional comparison. Setting Los Angeles and San Diego, CA, USA. Participants Abstinent cocaine‐dependent subjects (n = 32), abstinent alcohol‐dependent subjects (n = 73) and controls (n = 108); mean age 40.3 years recruited 2005–12. Measurements PSG measures of sleep continuity and sleep architecture primary outcomes of Stage 3 sleep and REM sleep. Covariates included age, ethnicity, education, smoking, body mass index and depressive symptoms. Findings Compared with controls, both groups of substance dependent subjects showed loss of Stage 3 sleep (P < 0.001). A substance dependence × age interaction was found in which both cocaine‐ and alcohol‐dependent groups showed loss of Stage 3 sleep at an earlier age than controls (P < 0.05 for all), and cocaine‐dependent subjects showed loss of Stage 3 sleep at an earlier age than alcoholics (P < 0.05). Compared with controls, REM sleep was increased in both substance‐dependent groups (P < 0.001), and cocaine and alcohol dependence were associated with earlier age‐related increase in REM sleep (P < 0.05 for all). Conclusions Cocaine and alcohol dependence appear to be associated with marked disturbances of sleep architecture, including increased rapid eye movement sleep and accelerated age‐related loss of slow wave, Stage 3 sleep. PMID:26749502

Slow wave and REM sleep deprivation effects on explicit and implicit memory during sleep.

PubMed

Casey, Sarah J; Solomons, Luke C; Steier, Joerg; Kabra, Neeraj; Burnside, Anna; Pengo, Martino F; Moxham, John; Goldstein, Laura H; Kopelman, Michael D

2016-11-01

It has been debated whether different stages in the human sleep cycle preferentially mediate the consolidation of explicit and implicit memories, or whether all of the stages in succession are necessary for optimal consolidation. Here we investigated whether the selective deprivation of slow wave sleep (SWS) or rapid eye movement (REM) sleep over an entire night would have a specific effect on consolidation in explicit and implicit memory tasks. Participants completed a set of explicit and implicit memory tasks at night, prior to sleep. They had 1 control night of undisturbed sleep and 2 experimental nights, during which either SWS or REM sleep was selectively deprived across the entire night (sleep conditions counterbalanced across participants). Polysomnography recordings quantified precisely the amount of SWS and REM sleep that occurred during each of the sleep conditions, and spindle counts were recorded. In the morning, participants completed the experimental tasks in the same sequence as the night before. SWS deprivation disrupted the consolidation of explicit memories for visuospatial information (ηp2 = .23), and both SWS (ηp2 = .53) and REM sleep (ηp2 = .52) deprivation adversely affected explicit verbal recall. Neither SWS nor REM sleep deprivation affected aspects of short-term or working memory, and did not affect measures of verbal implicit memory. Spindle counts did not correlate significantly with memory performance. These findings demonstrate the importance of measuring the sleep cycles throughout the entire night, and the contribution of both SWS and REM sleep to memory consolidation. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Synaptic Mechanisms of Memory Consolidation during Sleep Slow Oscillations

PubMed Central

Wei, Yina; Krishnan, Giri P.

2016-01-01

Sleep is critical for regulation of synaptic efficacy, memories, and learning. However, the underlying mechanisms of how sleep rhythms contribute to consolidating memories acquired during wakefulness remain unclear. Here we studied the role of slow oscillations, 0.2–1 Hz rhythmic transitions between Up and Down states during stage 3/4 sleep, on dynamics of synaptic connectivity in the thalamocortical network model implementing spike-timing-dependent synaptic plasticity. We found that the spatiotemporal pattern of Up-state propagation determines the changes of synaptic strengths between neurons. Furthermore, an external input, mimicking hippocampal ripples, delivered to the cortical network results in input-specific changes of synaptic weights, which persisted after stimulation was removed. These synaptic changes promoted replay of specific firing sequences of the cortical neurons. Our study proposes a neuronal mechanism on how an interaction between hippocampal input, such as mediated by sharp wave-ripple events, cortical slow oscillations, and synaptic plasticity, may lead to consolidation of memories through preferential replay of cortical cell spike sequences during slow-wave sleep. SIGNIFICANCE STATEMENT Sleep is critical for memory and learning. Replay during sleep of temporally ordered spike sequences related to a recent experience was proposed to be a neuronal substrate of memory consolidation. However, specific mechanisms of replay or how spike sequence replay leads to synaptic changes that underlie memory consolidation are still poorly understood. Here we used a detailed computational model of the thalamocortical system to report that interaction between slow cortical oscillations and synaptic plasticity during deep sleep can underlie mapping hippocampal memory traces to persistent cortical representation. This study provided, for the first time, a mechanistic explanation of how slow-wave sleep may promote consolidation of recent memory events. PMID

The Roles of Cortical Slow Waves in Synaptic Plasticity and Memory Consolidation.

PubMed

Miyamoto, Daisuke; Hirai, Daichi; Murayama, Masanori

2017-01-01

Sleep plays important roles in sensory and motor memory consolidation. Sleep oscillations, reflecting neural population activity, involve the reactivation of learning-related neurons and regulate synaptic strength and, thereby affect memory consolidation. Among sleep oscillations, slow waves (0.5-4 Hz) are closely associated with memory consolidation. For example, slow-wave power is regulated in an experience-dependent manner and correlates with acquired memory. Furthermore, manipulating slow waves can enhance or impair memory consolidation. During slow wave sleep, inter-areal interactions between the cortex and hippocampus (HC) have been proposed to consolidate declarative memory; however, interactions for non-declarative (HC-independent) memory remain largely uninvestigated. We recently showed that the directional influence in a slow-wave range through a top-down cortical long-range circuit is involved in the consolidation of non-declarative memory. At the synaptic level, the average cortical synaptic strength is known to be potentiated during wakefulness and depressed during sleep. Moreover, learning causes plasticity in a subset of synapses, allocating memory to them. Sleep may help to differentiate synaptic strength between allocated and non-allocated synapses (i.e., improving the signal-to-noise ratio, which may facilitate memory consolidation). Herein, we offer perspectives on inter-areal interactions and synaptic plasticity for memory consolidation during sleep.

The Roles of Cortical Slow Waves in Synaptic Plasticity and Memory Consolidation

PubMed Central

Miyamoto, Daisuke; Hirai, Daichi; Murayama, Masanori

2017-01-01

Sleep plays important roles in sensory and motor memory consolidation. Sleep oscillations, reflecting neural population activity, involve the reactivation of learning-related neurons and regulate synaptic strength and, thereby affect memory consolidation. Among sleep oscillations, slow waves (0.5–4 Hz) are closely associated with memory consolidation. For example, slow-wave power is regulated in an experience-dependent manner and correlates with acquired memory. Furthermore, manipulating slow waves can enhance or impair memory consolidation. During slow wave sleep, inter-areal interactions between the cortex and hippocampus (HC) have been proposed to consolidate declarative memory; however, interactions for non-declarative (HC-independent) memory remain largely uninvestigated. We recently showed that the directional influence in a slow-wave range through a top-down cortical long-range circuit is involved in the consolidation of non-declarative memory. At the synaptic level, the average cortical synaptic strength is known to be potentiated during wakefulness and depressed during sleep. Moreover, learning causes plasticity in a subset of synapses, allocating memory to them. Sleep may help to differentiate synaptic strength between allocated and non-allocated synapses (i.e., improving the signal-to-noise ratio, which may facilitate memory consolidation). Herein, we offer perspectives on inter-areal interactions and synaptic plasticity for memory consolidation during sleep. PMID:29213231

APOEε4 and slow wave sleep in older adults

PubMed Central

Yaffe, Kristine; Nievergelt, Caroline M.; Parimi, Neeta; Glymour, M. Maria; Ensrud, Kristine E.; Cauley, Jane A.; Ancoli-Israel, Sonia; Mariani, Sara; Redline, Susan; Stone, Katie L.

2018-01-01

Slow wave (or stage N3) sleep has been linked to a variety of cognitive processes. However, the role of stage N3 in the elderly is debated. The link between stage N3 and episodic memory may be weakened or changed in the older adult population, possibly due to several altered mechanisms impacting the cellular structure of the brain. The bases for the age-related dissociation between stage N3 and cognition are not understood. Since APOEε4 status is the strongest genetic risk factor for cognitive decline, we assessed whether the ε4 allele is associated with stage N3 sleep. Participants were from the population-based Osteoporotic Fractures in Men (MrOS) cohort with polysomnography and APOEε4 genotype data (n = 2,302, 100% male, mean age 76.6 years). Sleep stages were objectively measured using overnight in-home polysomnography and central electroencephalogram data were used to score stage N3 sleep. Cognitive function was assessed using the Modified Mini Mental State Exam (3MS). The APOE rs429358 single nucleotide polymorphism, which defines the APOEε4 allele, was genotyped using a custom genotyping array. Total time in stage N3 sleep was significantly higher (p<0.0001) among the 40 MrOS participants carrying two copies of the ε4 allele (62±5.2 minutes) compared with 43±1.5 minutes for carriers of one ε4 allele (n = 515) and 40±0.8 minutes for ε4 non-carriers (n = 1747). All results were independent of sleep efficiency, number of sleep cycles, and apnea hypopnea index. These findings support an association between APOEε4 genotype and sleep stage N3 in the elderly. Increased total stage N3 duration among ε4/ε4 carriers does not appear to reflect compensation for prior cognitive decline and may reflect overactive downscaling of synapses during sleep. If confirmed, these results might in part explain the high risk of age-related cognitive decline and AD among APOE ε4/ε4 carriers. PMID:29370207

Slow wave sleep in the chronically fatigued: Power spectra distribution patterns in chronic fatigue syndrome and primary insomnia.

PubMed

Neu, Daniel; Mairesse, Olivier; Verbanck, Paul; Le Bon, Olivier

2015-10-01

To investigate slow wave sleep (SWS) spectral power proportions in distinct clinical conditions sharing non-restorative sleep and fatigue complaints without excessive daytime sleepiness (EDS), namely the chronic fatigue syndrome (CFS) and primary insomnia (PI). Impaired sleep homeostasis has been suspected in both CFS and PI. We compared perceived sleep quality, fatigue and sleepiness symptom-intensities, polysomnography (PSG) and SWS spectral power distributions of drug-free CFS and PI patients without comorbid sleep or mental disorders, with a good sleeper control group. Higher fatigue without EDS and impaired perceived sleep quality were confirmed in both patient groups. PSG mainly differed in sleep fragmentation and SWS durations. Spectral analysis revealed a similar decrease in central ultra slow power (0.3-0.79Hz) proportion during SWS for both CFS and PI and an increase in frontal power proportions of faster frequencies during SWS in PI only. The latter was correlated to affective symptoms whereas lower central ultra slow power proportions were related to fatigue severity and sleep quality impairment. In combination with normal (PI) or even increased SWS durations (CFS), we found consistent evidence for lower proportions of slow oscillations during SWS in PI and CFS. Observing normal or increased SWS durations but lower proportions of ultra slow power, our findings suggest a possible quantitative compensation of altered homeostatic regulation. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

The role of sleep spindles and slow-wave activity in integrating new information in semantic memory.

PubMed

Tamminen, Jakke; Lambon Ralph, Matthew A; Lewis, Penelope A

2013-09-25

Assimilating new information into existing knowledge is a fundamental part of consolidating new memories and allowing them to guide behavior optimally and is vital for conceptual knowledge (semantic memory), which is accrued over many years. Sleep is important for memory consolidation, but its impact upon assimilation of new information into existing semantic knowledge has received minimal examination. Here, we examined the integration process by training human participants on novel words with meanings that fell into densely or sparsely populated areas of semantic memory in two separate sessions. Overnight sleep was polysomnographically monitored after each training session and recall was tested immediately after training, after a night of sleep, and 1 week later. Results showed that participants learned equal numbers of both word types, thus equating amount and difficulty of learning across the conditions. Measures of word recognition speed showed a disadvantage for novel words in dense semantic neighborhoods, presumably due to interference from many semantically related concepts, suggesting that the novel words had been successfully integrated into semantic memory. Most critically, semantic neighborhood density influenced sleep architecture, with participants exhibiting more sleep spindles and slow-wave activity after learning the sparse compared with the dense neighborhood words. These findings provide the first evidence that spindles and slow-wave activity mediate integration of new information into existing semantic networks.

Odors enhance slow-wave activity in non-rapid eye movement sleep

PubMed Central

Perl, Ofer; Arzi, Anat; Sela, Lee; Secundo, Lavi; Holtzman, Yael; Samnon, Perry; Oksenberg, Arie; Sobel, Noam

2016-01-01

Most forms of suprathreshold sensory stimulation perturb sleep. In contrast, presentation of pure olfactory or mild trigeminal odorants does not lead to behavioral or physiological arousal. In fact, some odors promote objective and subjective measures of sleep quality in humans and rodents. The brain mechanisms underlying these sleep-protective properties of olfaction remain unclear. Slow oscillations in the electroencephalogram (EEG) are a marker of deep sleep, and K complexes (KCs) are an EEG marker of cortical response to sensory interference. We therefore hypothesized that odorants presented during sleep will increase power in slow EEG oscillations. Moreover, given that odorants do not drive sleep interruption, we hypothesized that unlike other sensory stimuli odorants would not drive KCs. To test these hypotheses we used polysomnography to measure sleep in 34 healthy subjects (19 women, 15 men; mean age 26.5 ± 2.5 yr) who were repeatedly presented with odor stimuli via a computer-controlled air-dilution olfactometer over the course of a single night. Each participant was exposed to one of four odorants, lavender oil (n = 13), vetiver oil (n = 5), vanillin (n = 12), or ammonium sulfide (n = 4), for durations of 5, 10, and 20 s every 9–15 min. Consistent with our hypotheses, we found that odor presentation during sleep enhanced the power of delta (0.5–4 Hz) and slow spindle (9–12 Hz) frequencies during non-rapid eye movement sleep. The increase was proportionate to odor duration. In addition, odor presentation did not modulate the occurrence of KCs. These findings imply a sleep-promoting olfactory mechanism that may deepen sleep through driving increased slow-frequency oscillations. PMID:26888107

Odors enhance slow-wave activity in non-rapid eye movement sleep.

PubMed

Perl, Ofer; Arzi, Anat; Sela, Lee; Secundo, Lavi; Holtzman, Yael; Samnon, Perry; Oksenberg, Arie; Sobel, Noam; Hairston, Ilana S

2016-05-01

Most forms of suprathreshold sensory stimulation perturb sleep. In contrast, presentation of pure olfactory or mild trigeminal odorants does not lead to behavioral or physiological arousal. In fact, some odors promote objective and subjective measures of sleep quality in humans and rodents. The brain mechanisms underlying these sleep-protective properties of olfaction remain unclear. Slow oscillations in the electroencephalogram (EEG) are a marker of deep sleep, and K complexes (KCs) are an EEG marker of cortical response to sensory interference. We therefore hypothesized that odorants presented during sleep will increase power in slow EEG oscillations. Moreover, given that odorants do not drive sleep interruption, we hypothesized that unlike other sensory stimuli odorants would not drive KCs. To test these hypotheses we used polysomnography to measure sleep in 34 healthy subjects (19 women, 15 men; mean age 26.5 ± 2.5 yr) who were repeatedly presented with odor stimuli via a computer-controlled air-dilution olfactometer over the course of a single night. Each participant was exposed to one of four odorants, lavender oil (n = 13), vetiver oil (n = 5), vanillin (n = 12), or ammonium sulfide (n = 4), for durations of 5, 10, and 20 s every 9-15 min. Consistent with our hypotheses, we found that odor presentation during sleep enhanced the power of delta (0.5-4 Hz) and slow spindle (9-12 Hz) frequencies during non-rapid eye movement sleep. The increase was proportionate to odor duration. In addition, odor presentation did not modulate the occurrence of KCs. These findings imply a sleep-promoting olfactory mechanism that may deepen sleep through driving increased slow-frequency oscillations. Copyright © 2016 the American Physiological Society.

A mechanism for upper airway stability during slow wave sleep.

PubMed

McSharry, David G; Saboisky, Julian P; Deyoung, Pam; Matteis, Paul; Jordan, Amy S; Trinder, John; Smales, Erik; Hess, Lauren; Guo, Mengshuang; Malhotra, Atul

2013-04-01

The severity of obstructive sleep apnea is diminished (sometimes markedly) during slow wave sleep (SWS). We sought to understand why SWS stabilizes the upper airway. Increased single motor unit (SMU) activity of the major upper airway dilating muscle (genioglossus) should improve upper airway stability. Therefore, we hypothesized that genioglossus SMUs would increase their activity during SWS in comparison with Stage N2 sleep. The activity of genioglossus SMUs was studied on both sides of the transition between Stage N2 sleep and SWS. Sleep laboratory. Twenty-nine subjects (age 38 ± 13 yr, 17 males) were studied. SWS. Subjects slept overnight with fine-wire electrodes in their genioglossus muscles and with full polysomnographic and end tidal carbon dioxide monitors. Fifteen inspiratory phasic (IP) and 11 inspiratory tonic (IT) units were identified from seven subjects and these units exhibited significantly increased inspiratory discharge frequencies during SWS compared with Stage N2 sleep. The peak discharge frequency of the inspiratory units (IP and IT) was 22.7 ± 4.1 Hz in SWS versus 20.3 ± 4.5 Hz in Stage N2 (P < 0.001). The IP units also fired for a longer duration (expressed as a percentage of inspiratory time) during SWS (104.6 ± 39.5 %TI) versus Stage N2 sleep (82.6 ± 39.5 %TI, P < 0.001). The IT units fired faster during expiration in SWS (14.2 ± 1.8 Hz) versus Stage N2 sleep (12.6 ± 3.1 Hz, P = 0.035). There was minimal recruitment or derecruitment of units between SWS and Stage N2 sleep. Increased genioglossus SMU activity likely makes the airway more stable and resistant to collapse throughout the respiratory cycle during SWS.

Auditory closed-loop stimulation of the sleep slow oscillation enhances memory.

PubMed

Ngo, Hong-Viet V; Martinetz, Thomas; Born, Jan; Mölle, Matthias

2013-05-08

Brain rhythms regulate information processing in different states to enable learning and memory formation. The <1 Hz sleep slow oscillation hallmarks slow-wave sleep and is critical to memory consolidation. Here we show in sleeping humans that auditory stimulation in phase with the ongoing rhythmic occurrence of slow oscillation up states profoundly enhances the slow oscillation rhythm, phase-coupled spindle activity, and, consequently, the consolidation of declarative memory. Stimulation out of phase with the ongoing slow oscillation rhythm remained ineffective. Closed-loop in-phase stimulation provides a straight-forward tool to enhance sleep rhythms and their functional efficacy. Copyright © 2013 Elsevier Inc. All rights reserved.

Human longevity is associated with regular sleep patterns, maintenance of slow wave sleep, and favorable lipid profile

PubMed Central

Mazzotti, Diego Robles; Guindalini, Camila; Moraes, Walter André dos Santos; Andersen, Monica Levy; Cendoroglo, Maysa Seabra; Ramos, Luiz Roberto; Tufik, Sergio

2014-01-01

Some individuals are able to successfully reach very old ages, reflecting higher adaptation against age-associated effects. Sleep is one of the processes deeply affected by aging; however few studies evaluating sleep in long-lived individuals (aged over 85) have been reported to date. The aim of this study was to characterize the sleep patterns and biochemical profile of oldest old individuals (N = 10, age 85–105 years old) and compare them to young adults (N = 15, age 20–30 years old) and older adults (N = 13, age 60–70 years old). All subjects underwent full-night polysomnography, 1-week of actigraphic recording and peripheral blood collection. Sleep electroencephalogram spectral analysis was also performed. The oldest old individuals showed lower sleep efficiency and REM sleep when compared to the older adults, while stage N3 percentage and delta power were similar across the groups. Oldest old individuals maintained strictly regular sleep-wake schedules and also presented higher HDL-cholesterol and lower triglyceride levels than older adults. The present study revealed novel data regarding specific sleep patterns and maintenance of slow wave sleep in the oldest old group. Taken together with the favorable lipid profile, these results contribute with evidence to the importance of sleep and lipid metabolism regulation in the maintenance of longevity in humans. PMID:25009494

Effect of Slow Wave Sleep Disruption on Metabolic Parameters in Adolescents

PubMed Central

Shaw, Natalie D.; McHill, Andrew W.; Schiavon, Michele; Kangarloo, Tairmae; Mankowski, Piotr W.; Cobelli, Claudio; Klerman, Elizabeth B.; Hall, Janet E.

2016-01-01

Study Objectives: Cross-sectional studies report a correlation between slow wave sleep (SWS) duration and insulin sensitivity (SI) in children and adults. Suppression of SWS causes insulin resistance in adults but effects in children are unknown. This study was designed to determine the effect of SWS fragmentation on SI in children. Methods: Fourteen pubertal children (11.3–14.1 y, body mass index 29th to 97th percentile) were randomized to sleep studies and mixed meal (MM) tolerance tests with and without SWS disruption. Beta-cell responsiveness (Φ) and SI were determined using oral minimal modeling. Results: During the disruption night, auditory stimuli (68.1 ± 10.7/night; mean ± standard error) decreased SWS by 40.0 ± 8.0%. SWS fragmentation did not affect fasting glucose (non-disrupted 76.9 ± 2.3 versus disrupted 80.6 ± 2.1 mg/dL), insulin (9.2 ± 1.6 versus 10.4 ± 2.0 μIU/mL), or C-peptide (1.9 ± 0.2 versus 1.9 ± 0.1 ng/mL) levels and did not impair SI (12.9 ± 2.3 versus 10.1 ± 1.6 10−4 dL/kg/min per μIU/mL) or Φ (73.4 ± 7.8 versus 74.4 ± 8.4 10−9 min−1) to a MM challenge. Only the subjects in the most insulin-sensitive tertile demonstrated a consistent decrease in SI after SWS disruption. Conclusion: Pubertal children across a range of body mass indices may be resistant to the adverse metabolic effects of acute SWS disruption. Only those subjects with high SI (i.e., having the greatest “metabolic reserve”) demonstrated a consistent decrease in SI. These results suggest that adolescents may have a unique ability to adapt to metabolic stressors, such as acute SWS disruption, to maintain euglycemia. Additional studies are necessary to confirm that this resiliency is maintained in settings of chronic SWS disruption. Citation: Shaw ND, McHill AW, Schiavon M, Kangarloo T, Mankowski PW, Cobelli C, Klerman EB, Hall JE. Effect of slow wave sleep disruption on metabolic parameters in adolescents. SLEEP 2016;39(8):1591–1599. PMID:27166229

EEG slow waves in traumatic brain injury: Convergent findings in mouse and man

PubMed Central

Modarres, Mo; Kuzma, Nicholas N.; Kretzmer, Tracy; Pack, Allan I.; Lim, Miranda M.

2016-01-01

Objective Evidence from previous studies suggests that greater sleep pressure, in the form of EEG-based slow waves, accumulates in specific brain regions that are more active during prior waking experience. We sought to quantify the number and coherence of EEG slow waves in subjects with mild traumatic brain injury (mTBI). Methods We developed a method to automatically detect individual slow waves in each EEG channel, and validated this method using simulated EEG data. We then used this method to quantify EEG-based slow waves during sleep and wake states in both mouse and human subjects with mTBI. A modified coherence index that accounts for information from multiple channels was calculated as a measure of slow wave synchrony. Results Brain-injured mice showed significantly higher theta:alpha amplitude ratios and significantly more slow waves during spontaneous wakefulness and during prolonged sleep deprivation, compared to sham-injured control mice. Human subjects with mTBI showed significantly higher theta:beta amplitude ratios and significantly more EEG slow waves while awake compared to age-matched control subjects. We then quantified the global coherence index of slow waves across several EEG channels in human subjects. Individuals with mTBI showed significantly less EEG global coherence compared to control subjects while awake, but not during sleep. EEG global coherence was significantly correlated with severity of post-concussive symptoms (as assessed by the Neurobehavioral Symptom Inventory scale). Conclusion and implications Taken together, our data from both mouse and human studies suggest that EEG slow wave quantity and the global coherence index of slow waves may represent a sensitive marker for the diagnosis and prognosis of mTBI and post-concussive symptoms. PMID:28018987

EEG slow waves in traumatic brain injury: Convergent findings in mouse and man.

PubMed

Modarres, Mo; Kuzma, Nicholas N; Kretzmer, Tracy; Pack, Allan I; Lim, Miranda M

2016-07-01

Evidence from previous studies suggests that greater sleep pressure, in the form of EEG-based slow waves, accumulates in specific brain regions that are more active during prior waking experience. We sought to quantify the number and coherence of EEG slow waves in subjects with mild traumatic brain injury (mTBI). We developed a method to automatically detect individual slow waves in each EEG channel, and validated this method using simulated EEG data. We then used this method to quantify EEG-based slow waves during sleep and wake states in both mouse and human subjects with mTBI. A modified coherence index that accounts for information from multiple channels was calculated as a measure of slow wave synchrony. Brain-injured mice showed significantly higher theta:alpha amplitude ratios and significantly more slow waves during spontaneous wakefulness and during prolonged sleep deprivation, compared to sham-injured control mice. Human subjects with mTBI showed significantly higher theta:beta amplitude ratios and significantly more EEG slow waves while awake compared to age-matched control subjects. We then quantified the global coherence index of slow waves across several EEG channels in human subjects. Individuals with mTBI showed significantly less EEG global coherence compared to control subjects while awake, but not during sleep. EEG global coherence was significantly correlated with severity of post-concussive symptoms (as assessed by the Neurobehavioral Symptom Inventory scale). Taken together, our data from both mouse and human studies suggest that EEG slow wave quantity and the global coherence index of slow waves may represent a sensitive marker for the diagnosis and prognosis of mTBI and post-concussive symptoms.

Coordination of Slow Waves With Sleep Spindles Predicts Sleep-Dependent Memory Consolidation in Schizophrenia.

PubMed

Demanuele, Charmaine; Bartsch, Ullrich; Baran, Bengi; Khan, Sheraz; Vangel, Mark G; Cox, Roy; Hämäläinen, Matti; Jones, Matthew W; Stickgold, Robert; Manoach, Dara S

2017-01-01

Schizophrenia patients have correlated deficits in sleep spindle density and sleep-dependent memory consolidation. In addition to spindle density, memory consolidation is thought to rely on the precise temporal coordination of spindles with slow waves (SWs). We investigated whether this coordination is intact in schizophrenia and its relation to motor procedural memory consolidation. Twenty-one chronic medicated schizophrenia patients and 17 demographically matched healthy controls underwent two nights of polysomnography, with training on the finger tapping motor sequence task (MST) on the second night and testing the following morning. We detected SWs (0.5-4 Hz) and spindles during non-rapid eye movement (NREM) sleep. We measured SW-spindle phase-amplitude coupling and its relation with overnight improvement in MST performance. Patients did not differ from controls in the timing of SW-spindle coupling. In both the groups, spindles peaked during the SW upstate. For patients alone, the later in the SW upstate that spindles peaked and the more reliable this phase relationship, the greater the overnight MST improvement. Regression models that included both spindle density and SW-spindle coordination predicted overnight improvement significantly better than either parameter alone, suggesting that both contribute to memory consolidation. Schizophrenia patients show intact spindle-SW temporal coordination, and these timing relationships, together with spindle density, predict sleep-dependent memory consolidation. These relations were seen only in patients suggesting that their memory is more dependent on optimal spindle-SW timing, possibly due to reduced spindle density. Interventions to improve memory may need to increase spindle density while preserving or enhancing the coordination of NREM oscillations. © Sleep Research Society 2016. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e

Enhanced slow wave sleep and improved sleep maintenance after gaboxadol administration during seven nights of exposure to a traffic noise model of transient insomnia.

PubMed

Dijk, D-J; Stanley, N; Lundahl, J; Groeger, J A; Legters, A; Trap Huusom, A K; Deacon, S

2012-08-01

Slow wave sleep (SWS) has been reported to correlate with sleep maintenance, but whether pharmacological enhancement of SWS also leads to improved sleep maintenance is not known. Here we evaluate the time-course of the effects of gaboxadol, an extra-synaptic gamma-aminobutyric acid (GABA) agonist, on SWS, sleep maintenance, and other sleep measures in a traffic noise model of transient insomnia. After a placebo run-in, 101 healthy subjects (20-78 y) were randomized to gaboxadol (n = 50; 15 mg in subjects <65 y and 10 mg in subjects ≥65 y) or placebo (n = 51) for 7 nights (N1-N7). The model caused some disruption of sleep initiation and maintenance, with greatest effects on N1. Compared with placebo, gaboxadol increased SWS and slow wave activity throughout N1 to N7 (p < 0.05). Gaboxadol reduced latency to persistent sleep overall (N1-N7) by 4.5 min and on N1 by 11 min (both p < 0.05). Gaboxadol increased total sleep time (TST) overall by 16 min (p < 0.001) and on N1 by 38 min (p < 0.0001). Under gaboxadol, wakefulness after sleep onset was reduced by 11 min overall (p < 0.01) and by 29 min on N1 (p < 0.0001), and poly-somnographic awakenings were reduced on N1 (p < 0.05). Gaboxadol reduced self-reported sleep onset latency overall and on N1 (both p < 0.05) and increased self-reported TST overall (p < 0.05) and on N1 (p < 0.01). Subjective sleep quality improved overall (p < 0.01) and on N1 (p < 0.0001). Increases in SWS correlated with objective and subjective measures of sleep maintenance and subjective sleep quality under placebo and gaboxadol (p < 0.05). Gaboxadol enhanced SWS and reduced the disruptive effects of noise on sleep initiation and maintenance.

Daytime Ayahuasca administration modulates REM and slow-wave sleep in healthy volunteers.

PubMed

Barbanoj, Manel J; Riba, Jordi; Clos, S; Giménez, S; Grasa, E; Romero, S

2008-02-01

Ayahuasca is a traditional South American psychoactive beverage and the central sacrament of Brazilian-based religious groups, with followers in Europe and the United States. The tea contains the psychedelic indole N,N-dimethyltryptamine (DMT) and beta-carboline alkaloids with monoamine oxidase-inhibiting properties that render DMT orally active. DMT interacts with serotonergic neurotransmission acting as a partial agonist at 5-HT(1A) and 5-HT(2A/2C) receptor sites. Given the role played by serotonin in the regulation of the sleep/wake cycle, we investigated the effects of daytime ayahuasca consumption in sleep parameters. Subjective sleep quality, polysomnography (PSG), and spectral analysis were assessed in a group of 22 healthy male volunteers after the administration of a placebo, an ayahuasca dose equivalent to 1 mg DMT kg(-1) body weight, and 20 mg d-amphetamine, a proaminergic drug, as a positive control. Results show that ayahuasca did not induce any subjectively perceived deterioration of sleep quality or PSG-measured disruptions of sleep initiation or maintenance, in contrast with d-amphetamine, which delayed sleep initiation, disrupted sleep maintenance, induced a predominance of 'light' vs 'deep' sleep and significantly impaired subjective sleep quality. PSG analysis also showed that similarly to d-amphetamine, ayahuasca inhibits rapid eye movement (REM) sleep, decreasing its duration, both in absolute values and as a percentage of total sleep time, and shows a trend increase in its onset latency. Spectral analysis showed that d-amphetamine and ayahuasca increased power in the high frequency range, mainly during stage 2. Remarkably, whereas slow-wave sleep (SWS) power in the first night cycle, an indicator of sleep pressure, was decreased by d-amphetamine, ayahuasca enhanced power in this frequency band. Results show that daytime serotonergic psychedelic drug administration leads to measurable changes in PSG and sleep power spectrum and suggest an

Fast and Slow Spindles during the Sleep Slow Oscillation: Disparate Coalescence and Engagement in Memory Processing

PubMed Central

Mölle, Matthias; Bergmann, Til O.; Marshall, Lisa; Born, Jan

2011-01-01

Study Objectives: Thalamo-cortical spindles driven by the up-state of neocortical slow (< 1 Hz) oscillations (SOs) represent a candidate mechanism of memory consolidation during sleep. We examined interactions between SOs and spindles in human slow wave sleep, focusing on the presumed existence of 2 kinds of spindles, i.e., slow frontocortical and fast centro-parietal spindles. Design: Two experiments were performed in healthy humans (24.5 ± 0.9 y) investigating undisturbed sleep (Experiment I) and the effects of prior learning (word paired associates) vs. non-learning (Experiment II) on multichannel EEG recordings during sleep. Measurements and Results: Only fast spindles (12-15 Hz) were synchronized to the depolarizing SO up-state. Slow spindles (9-12 Hz) occurred preferentially at the transition into the SO down-state, i.e., during waning depolarization. Slow spindles also revealed a higher probability to follow rather than precede fast spindles. For sequences of individual SOs, fast spindle activity was largest for “initial” SOs, whereas SO amplitude and slow spindle activity were largest for succeeding SOs. Prior learning enhanced this pattern. Conclusions: The finding that fast and slow spindles occur at different times of the SO cycle points to disparate generating mechanisms for the 2 kinds of spindles. The reported temporal relationships during SO sequences suggest that fast spindles, driven by the SO up-state feed back to enhance the likelihood of succeeding SOs together with slow spindles. By enforcing such SO-spindle cycles, particularly after prior learning, fast spindles possibly play a key role in sleep-dependent memory processing. Citation: Mölle M; Bergmann TO; Marshall L; Born J. Fast and slow spindles during the sleep slow oscillation: disparate coalescence and engagement in memory processing. SLEEP 2011;34(10):1411–1421. PMID:21966073

Distinct associations between energy balance and the sleep characteristics slow wave sleep and rapid eye movement sleep.

PubMed

Rutters, F; Gonnissen, H K; Hursel, R; Lemmens, S G; Martens, E A; Westerterp-Plantenga, M S

2012-10-01

Epidemiologically, an inverse relationship between body mass index (BMI) and sleep duration is observed. Intra-individual variance in the amount of slow wave sleep (SWS) or rapid eye movement (REM) sleep has been related to variance of metabolic and endocrine parameters, which are risk factors for the disturbance of energy balance (EB). To investigate inter-individual relationships between EB (EB= energy intake-energy expenditure∣, MJ/24 h), SWS or REM sleep, and relevant parameters in normal-weight men during two 48 h stays in the controlled environment of a respiration chamber. A total of 16 men (age 23±3.7 years, BMI 23.9±1.9 kg m(-2)) stayed in the respiration chamber twice for 48 h to assure EB. Electroencephalography was used to monitor sleep (2330-0730 hrs). Hunger and fullness were scored by visual analog scales; mood was determined by State Trait Anxiety Index-state and food reward by liking and wanting. Baseline blood and salivary samples were collected before breakfast. Subjects were fed in EB, except for the last dinner, when energy intake was ad libitum. The subjects slept on average 441.8±49 min per night, and showed high within-subject reliability for the amount of SWS and REM sleep. Linear regression analyses showed that EB was inversely related to the amount of SWS (r=-0.43, P<0.03), and positively related to the amount of REM sleep (r=0.40, P<0.05). Relevant parameters such as hunger, reward, stress and orexigenic hormone concentrations were related to overeating, as well as to the amount of SWS and REM sleep, however, after inclusion of these parameters in a multiple regression, the amount of SWS and REM sleep did not add to the explained variance of EB, which suggests that due to their individual associations, these EB parameters are mediator variables. A positive EB due to overeating, was explained by a smaller amount of SWS and higher amount of REM sleep, mediated by hunger, fullness, State Trait Anxiety Index-state scores, glucose

Sustained increase in hippocampal sharp-wave ripple activity during slow-wave sleep after learning

PubMed Central

Eschenko, Oxana; Ramadan, Wiâm; Mölle, Matthias; Born, Jan; Sara, Susan J.

2008-01-01

High-frequency oscillations, known as sharp-wave/ripple (SPW-R) complexes occurring in hippocampus during slow-wave sleep (SWS), have been proposed to promote synaptic plasticity necessary for memory consolidation. We recorded sleep for 3 h after rats were trained on an odor-reward association task. Learning resulted in an increased number SPW-Rs during the first hour of post-learning SWS. The magnitude of ripple events and their duration were also elevated for up to 2 h after the newly formed memory. Rats that did not learn the discrimination during the training session did not show any change in SPW-Rs. Successful retrieval from remote memory was likewise accompanied by an increase in SPW-R density and magnitude, relative to the previously recorded baseline, but the effects were much shorter lasting and did not include increases in ripple duration and amplitude. A short-lasting increase of ripple activity was also observed when rats were rewarded for performing a motor component of the task only. There were no increases in ripple activity after habituation to the experimental environment. These experiments show that the characteristics of hippocampal high-frequency oscillations during SWS are affected by prior behavioral experience. Associative learning induces robust and sustained (up to 2 h) changes in several SPW-R characteristics, while after retrieval from remote memory or performance of a well-trained procedural aspect of the task, only transient changes in ripple density were induced. PMID:18385477

Influence of general anaesthesia on slow waves of intracranial pressure.

PubMed

Lalou, Despina A; Czosnyka, Marek; Donnelly, Joseph; Lavinio, Andrea; Pickard, John D; Garnett, Matthew; Czosnyka, Zofia

2016-07-01

Slow vasogenic intracranial pressure (ICP) waves are spontaneous ICP oscillations with a low frequency bandwidth of 0.3-4 cycles/min (B-waves). B-waves reflect dynamic oscillations in cerebral blood volume associated with autoregulatory cerebral vasodilation and vasoconstriction. This study quantifies the effects of general anaesthesia (GA) on the magnitude of B-waves compared to natural sleep and conscious state. The magnitude of B-waves was assessed in 4 groups of 30 patients each with clinical indications for ICP monitoring. Normal pressure hydrocephalus patients undergoing Cerebrospinal Fluid (CSF) infusion studies in the conscious state (GROUP A) and under GA (GROUP B), and hydrocephalus patients undergoing overnight ICP monitoring during physiological sleep (GROUP C) were compared to deeply sedated traumatic brain injury (TBI) patients with well-controlled ICP during the first night of Intensive Care Unit (ICU) stay (GROUP D). A total of 120 patients were included. During CSF infusion studies, the magnitude of slow waves was higher in conscious patients ( 0.23+/-0.10 mm Hg) when compared to anaesthetised patients ( 0.15+/-0.10 mm Hg; p = 0.011). Overnight magnitude of slow waves was higher in patients during natural sleep (GROUP C: 0.20+/-0.13 mm Hg) when compared to TBI patients under deep sedation (GROUP D: 0.11+/- 0.09 mm Hg; p = 0.002). GA and deep sedation are associated with a reduced magnitude of B-waves. ICP monitoring carried out under GA is affected by iatrogenic suppression of slow vasogenic waves of ICP. Accounting for the effects of anaesthesia on vasogenic waves may prevent the misidentification of potential shunt-responders as non-responders.

Fast and slow spindles during the sleep slow oscillation: disparate coalescence and engagement in memory processing.

PubMed

Mölle, Matthias; Bergmann, Til O; Marshall, Lisa; Born, Jan

2011-10-01

Thalamo-cortical spindles driven by the up-state of neocortical slow (< 1 Hz) oscillations (SOs) represent a candidate mechanism of memory consolidation during sleep. We examined interactions between SOs and spindles in human slow wave sleep, focusing on the presumed existence of 2 kinds of spindles, i.e., slow frontocortical and fast centro-parietal spindles. Two experiments were performed in healthy humans (24.5 ± 0.9 y) investigating undisturbed sleep (Experiment I) and the effects of prior learning (word paired associates) vs. non-learning (Experiment II) on multichannel EEG recordings during sleep. Only fast spindles (12-15 Hz) were synchronized to the depolarizing SO up-state. Slow spindles (9-12 Hz) occurred preferentially at the transition into the SO down-state, i.e., during waning depolarization. Slow spindles also revealed a higher probability to follow rather than precede fast spindles. For sequences of individual SOs, fast spindle activity was largest for "initial" SOs, whereas SO amplitude and slow spindle activity were largest for succeeding SOs. Prior learning enhanced this pattern. The finding that fast and slow spindles occur at different times of the SO cycle points to disparate generating mechanisms for the 2 kinds of spindles. The reported temporal relationships during SO sequences suggest that fast spindles, driven by the SO up-state feed back to enhance the likelihood of succeeding SOs together with slow spindles. By enforcing such SO-spindle cycles, particularly after prior learning, fast spindles possibly play a key role in sleep-dependent memory processing.

Nonlinear dynamical systems effects of homeopathic remedies on multiscale entropy and correlation dimension of slow wave sleep EEG in young adults with histories of coffee-induced insomnia.

PubMed

Bell, Iris R; Howerter, Amy; Jackson, Nicholas; Aickin, Mikel; Bootzin, Richard R; Brooks, Audrey J

2012-07-01

Investigators of homeopathy have proposed that nonlinear dynamical systems (NDS) and complex systems science offer conceptual and analytic tools for evaluating homeopathic remedy effects. Previous animal studies demonstrate that homeopathic medicines alter delta electroencephalographic (EEG) slow wave sleep. The present study extended findings of remedy-related sleep stage alterations in human subjects by testing the feasibility of using two different NDS analytic approaches to assess remedy effects on human slow wave sleep EEG. Subjects (N=54) were young adult male and female college students with a history of coffee-related insomnia who participated in a larger 4-week study of the polysomnographic effects of homeopathic medicines on home-based all-night sleep recordings. Subjects took one bedtime dose of a homeopathic remedy (Coffea cruda or Nux vomica 30c). We computed multiscale entropy (MSE) and the correlation dimension (Mekler-D2) for stages 3 and 4 slow wave sleep EEG sampled in artifact-free 2-min segments during the first two rapid-eye-movement (REM) cycles for remedy and post-remedy nights, controlling for placebo and post-placebo night effects. MSE results indicate significant, remedy-specific directional effects, especially later in the night (REM cycle 2) (CC: remedy night increases and post-remedy night decreases in MSE at multiple sites for both stages 3 and 4 in both REM cycles; NV: remedy night decreases and post-remedy night increases, mainly in stage 3 REM cycle 2 MSE). D2 analyses yielded more sporadic and inconsistent findings. Homeopathic medicines Coffea cruda and Nux vomica in 30c potencies alter short-term nonlinear dynamic parameters of slow wave sleep EEG in healthy young adults. MSE may provide a more sensitive NDS analytic method than D2 for evaluating homeopathic remedy effects on human sleep EEG patterns. Copyright © 2012 The Faculty of Homeopathy. Published by Elsevier Ltd. All rights reserved.

Nonlinear Dynamical Systems Effects of Homeopathic Remedies on Multiscale Entropy and Correlation Dimension of Slow Wave Sleep EEG in Young Adults with Histories of Coffee-Induced Insomnia

PubMed Central

Bell, Iris R.; Howerter, Amy; Jackson, Nicholas; Aickin, Mikel; Bootzin, Richard R.; Brooks, Audrey J.

2012-01-01

Background Investigators of homeopathy have proposed that nonlinear dynamical systems (NDS) and complex systems science offer conceptual and analytic tools for evaluating homeopathic remedy effects. Previous animal studies demonstrate that homeopathic medicines alter delta electroencephalographic (EEG) slow wave sleep. The present study extended findings of remedy-related sleep stage alterations in human subjects by testing the feasibility of using two different NDS analytic approaches to assess remedy effects on human slow wave sleep EEG. Methods Subjects (N=54) were young adult male and female college students with a history of coffee-related insomnia who participated in a larger 4-week study of the polysomnographic effects of homeopathic medicines on home-based all-night sleep recordings. Subjects took one bedtime dose of a homeopathic remedy (Coffea cruda or Nux vomica 30c). We computed multiscale entropy (MSE) and the correlation dimension (Mekler-D2) for stage 3 and 4 slow wave sleep EEG sampled in artifact-free 2-minute segments during the first two rapid-eye-movement (REM) cycles for remedy and post-remedy nights, controlling for placebo and post-placebo night effects. Results MSE results indicate significant, remedy-specific directional effects, especially later in the night (REM cycle 2) (CC: remedy night increases and post-remedy night decreases in MSE at multiple sites for both stages 3 and 4 in both REM cycles; NV: remedy night decreases and post-remedy night increases, mainly in stage 3 REM cycle 2 MSE). D2 analyses yielded more sporadic and inconsistent findings. Conclusions Homeopathic medicines Coffea cruda and Nux vomica in 30c potencies alter short-term nonlinear dynamic parameters of slow wave sleep EEG in healthy young adults. MSE may provide a more sensitive NDS analytic method than D2 for evaluating homeopathic remedy effects on human sleep EEG patterns. PMID:22818237

Desynchronization of slow oscillations in the basal ganglia during natural sleep.

PubMed

Mizrahi-Kliger, Aviv D; Kaplan, Alexander; Israel, Zvi; Bergman, Hagai

2018-05-01

Slow oscillations of neuronal activity alternating between firing and silence are a hallmark of slow-wave sleep (SWS). These oscillations reflect the default activity present in all mammalian species, and are ubiquitous to anesthesia, brain slice preparations, and neuronal cultures. In all these cases, neuronal firing is highly synchronous within local circuits, suggesting that oscillation-synchronization coupling may be a governing principle of sleep physiology regardless of anatomical connectivity. To investigate whether this principle applies to overall brain organization, we recorded the activity of individual neurons from basal ganglia (BG) structures and the thalamocortical (TC) network over 70 full nights of natural sleep in two vervet monkeys. During SWS, BG neurons manifested slow oscillations (∼0.5 Hz) in firing rate that were as prominent as in the TC network. However, in sharp contrast to any neural substrate explored thus far, the slow oscillations in all BG structures were completely desynchronized between individual neurons. Furthermore, whereas in the TC network single-cell spiking was locked to slow oscillations in the local field potential (LFP), the BG LFP exhibited only weak slow oscillatory activity and failed to entrain nearby cells. We thus show that synchrony is not inherent to slow oscillations, and propose that the BG desynchronization of slow oscillations could stem from its unique anatomy and functional connectivity. Finally, we posit that BG slow-oscillation desynchronization may further the reemergence of slow-oscillation traveling waves from multiple independent origins in the frontal cortex, thus significantly contributing to normal SWS.

Acoustic Enhancement of Sleep Slow Oscillations and Concomitant Memory Improvement in Older Adults

PubMed Central

Papalambros, Nelly A.; Santostasi, Giovanni; Malkani, Roneil G.; Braun, Rosemary; Weintraub, Sandra; Paller, Ken A.; Zee, Phyllis C.

2017-01-01

Acoustic stimulation methods applied during sleep in young adults can increase slow wave activity (SWA) and improve sleep-dependent memory retention. It is unknown whether this approach enhances SWA and memory in older adults, who generally have reduced SWA compared to younger adults. Additionally, older adults are at risk for age-related cognitive impairment and therefore may benefit from non-invasive interventions. The aim of this study was to determine if acoustic stimulation can increase SWA and improve declarative memory in healthy older adults. Thirteen participants 60–84 years old completed one night of acoustic stimulation and one night of sham stimulation in random order. During sleep, a real-time algorithm using an adaptive phase-locked loop modeled the phase of endogenous slow waves in midline frontopolar electroencephalographic recordings. Pulses of pink noise were delivered when the upstate of the slow wave was predicted. Each interval of five pulses (“ON interval”) was followed by a pause of approximately equal length (“OFF interval”). SWA during the entire sleep period was similar between stimulation and sham conditions, whereas SWA and spindle activity were increased during ON intervals compared to matched periods during the sham night. The increases in SWA and spindle activity were sustained across almost the entire five-pulse ON interval compared to matched sham periods. Verbal paired-associate memory was tested before and after sleep. Overnight improvement in word recall was significantly greater with acoustic stimulation compared to sham and was correlated with changes in SWA between ON and OFF intervals. Using the phase-locked-loop method to precisely target acoustic stimulation to the upstate of sleep slow oscillations, we were able to enhance SWA and improve sleep-dependent memory storage in older adults, which strengthens the theoretical link between sleep and age-related memory integrity. PMID:28337134

EEG slow-wave coherence changes in propofol-induced general anesthesia: experiment and theory

PubMed Central

Wang, Kaier; Steyn-Ross, Moira L.; Steyn-Ross, D. A.; Wilson, Marcus T.; Sleigh, Jamie W.

2014-01-01

The electroencephalogram (EEG) patterns recorded during general anesthetic-induced coma are closely similar to those seen during slow-wave sleep, the deepest stage of natural sleep; both states show patterns dominated by large amplitude slow waves. Slow oscillations are believed to be important for memory consolidation during natural sleep. Tracking the emergence of slow-wave oscillations during transition to unconsciousness may help us to identify drug-induced alterations of the underlying brain state, and provide insight into the mechanisms of general anesthesia. Although cellular-based mechanisms have been proposed, the origin of the slow oscillation has not yet been unambiguously established. A recent theoretical study by Steyn-Ross et al. (2013) proposes that the slow oscillation is a network, rather than cellular phenomenon. Modeling anesthesia as a moderate reduction in gap-junction interneuronal coupling, they predict an unconscious state signposted by emergent low-frequency oscillations with chaotic dynamics in space and time. They suggest that anesthetic slow-waves arise from a competitive interaction between symmetry-breaking instabilities in space (Turing) and time (Hopf), modulated by gap-junction coupling strength. A significant prediction of their model is that EEG phase coherence will decrease as the cortex transits from Turing–Hopf balance (wake) to Hopf-dominated chaotic slow-waves (unconsciousness). Here, we investigate changes in phase coherence during induction of general anesthesia. After examining 128-channel EEG traces recorded from five volunteers undergoing propofol anesthesia, we report a significant drop in sub-delta band (0.05–1.5 Hz) slow-wave coherence between frontal, occipital, and frontal–occipital electrode pairs, with the most pronounced wake-vs.-unconscious coherence changes occurring at the frontal cortex. PMID:25400558

Scatterplot analysis of EEG slow-wave magnitude and heart rate variability: an integrative exploration of cerebral cortical and autonomic functions.

PubMed

Kuo, Terry B J; Yang, Cheryl C H

2004-06-15

To explore interactions between cerebral cortical and autonomic functions in different sleep-wake states. Active waking (AW), quiet sleep (QS), and paradoxical sleep (PS) of adult male Wistar-Kyoto rats (WKY) on their daytime sleep were compared. Ten WKY. All rats had electrodes implanted for polygraphic recordings. One week later, a 6-hour daytime sleep-wakefulness recording session was performed. A scatterplot analysis of electroencephalogram (EEG) slow-wave magnitude (0.5-4 Hz) and heart rate variability (HRV) was applied in each rat. The EEG slow-wave-RR interval scatterplot from all of the recordings revealed a propeller-like pattern. If the scatterplot was divided into AW, PS, and QS according to the corresponding EEG mean power frequency and nuchal electromyogram, the EEG slow wave-RR interval relationship became nil, negative, and positive for AW, PS, and QS, respectively. A significant negative relationship was found for EEG slow-wave and high-frequency power of HRV (HF) coupling during PS and for EEG slow wave and low-frequency power of HRV to HF ratio (LF/HF) coupling during QS. The optimal time lags for the slow wave-LF/HF relationship were different between PS and QS. Bradycardia noted in QS and PS was related to sympathetic suppression and vagal excitation, respectively. The EEG slow wave-HRV scatterplot may provide unique insights into studies of sleep, and such a relationship may delineate the sleep-state-dependent fluctuations in autonomic nervous system activity.

Reactivation of emergent task-related ensembles during slow-wave sleep after neuroprosthetic learning

PubMed Central

Gulati, Tanuj; Ramanathan, Dhakshin; Wong, Chelsea; Ganguly, Karunesh

2017-01-01

Brain-Machine Interfaces can allow neural control over assistive devices. They also provide an important platform to study neural plasticity. Recent studies indicate that optimal engagement of learning is essential for robust neuroprosthetic control. However, little is known about the neural processes that may consolidate a neuroprosthetic skill. Based on the growing body of evidence linking slow-wave activity (SWA) during sleep to consolidation, we examined if there is ‘offline’ processing after neuroprosthetic learning. Using a rodent model, here we show that after successful learning, task-related units specifically experienced increased locking and coherency to SWA during sleep. Moreover, spike-spike coherence among these units was significantly enhanced. These changes were not present with poor skill acquisition or after control awake periods, demonstrating specificity of our observations to learning. Interestingly, time spent in SWA predicted performance gains. Thus, SWA appears to play a role in offline processing after neuroprosthetic learning. PMID:24997761

Human cortical–hippocampal dialogue in wake and slow-wave sleep

PubMed Central

Mitra, Anish; Hacker, Carl D.; Pahwa, Mrinal; Tagliazucchi, Enzo; Laufs, Helmut; Leuthardt, Eric C.; Raichle, Marcus E.

2016-01-01

Declarative memory consolidation is hypothesized to require a two-stage, reciprocal cortical–hippocampal dialogue. According to this model, higher frequency signals convey information from the cortex to hippocampus during wakefulness, but in the reverse direction during slow-wave sleep (SWS). Conversely, lower-frequency activity propagates from the information “receiver” to the “sender” to coordinate the timing of information transfer. Reversal of sender/receiver roles across wake and SWS implies that higher- and lower-frequency signaling should reverse direction between the cortex and hippocampus. However, direct evidence of such a reversal has been lacking in humans. Here, we use human resting-state fMRI and electrocorticography to demonstrate that δ-band activity and infraslow activity propagate in opposite directions between the hippocampus and cerebral cortex. Moreover, both δ activity and infraslow activity reverse propagation directions between the hippocampus and cerebral cortex across wake and SWS. These findings provide direct evidence for state-dependent reversals in human cortical–hippocampal communication. PMID:27791089

Deep sleep after social stress: NREM sleep slow-wave activity is enhanced in both winners and losers of a conflict.

PubMed

Kamphuis, Jeanine; Lancel, Marike; Koolhaas, Jaap M; Meerlo, Peter

2015-07-01

Sleep is considered to be a recovery process of prior wakefulness. Not only duration of the waking period affects sleep architecture and sleep EEG, the quality of wakefulness is also highly important. Studies in rats have shown that social defeat stress, in which experimental animals are attacked and defeated by a dominant conspecific, is followed by an acute increase in NREM sleep EEG slow wave activity (SWA). However, it is not known whether this effect is specific for the stress of social defeat or a result of the conflict per se. In the present experiment, we examined how sleep is affected in both the winners and losers of a social conflict. Sleep-wake patterns and sleep EEG were recorded in male wild-type Groningen rats that were subjected to 1h of social conflict in the middle of the light phase. All animals were confronted with a conspecific of similar aggression level and the conflict took place in a neutral arena where both individuals had an equal chance to either win or lose the conflict. NREM sleep SWA was significantly increased after the social conflict compared to baseline values and a gentle stimulation control condition. REM sleep was significantly suppressed in the first hours after the conflict. Winners and losers did not differ significantly in NREM sleep time, NREM sleep SWA and REM sleep time immediately after the conflict. Losers tended to have slightly more NREM sleep later in the recovery period. This study shows that in rats a social conflict with an unpredictable outcome has quantitatively and qualitatively largely similar acute effects on subsequent sleep in winners and losers. Copyright © 2015 Elsevier Inc. All rights reserved.

Dissociating the contributions of slow-wave sleep and rapid eye movement sleep to emotional item and source memory.

PubMed

Groch, S; Zinke, K; Wilhelm, I; Born, J

2015-07-01

Sleep benefits the consolidation of emotional memories, and this influence is commonly attributed to the rapid eye movement (REM) stage of sleep. However, the contributions of sleep stages to memory for an emotional episode may differ for the event per se (i.e., item memory), and the context in which it occurred (source memory). Here, we examined the effects of slow wave sleep (SWS) and REM sleep on the consolidation of emotionally negative and neutral item (picture recognition) and source memory (recall of picture-location and picture-frame color association) in humans. In Study 1, the participants (n=18) learned 48 negative and 48 neutral pictures which were presented at specific locations and preceded by colored frames that had to be associated with the picture. In a within-subject design, learning was either followed by a 3-h early-night SWS-rich or by a late-night REM sleep-rich retention interval, then retrieval was tested. Only after REM-rich sleep, and not after SWS-rich sleep, was there a significant emotional enhancement, i.e., a significantly superior retention of emotional over neutral pictures. On the other hand, after SWS-rich sleep the retention of picture-frame color associations was better than after REM-rich sleep. However, this benefit was observed only for neutral pictures; and it was completely absent for the emotional pictures. To examine whether this absent benefit reflected a suppressive effect of emotionality on associations of minor task relevance, in Study 2 we manipulated the relevance of the picture-frame color association by combining it with information about monetary reward, following otherwise comparable procedures. Here, rewarded picture-frame color associations were equally well retained over SWS-rich early sleep no matter if the frames were associated with emotional or neutral pictures. Results are consistent with the view that REM sleep favors the emotional enhancement of item memory whereas SWS appears to contribute primarily

Oscillating Square Wave Transcranial Direct Current Stimulation (tDCS) Delivered During Slow Wave Sleep Does Not Improve Declarative Memory More Than Sham: A Randomized Sham Controlled Crossover Study.

PubMed

Sahlem, Gregory L; Badran, Bashar W; Halford, Jonathan J; Williams, Nolan R; Korte, Jeffrey E; Leslie, Kimberly; Strachan, Martha; Breedlove, Jesse L; Runion, Jennifer; Bachman, David L; Uhde, Thomas W; Borckardt, Jeffery J; George, Mark S

2015-01-01

A 2006 trial in healthy medical students found that anodal slow oscillating tDCS delivered bi-frontally during slow wave sleep had an enhancing effect in declarative, but not procedural memory. Although there have been supporting animal studies, and similar findings in pathological groups, this study has not been replicated, or refuted, in the intervening years. We therefore tested these earlier results for replication using similar methods with the exception of current waveform (square in our study, nearly sinusoidal in the original). Our objective was to test the findings of a 2006 trial suggesting bi-frontal anodal tDCS during slow wave sleep enhances declarative memory. Twelve students (mean age 25, 9 women) free of medical problems underwent two testing conditions (active, sham) in a randomized counterbalanced fashion. Active stimulation consisted of oscillating square wave tDCS delivered during early Non-Rapid Eye Movement (NREM) sleep. The sham condition consisted of setting-up the tDCS device and electrodes, but not turning it on during sleep. tDCS was delivered bi-frontally with anodes placed at F3/F4, and cathodes placed at mastoids. Current density was 0.517 mA/cm(2), and oscillated between zero and maximal current at a frequency of 0.75 Hz. Stimulation occurred during five-five minute blocks with 1-min inter-block intervals (25 min total stimulation). The primary outcomes were both declarative memory consolidation measured by a paired word association test (PWA), and non-declarative memory, measured by a non-dominant finger-tapping test (FTT). We also recorded and analyzed sleep EEG. There was no difference in the number of paired word associations remembered before compared to after sleep [(active = 3.1 ± 3.0 SD more associations) (sham = 3.8 ± 3.1 SD more associations)]. Finger tapping improved, (non-significantly) following active stimulation [(3.6 ± 2.7 SD correctly typed sequences) compared to sham stimulation (2.3 ± 2.2 SD correctly typed

Oscillating square wave Transcranial Direct Current Stimulation (tDCS) delivered during slow wave sleep does not improve declarative memory more than sham: A randomized sham controlled crossover study

PubMed Central

Sahlem, Gregory L.; Badran, Bashar W.; Halford, Jonathan J.; Williams, Nolan R.; Korte, Jeffrey E.; Leslie, Kimberly; Strachan, Martha; Breedlove, Jesse L.; Runion, Jennifer; Bachman, David L.; Uhde, Thomas W.; Borckardt, Jeffery J.; George, Mark S.

2015-01-01

Background A 2006 trial in healthy medical students found that anodal slow oscillating tDCS delivered bi-frontally during slow wave sleep had an enhancing effect in declarative, but not procedural memory. Although there have been supporting animal studies, and similar findings in pathological groups, this study has not been replicated, or refuted, in the intervening years. We therefore tested these earlier results for replication using similar methods with the exception of current wave form (square in our study, nearly sinusoidal in the original). Objective/Hypothesis Our objective was to test the findings of a 2006 trial suggesting bi-frontal anodal tDCS during slow wave sleep enhances declarative memory. Methods Twelve students (mean age 25, 9 women) free of medical problems underwent two testing conditions (active, sham) in a randomized counterbalanced fashion. Active stimulation consisted of oscillating square wave tDCS delivered during early Non-Rapid Eye Movement (NREM) sleep. The sham condition consisted of setting-up the tDCS device and electrodes, but not turning it on during sleep. tDCS was delivered bi-frontally with anodes placed at F3/F4, and cathodes placed at mastoids. Current density was 0.517mA/CM2, and oscillated between zero and maximal current at a frequency of 0.75Hz. Stimulation occurred during five-five minute blocks with one-minute inter-block intervals (25 minutes total stimulation). The primary outcomes were both declarative memory consolidation measured by a paired word association test (PWA), and non-declarative memory, measured by a non-dominant finger-tapping test (FTT). We also recorded and analyzed sleep EEG. Results There was no difference in the number of paired word associations remembered before compared to after sleep [(active = 3.1±3.0SD more associations) (sham = 3.8±3.1S.D more associations)]. Finger tapping improved, (non-significantly) following active stimulation [(3.6±2.7 S.D. correctly typed sequences) compared to

Cerebral correlates of delta waves during non-REM sleep revisited.

PubMed

Dang-Vu, Thien Thanh; Desseilles, Martin; Laureys, Steven; Degueldre, Christian; Perrin, Fabien; Phillips, Christophe; Maquet, Pierre; Peigneux, Philippe

2005-10-15

We aimed at characterizing the neural correlates of delta activity during Non Rapid Eye Movement (NREM) sleep in non-sleep-deprived normal young adults, based on the statistical analysis of a positron emission tomography (PET) sleep data set. One hundred fifteen PET scans were obtained using H(2)(15)O under continuous polygraphic monitoring during stages 2-4 of NREM sleep. Correlations between regional cerebral blood flow (rCBF) and delta power (1.5-4 Hz) spectral density were analyzed using statistical parametric mapping (SPM2). Delta power values obtained at central scalp locations negatively correlated during NREM sleep with rCBF in the ventromedial prefrontal cortex, the basal forebrain, the striatum, the anterior insula, and the precuneus. These regions embrace the set of brain areas in which rCBF decreases during slow wave sleep (SWS) as compared to Rapid Eye Movement (REM) sleep and wakefulness (Maquet, P., Degueldre, C., Delfiore, G., Aerts, J., Peters, J.M., Luxen, A., Franck, G., 1997. Functional neuroanatomy of human slow wave sleep. J. Neurosci. 17, 2807-S2812), supporting the notion that delta activity is a valuable prominent feature of NREM sleep. A strong association was observed between rCBF in the ventromedial prefrontal regions and delta power, in agreement with electrophysiological studies. In contrast to the results of a previous PET study investigating the brain correlates of delta activity (Hofle, N., Paus, T., Reutens, D., Fiset, P., Gotman, J., Evans, A.C., Jones, B.E., 1997. Regional cerebral blood flow changes as a function of delta and spindle activity during slow wave sleep in humans. J. Neurosci. 17, 4800-4808), in which waking scans were mixed with NREM sleep scans, no correlation was found with thalamus activity. This latter result stresses the importance of an extra-thalamic delta rhythm among the synchronous NREM sleep oscillations. Consequently, this rCBF distribution might preferentially reflect a particular modulation of the

Is There a Relation between EEG-Slow Waves and Memory Dysfunction in Epilepsy? A Critical Appraisal

PubMed Central

Höller, Yvonne; Trinka, Eugen

2015-01-01

Is there a relationship between peri-ictal slow waves, loss of consciousness, memory, and slow-wave sleep, in patients with different forms of epilepsy? We hypothesize that mechanisms, which result in peri-ictal slow-wave activity as detected by the electroencephalogram, could negatively affect memory processes. Slow waves (≤4 Hz) can be found in seizures with impairment of consciousness and also occur in focal seizures without impairment of consciousness but with inhibited access to memory functions. Peri-ictal slow waves are regarded as dysfunctional and are probably caused by mechanisms, which are essential to disturb the consolidation of memory entries in these patients. This is in strong contrast to physiological slow-wave activity during deep sleep, which is thought to group memory-consolidating fast oscillatory activity. In patients with epilepsy, slow waves may not only correlate with the peri-ictal clouding of consciousness, but could be the epiphenomenon of mechanisms, which interfere with normal brain function in a wider range. These mechanisms may have transient impacts on memory, such as temporary inhibition of memory systems, altered patterns of hippocampal–neocortical interactions during slow-wave sleep, or disturbed cross-frequency coupling of slow and fast oscillations. In addition, repeated tonic–clonic seizures over the years in uncontrolled chronic epilepsy may cause a progressive cognitive decline. This hypothesis can only be assessed in long-term prospective studies. These studies could disentangle the reversible short-term impacts of seizures, and the impacts of chronic uncontrolled seizures. Chronic uncontrolled seizures lead to irreversible memory impairment. By contrast, short-term impacts do not necessarily lead to a progressive cognitive decline but result in significantly impaired peri-ictal memory performance. PMID:26124717

A review of short naps and sleep inertia: do naps of 30 min or less really avoid sleep inertia and slow-wave sleep?

PubMed

Hilditch, Cassie J; Dorrian, Jillian; Banks, Siobhan

2017-04-01

Napping is a widely used countermeasure to sleepiness and impaired performance caused by sleep loss and circadian pressure. Sleep inertia, the period of grogginess and impaired performance experienced after waking, is a potential side effect of napping. Many industry publications recommend naps of 30 min or less to avoid this side effect. However, the evidence to support this advice is yet to be thoroughly reviewed. Electronic databases were searched, and defined criteria were applied to select articles for review. The review covers literature on naps of 30 min or less regarding (a) sleep inertia, (b) slow-wave sleep (SWS) and (c) the relationship between sleep inertia and SWS. The review found that although the literature on short afternoon naps is relatively comprehensive, there are very few studies on naps of 30 min or less at night. Studies have mixed results regarding the onset of SWS and the duration and severity of sleep inertia following short naps, making guidelines regarding their use unclear. The varying results are likely due to differing sleep/wake profiles before the nap of interest and the time of the day at waking. The review highlights the need to have more detailed guidelines about the implementation of short naps according to the time of the day and prior sleep/wake history. Without this context, such a recommendation is potentially misleading. Further research is required to better understand the interactions between these factors, especially at night, and to provide more specific recommendations. Copyright © 2017 Elsevier B.V. All rights reserved.

Glucose Induces Slow-Wave Sleep by Exciting the Sleep-Promoting Neurons in the Ventrolateral Preoptic Nucleus: A New Link between Sleep and Metabolism.

PubMed

Varin, Christophe; Rancillac, Armelle; Geoffroy, Hélène; Arthaud, Sébastien; Fort, Patrice; Gallopin, Thierry

2015-07-08

Sleep-active neurons located in the ventrolateral preoptic nucleus (VLPO) play a crucial role in the induction and maintenance of slow-wave sleep (SWS). However, the cellular and molecular mechanisms responsible for their activation at sleep onset remain poorly understood. Here, we test the hypothesis that a rise in extracellular glucose concentration in the VLPO can promote sleep by increasing the activity of sleep-promoting VLPO neurons. We find that infusion of a glucose concentration into the VLPO of mice promotes SWS and increases the density of c-Fos-labeled neurons selectively in the VLPO. Moreover, we show in patch-clamp recordings from brain slices that VLPO neurons exhibiting properties of sleep-promoting neurons are selectively excited by glucose within physiological range. This glucose-induced excitation implies the catabolism of glucose, leading to a closure of ATP-sensitive potassium (KATP) channels. The extracellular glucose concentration monitors the gating of KATP channels of sleep-promoting neurons, highlighting that these neurons can adapt their excitability according to the extracellular energy status. Together, these results provide evidence that glucose may participate in the mechanisms of SWS promotion and/or consolidation. Although the brain circuitry underlying vigilance states is well described, the molecular mechanisms responsible for sleep onset remain largely unknown. Combining in vitro and in vivo experiments, we demonstrate that glucose likely contributes to sleep onset facilitation by increasing the excitability of sleep-promoting neurons in the ventrolateral preoptic nucleus (VLPO). We find here that these neurons integrate energetic signals such as ambient glucose directly to regulate vigilance states accordingly. Glucose-induced excitation of sleep-promoting VLPO neurons should therefore be involved in the drowsiness that one feels after a high-sugar meal. This novel mechanism regulating the activity of VLPO neurons reinforces the

Eye Movement Desensitization and Reprocessing and Slow Wave Sleep: A Putative Mechanism of Action.

PubMed

Pagani, Marco; Amann, Benedikt L; Landin-Romero, Ramon; Carletto, Sara

2017-01-01

Eye Movement Desensitization and Reprocessing (EMDR) is considered highly efficacious for the treatment of Post-traumatic Stress Disorder and has proved to be a valid treatment approach with a wide range of applications. However, EMDR's mechanisms of action is not yet fully understood. This is an active area of clinical and neurophysiological research, and several different hypotheses have been proposed. This paper discusses a conjecture which focuses on the similarity between the delta waves recorded by electroencephalography during Slow Wave Sleep (SWS) and those registered upon typical EMDR bilateral stimulation (eye movements or alternate tapping) during recurrent distressing memories of an emotionally traumatic event. SWS appears to have a key role in memory consolidation and in the reorganization of distant functional networks, as well as Eye Movements seem to reduce traumatic episodic memory and favor the reconsolidation of new associated information. The SWS hypothesis may put forward an explanation of how EMDR works, and is discussed also in light of other theories and neurobiological findings.

β oscillation during slow wave sleep and rapid eye movement sleep in the electroencephalogram of a transgenic mouse model of Huntington's disease.

PubMed

Jeantet, Yannick; Cayzac, Sebastien; Cho, Yoon H

2013-01-01

To search for early abnormalities in electroencephalogram (EEG) during sleep which may precede motor symptoms in a transgenic mouse model of hereditary neurodegenerative Huntington's disease (HD). In the R6/1 transgenic mouse model of HD, rhythmic brain activity in EEG recordings was monitored longitudinally and across vigilance states through the onset and progression of disease. Mice with chronic electrode implants were recorded monthly over wake-sleep cycles (4 hours), beginning at 9-11 weeks (presymptomatic period) through 6-7 months (symptomatic period). Recording data revealed a unique β rhythm (20-35 Hz), present only in R6/1 transgenic mice, which evolves in close parallel with the disease. In addition, there was an unusual relationship between this β oscillation and vigilance states: while nearly absent during the active waking state, the β oscillation appeared with drowsiness and during slow wave sleep (SWS) and, interestingly, strengthened rather than dissipating when the brain returned to an activated state during rapid eye movement (REM) sleep. In addition to providing a new in vivo biomarker and insight into Huntington's disease pathophysiology, this serendipitous observation opens a window onto the rarely explored neurophysiology of the cortico-basal ganglia circuit during SWS and REM sleep.

Effect of conditioned stimulus exposure during slow wave sleep on fear memory extinction in humans.

PubMed

He, Jia; Sun, Hong-Qiang; Li, Su-Xia; Zhang, Wei-Hua; Shi, Jie; Ai, Si-Zhi; Li, Yun; Li, Xiao-Jun; Tang, Xiang-Dong; Lu, Lin

2015-03-01

Repeated exposure to a neutral conditioned stimulus (CS) in the absence of a noxious unconditioned stimulus (US) elicits fear memory extinction. The aim of the current study was to investigate the effects of mild tone exposure (CS) during slow wave sleep (SWS) on fear memory extinction in humans. The healthy volunteers underwent an auditory fear conditioning paradigm on the experimental night, during which tones served as the CS, and a mild shock served as the US. They were then randomly assigned to four groups. Three groups were exposed to the CS for 3 or 10 min or an irrelevant tone (control stimulus, CtrS) for 10 min during SWS. The fourth group served as controls and was not subjected to any interventions. All of the subjects completed a memory test 4 h after SWS-rich stage to evaluate the effect on fear extinction. Moreover, we conducted similar experiments using an independent group of subjects during the daytime to test whether the memory extinction effect was specific to the sleep condition. Ninety-six healthy volunteers (44 males) aged 18-28 y. Participants exhibited undisturbed sleep during 2 consecutive nights, as assessed by sleep variables (all P > 0.05) from polysomnographic recordings and power spectral analysis. Participants who were re-exposed to the 10 min CS either during SWS and wakefulness exhibited attenuated fear responses (wake-10 min CS, P < 0.05; SWS-10 min CS, P < 0.01). Conditioned stimulus re-exposure during SWS promoted fear memory extinction without altering sleep profiles. © 2015 Associated Professional Sleep Societies, LLC.

Neurobehavioral consequences of continuous spike and waves during slow sleep (CSWS) in a pediatric population: A pattern of developmental hindrance.

PubMed

De Giorgis, Valentina; Filippini, Melissa; Macasaet, Joyce Ann; Masnada, Silvia; Veggiotti, Pierangelo

2017-09-01

Continuous spike and waves during slow sleep (CSWS) is a typical EEG pattern defined as diffuse, bilateral and recently also unilateral or focal localization spike-wave occurring in slow sleep or non-rapid eye movement sleep. Literature results so far point out a progressive deterioration and decline of intellectual functioning in CSWS patients, i.e. a loss of previously normally acquired skills, as well as persistent neurobehavioral disorders, beyond seizure and EEG control. The objective of this study was to shed light on the neurobehavioral impact of CSWS and to identify the potential clinical risk factors for development. We conducted a retrospective study involving a series of 16 CSWS idiopathic patients age 3-16years, considering the entire duration of epilepsy from the onset to the outcome, i.e. remission of CSWS pattern. All patients were longitudinally assessed taking into account clinical (sex, age at onset, lateralization and localization of epileptiform abnormalities, spike wave index, number of antiepileptic drugs) and behavioral features. Intelligent Quotient (IQ) was measured in the whole sample, whereas visuo-spatial attention, visuo-motor skills, short term memory and academic abilities (reading and writing) were tested in 6 out of 16 patients. Our results showed that the most vulnerable from an intellectual point of view were those children who had an early-onset of CSWS whereas those with later onset resulted less affected (p=0.004). Neuropsychological outcome was better than the behavioral one and the lexical-semantic route in reading and writing resulted more severely affected compared to the phonological route. Cognitive deterioration is one but not the only consequence of CSWS. Especially with respect to verbal skills, CSWS is responsible of a pattern of consequences in terms of developmental hindrance, including slowing of development and stagnation, whereas deterioration is rare. Behavioral and academic problems tend to persist beyond

Hippocampal gamma-slow oscillation coupling in macaques during sedation and sleep.

PubMed

Richardson, Andrew G; Liu, Xilin; Weigand, Pauline K; Hudgins, Eric D; Stein, Joel M; Das, Sandhitsu R; Proekt, Alexander; Kelz, Max B; Zhang, Milin; Van der Spiegel, Jan; Lucas, Timothy H

2017-11-01

Behavioral and neurophysiological evidence suggests that the slow (≤1 Hz) oscillation (SO) during sleep plays a role in consolidating hippocampal (HIPP)-dependent memories. The effects of the SO on HIPP activity have been studied in rodents and cats both during natural sleep and during anesthetic administration titrated to mimic sleep-like slow rhythms. In this study, we sought to document these effects in primates. First, HIPP field potentials were recorded during ketamine-dexmedetomidine sedation and during natural sleep in three rhesus macaques. Sedation produced regionally-specific slow and gamma (∼40 Hz) oscillations with strong coupling between the SO phase and gamma amplitude. These same features were seen in slow-wave sleep (SWS), but the coupling was weaker and the coupled gamma oscillation had a higher frequency (∼70 Hz) during SWS. Second, electrical stimuli were delivered to HIPP afferents in the parahippocampal gyrus (PHG) during sedation to assess the effects of sleep-like SO on excitability. Gamma bursts after the peak of SO cycles corresponded to periods of increased gain of monosynaptic connections between the PHG and HIPP. However, the two PHG-HIPP connectivity gains during sedation were both substantially lower than when the animal was awake. We conclude that the SO is correlated with rhythmic excitation and inhibition of the PHG-HIPP network, modulating connectivity and gamma generators intrinsic to this network. Ketamine-dexmedetomidine sedation produces a similar effect, but with a decreased contribution of the PHG to HIPP activity and gamma generation. © 2017 Wiley Periodicals, Inc.

β Oscillation during Slow Wave Sleep and Rapid Eye Movement Sleep in the Electroencephalogram of a Transgenic Mouse Model of Huntington’s Disease

PubMed Central

Jeantet, Yannick; Cayzac, Sebastien; Cho, Yoon H.

2013-01-01

Study objectives To search for early abnormalities in electroencephalogram (EEG) during sleep which may precede motor symptoms in a transgenic mouse model of hereditary neurodegenerative Huntington’s disease (HD). Design In the R6/1 transgenic mouse model of HD, rhythmic brain activity in EEG recordings was monitored longitudinally and across vigilance states through the onset and progression of disease. Measurements and results Mice with chronic electrode implants were recorded monthly over wake-sleep cycles (4 hours), beginning at 9–11 weeks (presymptomatic period) through 6–7 months (symptomatic period). Recording data revealed a unique β rhythm (20–35 Hz), present only in R6/1 transgenic mice, which evolves in close parallel with the disease. In addition, there was an unusual relationship between this β oscillation and vigilance states: while nearly absent during the active waking state, the β oscillation appeared with drowsiness and during slow wave sleep (SWS) and, interestingly, strengthened rather than dissipating when the brain returned to an activated state during rapid eye movement (REM) sleep. Conclusions In addition to providing a new in vivo biomarker and insight into Huntington's disease pathophysiology, this serendipitous observation opens a window onto the rarely explored neurophysiology of the cortico-basal ganglia circuit during SWS and REM sleep. PMID:24244517

The dream-lag effect: Selective processing of personally significant events during Rapid Eye Movement sleep, but not during Slow Wave Sleep.

PubMed

van Rijn, E; Eichenlaub, J-B; Lewis, P A; Walker, M P; Gaskell, M G; Malinowski, J E; Blagrove, M

2015-07-01

Incorporation of details from waking life events into Rapid Eye Movement (REM) sleep dreams has been found to be highest on the night after, and then 5-7 nights after events (termed, respectively, the day-residue and dream-lag effects). In experiment 1, 44 participants kept a daily log for 10 days, reporting major daily activities (MDAs), personally significant events (PSEs), and major concerns (MCs). Dream reports were collected from REM and Slow Wave Sleep (SWS) in the laboratory, or from REM sleep at home. The dream-lag effect was found for the incorporation of PSEs into REM dreams collected at home, but not for MDAs or MCs. No dream-lag effect was found for SWS dreams, or for REM dreams collected in the lab after SWS awakenings earlier in the night. In experiment 2, the 44 participants recorded reports of their spontaneously recalled home dreams over the 10 nights following the instrumental awakenings night, which thus acted as a controlled stimulus with two salience levels, high (sleep lab) and low (home awakenings). The dream-lag effect was found for the incorporation into home dreams of references to the experience of being in the sleep laboratory, but only for participants who had reported concerns beforehand about being in the sleep laboratory. The delayed incorporation of events from daily life into dreams has been proposed to reflect REM sleep-dependent memory consolidation. However, an alternative emotion processing or emotional impact of events account, distinct from memory consolidation, is supported by the finding that SWS dreams do not evidence the dream-lag effect. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Eye Movement Desensitization and Reprocessing and Slow Wave Sleep: A Putative Mechanism of Action

PubMed Central

Pagani, Marco; Amann, Benedikt L.; Landin-Romero, Ramon; Carletto, Sara

2017-01-01

Eye Movement Desensitization and Reprocessing (EMDR) is considered highly efficacious for the treatment of Post-traumatic Stress Disorder and has proved to be a valid treatment approach with a wide range of applications. However, EMDR’s mechanisms of action is not yet fully understood. This is an active area of clinical and neurophysiological research, and several different hypotheses have been proposed. This paper discusses a conjecture which focuses on the similarity between the delta waves recorded by electroencephalography during Slow Wave Sleep (SWS) and those registered upon typical EMDR bilateral stimulation (eye movements or alternate tapping) during recurrent distressing memories of an emotionally traumatic event. SWS appears to have a key role in memory consolidation and in the reorganization of distant functional networks, as well as Eye Movements seem to reduce traumatic episodic memory and favor the reconsolidation of new associated information. The SWS hypothesis may put forward an explanation of how EMDR works, and is discussed also in light of other theories and neurobiological findings. PMID:29163309

Slow sleep spindle and procedural memory consolidation in patients with major depressive disorder

PubMed Central

Nishida, Masaki; Nakashima, Yusaku; Nishikawa, Toru

2016-01-01

Introduction Evidence has accumulated, which indicates that, in healthy individuals, sleep enhances procedural memory consolidation, and that sleep spindle activity modulates this process. However, whether sleep-dependent procedural memory consolidation occurs in patients medicated for major depressive disorder remains unclear, as are the pharmacological and physiological mechanisms that underlie this process. Methods Healthy control participants (n=17) and patients medicated for major depressive disorder (n=11) were recruited and subjected to a finger-tapping motor sequence test (MST; nondominant hand) paradigm to compare the averaged scores of different learning phases (presleep, postsleep, and overnight improvement). Participants’ brain activity was recorded during sleep with 16 electroencephalography channels (between MSTs). Sleep scoring and frequency analyses were performed on the electroencephalography data. Additionally, we evaluated sleep spindle activity, which divided the spindles into fast-frequency spindle activity (12.5–16 Hz) and slow-frequency spindle activity (10.5–12.5 Hz). Result Sleep-dependent motor memory consolidation in patients with depression was impaired in comparison with that in control participants. In patients with depression, age correlated negatively with overnight improvement. The duration of slow-wave sleep correlated with the magnitude of motor memory consolidation in patients with depression, but not in healthy controls. Slow-frequency spindle activity was associated with reduction in the magnitude of motor memory consolidation in both groups. Conclusion Because the changes in slow-frequency spindle activity affected the thalamocortical network dysfunction in patients medicated for depression, dysregulated spindle generation may impair sleep-dependent memory consolidation. Our findings may help to elucidate the cognitive deficits that occur in patients with major depression both in the waking state and during sleep. PMID

Slow sleep spindle and procedural memory consolidation in patients with major depressive disorder.

PubMed

Nishida, Masaki; Nakashima, Yusaku; Nishikawa, Toru

2016-01-01

Evidence has accumulated, which indicates that, in healthy individuals, sleep enhances procedural memory consolidation, and that sleep spindle activity modulates this process. However, whether sleep-dependent procedural memory consolidation occurs in patients medicated for major depressive disorder remains unclear, as are the pharmacological and physiological mechanisms that underlie this process. Healthy control participants (n=17) and patients medicated for major depressive disorder (n=11) were recruited and subjected to a finger-tapping motor sequence test (MST; nondominant hand) paradigm to compare the averaged scores of different learning phases (presleep, postsleep, and overnight improvement). Participants' brain activity was recorded during sleep with 16 electroencephalography channels (between MSTs). Sleep scoring and frequency analyses were performed on the electroencephalography data. Additionally, we evaluated sleep spindle activity, which divided the spindles into fast-frequency spindle activity (12.5-16 Hz) and slow-frequency spindle activity (10.5-12.5 Hz). Sleep-dependent motor memory consolidation in patients with depression was impaired in comparison with that in control participants. In patients with depression, age correlated negatively with overnight improvement. The duration of slow-wave sleep correlated with the magnitude of motor memory consolidation in patients with depression, but not in healthy controls. Slow-frequency spindle activity was associated with reduction in the magnitude of motor memory consolidation in both groups. Because the changes in slow-frequency spindle activity affected the thalamocortical network dysfunction in patients medicated for depression, dysregulated spindle generation may impair sleep-dependent memory consolidation. Our findings may help to elucidate the cognitive deficits that occur in patients with major depression both in the waking state and during sleep.

Acute Optogenetic Silencing of Orexin/Hypocretin Neurons Induces Slow-Wave Sleep in Mice

PubMed Central

Tsunematsu, Tomomi; Kilduff, Thomas S.; Boyden, Edward S.; Takahashi, Satoru; Tominaga, Makoto; Yamanaka, Akihiro

2013-01-01

Orexin/hypocretin neurons have a crucial role in the regulation of sleep and wakefulness. To help determine how these neurons promote wakefulness, we generated transgenic mice in which orexin neurons expressed halorhodopsin (orexin/Halo mice), an orange light-activated neuronal silencer. Slice patch-clamp recordings of orexin neurons that expressed halorhodopsin demonstrated that orange light photic illumination immediately hyperpolarized membrane potential and inhibited orexin neuron discharge in proportion to illumination intensity. Acute silencing of orexin neurons in vivo during the day (the inactive period) induced synchronization of the electroencephalogram and a reduction in amplitude of the electromyogram that is characteristic of slow-wave sleep (SWS). In contrast, orexin neuron photoinhibition was ineffective during the night (active period). Acute photoinhibition of orexin neurons during the day in orexin/Halo mice also reduced discharge of neurons in an orexin terminal field, the dorsal raphe (DR) nucleus. However, serotonergic DR neurons exhibited normal discharge rates in mice lacking orexin neurons. Thus, although usually highly dependent on orexin neuronal activity, serotonergic DR neuronal activity can be regulated appropriately in the chronic absence of orexin input. Together, these results demonstrate that acute inhibition of orexin neurons results in time-of-day-dependent induction of SWS and in reduced firing rate of neurons in an efferent projection site thought to be involved in arousal state regulation. The results presented here advance our understanding of the role of orexin neurons in the regulation of sleep/wakefulness and may be relevant to the mechanisms that underlie symptom progression in narcolepsy. PMID:21775598

Napping to renew learning capacity: enhanced encoding after stimulation of sleep slow oscillations.

PubMed

Antonenko, Daria; Diekelmann, Susanne; Olsen, Cathrin; Born, Jan; Mölle, Matthias

2013-04-01

As well as consolidating memory, sleep has been proposed to serve a second important function for memory, i.e. to free capacities for the learning of new information during succeeding wakefulness. The slow wave activity (SWA) that is a hallmark of slow wave sleep could be involved in both functions. Here, we aimed to demonstrate a causative role for SWA in enhancing the capacity for encoding of information during subsequent wakefulness, using transcranial slow oscillation stimulation (tSOS) oscillating at 0.75 Hz to induce SWA in healthy humans during an afternoon nap. Encoding following the nap was tested for hippocampus-dependent declarative materials (pictures, word pairs, and word lists) and procedural skills (finger sequence tapping). As compared with a sham stimulation control condition, tSOS during the nap enhanced SWA and significantly improved subsequent encoding on all three declarative tasks (picture recognition, cued recall of word pairs, and free recall of word lists), whereas procedural finger sequence tapping skill was not affected. Our results indicate that sleep SWA enhances the capacity for encoding of declarative materials, possibly by down-scaling hippocampal synaptic networks that were potentiated towards saturation during the preceding period of wakefulness. © 2013 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

Effect of Slow Wave Sleep Disruption on Metabolic Parameters in Adolescents.

PubMed

Shaw, Natalie D; McHill, Andrew W; Schiavon, Michele; Kangarloo, Tairmae; Mankowski, Piotr W; Cobelli, Claudio; Klerman, Elizabeth B; Hall, Janet E

2016-08-01

Cross-sectional studies report a correlation between slow wave sleep (SWS) duration and insulin sensitivity (SI) in children and adults. Suppression of SWS causes insulin resistance in adults but effects in children are unknown. This study was designed to determine the effect of SWS fragmentation on SI in children. Fourteen pubertal children (11.3-14.1 y, body mass index 29(th) to 97(th) percentile) were randomized to sleep studies and mixed meal (MM) tolerance tests with and without SWS disruption. Beta-cell responsiveness (Φ) and SI were determined using oral minimal modeling. During the disruption night, auditory stimuli (68.1 ± 10.7/night; mean ± standard error) decreased SWS by 40.0 ± 8.0%. SWS fragmentation did not affect fasting glucose (non-disrupted 76.9 ± 2.3 versus disrupted 80.6 ± 2.1 mg/dL), insulin (9.2 ± 1.6 versus 10.4 ± 2.0 μIU/mL), or C-peptide (1.9 ± 0.2 versus 1.9 ± 0.1 ng/mL) levels and did not impair SI (12.9 ± 2.3 versus 10.1 ± 1.6 10(-4) dL/kg/min per μIU/mL) or Φ (73.4 ± 7.8 versus 74.4 ± 8.4 10(-9) min(-1)) to a MM challenge. Only the subjects in the most insulin-sensitive tertile demonstrated a consistent decrease in SI after SWS disruption. Pubertal children across a range of body mass indices may be resistant to the adverse metabolic effects of acute SWS disruption. Only those subjects with high SI (i.e., having the greatest "metabolic reserve") demonstrated a consistent decrease in SI. These results suggest that adolescents may have a unique ability to adapt to metabolic stressors, such as acute SWS disruption, to maintain euglycemia. Additional studies are necessary to confirm that this resiliency is maintained in settings of chronic SWS disruption. © 2016 Associated Professional Sleep Societies, LLC.

Are Slow Waves of Intracranial Pressure Suppressed by General Anaesthesia?

PubMed

Lalou, Despina Afroditi; Czosnyka, Marek; Donnelly, Joseph; Lavinio, Andrea; Pickard, John D; Garnett, Matthew; Czosnyka, Zofia

2018-01-01

Slow waves of intracranial pressure (ICP) are spontaneous oscillations with a frequency of 0.3-4 cycles/min. They are often associated with pathological conditions, following vasomotor activity in the cranial enclosure. This study quantifies the effects of general anaesthesia (GA) on the magnitude of B-waves compared with natural sleep and the conscious state. Four groups of 30 patients each were formed to assess the magnitude of slow waves. Group A and group B consisted of normal pressure hydrocephalus (NPH) patients, each undergoing cerebrospinal fluid (CSF) infusion studies, conscious and under GA respectively. Group C comprised conscious, naturally asleep hydrocephalic patients undergoing overnight ICP monitoring; group D, which included deeply sedated head injury patients monitored in the intensive care unit (ICU), was compared with group C. The average amplitude for group A patients was higher (0.23 ± 0.10 mmHg) than that of group B (0.15 ± 0.10 mmHg; p = 0.01). Overnight magnitude of slow waves was higher in group C (0.20 ± 0.13 mmHg) than in group D (0.11 ± 0.09 mmHg; p = 0.002). Slow waves of ICP are suppressed by GA and deep sedation. When using slow waves in clinical decision-making, it is important to consider the patients' level of consciousness to avoid incorrect therapeutic and management decisions.

Slow oscillating transcranial direct current stimulation during non-rapid eye movement sleep improves behavioral inhibition in attention-deficit/hyperactivity disorder

PubMed Central

Munz, Manuel T.; Prehn-Kristensen, Alexander; Thielking, Frederieke; Mölle, Matthias; Göder, Robert; Baving, Lioba

2015-01-01

Background: Behavioral inhibition, which is a later-developing executive function (EF) and anatomically located in prefrontal areas, is impaired in attention-deficit and hyperactivity disorder (ADHD). While optimal EFs have been shown to depend on efficient sleep in healthy subjects, the impact of sleep problems, frequently reported in ADHD, remains elusive. Findings of macroscopic sleep changes in ADHD are inconsistent, but there is emerging evidence for distinct microscopic changes with a focus on prefrontal cortical regions and non-rapid eye movement (non-REM) slow-wave sleep. Recently, slow oscillations (SO) during non-REM sleep were found to be less functional and, as such, may be involved in sleep-dependent memory impairments in ADHD. Objective:By augmenting slow-wave power through bilateral, slow oscillating transcranial direct current stimulation (so-tDCS, frequency = 0.75 Hz) during non-REM sleep, we aimed to improve daytime behavioral inhibition in children with ADHD. Methods: Fourteen boys (10–14 years) diagnosed with ADHD were included. In a randomized, double-blind, cross-over design, patients received so-tDCS either in the first or in the second experimental sleep night. Inhibition control was assessed with a visuomotor go/no-go task. Intrinsic alertness was assessed with a simple stimulus response task. To control for visuomotor performance, motor memory was assessed with a finger sequence tapping task. Results: SO-power was enhanced during early non-REM sleep, accompanied by slowed reaction times and decreased standard deviations of reaction times, in the go/no-go task after so-tDCS. In contrast, intrinsic alertness, and motor memory performance were not improved by so-tDCS. Conclusion: Since behavioral inhibition but not intrinsic alertness or motor memory was improved by so-tDCS, our results suggest that lateral prefrontal slow oscillations during sleep might play a specific role for executive functioning in ADHD. PMID:26321911

Slow oscillating transcranial direct current stimulation during non-rapid eye movement sleep improves behavioral inhibition in attention-deficit/hyperactivity disorder.

PubMed

Munz, Manuel T; Prehn-Kristensen, Alexander; Thielking, Frederieke; Mölle, Matthias; Göder, Robert; Baving, Lioba

2015-01-01

Behavioral inhibition, which is a later-developing executive function (EF) and anatomically located in prefrontal areas, is impaired in attention-deficit and hyperactivity disorder (ADHD). While optimal EFs have been shown to depend on efficient sleep in healthy subjects, the impact of sleep problems, frequently reported in ADHD, remains elusive. Findings of macroscopic sleep changes in ADHD are inconsistent, but there is emerging evidence for distinct microscopic changes with a focus on prefrontal cortical regions and non-rapid eye movement (non-REM) slow-wave sleep. Recently, slow oscillations (SO) during non-REM sleep were found to be less functional and, as such, may be involved in sleep-dependent memory impairments in ADHD. By augmenting slow-wave power through bilateral, slow oscillating transcranial direct current stimulation (so-tDCS, frequency = 0.75 Hz) during non-REM sleep, we aimed to improve daytime behavioral inhibition in children with ADHD. Fourteen boys (10-14 years) diagnosed with ADHD were included. In a randomized, double-blind, cross-over design, patients received so-tDCS either in the first or in the second experimental sleep night. Inhibition control was assessed with a visuomotor go/no-go task. Intrinsic alertness was assessed with a simple stimulus response task. To control for visuomotor performance, motor memory was assessed with a finger sequence tapping task. SO-power was enhanced during early non-REM sleep, accompanied by slowed reaction times and decreased standard deviations of reaction times, in the go/no-go task after so-tDCS. In contrast, intrinsic alertness, and motor memory performance were not improved by so-tDCS. Since behavioral inhibition but not intrinsic alertness or motor memory was improved by so-tDCS, our results suggest that lateral prefrontal slow oscillations during sleep might play a specific role for executive functioning in ADHD.

Activity-Dependent Downscaling of Subthreshold Synaptic Inputs during Slow-Wave-Sleep-like Activity In Vivo.

PubMed

González-Rueda, Ana; Pedrosa, Victor; Feord, Rachael C; Clopath, Claudia; Paulsen, Ole

2018-03-21

Activity-dependent synaptic plasticity is critical for cortical circuit refinement. The synaptic homeostasis hypothesis suggests that synaptic connections are strengthened during wake and downscaled during sleep; however, it is not obvious how the same plasticity rules could explain both outcomes. Using whole-cell recordings and optogenetic stimulation of presynaptic input in urethane-anesthetized mice, which exhibit slow-wave-sleep (SWS)-like activity, we show that synaptic plasticity rules are gated by cortical dynamics in vivo. While Down states support conventional spike timing-dependent plasticity, Up states are biased toward depression such that presynaptic stimulation alone leads to synaptic depression, while connections contributing to postsynaptic spiking are protected against this synaptic weakening. We find that this novel activity-dependent and input-specific downscaling mechanism has two important computational advantages: (1) improved signal-to-noise ratio, and (2) preservation of previously stored information. Thus, these synaptic plasticity rules provide an attractive mechanism for SWS-related synaptic downscaling and circuit refinement. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Association between slow-wave activity, cognition and behaviour in children with sleep-disordered breathing.

PubMed

Weichard, Aidan J; Walter, Lisa M; Hollis, Samantha L; Nixon, Gillian M; Davey, Margot J; Horne, Rosemary S C; Biggs, Sarah N

2016-09-01

It has been suggested that impaired dissipation of slow-wave activity (SWA) in children with sleep-disordered breathing (SDB) may be a potential mechanism for daytime dysfunction. We aimed to examine whether resolution of SDB resulted in normalisation of SWA dissipation and whether this was associated with improved cognition and behaviour. Children (aged 3-6 y) diagnosed with SDB and age-matched non-snoring control children were followed up for 3 y after a baseline study. At the follow-up, children were categorised into control (N = 13), resolved SDB (N = 15) and unresolved SDB (N = 14). Delta activity on the electroencephalogram over the sleep period was used to calculate SWA and a battery of cognitive assessments and behaviour questionnaires were conducted at both time points. There was no change in the average SWA between the baseline and follow-up and no differences between the groups. Cognitive and behavioural performance in the resolved group did not improve to control levels. However, decreased SWA at the beginning of the sleep period (β = -0.04, p = 0.002) and a decrease in obstructive apnoea-hypopnoea index (β = -2.2, p = 0.022) between the baseline and follow-up predicted improvements in measures of sustained attention. Increased SWA at the beginning of the sleep period between the baseline and follow-up predicted worsening of externalising behaviour (β = 0.02, p = 0.039). This study suggests that resolution of SDB is not associated with changes in the dissipation of SWA. However, the association between decreases in SWA and improvements in cognitive and behavioural outcomes suggest that irrespective of disease, children whose quantitative sleepiness improves have improved attention and reduced externalising behaviours. Copyright © 2016 Elsevier B.V. All rights reserved.

Slow-oscillatory Transcranial Direct Current Stimulation Modulates Memory in Temporal Lobe Epilepsy by Altering Sleep Spindle Generators: A Possible Rehabilitation Tool.

PubMed

Del Felice, Alessandra; Magalini, Alessandra; Masiero, Stefano

2015-01-01

Temporal lobe epilepsy (TLE) is often associated with memory deficits. Given the putative role for sleep spindles memory consolidation, spindle generators skewed toward the affected lobe in TLE subjects may be a neurophysiological marker of defective memory. Slow-oscillatory transcranial direct current stimulation (sotDCS) during slow waves sleep (SWS) has previously been shown to enhance sleep-dependent memory consolidation by increasing slow-wave sleep and modulating sleep spindles. To test if anodal sotDCS over the affected TL prior to a nap affects sleep spindles and whether this improves memory consolidation. Randomized controlled cross-over study. 12 people with TLE underwent sotDCS (0.75 Hz; 0-250 μV, 30 min) or sham before daytime nap. Declarative verbal and visuospatial learning were tested. Fast and slow spindle signals were recorded by 256-channel EEG during sleep. In both study arms, electrical source imaging (ESI) localized cortical generators. Neuropsychological data were analyzed with general linear model statistics or the Kruskal-Wallis test (P or Z < 0.05), and neurophysiological data tested with the Mann-Whitney t test and binomial distribution test (P or Z < 0.05). An improvement in declarative (P = 0.05) and visuospatial memory performance (P = 0.048) emerged after sotDCS. SotDCS increased slow spindle generators current density (Z = 0.001), with a shift to the anterior cortical areas. Anodal sotDCS over the affected temporal lobe improves declarative and visuospatial memory performance by modulating slow sleep spindles cortical source generators. SotDCS appears a promising tool for memory rehabilitation in people with TLE. Copyright © 2015 Elsevier Inc. All rights reserved.

Cycle-Triggered Cortical Stimulation during Slow Wave Sleep Facilitates Learning a BMI Task: A Case Report in a Non-Human Primate

PubMed Central

Rembado, Irene; Zanos, Stavros; Fetz, Eberhard E.

2017-01-01

Slow wave sleep (SWS) has been identified as the sleep stage involved in consolidating newly acquired information. A growing body of evidence has shown that delta (1–4 Hz) oscillatory activity, the characteristic electroencephalographic signature of SWS, is involved in coordinating interaction between the hippocampus and the neocortex and is thought to take a role in stabilizing memory traces related to a novel task. This case report describes a new protocol that uses neuroprosthetics training of a non-human primate to evaluate the effects of surface cortical electrical stimulation triggered from SWS cycles. The results suggest that stimulation phase-locked to SWS oscillatory activity promoted learning of the neuroprosthetic task. This protocol could be used to elucidate mechanisms of synaptic plasticity underlying off-line learning during sleep and offers new insights into the role of brain oscillations in information processing and memory consolidation. PMID:28450831

Restricting Time in Bed in Early Adolescence Reduces Both NREM and REM Sleep but Does Not Increase Slow Wave EEG

PubMed Central

Campbell, Ian G.; Kraus, Amanda M.; Burright, Christopher S.; Feinberg, Irwin

2016-01-01

Study Objectives: School night total sleep time decreases across adolescence (9–18 years) by 10 min/year. This decline is comprised entirely of a selective decrease in NREM sleep; REM sleep actually increases slightly. Decreasing sleep duration across adolescence is often attributed to insufficient time in bed. Here we tested whether sleep restriction in early adolescence produces the same sleep stage changes observed on school nights across adolescence. Methods: All-night sleep EEG was recorded in 76 children ranging in age from 9.9 to 14.0 years. Each participant kept 3 different sleep schedules that consisted of 3 nights of 8.5 h in bed followed by 4 nights of either 7, 8.5, or 10 h in bed. Sleep stage durations and NREM delta EEG activity were compared across the 3 time in bed conditions. Results: Shortening time in bed from 10 to 7 hours reduced sleep duration by approximately 2 hours, roughly equal to the decrease in sleep duration we recorded longitudinally across adolescence. However, sleep restriction significantly reduced both NREM (by 83 min) and REM (by 47 min) sleep. Sleep restriction did not affect NREM delta EEG activity. Conclusions: Our findings suggest that the selective NREM reduction and the small increase in REM we observed longitudinally across 9–18 years are not produced by sleep restriction. We hypothesize that the selective NREM decline reflects adolescent brain maturation (synaptic elimination) that reduces the need for the restorative processes of NREM sleep. Citation: Campbell IG, Kraus AM, Burright CS, Feinberg I. Restricting time in bed in early adolescence reduces both NREM and REM sleep but does not increase slow wave EEG. SLEEP 2016;39(9):1663–1670. PMID:27397569

The role of fast and slow EEG activity during sleep in males and females with Major Depressive Disorder

PubMed Central

Cheng, Philip; Goldschmied, Jennifer; Deldin, Patricia; Hoffmann, Robert; Armitage, Roseanne

2015-01-01

Sleep difficulties are highly prevalent in depression, and appears to be a contributing factor in the development and maintenance of symptoms. However, despite the generally acknowledged relationship between sleep and depression, the neurophysiological substrates underlying this relationship still remain unclear. Two main hypotheses were tested in this study. The first hypothesis states that sleep in depression is characterized by inadequate generation of restorative sleep, as indexed by reduced amounts of slow-wave activity. Conversely, the second hypothesis states that poor sleep in depression is due to intrusions of fast-frequency activity that may be reflective of a hyperaroused central nervous system. This study aimed to test both hypotheses in a large sample of individuals with clinically validated depression, as well as examine sex as a moderator. Results suggest that depression is better characterized by an overall decrease in slow-wave activity, which is related to elevated anxious and depressed mood the following morning. Results also suggest that females may be more likely to experience fast frequency activity related to depression symptom severity. PMID:26175101

Slow spontaneous hemodynamic oscillations during sleep measured with near-infrared spectroscopy

NASA Astrophysics Data System (ADS)

Virtanen, Jaakko; Näsi, Tiina; Noponen, Tommi; Toppila, Jussi; Salmi, Tapani; Ilmoniemi, Risto J.

2011-07-01

Spontaneous cerebral hemodynamic oscillations below 100 mHz reflect the level of cerebral activity, modulate hemodynamic responses to tasks and stimuli, and may aid in detecting various pathologies of the brain. Near-infrared spectroscopy (NIRS) is ideally suited for both measuring spontaneous hemodynamic oscillations and monitoring sleep, but little research has been performed to combine these two applications. We analyzed 30 all-night NIRS-electroencephalography (EEG) sleep recordings to investigate spontaneous hemodynamic activity relative to sleep stages determined by polysomnography. Signal power of hemodynamic oscillations in the low-frequency (LF, 40-150 mHz) and very-low-frequency (VLF, 3-40 mHz) bands decreased in slow-wave sleep (SWS) compared to light sleep (LS) and rapid-eye-movement (REM) sleep. No statistically significant (p < 0.05) differences in oscillation power between LS and REM were observed. However, the period of VLF oscillations around 8 mHz increased in REM sleep in line with earlier studies with other modalities. These results increase our knowledge of the physiology of sleep, complement EEG data, and demonstrate the applicability of NIRS to studying spontaneous hemodynamic fluctuations during sleep.

Slow-Wave Sleep-Imposed Replay Modulates Both Strength and Precision of Memory

PubMed Central

2014-01-01

Odor perception is hypothesized to be an experience-dependent process involving the encoding of odor objects by distributed olfactory cortical ensembles. Olfactory cortical neurons coactivated by a specific pattern of odorant evoked input become linked through association fiber synaptic plasticity, creating a template of the familiar odor. In this way, experience and memory play an important role in odor perception and discrimination. In other systems, memory consolidation occurs partially via slow-wave sleep (SWS)-dependent replay of activity patterns originally evoked during waking. SWS is ideal for replay given hyporesponsive sensory systems, and thus reduced interference. Here, using artificial patterns of olfactory bulb stimulation in a fear conditioning procedure in the rat, we tested the effects of imposed post-training replay during SWS and waking on strength and precision of pattern memory. The results show that imposed replay during post-training SWS enhanced the subsequent strength of memory, whereas the identical replay during waking induced extinction. The magnitude of this enhancement was dependent on the timing of imposed replay relative to cortical sharp-waves. Imposed SWS replay of stimuli, which differed from the conditioned stimulus, did not affect conditioned stimulus memory strength but induced generalization of the fear memory to novel artificial patterns. Finally, post-training disruption of piriform cortex intracortical association fiber synapses, hypothesized to be critical for experience-dependent odor coding, also impaired subsequent memory precision but not strength. These results suggest that SWS replay in the olfactory cortex enhances memory consolidation, and that memory precision is dependent on the fidelity of that replay. PMID:24719093

Initiation of sleep-dependent cortical-hippocampal correlations at wakefulness-sleep transition.

PubMed

Haggerty, Daniel C; Ji, Daoyun

2014-10-01

Sleep is involved in memory consolidation. Current theories propose that sleep-dependent memory consolidation requires active communication between the hippocampus and neocortex. Indeed, it is known that neuronal activities in the hippocampus and various neocortical areas are correlated during slow-wave sleep. However, transitioning from wakefulness to slow-wave sleep is a gradual process. How the hippocampal-cortical correlation is established during the wakefulness-sleep transition is unknown. By examining local field potentials and multiunit activities in the rat hippocampus and visual cortex, we show that the wakefulness-sleep transition is characterized by sharp-wave ripple events in the hippocampus and high-voltage spike-wave events in the cortex, both of which are accompanied by highly synchronized multiunit activities in the corresponding area. Hippocampal ripple events occur earlier than the cortical high-voltage spike-wave events, and hippocampal ripple incidence is attenuated by the onset of cortical high-voltage spike waves. This attenuation leads to a temporary weak correlation in the hippocampal-cortical multiunit activities, which eventually evolves to a strong correlation as the brain enters slow-wave sleep. The results suggest that the hippocampal-cortical correlation is established through a concerted, two-step state change that first synchronizes the neuronal firing within each brain area and then couples the synchronized activities between the two regions. Copyright © 2014 the American Physiological Society.

Induction of slow oscillations by rhythmic acoustic stimulation.

PubMed

Ngo, Hong-Viet V; Claussen, Jens C; Born, Jan; Mölle, Matthias

2013-02-01

Slow oscillations are electrical potential oscillations with a spectral peak frequency of ∼0.8 Hz, and hallmark the electroencephalogram during slow-wave sleep. Recent studies have indicated a causal contribution of slow oscillations to the consolidation of memories during slow-wave sleep, raising the question to what extent such oscillations can be induced by external stimulation. Here, we examined whether slow oscillations can be effectively induced by rhythmic acoustic stimulation. Human subjects were examined in three conditions: (i) with tones presented at a rate of 0.8 Hz ('0.8-Hz stimulation'); (ii) with tones presented at a random sequence ('random stimulation'); and (iii) with no tones presented in a control condition ('sham'). Stimulation started during wakefulness before sleep and continued for the first ∼90 min of sleep. Compared with the other two conditions, 0.8-Hz stimulation significantly delayed sleep onset. However, once sleep was established, 0.8-Hz stimulation significantly increased and entrained endogenous slow oscillation activity. Sleep after the 90-min period of stimulation did not differ between the conditions. Our data show that rhythmic acoustic stimulation can be used to effectively enhance slow oscillation activity. However, the effect depends on the brain state, requiring the presence of stable non-rapid eye movement sleep. © 2012 European Sleep Research Society.

Substance P and the neurokinin-1 receptor regulate electroencephalogram non-rapid eye movement sleep slow-wave activity locally

PubMed Central

Zielinski, Mark R.; Karpova, Svetlana A.; Yang, Xiaomei; Gerashchenko, Dmitry

2014-01-01

The neuropeptide substance P is an excitatory neurotransmitter produced by various cells including neurons and microglia that is involved in regulating inflammation and cerebral blood flow—functions that affect sleep and slow-wave activity (SWA). Substance P is the major ligand for the neurokinin-1 receptor (NK-1R), which is found throughout the brain including the cortex. The NK-1R is found on sleep-active cortical neurons expressing neuronal nitric oxide synthase whose activity is associated with SWA. We determined the effects of local cortical administration of a NK-1R agonist (substance P-fragment 1, 7) and a NK-1R antagonist (CP96345) on sleep and SWA in mice. The NK-1R agonist significantly enhanced SWA for several hours when applied locally to the cortex of the ipsilateral hemisphere as the electroencephalogram (EEG) electrode but not after application to the contralateral hemisphere when compared to saline vehicle control injections. In addition, a significant compensatory reduction in SWA was found after the NK-1R agonist-induced enhancements in SWA. Conversely, injections of the NK-1R antagonist into the cortex of the ipsilateral hemisphere of the EEG electrode attenuated SWA compared to vehicle injections but this effect was not found after injections of the NK-1R antagonist into contralateral hemisphere as the EEG electrode. Non-rapid eye movement sleep and rapid eye movement sleep duration responses after NK-1R agonist and antagonist injections were not significantly different from the responses to the vehicle. Our findings indicate that the substance P and the NK-1R are involved in regulating SWA locally. PMID:25301750

Time course of EEG slow-wave activity in pre-school children with sleep disordered breathing: a possible mechanism for daytime deficits?

PubMed

Biggs, Sarah N; Walter, Lisa M; Nisbet, Lauren C; Jackman, Angela R; Anderson, Vicki; Nixon, Gillian M; Davey, Margot J; Trinder, John; Hoffmann, Robert; Armitage, Roseanne; Horne, Rosemary S C

2012-09-01

Daytime deficits in children with sleep disordered breathing (SDB) are theorized to result from hypoxic insult to the developing brain or fragmented sleep. Yet, these do not explain why deficits occur in primary snorers (PS). The time course of slow wave EEG activity (SWA), a proxy of homeostatic regulation and cortical maturation, may provide insight. Clinical and control subjects (N=175: mean age 4.3±0.9 y: 61% male) participated in overnight polysomnography (PSG). Standard sleep scoring and power spectral analyses were conducted on EEG (C4/A1; 0.5-<3.9Hz). Univariate ANOVA's evaluated group differences in sleep stages and respiratory parameters. Repeated-measures ANCOVA evaluated group differences in the time course of SWA. Four groups were classified: controls (OAHI ≤ 1 event/h; no clinical history); PS (OAHI ≤ 1 event/h; clinical history); mild OSA (OAHI=1-5 events/h); and moderate to severe OSA (MS OSA: OAHI>5 events/h). Group differences were found in the percentage of time spent in NREM Stages 1 and 4 (p<0.001) and in the time course of SWA. PS and Mild OSA children had higher SWA in the first NREM period than controls (p<0.05). All SDB groups had higher SWA in the fourth NREM period (p<0.01). These results suggest enhanced sleep pressure but impaired restorative sleep function in pre-school children with SDB, providing new insights into the possible mechanism for daytime deficits observed in all severities of SDB. Copyright © 2012 Elsevier B.V. All rights reserved.

Propofol Anesthesia and Sleep: A High-Density EEG Study

PubMed Central

Murphy, Michael; Bruno, Marie-Aurelie; Riedner, Brady A.; Boveroux, Pierre; Noirhomme, Quentin; Landsness, Eric C.; Brichant, Jean-Francois; Phillips, Christophe; Massimini, Marcello; Laureys, Steven; Tononi, Giulio; Boly, Melanie

2011-01-01

Study Objectives: The electrophysiological correlates of anesthetic sedation remain poorly understood. We used high-density electroencephalography (hd-EEG) and source modeling to investigate the cortical processes underlying propofol anesthesia and compare them to sleep. Design: 256-channel EEG recordings in humans during propofol anesthesia. Setting: Hospital operating room. Patients or Participants: 8 healthy subjects (4 males) Interventions: N/A Measurements and Results: Initially, propofol induced increases in EEG power from 12–25 Hz. Loss of consciousness (LOC) was accompanied by the appearance of EEG slow waves that resembled the slow waves of NREM sleep. We compared slow waves in propofol to slow waves recorded during natural sleep and found that both populations of waves share similar cortical origins and preferentially propagate along the mesial components of the default network. However, propofol slow waves were spatially blurred compared to sleep slow waves and failed to effectively entrain spindle activity. Propofol also caused an increase in gamma (25–40 Hz) power that persisted throughout LOC. Source modeling analysis showed that this increase in gamma power originated from the anterior and posterior cingulate cortices. During LOC, we found increased gamma functional connectivity between these regions compared to the wakefulness. Conclusions: Propofol anesthesia is a sleep-like state and slow waves are associated with diminished consciousness even in the presence of high gamma activity. Citation: Murphy M; Bruno MA; Riedner BA; Boveroux P; Noirhomme Q; Landsness EC; Brichant JF; Phillips C; Massimini M; Laureys S; Tononi G; Boly M. Propofol anesthesia and sleep: a high-density EEG study. SLEEP 2011;34(3):283-291. PMID:21358845

Developmental trajectories of EEG sleep slow wave activity as a marker for motor skill development during adolescence: a pilot study.

PubMed

Lustenberger, Caroline; Mouthon, Anne-Laure; Tesler, Noemi; Kurth, Salome; Ringli, Maya; Buchmann, Andreas; Jenni, Oskar G; Huber, Reto

2017-01-01

Reliable markers for brain maturation are important to identify neural deviations that eventually predict the development of mental illnesses. Recent studies have proposed topographical EEG-derived slow wave activity (SWA) during NREM sleep as a mirror of cortical development. However, studies about the longitudinal stability as well as the relationship with behavioral skills are needed before SWA topography may be considered such a reliable marker. We examined six subjects longitudinally (over 5.1 years) using high-density EEG and a visuomotor learning task. All subjects showed a steady increase of SWA at a frontal electrode and a decrease in central electrodes. Despite these large changes in EEG power, SWA topography was relatively stable within each subject during development indicating individual trait-like characteristics. Moreover, the SWA changes in the central cluster were related to the development of specific visuomotor skills. Taken together with the previous work in this domain, our results suggest that EEG sleep SWA represents a marker for motor skill development and further supports the idea that SWA mirrors cortical development during childhood and adolescence. © 2016 Wiley Periodicals, Inc.

Age affects sleep microstructure more than sleep macrostructure.

PubMed

Schwarz, Johanna F A; Åkerstedt, Torbjörn; Lindberg, Eva; Gruber, Georg; Fischer, Håkan; Theorell-Haglöw, Jenny

2017-06-01

It is well known that the quantity and quality of physiological sleep changes across age. However, so far the effect of age on sleep microstructure has been mostly addressed in small samples. The current study examines the effect of age on several measures of sleep macro- and microstructure in 211 women (22-71 years old) of the 'Sleep and Health in Women' study for whom ambulatory polysomnography was registered. Older age was associated with significantly lower fast spindle (effect size f 2  = 0.32) and K-complex density (f 2  = 0.19) during N2 sleep, as well as slow-wave activity (log) in N3 sleep (f 2  = 0.21). Moreover, total sleep time (f 2  = 0.10), N3 sleep (min) (f 2  = 0.10), rapid eye movement sleep (min) (f 2  = 0.11) and sigma (log) (f 2  = 0.05) and slow-wave activity (log) during non-rapid eye movement sleep (f 2  = 0.09) were reduced, and N1 sleep (f 2  = 0.03) was increased in older age. No significant effects of age were observed on slow spindle density, rapid eye movement density and beta power (log) during non-rapid eye movement sleep. In conclusion, effect sizes indicate that traditional sleep stage scoring may underestimate age-related changes in sleep. © 2017 European Sleep Research Society.

Fear Extinction Memory Consolidation Requires Potentiation of Pontine-Wave Activity during REM Sleep

PubMed Central

Datta, Subimal; O'Malley, Matthew W .

2013-01-01

Sleep plays an important role in memory consolidation within multiple memory systems including contextual fear extinction memory, but little is known about the mechanisms that underlie this process. Here, we show that fear extinction training in rats, which extinguished conditioned fear, increased both slow-wave sleep and rapid-eye movement (REM) sleep. Surprisingly, 24 h later, during memory testing, only 57% of the fear-extinguished animals retained fear extinction memory. We found that these animals exhibited an increase in phasic pontine-wave (P-wave) activity during post-training REM sleep, which was absent in the 43% of animals that failed to retain fear extinction memory. The results of this study provide evidence that brainstem activation, specifically potentiation of phasic P-wave activity, during post-training REM sleep is critical for consolidation of fear extinction memory. The results of this study also suggest that, contrary to the popular hypothesis of sleep and memory, increased sleep after training alone does not guarantee consolidation and/or retention of fear extinction memory. Rather, the potentiation of specific sleep-dependent physiological events may be a more accurate predictor for successful consolidation of fear extinction memory. Identification of this unique mechanism will significantly improve our present understanding of the cellular and molecular mechanisms that underlie the sleep-dependent regulation of emotional memory. Additionally, this discovery may also initiate development of a new, more targeted treatment method for clinical disorders of fear and anxiety in humans that is more efficacious than existing methods such as exposure therapy that incorporate only fear extinction. PMID:23467372

An 8-year old boy with continuous spikes and waves during slow sleep presenting with positive onconeuronal antibodies.

PubMed

Hu, Lin-Yan; Shi, Xiu-Yu; Feng, Chen; Wang, Jian-Wen; Yang, Guan; Lammers, Stephen H T; Yang, Xiao Fan; Ebrahimi-Fakhari, Darius; Zou, Li-Ping

2015-03-01

To determine the etiology of epilepsy with continuous spikes and waves during slow sleep (CSWS)/electrical status epilepticus during sleep (ESES) in an 8-year old boy with a history of neuroblastoma and opsoclonus-myoclonus. A combination of clinical characterization and follow-up, video EEG and laboratory investigations. We report the case of an 8-year old boy with a history of neuroblastoma and opsoclonus-myoclonus, who presented with intellectual disability, pharmacotherapy-resistant epilepsy and CSWS/ESES. Although the patient's neuroblastoma had been successfully treated 8 years prior to presentation and an extensive workup did not show a tumor reoccurrence, testing for onconeuronal antibodies was positive for anti-Ma2 and anti-CV2/CRMP5 antibodies. High-dose intravenous methylprednisolone and a taper of oral methylprednisolone were given, leading to a significant clinical improvement. During the taper the patient's condition and EEG manifestations deteriorated again necessitating another cycle of steroid therapy, which lead to a stable improvement. During a 6-month follow-up no CSWS/ESES was seen on EEG and anti-Ma2 and anti-CV2/CRMP5 antibodies remained undetectable. This case suggests that onconeuronal antibodies may be involved in the pathogenesis of CSWS/ESES. Copyright © 2015 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.

Traveling Slow Oscillations During Sleep: A Marker of Brain Connectivity in Childhood.

PubMed

Kurth, Salome; Riedner, Brady A; Dean, Douglas C; O'Muircheartaigh, Jonathan; Huber, Reto; Jenni, Oskar G; Deoni, Sean C L; LeBourgeois, Monique K

2017-09-01

Slow oscillations, a defining characteristic of the nonrapid eye movement sleep electroencephalogram (EEG), proliferate across the scalp in highly reproducible patterns. In adults, the propagation of slow oscillations is a recognized fingerprint of brain connectivity and excitability. In this study, we (1) describe for the first time maturational features of sleep slow oscillation propagation in children (n = 23; 2-13 years) using high-density (hd) EEG and (2) examine associations between sleep slow oscillatory propagation characteristics (ie, distance, traveling speed, cortical involvement) and white matter myelin microstructure as measured with multicomponent Driven Equilibrium Single Pulse Observation of T1 and T2-magnetic resonance imaging (mcDESPOT-MRI). Results showed that with increasing age, slow oscillations propagated across longer distances (average growth of 0.2 cm per year; R(21) = 0.50, p < .05), while traveling speed and cortical involvement (ie, slow oscillation expanse) remained unchanged across childhood. Cortical involvement (R(20) = 0.44) and slow oscillation speed (R(20) = -0.47; both p < .05, corrected for age) were associated with myelin content in the superior longitudinal fascicle, the largest anterior-posterior, intrahemispheric white matter connectivity tract. Furthermore, slow oscillation distance was moderately associated with whole-brain (R(21) = 0.46, p < .05) and interhemispheric myelin content, the latter represented by callosal myelin water fraction (R(21) = 0.54, p < .01, uncorrected). Thus, we demonstrate age-related changes in slow oscillation propagation distance, as well as regional associations between brain activity during sleep and the anatomical connectivity of white matter microstructure. Our findings make an important contribution to knowledge of the brain connectome using a noninvasive and novel analytic approach. These data also have implications for understanding the emergence of neurodevelopmental disorders and the

Gene expression in the rat cerebral cortex: comparison of recovery sleep and hypnotic-induced sleep.

PubMed

Wisor, J P; Morairty, S R; Huynh, N T; Steininger, T L; Kilduff, T S

2006-08-11

Most hypnotic medications currently on the market target some aspect of GABAergic neurotransmission. Although all such compounds increase sleep, these drugs differentially affect the activity of the cerebral cortex as measured by the electroencephalogram. Whereas benzodiazepine medications such as triazolam tend to suppress slow wave activity in the cortex, the GABA(B) ligand gamma-hydroxybutyrate greatly enhances slow wave activity and the non-benzodiazepine, zolpidem, which binds to the omega1 site on the GABA(A) receptor/Cl(-) ionophore complex, is intermediate in this regard. Our previous studies have demonstrated that a small number of genes exhibit increased expression in the cerebral cortex of the mouse and rat during recovery sleep after sleep deprivation: egr-3, fra-2, grp78, grp94, ngfi-b, and nr4a3. Using these genes as a panel of biomarkers associated with sleep, we asked whether hypnotic medications induce similar molecular changes in the rat cerebral cortex to those observed when both sleep continuity and slow wave activity are enhanced during recovery sleep. We find that, although each drug increases the expression of a subset of genes in the panel of biomarkers, no drug fully replicates the molecular changes in the cortex associated with recovery sleep. Furthermore, high levels of slow wave activity in the cortex are correlated with increased expression of fra-2 whereas the expression of grp94 is correlated with body temperature. These results demonstrate that sleep-related changes in gene expression may be affected by physiological covariates of sleep and wakefulness rather than by vigilance state per se.

Phase-Locked Loop for Precisely Timed Acoustic Stimulation during Sleep

PubMed Central

Santostasi, Giovanni; Malkani, Roneil; Riedner, Brady; Bellesi, Michele; Tononi, Giulio; Paller, Ken A.; Zee, Phyllis C.

2016-01-01

Background A Brain-Computer Interface could potentially enhance the various benefits of sleep. New Method We describe a strategy for enhancing slow-wave sleep (SWS) by stimulating the sleeping brain with periodic acoustic stimuli that produce resonance in the form of enhanced slow-wave activity in the electroencephalogram (EEG). The system delivers each acoustic stimulus at a particular phase of an electrophysiological rhythm using a Phase-Locked Loop (PLL). Results The PLL is computationally economical and well suited to follow and predict the temporal behavior of the EEG during slow-wave sleep. Comparison with Existing Methods Acoustic stimulation methods may be able to enhance SWS without the risks inherent in electrical stimulation or pharmacological methods. The PLL method differs from other acoustic stimulation methods that are based on detecting a single slow wave rather than modeling slow-wave activity over an extended period of time. Conclusions By providing real-time estimates of the phase of ongoing EEG oscillations, the PLL can rapidly adjust to physiological changes, thus opening up new possibilities to study brain dynamics during sleep. Future application of these methods hold promise for enhancing sleep quality and associated daytime behavior and improving physiologic function. PMID:26617321

REM sleep behaviour disorder is associated with lower fast and higher slow sleep spindle densities.

PubMed

O'Reilly, Christian; Godin, Isabelle; Montplaisir, Jacques; Nielsen, Tore

2015-12-01

To investigate differences in sleep spindle properties and scalp topography between patients with rapid eye movement sleep behaviour disorder (RBD) and healthy controls, whole-night polysomnograms of 35 patients diagnosed with RBD and 35 healthy control subjects matched for age and sex were compared. Recordings included a 19-lead 10-20 electroencephalogram montage and standard electromyogram, electrooculogram, electrocardiogram and respiratory leads. Sleep spindles were automatically detected using a standard algorithm, and their characteristics (amplitude, duration, density, frequency and frequency slope) compared between groups. Topological analyses of group-discriminative features were conducted. Sleep spindles occurred at a significantly (e.g. t34 = -4.49; P = 0.00008 for C3) lower density (spindles ∙ min(-1) ) for RBD (mean ± SD: 1.61 ± 0.56 for C3) than for control (2.19 ± 0.61 for C3) participants. However, when distinguishing slow and fast spindles using thresholds individually adapted to the electroencephalogram spectrum of each participant, densities smaller (31-96%) for fast but larger (20-120%) for slow spindles were observed in RBD in all derivations. Maximal differences were in more posterior regions for slow spindles, but over the entire scalp for fast spindles. Results suggest that the density of sleep spindles is altered in patients with RBD and should therefore be investigated as a potential marker of future neurodegeneration in these patients. © 2015 European Sleep Research Society.

Slow Sleep Spindle Activity, Declarative Memory, and General Cognitive Abilities in Children

PubMed Central

Hoedlmoser, Kerstin; Heib, Dominik P.J.; Roell, Judith; Peigneux, Philippe; Sadeh, Avi; Gruber, Georg; Schabus, Manuel

2014-01-01

Study Objectives: Functional interactions between sleep spindle activity, declarative memory consolidation, and general cognitive abilities in school-aged children. Design: Healthy, prepubertal children (n = 63; mean age 9.56 ± 0.76 y); ambulatory all-night polysomnography (2 nights); investigating the effect of prior learning (word pair association task; experimental night) versus nonlearning (baseline night) on sleep spindle activity; general cognitive abilities assessed using the Wechsler Intelligence Scale for Children-IV (WISC-IV). Measurements and Results: Analysis of spindle activity during nonrapid eye movement sleep (N2 and N3) evidenced predominant peaks in the slow (11-13 Hz) but not in the fast (13-15 Hz) sleep spindle frequency range (baseline and experimental night). Analyses were restricted to slow sleep spindles. Changes in spindle activity from the baseline to the experimental night were not associated with the overnight change in the number of recalled words reflecting declarative memory consolidation. Children with higher sleep spindle activity as measured at frontal, central, parietal, and occipital sites during both baseline and experimental nights exhibited higher general cognitive abilities (WISC-IV) and declarative learning efficiency (i.e., number of recalled words before and after sleep). Conclusions: Slow sleep spindles (11-13 Hz) in children age 8–11 y are associated with inter-individual differences in general cognitive abilities and learning efficiency. Citation: Hoedlmoser K, Heib DPJ, Roell J, Peigneux P, Sadeh A, Gruber G, Schabus M. Slow sleep spindle activity, declarative memory, and general cognitive abilities in children. SLEEP 2014;37(9):1501-1512. PMID:25142558

Neurocognitive and neurobehavioral disabilities in Epilepsy with Electrical Status Epilepticus in slow sleep (ESES) and related syndromes.

PubMed

Raha, Sarbani; Shah, Urvashi; Udani, Vrajesh

2012-11-01

The aims of this study were to assess the cognitive and behavioral problems of patients with Epilepsy with Electrical Status Epilepticus in slow sleep (ESES) and related syndromes and to review their EEG (electroencephalography) findings and treatment options. Fourteen patients with ESES were evaluated and treated in 2010. Nine children had continuous spike and wave during slow-wave sleep (CSWS)/ESES syndrome, 3 had Atypical BECTS (benign epilepsy with centrotemporal spikes), 1 had Opercular syndrome, and 1 had Landau-Kleffner syndrome. The duration of ESES ranged from 6 to 52 months. Eleven (91%) children had behavioral issues, most prominent being hyperactivity. Seven of the 13 children (53%) showed evidence of borderline to moderate cognitive impairment. A total of 28 EEG findings of ESES were analyzed for SWI (spike-wave index). Antiepileptic drugs received by the patients included valproate, clobazam, levetiracetam, and others. Eleven patients had been treated with oral steroids and it was found to be efficacious in seven (63%). Disabilities caused by ESES affect multiple domains. Patients with an SWI>50% should be followed up frequently with neuropsychological assessments. Steroids appear to be effective, although there is a need to standardize the dose and duration of treatment. Copyright © 2012 Elsevier Inc. All rights reserved.

Local sleep homeostasis in the avian brain: convergence of sleep function in mammals and birds?

PubMed

Lesku, John A; Vyssotski, Alexei L; Martinez-Gonzalez, Dolores; Wilzeck, Christiane; Rattenborg, Niels C

2011-08-22

The function of the brain activity that defines slow wave sleep (SWS) and rapid eye movement (REM) sleep in mammals is unknown. During SWS, the level of electroencephalogram slow wave activity (SWA or 0.5-4.5 Hz power density) increases and decreases as a function of prior time spent awake and asleep, respectively. Such dynamics occur in response to waking brain use, as SWA increases locally in brain regions used more extensively during prior wakefulness. Thus, SWA is thought to reflect homeostatically regulated processes potentially tied to maintaining optimal brain functioning. Interestingly, birds also engage in SWS and REM sleep, a similarity that arose via convergent evolution, as sleeping reptiles and amphibians do not show similar brain activity. Although birds deprived of sleep show global increases in SWA during subsequent sleep, it is unclear whether avian sleep is likewise regulated locally. Here, we provide, to our knowledge, the first electrophysiological evidence for local sleep homeostasis in the avian brain. After staying awake watching David Attenborough's The Life of Birds with only one eye, SWA and the slope of slow waves (a purported marker of synaptic strength) increased only in the hyperpallium--a primary visual processing region--neurologically connected to the stimulated eye. Asymmetries were specific to the hyperpallium, as the non-visual mesopallium showed a symmetric increase in SWA and wave slope. Thus, hypotheses for the function of mammalian SWS that rely on local sleep homeostasis may apply also to birds.

Theta-rhythmic drive between medial septum and hippocampus in slow-wave sleep and microarousal: a Granger causality analysis.

PubMed

Kang, D; Ding, M; Topchiy, I; Shifflett, L; Kocsis, B

2015-11-01

Medial septum (MS) plays a critical role in controlling the electrical activity of the hippocampus (HIPP). In particular, theta-rhythmic burst firing of MS neurons is thought to drive lasting HIPP theta oscillations in rats during waking motor activity and REM sleep. Less is known about MS-HIPP interactions in nontheta states such as non-REM sleep, in which HIPP theta oscillations are absent but theta-rhythmic burst firing in subsets of MS neurons is preserved. The present study used Granger causality (GC) to examine the interaction patterns between MS and HIPP in slow-wave sleep (SWS, a nontheta state) and during its short interruptions called microarousals (a transient theta state). We found that during SWS, while GC revealed a unidirectional MS→HIPP influence over a wide frequency band (2-12 Hz, maximum: ∼8 Hz), there was no theta peak in the hippocampal power spectra, indicating a lack of theta activity in HIPP. In contrast, during microarousals, theta peaks were seen in both MS and HIPP power spectra and were accompanied by bidirectional GC with MS→HIPP and HIPP→MS theta drives being of equal magnitude. Thus GC in a nontheta state (SWS) vs. a theta state (microarousal) primarily differed in the level of HIPP→MS. The present findings suggest a modification of our understanding of the role of MS as the theta generator in two regards. First, a MS→HIPP theta drive does not necessarily induce theta field oscillations in the hippocampus, as found in SWS. Second, HIPP theta oscillations entail bidirectional theta-rhythmic interactions between MS and HIPP. Copyright © 2015 the American Physiological Society.

The Effects of Sleep Continuity Disruption on Positive Mood and Sleep Architecture in Healthy Adults.

PubMed

Finan, Patrick H; Quartana, Phillip J; Smith, Michael T

2015-11-01

The purpose of this study was to test an experimental model of the effects of sleep continuity disturbance on sleep architecture and positive mood in order to better understand the mechanisms linking insomnia and depression. Participants were randomized to receive 3 consecutive nights of sleep continuity disruption via forced nocturnal awakenings (FA, n = 21), or one of two control conditions: restricted sleep opportunity (RSO, n = 17) or uninterrupted sleep (US, n = 24). The study was set in an inpatient clinical research suite. Healthy, good-sleeping men and women were included. Polysomnography was used to measure sleep architecture, and mood was assessed via self-report each day. Compared to restricted sleep opportunity controls, forced awakenings subjects had significantly less slow wave sleep (P < 0.05) after the first night of sleep deprivation, and significantly lower positive mood (P < 0.05) after the second night of sleep deprivation. The differential change in slow wave sleep statistically mediated the observed group differences in positive mood (P = 0.002). To our knowledge, this is the first human experimental study to demonstrate that, despite comparable reductions in total sleep time, partial sleep loss from sleep continuity disruption is more detrimental to positive mood than partial sleep loss from delaying bedtime, even when controlling for concomitant increases in negative mood. With these findings, we provide temporal evidence in support of a putative biologic mechanism (slow wave sleep deficit) that could help explain the strong comorbidity between insomnia and depression. © 2015 Associated Professional Sleep Societies, LLC.

Ketogenic diet in the treatment of refractory continuous spikes and waves during slow sleep.

PubMed

Nikanorova, Marina; Miranda, Maria J; Atkins, Mary; Sahlholdt, Lene

2009-05-01

To evaluate the effect of the ketogenic diet on electroclinical characteristics and cognitive function in children with continuous spikes and waves during slow sleep (CSWS). Five children (four boys, one girl) aged between 8 and 13 years with CSWS refractory to conventional antiepileptic drugs (AEDs), including levetiracetam, and steroids were included. The prospective electroclinical assessment was performed prior to the ketogenic diet and once every 6 months post initiation during the 2-year period. All children underwent neuropsychological testing prior to the ketogenic diet and four of the children again 12 months after the diet's introduction. In case 4 the testing has been performed after 7 months and the diet was withdrawn after 9 months because of the lack of efficacy and the parent's wishes. In two patients the cognitive functions were also evaluated after 24 months since the diet's initiation. During the period on the ketogenic diet the concomitant AED treatment was unchanged. Electrographic evaluation after 24 months on the ketogenic diet showed CSWS resolution in one patient, mild decrease of the spike-wave index in one, and lack of response in three patients. The ketogenic diet did not influence the neuropsychological outcome, and intelligence quotient (IQ) scores remained low at the end of the follow-up period. However, in two patients an improvement in attention and behavior was demonstrated. This is the first study evaluating the efficacy of the ketogenic diet in children with CSWS. Five presented cases were refractory to AEDs and steroids. Only one case responded with complete CSWS disappearance; in one the effect of the ketogenic diet was partial and intermittent, whereas in three patients no response has been observed. These results show that the ketogenic diet did not appear to influence the neuropsychological outcome; however, the absence of a control group makes it impossible to conclude with certainty.

Asynchronous ripple oscillations between left and right hippocampi during slow-wave sleep

PubMed Central

Villalobos, Claudio

2017-01-01

Spatial memory, among many other brain processes, shows hemispheric lateralization. Most of the published evidence suggests that the right hippocampus plays a leading role in the manipulation of spatial information. Concurrently in the hippocampus, memory consolidation during sleep periods is one of the key steps in the formation of newly acquired spatial memory traces. One of the most characteristic oscillatory patterns in the hippocampus are sharp-wave ripple (SWR) complexes. Within this complex, fast-field oscillations or ripples have been demonstrated to be instrumental in the memory consolidation process. Since these ripples are relevant for the consolidation of memory traces associated with spatial navigation, and this process appears to be lateralized, we hypothesize that ripple events between both hippocampi would exhibit different temporal dynamics. We tested this idea by using a modified "split-hyperdrive" that allows us to record simultaneous LFPs from both right and left hippocampi of Sprague-Dawley rats during sleep. We detected individual events and found that during sleep periods these ripples exhibited a different occurrence patterns between hemispheres. Most ripple events were synchronous between intra- rather than inter-hemispherical recordings, suggesting that ripples in the hippocampus are independently generated and locally propagated within a specific hemisphere. In this study, we propose the ripples’ lack of synchrony between left and right hippocampi as the putative physiological mechanism underlying lateralization of spatial memory. PMID:28158285

Asynchronous ripple oscillations between left and right hippocampi during slow-wave sleep.

PubMed

Villalobos, Claudio; Maldonado, Pedro E; Valdés, José L

2017-01-01

Spatial memory, among many other brain processes, shows hemispheric lateralization. Most of the published evidence suggests that the right hippocampus plays a leading role in the manipulation of spatial information. Concurrently in the hippocampus, memory consolidation during sleep periods is one of the key steps in the formation of newly acquired spatial memory traces. One of the most characteristic oscillatory patterns in the hippocampus are sharp-wave ripple (SWR) complexes. Within this complex, fast-field oscillations or ripples have been demonstrated to be instrumental in the memory consolidation process. Since these ripples are relevant for the consolidation of memory traces associated with spatial navigation, and this process appears to be lateralized, we hypothesize that ripple events between both hippocampi would exhibit different temporal dynamics. We tested this idea by using a modified "split-hyperdrive" that allows us to record simultaneous LFPs from both right and left hippocampi of Sprague-Dawley rats during sleep. We detected individual events and found that during sleep periods these ripples exhibited a different occurrence patterns between hemispheres. Most ripple events were synchronous between intra- rather than inter-hemispherical recordings, suggesting that ripples in the hippocampus are independently generated and locally propagated within a specific hemisphere. In this study, we propose the ripples' lack of synchrony between left and right hippocampi as the putative physiological mechanism underlying lateralization of spatial memory.

Characterization of the sleep-wake patterns in mice lacking fatty acid amide hydrolase.

PubMed

Huitron-Resendiz, Salvador; Sanchez-Alavez, Manuel; Wills, Derek N; Cravatt, Benjamin F; Henriksen, Steven J

2004-08-01

Oleamide and anandamide are fatty acid amides implicated in the regulatory mechanisms of sleep processes. However, due to their prompt catabolism by fatty acid amide hydrolase (FAAH), their pharmacologic and behavioral effects, in vivo, disappear rapidly. To determine if, in the absence of FAAH, the hypnogenic fatty acid amides induce an increase of sleep, we characterized the sleep-wake patters in FAAH-knockout mice [FAAH (-/-)] before and after sleep deprivation. FAAH (-/-), FAAH (+/-), and FAAH (+/+) mice were implanted chronically for sleep, body temperature (Tb), and locomotor activity (LMA) recordings. Sleep-wake states were recorded during a 24-hour baseline session followed by 8 hours of sleep deprivation. Recovery recordings were done during the 16 hours following sleep deprivation. Total amount of wake, slow-wave sleep, and rapid eye movement sleep were calculated and compared between genotypes. The electroencephalographic spectral analysis was performed by fast Fourier transform analysis. Telemetry recordings of Tb and LMA were carried out continuously during 4 days under baseline conditions. N/A. FAAH (-/-) mice and their heterozygote (+/-) and control (+/+) littermates were used. Sleep deprivation. FAAH (-/-) mice possess higher values of slow-wave sleep and more intense episodes of slow-wave sleep than do control littermates under baseline conditions that are not related to differences in Tb and LMA. A rebound of slow-wave sleep and rapid eye movement sleep as well an increase in the levels of slow-wave activity were observed after sleep deprivation in all genotypes. These findings support the role of fatty acid amides as possible modulators of sleep and indicate that the homeostatic mechanisms of sleep in FAAH (-/-) mice are not disrupted.

Information processing during sleep and stress-related sleep vulnerability.

PubMed

Lin, Yen-Hsuan; Jen, Chun-Hui; Yang, Chien-Ming

2015-02-01

Previous studies showed enhanced attention and decreased inhibitory processes during early non-rapid eye movement sleep in primary insomnia patients, as measured by event-related potentials. The current study aims to examine information processing during sleep in non-insomniac individuals with high vulnerability (HV) to stress-related sleep disturbances. Twenty-seven non-insomniac individuals were recruited, 14 with low vulnerability and 13 with HV. After passing a screening interview and polysomnographic recording, subjects came to the sleep laboratory for 2 nights (a baseline night and a stress-inducing night) for event-related potentials recordings. The HV group demonstrated shorter P2 latency during the first 5 min of stage 2 sleep and higher P900 amplitudes under the stress condition during slow-wave sleep, which indicates an increased level of inhibitory processes. In addition, they had shorter N1 latencies during slow-wave sleep that could indicate an elevated level of attention processing during deep sleep. Unlike patients with chronic insomnia, individuals with high sleep vulnerability to stress show a compensatory process that may prevent external stimulation from interfering with their sleep. This may be one of the factors preventing their acute sleep disturbances from becoming chronic problems. © 2014 The Authors. Psychiatry and Clinical Neurosciences © 2014 Japanese Society of Psychiatry and Neurology.

The Effects of Sleep Continuity Disruption on Positive Mood and Sleep Architecture in Healthy Adults

PubMed Central

Finan, Patrick H.; Quartana, Phillip J.; Smith, Michael T.

2015-01-01

Objective: The purpose of this study was to test an experimental model of the effects of sleep continuity disturbance on sleep architecture and positive mood in order to better understand the mechanisms linking insomnia and depression. Design: Participants were randomized to receive 3 consecutive nights of sleep continuity disruption via forced nocturnal awakenings (FA, n = 21), or one of two control conditions: restricted sleep opportunity (RSO, n = 17) or uninterrupted sleep (US, n = 24). Setting: The study was set in an inpatient clinical research suite. Participants: Healthy, good-sleeping men and women were included. Measurement and Results: Polysomnography was used to measure sleep architecture, and mood was assessed via self-report each day. Compared to restricted sleep opportunity controls, forced awakenings subjects had significantly less slow wave sleep (P < 0.05) after the first night of sleep deprivation, and significantly lower positive mood (P < 0.05) after the second night of sleep deprivation. The differential change in slow wave sleep statistically mediated the observed group differences in positive mood (P = 0.002). Conclusions: To our knowledge, this is the first human experimental study to demonstrate that, despite comparable reductions in total sleep time, partial sleep loss from sleep continuity disruption is more detrimental to positive mood than partial sleep loss from delaying bedtime, even when controlling for concomitant increases in negative mood. With these findings, we provide temporal evidence in support of a putative biologic mechanism (slow wave sleep deficit) that could help explain the strong comorbidity between insomnia and depression. Citation: Finan PH, Quartana PJ, Smith MT. The effects of sleep continuity disruption on positive mood and sleep architecture in healthy adults. SLEEP 2015;38(11):1735–1742. PMID:26085289

Two Distinct Synchronization Processes in the Transition to Sleep: A High-Density Electroencephalographic Study

PubMed Central

Siclari, Francesca; Bernardi, Giulio; Riedner, Brady A.; LaRocque, Joshua J.; Benca, Ruth M.; Tononi, Giulio

2014-01-01

Objectives: To assess how the characteristics of slow waves and spindles change in the falling-asleep process. Design: Participants undergoing overnight high-density electroencephalographic recordings were awakened at 15- to 30-min intervals. One hundred forty-one falling-asleep periods were analyzed at the scalp and source level. Setting: Sleep laboratory. Participants: Six healthy participants. Interventions: Serial awakenings. Results: The number and amplitude of slow waves followed two dissociated, intersecting courses during the transition to sleep: slow wave number increased slowly at the beginning and rapidly at the end of the falling-asleep period, whereas amplitude at first increased rapidly and then decreased linearly. Most slow waves occurring early in the transition to sleep had a large amplitude, a steep slope, involved broad regions of the cortex, predominated over frontomedial regions, and preferentially originated from the sensorimotor and the posteromedial parietal cortex. Most slow waves occurring later had a smaller amplitude and slope, involved more circumscribed parts of the cortex, and had more evenly distributed origins. Spindles were initially sparse, fast, and involved few cortical regions, then became more numerous and slower, and involved more areas. Conclusions: Our results provide evidence for two types of slow waves, which follow dissociated temporal courses in the transition to sleep and have distinct cortical origins and distributions. We hypothesize that these two types of slow waves result from two distinct synchronization processes: (1) a “bottom-up,” subcorticocortical, arousal system-dependent process that predominates in the early phase and leads to type I slow waves, and (2) a “horizontal,” corticocortical synchronization process that predominates in the late phase and leads to type II slow waves. The dissociation between these two synchronization processes in time and space suggests that they may be differentially

An Adenosine-Mediated Glial-Neuronal Circuit for Homeostatic Sleep.

PubMed

Bjorness, Theresa E; Dale, Nicholas; Mettlach, Gabriel; Sonneborn, Alex; Sahin, Bogachan; Fienberg, Allen A; Yanagisawa, Masashi; Bibb, James A; Greene, Robert W

2016-03-30

Sleep homeostasis reflects a centrally mediated drive for sleep, which increases during waking and resolves during subsequent sleep. Here we demonstrate that mice deficient for glial adenosine kinase (AdK), the primary metabolizing enzyme for adenosine (Ado), exhibit enhanced expression of this homeostatic drive by three independent measures: (1) increased rebound of slow-wave activity; (2) increased consolidation of slow-wave sleep; and (3) increased time constant of slow-wave activity decay during an average slow-wave sleep episode, proposed and validated here as a new index for homeostatic sleep drive. Conversely, mice deficient for the neuronal adenosine A1 receptor exhibit significantly decreased sleep drive as judged by these same indices. Neuronal knock-out of AdK did not influence homeostatic sleep need. Together, these findings implicate a glial-neuronal circuit mediated by intercellular Ado, controlling expression of homeostatic sleep drive. Because AdK is tightly regulated by glial metabolic state, our findings suggest a functional link between cellular metabolism and sleep homeostasis. The work presented here provides evidence for an adenosine-mediated regulation of sleep in response to waking (i.e., homeostatic sleep need), requiring activation of neuronal adenosine A1 receptors and controlled by glial adenosine kinase. Adenosine kinase acts as a highly sensitive and important metabolic sensor of the glial ATP/ADP and AMP ratio directly controlling intracellular adenosine concentration. Glial equilibrative adenosine transporters reflect the intracellular concentration to the extracellular milieu to activate neuronal adenosine receptors. Thus, adenosine mediates a glial-neuronal circuit linking glial metabolic state to neural-expressed sleep homeostasis. This indicates a metabolically related function(s) for this glial-neuronal circuit in the buildup and resolution of our need to sleep and suggests potential therapeutic targets more directly related to

Topographical distribution of fast and slow sleep spindles in medicated depressive patients.

PubMed

Nishida, Masaki; Nakashima, Yusaku; Nishikawa, Toru

2014-10-01

To compare the properties of sleep spindles between healthy subjects and medicated patients with major depressive episode, including frequency range, spectra power, and spatial distribution of spindle power. Continuous 16-channel EEG was used to record nocturnal sleep in healthy control subjects and medicated depressive patients. Recordings were analyzed for changes in EEG power spectra and power topography. Additionally, we graphically demonstrated the pattern of spatial distribution of each type of sleep spindle, divided into fast (12.5-14 Hz) and slow spindles (11-12.5 Hz). Sleep EEG records of depressive subjects exhibited a significantly higher amplitude of slow spindles in the prefrontal region, compared with the healthy controls (P < 0.01). Fast spindles were dominant in the centroparietal region in both depressive patients and the control group. Enhanced slow spindles in the prefrontal region were observed in the medicated depressive patients and not in the healthy controls. The frequency of fast spindles in depressive patients was globally higher than that in healthy participants. The alteration in sleep spindles seen in medicated depressive subjects may reflect a pharmacological modulation of synaptic function involving the thalamic-reticular and thalamocortical mechanisms.

Sex-related differences in sleep slow wave activity in major depressive disorder: a high-density EEG investigation.

PubMed

Plante, David T; Landsness, Eric C; Peterson, Michael J; Goldstein, Michael R; Riedner, Brady A; Wanger, Timothy; Guokas, Jeffrey J; Tononi, Giulio; Benca, Ruth M

2012-09-18

Sleep disturbance plays an important role in major depressive disorder (MDD). Prior investigations have demonstrated that slow wave activity (SWA) during sleep is altered in MDD; however, results have not been consistent across studies, which may be due in part to sex-related differences in SWA and/or limited spatial resolution of spectral analyses. This study sought to characterize SWA in MDD utilizing high-density electroencephalography (hdEEG) to examine the topography of SWA across the cortex in MDD, as well as sex-related variation in SWA topography in the disorder. All-night recordings with 256 channel hdEEG were collected in 30 unipolar MDD subjects (19 women) and 30 age and sex-matched control subjects. Spectral analyses of SWA were performed to determine group differences. SWA was compared between MDD and controls, including analyses stratified by sex, using statistical non-parametric mapping to correct for multiple comparisons of topographic data. As a group, MDD subjects demonstrated significant increases in all-night SWA primarily in bilateral prefrontal channels. When stratified by sex, MDD women demonstrated global increases in SWA relative to age-matched controls that were most consistent in bilateral prefrontal regions; however, MDD men showed no significant differences relative to age-matched controls. Further analyses demonstrated increased SWA in MDD women was most prominent in the first portion of the night. Women, but not men with MDD demonstrate significant increases in SWA in multiple cortical areas relative to control subjects. Further research is warranted to investigate the role of SWA in MDD, and to clarify how increased SWA in women with MDD is related to the pathophysiology of the disorder.

Comparison of filtering methods for extracellular gastric slow wave recordings.

PubMed

Paskaranandavadivel, Niranchan; O'Grady, Gregory; Du, Peng; Cheng, Leo K

2013-01-01

Extracellular recordings are used to define gastric slow wave propagation. Signal filtering is a key step in the analysis and interpretation of extracellular slow wave data; however, there is controversy and uncertainty regarding the appropriate filtering settings. This study investigated the effect of various standard filters on the morphology and measurement of extracellular gastric slow waves. Experimental extracellular gastric slow waves were recorded from the serosal surface of the stomach from pigs and humans. Four digital filters: finite impulse response filter (0.05-1 Hz); Savitzky-Golay filter (0-1.98 Hz); Bessel filter (2-100 Hz); and Butterworth filter (5-100 Hz); were applied on extracellular gastric slow wave signals to compare the changes temporally (morphology of the signal) and spectrally (signals in the frequency domain). The extracellular slow wave activity is represented in the frequency domain by a dominant frequency and its associated harmonics in diminishing power. Optimal filters apply cutoff frequencies consistent with the dominant slow wave frequency (3-5 cpm) and main harmonics (up to ≈ 2 Hz). Applying filters with cutoff frequencies above or below the dominant and harmonic frequencies was found to distort or eliminate slow wave signal content. Investigators must be cognizant of these optimal filtering practices when detecting, analyzing, and interpreting extracellular slow wave recordings. The use of frequency domain analysis is important for identifying the dominant and harmonics of the signal of interest. Capturing the dominant frequency and major harmonics of slow wave is crucial for accurate representation of slow wave activity in the time domain. Standardized filter settings should be determined. © 2012 Blackwell Publishing Ltd.

Enhanced Memory Consolidation Via Automatic Sound Stimulation During Non-REM Sleep.

PubMed

Leminen, Miika M; Virkkala, Jussi; Saure, Emma; Paajanen, Teemu; Zee, Phyllis C; Santostasi, Giovanni; Hublin, Christer; Müller, Kiti; Porkka-Heiskanen, Tarja; Huotilainen, Minna; Paunio, Tiina

2017-03-01

Slow-wave sleep (SWS) slow waves and sleep spindle activity have been shown to be crucial for memory consolidation. Recently, memory consolidation has been causally facilitated in human participants via auditory stimuli phase-locked to SWS slow waves. Here, we aimed to develop a new acoustic stimulus protocol to facilitate learning and to validate it using different memory tasks. Most importantly, the stimulation setup was automated to be applicable for ambulatory home use. Fifteen healthy participants slept 3 nights in the laboratory. Learning was tested with 4 memory tasks (word pairs, serial finger tapping, picture recognition, and face-name association). Additional questionnaires addressed subjective sleep quality and overnight changes in mood. During the stimulus night, auditory stimuli were adjusted and targeted by an unsupervised algorithm to be phase-locked to the negative peak of slow waves in SWS. During the control night no sounds were presented. Results showed that the sound stimulation increased both slow wave (p = .002) and sleep spindle activity (p < .001). When overnight improvement of memory performance was compared between stimulus and control nights, we found a significant effect in word pair task but not in other memory tasks. The stimulation did not affect sleep structure or subjective sleep quality. We showed that the memory effect of the SWS-targeted individually triggered single-sound stimulation is specific to verbal associative memory. Moreover, the ambulatory and automated sound stimulus setup was promising and allows for a broad range of potential follow-up studies in the future. © Sleep Research Society 2017. Published by Oxford University Press [on behalf of the Sleep Research Society].

Epileptic encephalopathy with continuous spike-waves during sleep: the need for transition from childhood to adulthood medical care appears to be related to etiology.

PubMed

de Saint-Martin, Anne; Rudolf, Gabrielle; Seegmuller, Caroline; Valenti-Hirsch, Maria Paola; Hirsch, Edouard

2014-08-01

Epileptic encephalopathy with continuous diffuse spike-waves during slow-wave sleep (ECSWS) presents clinically with infrequent nocturnal focal seizures, atypical absences related to secondary bilateral synchrony, negative myoclonia, and atonic and rare generalized tonic-clonic seizures. The unique electroencephalography (EEG) pattern found in ECSWS consists of continuous, diffuse, bilateral spike-waves during slow-wave sleep. Despite the eventual disappearance of clinical seizures and EEG abnormalities by adolescence, the prognosis is guarded in most cases because of neuropsychological and behavioral deficits. ECSWS has a heterogeneous etiology (genetic, structural, and unknown). Because epilepsy and electroencephalography (EEG) abnormalities in epileptic encephalopathy with continuous diffuse spike-waves during slow-wave sleep (ECSWS) are self-limited and age related, the need for ongoing medical care and transition to adult care might be questioned. For adolescents in whom etiology remains unknown (possibly genetic) and who experience the disappearance of seizures and EEG abnormalities, there is rarely need for long-term neurologic follow-up, because often a relatively normal cognitive and social evolution follows. However, the majority of patients with structural and possibly "genetic syndromic" etiologies will have persistent cognitive deficits and will need suitable socioeducative care. Therefore, the transition process in ECSWS will depend mainly on etiology and its related features (epileptic active phase duration, and cognitive and behavioral evolution) and revolve around neuropsychological and social support rather than medical and pharmacologic follow-up. Wiley Periodicals, Inc. © 2014 International League Against Epilepsy.

An automated sleep-state classification algorithm for quantifying sleep timing and sleep-dependent dynamics of electroencephalographic and cerebral metabolic parameters

PubMed Central

Rempe, Michael J; Clegern, William C; Wisor, Jonathan P

2015-01-01

Introduction Rodent sleep research uses electroencephalography (EEG) and electromyography (EMG) to determine the sleep state of an animal at any given time. EEG and EMG signals, typically sampled at >100 Hz, are segmented arbitrarily into epochs of equal duration (usually 2–10 seconds), and each epoch is scored as wake, slow-wave sleep (SWS), or rapid-eye-movement sleep (REMS), on the basis of visual inspection. Automated state scoring can minimize the burden associated with state and thereby facilitate the use of shorter epoch durations. Methods We developed a semiautomated state-scoring procedure that uses a combination of principal component analysis and naïve Bayes classification, with the EEG and EMG as inputs. We validated this algorithm against human-scored sleep-state scoring of data from C57BL/6J and BALB/CJ mice. We then applied a general homeostatic model to characterize the state-dependent dynamics of sleep slow-wave activity and cerebral glycolytic flux, measured as lactate concentration. Results More than 89% of epochs scored as wake or SWS by the human were scored as the same state by the machine, whether scoring in 2-second or 10-second epochs. The majority of epochs scored as REMS by the human were also scored as REMS by the machine. However, of epochs scored as REMS by the human, more than 10% were scored as SWS by the machine and 18 (10-second epochs) to 28% (2-second epochs) were scored as wake. These biases were not strain-specific, as strain differences in sleep-state timing relative to the light/dark cycle, EEG power spectral profiles, and the homeostatic dynamics of both slow waves and lactate were detected equally effectively with the automated method or the manual scoring method. Error associated with mathematical modeling of temporal dynamics of both EEG slow-wave activity and cerebral lactate either did not differ significantly when state scoring was done with automated versus visual scoring, or was reduced with automated state

Insufficient sleep: Enhanced risk-seeking relates to low local sleep intensity.

PubMed

Maric, Angelina; Montvai, Eszter; Werth, Esther; Storz, Matthias; Leemann, Janina; Weissengruber, Sebastian; Ruff, Christian C; Huber, Reto; Poryazova, Rositsa; Baumann, Christian R

2017-09-01

Chronic sleep restriction is highly prevalent in modern society and is, in its clinical form, insufficient sleep syndrome, one of the most prevalent diagnoses in clinical sleep laboratories, with substantial negative impact on health and community burden. It reflects every-day sleep loss better than acute sleep deprivation, but its effects and particularly the underlying mechanisms remain largely unknown for a variety of critical cognitive domains, as, for example, risky decision making. We assessed financial risk-taking behavior after 7 consecutive nights of sleep restriction and after 1 night of acute sleep deprivation compared to a regular sleep condition in a within-subject design. We further investigated potential underlying mechanisms of sleep-loss-induced changes in behavior by high-density electroencephalography recordings during restricted sleep. We show that chronic sleep restriction increases risk-seeking, whereas this was not observed after acute sleep deprivation. This increase was subjectively not noticed and was related to locally lower values of slow-wave energy during preceding sleep, an electrophysiological marker of sleep intensity and restoration, in electrodes over the right prefrontal cortex. This study provides, for the first time, evidence that insufficient sleep restoration over circumscribed cortical areas leads to aberrant behavior. In chronically sleep restricted subjects, low slow-wave sleep intensity over the right prefrontal cortex-which has been shown to be linked to risk behavior-may lead to increased and subjectively unnoticed risk-seeking. Ann Neurol 2017;82:409-418. © 2017 American Neurological Association.

Sleep characteristics in the quail Coturnix coturnix.

PubMed

Mexicano, Graciela; Montoya-Loaiza, Bibiana; Ayala-Guerrero, Fructuoso

2014-04-22

As mammals, birds exhibit two sleep phases, slow wave sleep (SWS) and REM (Rapid Eye Movement) sleep characterized by presenting different electrophysiological patterns of brain activity. During SWS a high amplitude slow wave pattern in brain activity is observed. This activity is substituted by a low amplitude fast frequency pattern during REM sleep. Common quail (Coturnix coturnix) is an animal model that has provided information related to different physiological mechanisms present in man. There are reports related to its electrophysiological brain activity, however the sleep characteristics that have been described are not. The objectives of this study is describing the sleep characteristics throughout the nychthemeral cycle of the common quail and consider this bird species as an avian model to analyze the regulatory mechanisms of sleep. Experiments were carried out in implanted exemplars of C. coturnix. Under general anesthesia induced by ether inhalation, stainless steel electrodes were placed to register brain activity from the anterior and posterior areas during 24 continuous hours throughout the sleep-wake cycle. Ocular and motor activities were visually monitored. Quail showed four electrophysiologically and behaviorally different states of vigilance: wakefulness (53.28%), drowsiness (14.27%), slow wave sleep (30.47%) and REM sleep (1.98%). The animals presented 202 REM sleep episodes throughout the nychthemeral cycle. Sleep distribution was polyphasic; however sleep amount was significantly greater during the period corresponding to the night. The number of nocturnal REM sleep episodes was significantly greater than that of diurnal one. The quail C. coturnix shows a polyphasic distribution of sleep; however the amount of this state of vigilance is significantly greater during the nocturnal period. Copyright © 2014 Elsevier Inc. All rights reserved.

Sustained Sleep Fragmentation Induces Sleep Homeostasis in Mice

PubMed Central

Baud, Maxime O.; Magistretti, Pierre J.; Petit, Jean-Marie

2015-01-01

Study Objectives: Sleep fragmentation (SF) is an integral feature of sleep apnea and other prevalent sleep disorders. Although the effect of repetitive arousals on cognitive performance is well documented, the effects of long-term SF on electroencephalography (EEG) and molecular markers of sleep homeostasis remain poorly investigated. To address this question, we developed a mouse model of chronic SF and characterized its effect on EEG spectral frequencies and the expression of genes previously linked to sleep homeostasis including clock genes, heat shock proteins, and plasticity-related genes. Design: N/A. Setting: Animal sleep research laboratory. Participants : Sixty-six C57BL6/J adult mice. Interventions: Instrumental sleep disruption at a rate of 60/h during 14 days Measurements and Results: Locomotor activity and EEG were recorded during 14 days of SF followed by recovery for 2 days. Despite a dramatic number of arousals and decreased sleep bout duration, SF minimally reduced total quantity of sleep and did not significantly alter its circadian distribution. Spectral analysis during SF revealed a homeostatic drive for slow wave activity (SWA; 1–4 Hz) and other frequencies as well (4–40 Hz). Recordings during recovery revealed slow wave sleep consolidation and a transient rebound in SWA, and paradoxical sleep duration. The expression of selected genes was not induced following chronic SF. Conclusions: Chronic sleep fragmentation (SF) increased sleep pressure confirming that altered quality with preserved quantity triggers core sleep homeostasis mechanisms. However, it did not induce the expression of genes induced by sleep loss, suggesting that these molecular pathways are not sustainably activated in chronic diseases involving SF. Citation: Baud MO, Magistretti PJ, Petit JM. Sustained sleep fragmentation induces sleep homeostasis in mice. SLEEP 2015;38(4):567–579. PMID:25325477

Ketamine, sleep, and depression: current status and new questions.

PubMed

Duncan, Wallace C; Zarate, Carlos A

2013-09-01

Ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, has well-described rapid antidepressant effects in clinical studies of individuals with treatment-resistant major depressive disorder (MDD). Preclinical studies investigating the effects of ketamine on brain-derived neurotrophic factor (BDNF) and on sleep slow wave activity (SWA) support its use as a prototype for investigating the neuroplastic mechanisms presumably involved in the mechanism of rapidly acting antidepressants. This review discusses human EEG slow wave sleep parameters and plasma BDNF as central and peripheral surrogate markers of plasticity, and their use in assessing ketamine's effects. Acutely, ketamine elevates BDNF levels, as well as early night SWA and high-amplitude slow waves; each of these measures correlates with change in mood in depressed patients who respond to ketamine. The slow wave effects are limited to the first night post-infusion, suggesting that their increase is part of an early cascade of events triggering improved mood. Increased total sleep and decreased waking occur during the first and second night post infusion, suggesting that these measures are associated with the enduring treatment response observed with ketamine.

Characterization of ictal slow waves in epileptic spasms.

PubMed

Honda, Ryoko; Saito, Yoshiaki; Okumura, Akihisa; Abe, Shinpei; Saito, Takashi; Nakagawa, Eiji; Sugai, Kenji; Sasaki, Masayuki

2015-12-01

We characterized the clinico-neurophysiological features of epileptic spasms, particularly focusing on high-voltage slow waves during ictal EEG. We studied 22 patients with epileptic spasms recorded during digital video-scalp EEG, including five individuals who still had persistent spasms after callosotomy. We analysed the duration, amplitude, latency to onset of electromyographic bursts, and distribution of the highest positive and negative peaks of slow waves in 352 spasms. High-voltage positive slow waves preceded the identifiable muscle contractions of spasms. The mean duration of these positive waves was 569±228 m, and the mean latency to electromyographic onset was 182±127 m. These parameters varied markedly even within a patient. The highest peak of the positive component was distributed in variable regions, which was not consistent with the location of lesions on MRI. The peak of the negative component following the positivity was distributed in the neighbouring or opposite areas of the positive peak distribution. No changes were evident in the pre- or post-surgical distributions of the positive peak, or in the interhemispheric delay between both hemispheres, in individuals with callosotomy. Our data imply that ictal positive slow waves are the most common EEG changes during spasms associated with a massive motor component. Plausible explanations for these widespread positive slow waves include the notion that EEG changes possibly reflect involvement of both cortical and subcortical structures.

Natural sleep modifies the rat electroretinogram.

PubMed Central

Galambos, R; Juhász, G; Kékesi, A K; Nyitrai, G; Szilágyi, N

1994-01-01

We show here electroretinograms (ERGs) recorded from freely moving rats during sleep and wakefulness. Bilateral ERGs were evoked by flashes delivered through a light-emitting diode implanted under the skin above one eye and recorded through electrodes inside each orbit near the optic nerve. Additional electrodes over each visual cortex monitored the brain waves and collected flash-evoked cortical potentials to compare with the ERGs. Connections to the stimulating and recording instruments through a plug on the head made data collection possible at any time without physically disturbing the animal. The three major findings are (i) the ERG amplitude during slow-wave sleep can be 2 or more times that of the waking response; (ii) the ERG patterns in slow-wave and REM sleep are different; and (iii) the sleep-related ERG changes closely mimic those taking place at the same time in the responses evoked from the visual cortex. We conclude that the mechanisms that alter the visual cortical-evoked responses during sleep operate also and similarly at the retinal level. PMID:8197199

Soliton wave-speed management: Slowing, stopping, or reversing a solitary wave

NASA Astrophysics Data System (ADS)

Baines, Luke W. S.; Van Gorder, Robert A.

2018-06-01

While dispersion management is a well-known tool to control soliton properties such as shape or amplitude, far less effort has been directed toward the theoretical control of the soliton wave speed. However, recent experiments concerning the stopping or slowing of light demonstrate that the control of the soliton wave speed is of experimental interest. Motivated by these and other studies, we propose a management approach for modifying the wave speed of a soliton (or of other nonlinear wave solutions, such as periodic cnoidal waves) under the nonlinear Schrödinger equation. Making use of this approach, we are able to slow, stop, or even reverse a solitary wave, and we give several examples to bright solitons, dark solitons, and periodic wave trains, to demonstrate the method. An extension of the approach to spatially heterogeneous media, for which the wave may propagate differently at different spatial locations, is also discussed.

Sleep-Related Electrophysiology and Behavior of Tinamous (Eudromia elegans): Tinamous Do Not Sleep Like Ostriches.

PubMed

Tisdale, Ryan K; Vyssotski, Alexei L; Lesku, John A; Rattenborg, Niels C

2017-01-01

The functions of slow wave sleep (SWS) and rapid eye movement (REM) sleep, distinct sleep substates present in both mammals and birds, remain unresolved. One approach to gaining insight into their function is to trace the evolution of these states through examining sleep in as many taxonomic groups as possible. The mammalian and avian clades are each composed of two extant groups, i.e., the monotremes (echidna and platypus) and therian (marsupial and eutherian [or placental]) mammals, and Palaeognaths (cassowaries, emus, kiwi, ostriches, rheas, and tinamous) and Neognaths (all other birds) among birds. Previous electrophysiological studies of monotremes and ostriches have identified a unique "mixed" sleep state combining features of SWS and REM sleep unlike the well-delineated sleep states observed in all therian mammals and Neognath birds. In the platypus this state is characterized by periods of REM sleep-related myoclonic twitching, relaxed skeletal musculature, and rapid eye movements, occurring in conjunction with SWS-related slow waves in the forebrain electroencephalogram (EEG). A similar mixed state was also observed in ostriches; although in addition to occurring during periods with EEG slow waves, reduced muscle tone and rapid eye movements also occurred in conjunction with EEG activation, a pattern typical of REM sleep in Neognath birds. Collectively, these studies suggested that REM sleep occurring exclusively as an integrated state with forebrain activation might have evolved independently in the therian and Neognath lineages. To test this hypothesis, we examined sleep in the elegant crested tinamou (Eudromia elegans), a small Palaeognath bird that more closely resembles Neognath birds in size and their ability to fly. A 24-h period was scored for sleep state based on electrophysiology and behavior. Unlike ostriches, but like all of the Neognath birds examined, all indicators of REM sleep usually occurred in conjunction with forebrain activation in

Neuronal plasticity and thalamocortical sleep and waking oscillations

PubMed Central

Timofeev, Igor

2011-01-01

Throughout life, thalamocortical (TC) network alternates between activated states (wake or rapid eye movement sleep) and slow oscillatory state dominating slow-wave sleep. The patterns of neuronal firing are different during these distinct states. I propose that due to relatively regular firing, the activated states preset some steady state synaptic plasticity and that the silent periods of slow-wave sleep contribute to a release from this steady state synaptic plasticity. In this respect, I discuss how states of vigilance affect short-, mid-, and long-term synaptic plasticity, intrinsic neuronal plasticity, as well as homeostatic plasticity. Finally, I suggest that slow oscillation is intrinsic property of cortical network and brain homeostatic mechanisms are tuned to use all forms of plasticity to bring cortical network to the state of slow oscillation. However, prolonged and profound shift from this homeostatic balance could lead to development of paroxysmal hyperexcitability and seizures as in the case of brain trauma. PMID:21854960

Deepening Sleep by Hypnotic Suggestion

PubMed Central

Cordi, Maren J.; Schlarb, Angelika A.; Rasch, Björn

2014-01-01

Study Objectives: Slow wave sleep (SWS) plays a critical role in body restoration and promotes brain plasticity; however, it markedly declines across the lifespan. Despite its importance, effective tools to increase SWS are rare. Here we tested whether a hypnotic suggestion to “sleep deeper” extends the amount of SWS. Design: Within-subject, placebo-controlled crossover design. Setting: Sleep laboratory at the University of Zurich, Switzerland. Participants: Seventy healthy females 23.27 ± 3.17 y. Intervention: Participants listened to an auditory text with hypnotic suggestions or a control tape before napping for 90 min while high-density electroencephalography was recorded. Measurements and Results: After participants listened to the hypnotic suggestion to “sleep deeper” subsequent SWS was increased by 81% and time spent awake was reduced by 67% (with the amount of SWS or wake in the control condition set to 100%). Other sleep stages remained unaffected. Additionally, slow wave activity was significantly enhanced after hypnotic suggestions. During the hypnotic tape, parietal theta power increases predicted the hypnosis-induced extension of SWS. Additional experiments confirmed that the beneficial effect of hypnotic suggestions on SWS was specific to the hypnotic suggestion and did not occur in low suggestible participants. Conclusions: Our results demonstrate the effectiveness of hypnotic suggestions to specifically increase the amount and duration of slow wave sleep (SWS) in a midday nap using objective measures of sleep in young, healthy, suggestible females. Hypnotic suggestions might be a successful tool with a lower risk of adverse side effects than pharmacological treatments to extend SWS also in clinical and elderly populations. Citation: Cordi MJ, Schlarb AA, Rasch B. Deepening sleep by hypnotic suggestion. SLEEP 2014;37(6):1143-1152. PMID:24882909

Progress in Mathematical Modeling of Gastrointestinal Slow Wave Abnormalities

PubMed Central

Du, Peng; Calder, Stefan; Angeli, Timothy R.; Sathar, Shameer; Paskaranandavadivel, Niranchan; O'Grady, Gregory; Cheng, Leo K.

2018-01-01

Gastrointestinal (GI) motility is regulated in part by electrophysiological events called slow waves, which are generated by the interstitial cells of Cajal (ICC). Slow waves propagate by a process of “entrainment,” which occurs over a decreasing gradient of intrinsic frequencies in the antegrade direction across much of the GI tract. Abnormal initiation and conduction of slow waves have been demonstrated in, and linked to, a number of GI motility disorders. A range of mathematical models have been developed to study abnormal slow waves and applied to propose novel methods for non-invasive detection and therapy. This review provides a general outline of GI slow wave abnormalities and their recent classification using multi-electrode (high-resolution) mapping methods, with a particular emphasis on the spatial patterns of these abnormal activities. The recently-developed mathematical models are introduced in order of their biophysical scale from cellular to whole-organ levels. The modeling techniques, main findings from the simulations, and potential future directions arising from notable studies are discussed. PMID:29379448

Is sleep-related verbal memory consolidation impaired in sleepwalkers?

PubMed

Uguccioni, Ginevra; Pallanca, Olivier; Golmard, Jean-Louis; Leu-Semenescu, Smaranda; Arnulf, Isabelle

2015-04-01

In order to evaluate verbal memory consolidation during sleep in subjects experiencing sleepwalking or sleep terror, 19 patients experiencing sleepwalking/sleep terror and 19 controls performed two verbal memory tasks (16-word list from the Free and Cued Selective Reminding Test, and a 220- and 263-word modified story recall test) in the evening, followed by nocturnal video polysomnography (n = 29) and morning recall (night-time consolidation after 14 h, n = 38). The following morning, they were given a daytime learning task using the modified story recall test in reverse order, followed by an evening recall test after 9 h of wakefulness (daytime consolidation, n = 38). The patients experiencing sleepwalking/sleep terror exhibited more frequent awakenings during slow-wave sleep and longer wakefulness after sleep onset than the controls. Despite this reduction in sleep quality among sleepwalking/sleep terror patients, they improved their scores on the verbal tests the morning after sleep compared with the previous evening (+16 ± 33%) equally well as the controls (+2 ± 13%). The performance of both groups worsened during the daytime in the absence of sleep (-16 ± 15% for the sleepwalking/sleep terror group and -14 ± 11% for the control group). There was no significant correlation between the rate of memory consolidation and any of the sleep measures. Seven patients experiencing sleepwalking also sleep-talked during slow-wave sleep, but their sentences were unrelated to the tests or the list of words learned during the evening. In conclusion, the alteration of slow-wave sleep during sleepwalking/sleep terror does not noticeably impact on sleep-related verbal memory consolidation. © 2014 European Sleep Research Society.

The effects of slow-wave sleep (SWS) deprivation and time of night on behavioral performance upon awakening.

PubMed

Ferrara, M; De Gennaro, L; Bertini, M

The aim of the present study is to evaluate the effects of selective SWS deprivation on the motor and sensory motor performance impairment immediately after awakening from nocturnal sleep at different times of the night. Ten normal males slept for 6 consecutive nights in the laboratory: one adaptation, two baseline, two selective SWS deprivation, and one recovery night. During the last 4 nights performance was assessed four times: (a) before sleep, as a baseline measure; (b) within 30 s from the first nighttime awakening, after 2 h of sleep; (c) within 30 s from the second nighttime awakening, after 5 h of sleep; (d) within 30 s from the final morning awakening. After each awakening, following a 3-min cognitive test, a simple Auditory Reaction Time task (ART, about 5 min) and a Finger Tapping Task (FTT, 3 min) were administered. Median of Reaction Times (RT) and of Intertapping Intervals (ITI), 10% fastest RT, 10% slowest RT, and number of misses were considered as dependent variables. The selective SWS deprivation was very effective: SWS percentage during both the deprivation nights was close to zero. This strong manipulation of SWS amount interacted with time-of-night factors in influencing sleep inertia. The SWS deprivation procedure caused a worsening of behavioral performance during the deprivation nights. as well as upon the final awakening of the recovery night. Behavioral performance slowing upon awakening is accounted for by: (1) a general decrement in overall response speed (median of RT); (2) an "optimum response shift", i.e., a decrease in speed of the fastest responses; (3) an increase of lapsing, with more marked response delays resulting in a further decrease in response speed in the "lapse domain". Finally, our results do not support the existence of a circadian rhythm of sleep inertia linked to body temperature rhythm.

The Effects of Caffeine on Sleep and Maturational Markers in the Rat

PubMed Central

Olini, Nadja; Kurth, Salomé; Huber, Reto

2013-01-01

Adolescence is a critical period for brain maturation during which a massive reorganization of cortical connectivity takes place. In humans, slow wave activity (<4.5 Hz) during NREM sleep was proposed to reflect cortical maturation which relies on use-dependent processes. A stimulant like caffeine, whose consumption has recently increased especially in adolescents, is known to affect sleep wake regulation. The goal of this study was to establish a rat model allowing to assess the relationship between cortical maturation and sleep and to further investigate how these parameters are affected by caffeine consumption. To do so, we assessed sleep and markers of maturation by electrophysiological recordings, behavioral and structural readouts in the juvenile rat. Our results show that sleep slow wave activity follows a similar inverted U-shape trajectory as already known in humans. Caffeine treatment exerted short-term stimulating effects and altered the trajectory of slow wave activity. Moreover, caffeine affected behavioral and structural markers of maturation. Thus, caffeine consumption during a critical developmental period shows long lasting effects on sleep and brain maturation. PMID:24023748

Insufficient non-REM sleep intensity in narcolepsy-cataplexy.

PubMed

Khatami, Ramin; Landolt, Hans-Peter; Achermann, Peter; Rétey, Julia V; Werth, Esther; Mathis, Johannes; Bassetti, Claudio L

2007-08-01

To compare electroencephalogram (EEG) dynamics during nocturnal sleep in patients with narcolepsy-cataplexy and healthy controls. Fragmented nocturnal sleep is a prominent feature and contributes to excessive daytime sleepiness in narcolepsy-cataplexy. Only 3 studies have addressed changes in homeostatic sleep regulation as a possible mechanism underlying nocturnal sleep fragmentation in narcolepsy-cataplexy. Baseline sleep of 11 drug-naive patients with narcolepsy-cataplexy (19-37 years) and 11 matched controls (18-41 years) was polysomnographically recorded. The EEG was subjected to spectral analysis. None, baseline condition. All patients with narcolepsy-cataplexy but no control subjects showed a sleep-onset rapid eye movement (REM) episode. Non-REM (NREM)-REM sleep cycles were longer in patients with narcolepsy-cataplexy than in controls (P = 0.04). Mean slow-wave activity declined in both groups across the first 3 NREM sleep episodes (P<0.001). The rate of decline, however, appeared to be steeper in patients with narcolepsy-cataplexy (time constant: narcolepsy-cataplexy 51.1 +/- 23.8 minutes [mean +/- SEM], 95% confidence interval [CI]: 33.4-108.8 minutes) than in controls (169.4 +/- 81.5 minutes, 95% CI: 110.9-357.6 minutes) as concluded from nonoverlapping 95% confidence interval of the time constants. The steeper decline of SWA in narcolepsy-cataplexy compared to controls was related to an impaired build-up of slow-wave activity in the second cycle. Sleep in the second cycle was interrupted in patients with narcolepsy-cataplexy, when compared with controls, by an increased number (P = 0.01) and longer duration (P = 0.01) of short wake episodes. Insufficient NREM sleep intensity is associated with nonconsolidated nocturnal sleep in narcolepsy-cataplexy. The inability to consolidate sleep manifests itself when NREM sleep intensity has decayed below a certain level and is reflected in an altered time course of slow-wave activity across NREM sleep episodes.

Cognitive neuroscience. Unlearning implicit social biases during sleep.

PubMed

Hu, Xiaoqing; Antony, James W; Creery, Jessica D; Vargas, Iliana M; Bodenhausen, Galen V; Paller, Ken A

2015-05-29

Although people may endorse egalitarianism and tolerance, social biases can remain operative and drive harmful actions in an unconscious manner. Here, we investigated training to reduce implicit racial and gender bias. Forty participants processed counterstereotype information paired with one sound for each type of bias. Biases were reduced immediately after training. During subsequent slow-wave sleep, one sound was unobtrusively presented to each participant, repeatedly, to reactivate one type of training. Corresponding bias reductions were fortified in comparison with the social bias not externally reactivated during sleep. This advantage remained 1 week later, the magnitude of which was associated with time in slow-wave and rapid-eye-movement sleep after training. We conclude that memory reactivation during sleep enhances counterstereotype training and that maintaining a bias reduction is sleep-dependent. Copyright © 2015, American Association for the Advancement of Science.

Prevalence and Correlates of Alpha-Delta Sleep in Major Depressive Disorders

PubMed Central

Jaimchariyatam, Nattapong; Rodriguez, Carlos L.

2011-01-01

Objective. Major depressive disorder is associated with sleep disturbances. An electroencephalographic pattern of alpha wave intrusion in delta wave sleep (alpha-delta sleep) is observed in some subjects with major depressive disorder. The treatment-resistant symptoms in major depressive disorder, nonrestorative sleep and fatigue, are associated with alpha-delta sleep. The objective of this study is to identify the prevalence and clinical correlates of alpha-delta sleep in major depressive disorder. Design. Retrospective study Setting. Sleep Disorders Center, Cleveland Clinic, Cleveland, Ohio Participants. Polysomnograms were conducted on 150 subjects 18 years of age or older (75 with and 75 without major depressive disorder) were reviewed. Measurements. The percent of delta waves with alpha intrusion was collected and analyzed. Results. Subjects with major depressive disorder compared to nondepressed subjects had a higher sleep efficiency (83.0±9.6; 78.1±8.2%), shorter rapid eye movement latency (85.0±44.5; 189.9±25.6 min), less slow wave sleep (8.3±3.0; 13.5±6.2%), and greater rapid eye movement (24.7±7.0; 19.2±8.2%), and all of these findings were statistically significant. Patients with major depressive disorder had higher alpha-delta sleep (23.4±14.2%; 2.3±6.7%, p<0.01). Patients with major depressive disorder were categorized into high and low alpha-delta sleep based on percentage of alpha-delta sleep present in slow wave sleep (alpha-delta sleep was present ≥15% or ≤15% of slow wave sleep, respectively). Patients with major depressive disorder with high alpha-delta sleep were at 3.15 greater odds (1.22–8.14; p=0.018) to have excessive daytime sleepiness. Conclusion. Patients with major depressive disorder have a higher prevalence of alpha-delta sleep. Alpha-delta sleep is associated with daytime sleepiness in patients with major depressive disorder. Study limitations include the retrospective nature of the project and the fact that the

Sleep effects on slow-brain-potential reflections of associative learning.

PubMed

Verleger, Rolf; Ludwig, Janna; Kolev, Vasil; Yordanova, Juliana; Wagner, Ullrich

2011-03-01

Previous research has indicated that information acquired before sleep gets consolidated during sleep. This process of consolidation might be reflected after sleep in changed extent and topography of cortical activation during retrieval of information. Here, we designed an experiment to measure those changes by means of slow event-related EEG potentials (SPs). Retrieval of newly learnt verbal or spatial associations was tested both immediately after learning and two days later. In the night directly following immediate recall, participants either slept or stayed awake. In line with previous studies, SPs measured during retrieval from memory had parietal or left-frontal foci depending on whether the retrieved associations were spatial or verbal. However, contrary to our expectations, sleep-related consolidation did not further accentuate these content-specific topographic profiles. Rather, sleep modified SPs independently of the spatial or verbal type of learned association: SPs were reduced more after sleep than after waking specifically for those stimulus configurations that had been presented in the same combination at retrieval before sleep. The association-independent stimulus-specific effect might generally form a major component of sleep-related effects on memory. Copyright © 2010 Elsevier B.V. All rights reserved.

Reverberation, Storage, and Postsynaptic Propagation of Memories during Sleep

ERIC Educational Resources Information Center

Ribeiro, Sidarta; Nicolelis, Miguel A. L.

2004-01-01

In mammals and birds, long episodes of nondreaming sleep ("slow-wave" sleep, SW) are followed by short episodes of dreaming sleep ("rapid-eye-movement" sleep, REM). Both SW and REM sleep have been shown to be important for the consolidation of newly acquired memories, but the underlying mechanisms remain elusive. Here we review…

Global Intracellular Slow-Wave Dynamics of the Thalamocortical System

PubMed Central

Sheroziya, Maxim

2014-01-01

It is widely accepted that corticothalamic neurons recruit the thalamus in slow oscillation, but global slow-wave thalamocortical dynamics have never been experimentally shown. We analyzed intracellular activities of neurons either from different cortical areas or from a variety of specific and nonspecific thalamic nuclei in relation to the phase of global EEG signal in ketamine-xylazine anesthetized mice. We found that, on average, slow-wave active states started off within frontal cortical areas as well as higher-order and intralaminar thalamus (posterior and parafascicular nuclei) simultaneously. Then, the leading edge of active states propagated in the anteroposterior/lateral direction over the cortex at ∼40 mm/s. The latest structure we recorded within the slow-wave cycle was the anterior thalamus, which followed active states of the retrosplenial cortex. Active states from different cortical areas tended to terminate simultaneously. Sensory thalamic ventral posterior medial and lateral geniculate nuclei followed cortical active states with major inhibitory and weak tonic-like “modulator” EPSPs. In these nuclei, sharp-rising, large-amplitude EPSPs (“drivers”) were not modulated by cortical slow waves, suggesting their origin in ascending pathways. The thalamic active states in other investigated nuclei were composed of depolarization: some revealing “driver”- and “modulator”-like EPSPs, others showing “modulator”-like EPSPs only. We conclude that sensory thalamic nuclei follow the propagating cortical waves, whereas neurons from higher-order thalamic nuclei display “hub dynamics” and thus may contribute to the generation of cortical slow waves. PMID:24966387

Relationship of slow and rapid EEG components of CAP to ASDA arousals in normal sleep.

PubMed

Parrino, L; Smerieri, A; Rossi, M; Terzano, M G

2001-12-15

Besides arousals (according to the ASDA definition), sleep contains also K-complexes and delta bursts which, in spite of their sleep-like features, are endowed with activating effects on autonomic functions. The link between phasic delta activities and enhancement of vegetative functions indicates the possibility of physiological activation without sleep disruption (i.e., arousal without awakening). A functional connection seems to include slow (K-complexes and delta bursts) and rapid (arousals) EEG events within the comprehensive term of activating complexes. CAP (cyclic alternating pattern) is the spontaneous EEG rhythm that ties both slow and rapid activating complexes together during NREM sleep. The present study aims at exploring the relationship between arousals and CAP components in a selected sample of healthy sleepers. Polysomnographic analysis according to the scoring rules for sleep stages and arousals. CAP analysis included also tabulation of subtypes A1 (slow EEG activating complexes), A2 and A3 (activating complexes with fast EEG components). 40 sleep-lab accomplished recordings. Healthy subjects belonging to a wide age range (38 +/- 20 yrs.). N/A. Of all the arousals occurring in NREM sleep, 87% were inserted within CAP. Subtypes A2 and A3 of CAP corresponded strikingly with arousals (r=0.843; p<0.0001), while no statistical relationship emerged when arousals were matched with subtypes A1 of CAP. Subtypes A1 instead correlated positively with the percentages of deep sleep (r=0.366; p<0.02). The CAP subtype classification encompasses both the process of sleep maintenance (subtypes A1) and sleep fragmentation (subtypes A2 and A3), and provides a periodicity dimension to the activating events of NREM sleep.

Synchronization Properties of Slow Cortical Oscillations

NASA Astrophysics Data System (ADS)

Takekawa, T.; Aoyagi, T.; Fukai, T.

During slow-wave sleep, the brain shows slow oscillatory activity with remarkable long-range synchrony. Intracellular recordings show that the slow oscillation consists of two phases: an textit{up} state and a textit{down} state. Deriving the phase-response function of simplified neuronal systems, we examine the synchronization properties on slow oscillations between the textit{up} state and the textit{down} state. As a result, the strange interaction functions are found in some parameter ranges. These functions indicate that the states with the smaller phase lag than a critical value are all stable.

Light sleep versus slow wave sleep in memory consolidation: a question of global versus local processes?

PubMed

Genzel, Lisa; Kroes, Marijn C W; Dresler, Martin; Battaglia, Francesco P

2014-01-01

Sleep is strongly involved in memory consolidation, but its role remains unclear. 'Sleep replay', the active potentiation of relevant synaptic connections via reactivation of patterns of network activity that occurred during previous experience, has received considerable attention. Alternatively, sleep has been suggested to regulate synaptic weights homeostatically and nonspecifically, thereby improving the signal:noise ratio of memory traces. Here, we reconcile these theories by highlighting the distinction between light and deep nonrapid eye movement (NREM) sleep. Specifically, we draw on recent studies to suggest a link between light NREM and active potentiation, and between deep NREM and homeostatic regulation. This framework could serve as a key for interpreting the physiology of sleep stages and reconciling inconsistencies in terminology in this field. Copyright © 2013 Elsevier Ltd. All rights reserved.

Circadian Gene Variants Influence Sleep and the Sleep Electroencephalogram in Humans

PubMed Central

Chang, Anne-Marie; Bjonnes, Andrew; Aeschbach, Daniel; Buxton, Orfeu M.; Gooley, Joshua J.; Anderson, Clare; Van Reen, Eliza; Cain, Sean W.; Czeisler, Charles A.; Duffy, Jeanne F.; Lockley, Steven W.; Shea, Steven; Scheer, Frank A.J.L.; Saxena, Richa

2017-01-01

The sleep electroencephalogram is highly heritable in humans and yet little is known about the genetic basis of inter-individual differences in sleep architecture. The aim of this study was to identify associations between candidate circadian gene variants and the polysomnogram, recorded under highly controlled laboratory conditions during a baseline, overnight, 8-h sleep opportunity. A candidate gene approach was employed to analyze single nucleotide polymorphisms from five circadian-related genes in a two-phase analysis of 84 healthy young adults (28 F; 23.21 ± 2.97 years) of European ancestry. A common variant in Period2 (PER2) was associated with 20 minutes less slow wave sleep (SWS) in carriers of the minor allele than in non-carriers, representing a 22% difference in SWS duration. Moreover, spectral analysis in a subset of samples (n=37), showed the same PER2 polymorphism was associated with reduced EEG power density in the low delta range (0.25–1.0 Hz) during non-REM sleep and lower slow-wave activity (0.75–4.5 Hz) in the early part of the sleep episode. These results indicate the involvement of PER2 in the homeostatic process of sleep. Additionally, a rare variant in Melatonin Receptor 1B was associated with longer REM sleep latency, with minor allele carriers exhibiting an average of 65 minutes (87%) longer latency from sleep onset to REM sleep, compared to non-carriers. These findings suggest that circadian-related genes may modulate sleep architecture and the sleep EEG, including specific parameters previously implicated in the homeostatic regulation of sleep. PMID:27089043

Prefrontal atrophy, disrupted NREM slow waves, and impaired hippocampal-dependent memory in aging

PubMed Central

Mander, Bryce A.; Rao, Vikram; Lu, Brandon; Saletin, Jared M.; Lindquist, John R.; Ancoli-Israel, Sonia; Jagust, William; Walker, Matthew P.

2014-01-01

Aging has independently been associated with regional brain atrophy, reduced non-rapid eye movement (NREM) slow-wave activity (SWA), and impaired long-term retention of episodic memories. However, that the interaction of these factors represents a neuropatholgical pathway associated with cognitive decline in later life remains unknown. Here, we show that age-related medial prefrontal cortex (mPFC) grey-matter atrophy is associated with reduced NREM SWA activity in older adults, the extent to which statistically mediates the impairment of overnight sleep-dependent memory retention. Moreover, this memory impairment was further associated with persistent hippocampal activation and reduced task-related hippocampal-prefrontal cortex connectivity, potentially representing impoverished hippocampal-neocortical memory transformation. Together, these data support a model in which age-related mPFC atrophy diminishes SWA, the functional consequence of which is impaired long-term memory. Such findings suggest that sleep disruption in the elderly, mediated by structural brain changes, represent a novel contributing factor to age-related cognitive decline in later life. PMID:23354332

β-amyloid disrupts human NREM slow waves and related hippocampus-dependent memory consolidation

PubMed Central

Mander, Bryce A.; Marks, Shawn M.; Vogel, Jacob W.; Rao, Vikram; Lu, Brandon; Saletin, Jared M.; Ancoli-Israel, Sonia; Jagust, William J.; Walker, Matthew P.

2015-01-01

Independent evidence associates β-amyloid pathology with both NREM sleep disruption and memory impairment in older adults. However, whether the influence of β-amyloid pathology on hippocampus-dependent memory is, in part, driven by impairments of NREM slow wave activity (SWA) and associated overnight memory consolidation is unknown. Here, we show that β-amyloid burden within medial prefrontal cortex (mPFC) is significantly correlated with the severity of impairment in NREM SWA generation. Moreover, reduced NREM SWA generation was further associated with impaired overnight memory consolidation and impoverished hippocampal-neocortical memory transformation. Furthermore, structural equation models revealed that the association between mPFC β-amyloid pathology and impaired hippocampus-dependent memory consolidation is not direct, but instead, statistically depends on the intermediary factor of diminished NREM SWA. By linking β-amyloid pathology with impaired NREM SWA, these data implicate sleep disruption as a novel mechanistic pathway through which β-amyloid pathology may contribute to hippocampus-dependent cognitive decline in the elderly. PMID:26030850

Reduction of nocturnal slow-wave activity affects daytime vigilance lapses and memory encoding but not reaction time or implicit learning.

PubMed

Van Der Werf, Ysbrand D; Altena, Ellemarije; Vis, José C; Koene, Teddy; Van Someren, Eus J W

2011-01-01

Total sleep deprivation in healthy subjects has a profound effect on the performance on tasks measuring sustained attention or vigilance. We here report how a selective disruption of deep sleep only, that is, selective slow-wave activity (SWA) reduction, affects the performance of healthy well-sleeping subjects on several tasks: a "simple" and a "complex" vigilance task, a declarative learning task, and an implicit learning task despite unchanged duration of sleep. We used automated electroencephalogram (EEG) dependent acoustic feedback aimed at selective interference with-and reduction of-SWA. In a within-subject repeated measures crossover design, performance on the tasks was assessed in 13 elderly adults without sleep complaints after either SWA-reduction or after normal sleep. The number of vigilance lapses increased as a result of SWA reduction, irrespective of the type of vigilance task. Recognition on the declarative memory task was also affected by SWA reduction, associated with a decreased activation of the right hippocampus on encoding (measured with fMRI) suggesting a weaker memory trace. SWA reduction, however, did not affect reaction time on either of the vigilance tasks or implicit memory task performance. These findings suggest a specific role of slow oscillations in the subsequent daytime ability to maintain sustained attention and to encode novel declarative information but not to maintain response speed or to build implicit memories. Of particular interest is that selective SWA reduction can mimic some of the effects of total sleep deprivation, while not affecting sleep duration. Copyright © 2011 Elsevier B.V. All rights reserved.

Non-REM sleep EEG power distribution in fatigue and sleepiness.

PubMed

Neu, Daniel; Mairesse, Olivier; Verbanck, Paul; Linkowski, Paul; Le Bon, Olivier

2014-04-01

The aim of this study is to contribute to the sleep-related differentiation between daytime fatigue and sleepiness. 135 subjects presenting with sleep apnea-hypopnea syndrome (SAHS, n=58) or chronic fatigue syndrome (CFS, n=52) with respective sleepiness or fatigue complaints and a control group (n=25) underwent polysomnography and psychometric assessments for fatigue, sleepiness, affective symptoms and perceived sleep quality. Sleep EEG spectral analysis for ultra slow, delta, theta, alpha, sigma and beta power bands was performed on frontal, central and occipital derivations. Patient groups presented with impaired subjective sleep quality and higher affective symptom intensity. CFS patients presented with highest fatigue and SAHS patients with highest sleepiness levels. All groups showed similar total sleep time. Subject groups mainly differed in sleep efficiency, wake after sleep onset, duration of light sleep (N1, N2) and slow wave sleep, as well as in sleep fragmentation and respiratory disturbance. Relative non-REM sleep power spectra distributions suggest a pattern of power exchange in higher frequency bands at the expense of central ultra slow power in CFS patients during all non-REM stages. In SAHS patients, however, we found an opposite pattern at occipital sites during N1 and N2. Slow wave activity presents as a crossroad of fatigue and sleepiness with, however, different spectral power band distributions during non-REM sleep. The homeostatic function of sleep might be compromised in CFS patients and could explain why, in contrast to sleepiness, fatigue does not resolve with sleep in these patients. The present findings thus contribute to the differentiation of both phenomena. Copyright © 2014 Elsevier Inc. All rights reserved.

Sleep in the domestic hen (Gallus domesticus).

PubMed

van Luijtelaar, E L; van der Grinten, C P; Blokhuis, H J; Coenen, A M

1987-01-01

Electrophysiological recordings were made of five closely observed hens, all permanently implanted with both EEG and EMG electrodes. Five behavioural postures were distinguished and percentages of wakefulness, sleep and presumably paradoxical sleep (PS) were determined during the third and sixth hour of the dark period. Substantial agreement was generally found between behaviour and sleep with the exception of sitting or standing motionless with at least one eye open. During two thirds of this behavioural posture, the EEG showed large amplitude slow waves undistinguishable from slow wave sleep. Characteristics of PS were determined: periods were short, whereas its percentage increased during the night. Furthermore, EMG atonia was never found. An all night recording was made, and delta activity (2-5 Hz) was filtered and plotted against time for three of the hens. A significant decrease in delta activity across the night was found. Differences and similarities between sleep in hens and in mammals are discussed. Although large similarities exist it is concluded that some properties of birds' sleep make it unique and are a challenge for further study.

GABA(B) receptors, schizophrenia and sleep dysfunction: a review of the relationship and its potential clinical and therapeutic implications.

PubMed

Kantrowitz, Joshua; Citrome, Leslie; Javitt, Daniel

2009-08-01

Evidence for an intrinsic relationship between sleep, cognition and the symptomatic manifestations of schizophrenia is accumulating. This review presents evidence for the possible utility of GABA(B) receptor agonists for the treatment of subjective and objective sleep abnormalities related to schizophrenia. At the phenotypic level, sleep disturbance occurs in 16-30% of patients with schizophrenia and is related to reduced quality of life and poor coping skills. On the neurophysiological level, studies suggest that sleep deficits reflect a core component of schizophrenia. Specifically, slow-wave sleep deficits, which are inversely correlated with cognition scores, are seen. Moreover, sleep plays an increasingly well documented role in memory consolidation in schizophrenia. Correlations of slow-wave sleep deficits with impaired reaction time and declarative memory have also been reported. Thus, both behavioural insomnia and sleep architecture are critical therapeutic targets in patients with schizophrenia. However, long-term treatment with antipsychotics often results in residual sleep dysfunction and does not improve slow-wave sleep, and adjunctive GABA(A) receptor modulators, such as benzodiazepines and zolpidem, can impair sleep architecture and cognition in schizophrenia. GABA(B) receptor agonists have therapeutic potential in schizophrenia. These agents have minimal effect on rapid eye movement sleep while increasing slow-wave sleep. Preclinical associations with increased expression of genes related to slow-wave sleep production and circadian rhythm function have also been reported. GABA(B) receptor deficits result in a sustained hyperdopaminergic state and can be reversed by a GABA(B) receptor agonist. Genetic, postmortem and electrophysiological studies also associate GABA(B) receptors with schizophrenia. While studies thus far have not shown significant effects, prior focus on the use of GABA(B) receptor agonists has been on the positive symptoms of

Sleep for cognitive enhancement.

PubMed

Diekelmann, Susanne

2014-01-01

Sleep is essential for effective cognitive functioning. Loosing even a few hours of sleep can have detrimental effects on a wide variety of cognitive processes such as attention, language, reasoning, decision making, learning and memory. While sleep is necessary to ensure normal healthy cognitive functioning, it can also enhance performance beyond the boundaries of the normal condition. This article discusses the enhancing potential of sleep, mainly focusing on the domain of learning and memory. Sleep is known to facilitate the consolidation of memories learned before sleep as well as the acquisition of new memories to be learned after sleep. According to a widely held model this beneficial effect of sleep relies on the neuronal reactivation of memories during sleep that is associated with sleep-specific brain oscillations (slow oscillations, spindles, ripples) as well as a characteristic neurotransmitter milieu. Recent research indicates that memory processing during sleep can be boosted by (i) cueing memory reactivation during sleep; (ii) stimulating sleep-specific brain oscillations; and (iii) targeting specific neurotransmitter systems pharmacologically. Olfactory and auditory cues can be used, for example, to increase reactivation of associated memories during post-learning sleep. Intensifying neocortical slow oscillations (the hallmark of slow wave sleep (SWS)) by electrical or auditory stimulation and modulating specific neurotransmitters such as noradrenaline and glutamate likewise facilitates memory processing during sleep. With this evidence in mind, this article concludes by discussing different methodological caveats and ethical issues that should be considered when thinking about using sleep for cognitive enhancement in everyday applications.

Sleep for cognitive enhancement

PubMed Central

Diekelmann, Susanne

2014-01-01

Sleep is essential for effective cognitive functioning. Loosing even a few hours of sleep can have detrimental effects on a wide variety of cognitive processes such as attention, language, reasoning, decision making, learning and memory. While sleep is necessary to ensure normal healthy cognitive functioning, it can also enhance performance beyond the boundaries of the normal condition. This article discusses the enhancing potential of sleep, mainly focusing on the domain of learning and memory. Sleep is known to facilitate the consolidation of memories learned before sleep as well as the acquisition of new memories to be learned after sleep. According to a widely held model this beneficial effect of sleep relies on the neuronal reactivation of memories during sleep that is associated with sleep-specific brain oscillations (slow oscillations, spindles, ripples) as well as a characteristic neurotransmitter milieu. Recent research indicates that memory processing during sleep can be boosted by (i) cueing memory reactivation during sleep; (ii) stimulating sleep-specific brain oscillations; and (iii) targeting specific neurotransmitter systems pharmacologically. Olfactory and auditory cues can be used, for example, to increase reactivation of associated memories during post-learning sleep. Intensifying neocortical slow oscillations (the hallmark of slow wave sleep (SWS)) by electrical or auditory stimulation and modulating specific neurotransmitters such as noradrenaline and glutamate likewise facilitates memory processing during sleep. With this evidence in mind, this article concludes by discussing different methodological caveats and ethical issues that should be considered when thinking about using sleep for cognitive enhancement in everyday applications. PMID:24765066

Slow oscillation amplitudes and up-state lengths relate to memory improvement.

PubMed

Heib, Dominik P J; Hoedlmoser, Kerstin; Anderer, Peter; Zeitlhofer, Josef; Gruber, Georg; Klimesch, Wolfgang; Schabus, Manuel

2013-01-01

There is growing evidence of the active involvement of sleep in memory consolidation. Besides hippocampal sharp wave-ripple complexes and sleep spindles, slow oscillations appear to play a key role in the process of sleep-associated memory consolidation. Furthermore, slow oscillation amplitude and spectral power increase during the night after learning declarative and procedural memory tasks. However, it is unresolved whether learning-induced changes specifically alter characteristics of individual slow oscillations, such as the slow oscillation up-state length and amplitude, which are believed to be important for neuronal replay. 24 subjects (12 men) aged between 20 and 30 years participated in a randomized, within-subject, multicenter study. Subjects slept on three occasions for a whole night in the sleep laboratory with full polysomnography. Whereas the first night only served for adaptation purposes, the two remaining nights were preceded by a declarative word-pair task or by a non-learning control task. Slow oscillations were detected in non-rapid eye movement sleep over electrode Fz. Results indicate positive correlations between the length of the up-state as well as the amplitude of both slow oscillation phases and changes in memory performance from pre to post sleep. We speculate that the prolonged slow oscillation up-state length might extend the timeframe for the transfer of initial hippocampal to long-term cortical memory representations, whereas the increase in slow oscillation amplitudes possibly reflects changes in the net synaptic strength of cortical networks.

Cortex-wide BOLD fMRI activity reflects locally-recorded slow oscillation-associated calcium waves.

PubMed

Schwalm, Miriam; Schmid, Florian; Wachsmuth, Lydia; Backhaus, Hendrik; Kronfeld, Andrea; Aedo Jury, Felipe; Prouvot, Pierre-Hugues; Fois, Consuelo; Albers, Franziska; van Alst, Timo; Faber, Cornelius; Stroh, Albrecht

2017-09-15

Spontaneous slow oscillation-associated slow wave activity represents an internally generated state which is characterized by alternations of network quiescence and stereotypical episodes of neuronal activity - slow wave events. However, it remains unclear which macroscopic signal is related to these active periods of the slow wave rhythm. We used optic fiber-based calcium recordings of local neural populations in cortex and thalamus to detect neurophysiologically defined slow calcium waves in isoflurane anesthetized rats. The individual slow wave events were used for an event-related analysis of simultaneously acquired whole-brain BOLD fMRI. We identified BOLD responses directly related to onsets of slow calcium waves, revealing a cortex-wide BOLD correlate: the entire cortex was engaged in this specific type of slow wave activity. These findings demonstrate a direct relation of defined neurophysiological events to a specific BOLD activity pattern and were confirmed for ongoing slow wave activity by independent component and seed-based analyses.

Cortex-wide BOLD fMRI activity reflects locally-recorded slow oscillation-associated calcium waves

PubMed Central

Backhaus, Hendrik; Kronfeld, Andrea; Aedo Jury, Felipe; Prouvot, Pierre-Hugues; Fois, Consuelo; Albers, Franziska; van Alst, Timo

2017-01-01

Spontaneous slow oscillation-associated slow wave activity represents an internally generated state which is characterized by alternations of network quiescence and stereotypical episodes of neuronal activity - slow wave events. However, it remains unclear which macroscopic signal is related to these active periods of the slow wave rhythm. We used optic fiber-based calcium recordings of local neural populations in cortex and thalamus to detect neurophysiologically defined slow calcium waves in isoflurane anesthetized rats. The individual slow wave events were used for an event-related analysis of simultaneously acquired whole-brain BOLD fMRI. We identified BOLD responses directly related to onsets of slow calcium waves, revealing a cortex-wide BOLD correlate: the entire cortex was engaged in this specific type of slow wave activity. These findings demonstrate a direct relation of defined neurophysiological events to a specific BOLD activity pattern and were confirmed for ongoing slow wave activity by independent component and seed-based analyses. PMID:28914607

The Role of Sleep in Changing Our Minds: A Psychologist's Discussion of Papers on Memory Reactivation and Consolidation in Sleep

ERIC Educational Resources Information Center

Cartwright, Rosalind D.

2004-01-01

The group of papers on memory reactivation and consolidation during sleep included in this volume represents cutting edge work in both animals and humans. They support that the two types of sleep serve different necessary functions. The role of slow wave sleep (SWS) is reactivation of the hippocampal-neocortical circuits activated during a waking…

Slow Magnetosonic Waves and Fast Flows in Active Region Loops

NASA Technical Reports Server (NTRS)

Ofman, L.; Wang, T. J.; Davila, J. M.

2012-01-01

Recent extreme ultraviolet spectroscopic observations indicate that slow magnetosonic waves are present in active region (AR) loops. Some of the spectral data were also interpreted as evidence of fast (approx 100-300 km/s) quasiperiodic flows. We have performed three-dimensional magnetohydrodynamic (3D MHD) modeling of a bipolar AR that contains impulsively generated waves and flows in coronal loops. The model AR is initiated with a dipole magnetic field and gravitationally stratified density, with an upflow-driven steadily or periodically in localized regions at the footpoints of magnetic loops. The resulting flows along the magnetic field lines of the AR produce higher density loops compared to the surrounding plasma by injection of material into the flux tubes and the establishment of siphon flow.We find that the impulsive onset of flows with subsonic speeds result in the excitation of damped slow magnetosonic waves that propagate along the loops and coupled nonlinearly driven fast-mode waves. The phase speed of the slow magnetosonic waves is close to the coronal sound speed. When the amplitude of the driving pulses is increased we find that slow shock-like wave trains are produced. When the upflows are driven periodically, undamped oscillations are produced with periods determined by the periodicity of the upflows. Based on the results of the 3D MHD model we suggest that the observed slow magnetosonic waves and persistent upflows may be produced by the same impulsive events at the bases of ARs.

The Nucleus Reuniens Controls Long-Range Hippocampo-Prefrontal Gamma Synchronization during Slow Oscillations.

PubMed

Ferraris, Maëva; Ghestem, Antoine; Vicente, Ana F; Nallet-Khosrofian, Lauriane; Bernard, Christophe; Quilichini, Pascale P

2018-03-21

Gamma oscillations are involved in long-range coupling of distant regions that support various cognitive operations. Here we show in adult male rats that synchronized bursts of gamma oscillations bind the hippocampus (HPC) and prefrontal cortex (mPFC) during slow oscillations and slow-wave sleep, a brain state that is central for consolidation of memory traces. These gamma bursts entrained the firing of the local HPC and mPFC neuronal populations. Neurons of the nucleus reuniens (NR), which is a structural and functional hub between HPC and mPFC, demonstrated a specific increase in their firing before gamma burst onset, suggesting their involvement in HPC-mPFC binding. Chemical inactivation of NR disrupted the temporal pattern of gamma bursts and their synchronization, as well as mPFC neuronal firing. We propose that the NR drives long-range hippocampo-prefrontal coupling via gamma bursts providing temporal windows for information exchange between the HPC and mPFC during slow-wave sleep. SIGNIFICANCE STATEMENT Long-range coupling between hippocampus (HPC) and prefrontal cortex (mPFC) is believed to support numerous cognitive functions, including memory consolidation occurring during sleep. Gamma-band synchronization is a fundamental process in many neuronal operations and is instrumental in long-range coupling. Recent evidence highlights the role of nucleus reuniens (NR) in consolidation; however, how it influences hippocampo-prefrontal coupling is unknown. In this study, we show that HPC and mPFC are synchronized by gamma bursts during slow oscillations in anesthesia and natural sleep. By manipulating and recording the NR-HPC-mPFC network, we provide evidence that the NR actively promotes this long-range gamma coupling. This coupling provides the hippocampo-prefrontal circuit with a novel mechanism to exchange information during slow-wave sleep. Copyright © 2018 the authors 0270-6474/18/383026-13$15.00/0.

Sleep reduces false memory in healthy older adults.

PubMed

Lo, June C; Sim, Sam K Y; Chee, Michael W L

2014-04-01

To investigate the effects of post-learning sleep and sleep architecture on false memory in healthy older adults. Balanced, crossover design. False memory was induced using the Deese-Roediger-McDermott (DRM) paradigm and assessed following nocturnal sleep and following a period of daytime wakefulness. Post-learning sleep structure was evaluated using polysomnography (PSG). Sleep research laboratory. Fourteen healthy older adults from the Singapore-Longitudinal Aging Brain Study (mean age ± standard deviation = 66.6 ± 4.1 y; 7 males). At encoding, participants studied lists of words that were semantically related to non-presented critical lures. At retrieval, they made "remember"/"know" and "new" judgments. Compared to wakefulness, post-learning sleep was associated with reduced "remember" responses, but not "know" responses to critical lures. In contrast, there were no significant differences in the veridical recognition of studied words, false recognition of unrelated distractors, discriminability, or response bias between the sleep and the wake conditions. More post-learning slow wave sleep was associated with greater reduction in false memory. In healthy older adults, sleep facilitates the reduction in false memory without affecting veridical memory. This benefit correlates with the amount of slow wave sleep in the post-learning sleep episode.

A KCNQ2 E515D mutation associated with benign familial neonatal seizures and continuous spike and waves during slow-wave sleep syndrome in Taiwan.

PubMed

Lee, Inn-Chi; Yang, Jiann-Jou; Li, Shuan-Yow

2017-09-01

Pediatric epilepsy caused by a KCNQ2 gene mutation usually manifests as benign familial neonatal seizures (BFNS) during the 1 st week of life. However, the exact mechanism, phenotype, and genotype of the KCNQ2 mutation are unclear. We studied the KCNQ2 genotype from 75 nonconsanguineous patients with childhood epilepsy without an identified cause (age range: from 2 days to 18 years) and from 55 healthy adult controls without epilepsy. KCNQ2 mutation variants were transfected into HEK293 cells to investigate what functional changes they induced. Four (5%) of the patients had the E515D KCNQ2 mutation, which the computer-based PolyPhen algorithm predicted to be deleterious. Their seizure outcomes were favorable, but three had an intellectual disability. Two patients with E515D presented with continuous spikes and waves during slow-wave sleep (CSWS), and the other two presented with BFNS. We also analyzed 10 affected family members with the same KCNQ2 mutation: all had epilepsy (8 had BFNS and 2 had CSWS). A functional analysis showed that the recordings of the E515D currents were significantly different (p<0.05), which suggested that channels with KCNQ2 E515D variants are less sensitive to voltage and require stronger depolarization to reach opening probabilities than those with the wild type or N780T (a benign polymorphism). KCNQ2 mutations can cause various phenotypes in children: they lead to BFNS and CSWS. We hypothesize that patients with the KCNQ2 E515D mutation are susceptible to seizures. Copyright © 2016. Published by Elsevier B.V.

Sleep, Torpor and Memory Impairment

NASA Astrophysics Data System (ADS)

Palchykova, S.; Tobler, I.

It is now well known that daily torpor induces a sleep deficit. Djungarian hamsters emerging from this hypometabolic state spend most of the time in sleep. This sleep is characterized by high initial values of EEG slow-wave activity (SWA) that monotonically decline during recovery sleep. These features resemble the changes seen in numerous species during recovery after prolonged wakefulness or sleep deprivation (SD). When hamsters are totally or partially sleep deprived immediately after emerging from torpor, an additional increase in SWA can be induced. It has been therefore postulated, that these slow- waves are homeostatically regulated, as predicted by the two-process model of sleep regulation, and that during daily torpor a sleep deficit is accumulated as it is during prolonged waking. The predominance of SWA in the frontal EEG observed both after SD and daily torpor provides further evidence for the similarity of these conditions. It has been shown in several animal and human studies that sleep can enhance memory consolidation, and that SD leads to memory impairment. Preliminary data obtained in the Djungarian hamster showed that both SD and daily torpor result in object recognition deficits. Thus, animals subjected to SD immediately after learning, or if they underwent an episode of daily torpor between learning and retention, displayed impaired recognition memory for complex object scenes. The investigation of daily torpor can reveal mechanisms that could have important implications for hypometabolic state induction in other mammalian species, including humans.

Insights into sleep's role for insight: Studies with the number reduction task

PubMed Central

Verleger, Rolf; Rose, Michael; Wagner, Ullrich; Yordanova, Juliana; Kolev, Vasil

2013-01-01

In recent years, vibrant research has developed on “consolidation” during sleep: To what extent are newly experienced impressions reprocessed or even restructured during sleep? We used the number reduction task (NRT) to study if and how sleep does not only reiterate new experiences but may even lead to new insights. In the NRT, covert regularities may speed responses. This implicit acquisition of regularities may become explicitly conscious at some point, leading to a qualitative change in behavior which reflects this insight. By applying the NRT at two consecutive sessions separated by an interval, we investigated the role of sleep in this interval for attaining insight at the second session. In the first study, a night of sleep was shown to triple the number of participants attaining insight above the base rate of about 20%. In the second study, this hard core of 20% discoverers differed from other participants in their task-related EEG potentials from the very beginning already. In the third study, the additional role of sleep was specified as an effect of the deep-sleep phase of slow-wave sleep on participants who had implicitly acquired the covert regularity before sleep. It was in these participants that a specific increase of EEG during slow-wave sleep in the 10-12 Hz band was obtained. These results support the view that neuronal memory reprocessing during slow-wave sleep restructures task-related representations in the brain, and that such restructuring promotes the gain of explicit knowledge. PMID:24605175

Plasma production by helicon and slow waves.

PubMed

Sakawa, Youichi; Kunimatsu, Hiroyuki; Kikuchi, Hideki; Fukui, Yasuaki; Shoji, Tatsuo

2003-03-14

The observation of slow-wave sustained (SW) discharge in a whistler- or helicon-wave range of frequency is made using high-frequency and very-high-frequency bands of rf. The SW discharge occurs at an extremely low rf power and plasma density, which are lower than a capacitive-coupling discharge region.

Coupled Transmission Line Based Slow Wave Structures for Traveling Wave Tubes Applications

NASA Astrophysics Data System (ADS)

Zuboraj, Md. Rashedul Alam

High power microwave devices especially Traveling Wave Tubes (TWTs) and Backward Wave Oscillators (BWOs) are largely dependent on Slow Wave Structures for efficient beam to RF coupling. In this work, a novel approach of analyzing SWSs is proposed and investigated. Specifically, a rigorous study of helical geometries is carried out and a novel SWS "Half-Ring-Helix" is designed. This Half-Ring-Helix circuit achieves 27% miniaturization and delivers 10dB more gain than conventional helices. A generalization of the helix structures is also proposed in the form of Coupled Transmission Line (CTL). It is demonstrated that control of coupling among the CTLs leads to new propagation properties. With this in mind, a novel geometry referred to as "Curved Ring-Bar" is introduced. This geometry is shown to deliver 1MW power across a 33% bandwidth. Notably, this is the first demonstration of MW power TWT across large bandwidth. The CTL is further expanded to enable engineered propagation characteristics. This is done by introducing CTLs having non-identical transmission lines and CTLs with as many as four transmission lines in the same slow wave structure circuit. These non-identical CTLs are demonstrated to generate fourth order dispersion curves. Building on the property of CTLs, a `butterfly' slow wave structure is developed and demonstrated to provide degenerate band edge (DBE) mode. This mode are known to provide large feld enhancement that can be exploited to design high power backward wave oscillators.

Retinoic Acid Signaling Affects Cortical Synchrony During Sleep

NASA Astrophysics Data System (ADS)

Maret, Stéphanie; Franken, Paul; Dauvilliers, Yves; Ghyselinck, Norbert B.; Chambon, Pierre; Tafti, Mehdi

2005-10-01

Delta oscillations, characteristic of the electroencephalogram (EEG) of slow wave sleep, estimate sleep depth and need and are thought to be closely linked to the recovery function of sleep. The cellular mechanisms underlying the generation of delta waves at the cortical and thalamic levels are well documented, but the molecular regulatory mechanisms remain elusive. Here we demonstrate in the mouse that the gene encoding the retinoic acid receptor beta determines the contribution of delta oscillations to the sleep EEG. Thus, retinoic acid signaling, which is involved in the patterning of the brain and dopaminergic pathways, regulates cortical synchrony in the adult.

Interneuron-mediated inhibition synchronizes neuronal activity during slow oscillation.

PubMed

Chen, Jen-Yung; Chauvette, Sylvain; Skorheim, Steven; Timofeev, Igor; Bazhenov, Maxim

2012-08-15

The signature of slow-wave sleep in the electroencephalogram (EEG) is large-amplitude fluctuation of the field potential, which reflects synchronous alternation of activity and silence across cortical neurons. While initiation of the active cortical states during sleep slow oscillation has been intensively studied, the biological mechanisms which drive the network transition from an active state to silence remain poorly understood. In the current study, using a combination of in vivo electrophysiology and thalamocortical network simulation, we explored the impact of intrinsic and synaptic inhibition on state transition during sleep slow oscillation. We found that in normal physiological conditions, synaptic inhibition controls the duration and the synchrony of active state termination. The decline of interneuron-mediated inhibition led to asynchronous downward transition across the cortical network and broke the regular slow oscillation pattern. Furthermore, in both in vivo experiment and computational modelling, we revealed that when the level of synaptic inhibition was reduced significantly, it led to a recovery of synchronized oscillations in the form of seizure-like bursting activity. In this condition, the fast active state termination was mediated by intrinsic hyperpolarizing conductances. Our study highlights the significance of both intrinsic and synaptic inhibition in manipulating sleep slow rhythms.

Interneuron-mediated inhibition synchronizes neuronal activity during slow oscillation

PubMed Central

Chen, Jen-Yung; Chauvette, Sylvain; Skorheim, Steven; Timofeev, Igor; Bazhenov, Maxim

2012-01-01

The signature of slow-wave sleep in the electroencephalogram (EEG) is large-amplitude fluctuation of the field potential, which reflects synchronous alternation of activity and silence across cortical neurons. While initiation of the active cortical states during sleep slow oscillation has been intensively studied, the biological mechanisms which drive the network transition from an active state to silence remain poorly understood. In the current study, using a combination of in vivo electrophysiology and thalamocortical network simulation, we explored the impact of intrinsic and synaptic inhibition on state transition during sleep slow oscillation. We found that in normal physiological conditions, synaptic inhibition controls the duration and the synchrony of active state termination. The decline of interneuron-mediated inhibition led to asynchronous downward transition across the cortical network and broke the regular slow oscillation pattern. Furthermore, in both in vivo experiment and computational modelling, we revealed that when the level of synaptic inhibition was reduced significantly, it led to a recovery of synchronized oscillations in the form of seizure-like bursting activity. In this condition, the fast active state termination was mediated by intrinsic hyperpolarizing conductances. Our study highlights the significance of both intrinsic and synaptic inhibition in manipulating sleep slow rhythms. PMID:22641778

Slow-wave propagation on monolithic microwave integrated circuits with layered and non-layered structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tzuang, C.K.C.

1986-01-01

Various MMIC (monolithic microwave integrated circuit) planar waveguides have shown possible existence of a slow-wave propagation. In many practical applications of these slow-wave circuits, the semiconductor devices have nonuniform material properties that may affect the slow-wave propagation. In the first part of the dissertation, the effects of the nonuniform material properties are studied by a finite-element method. In addition, the transient pulse excitations of these slow-wave circuits also have great theoretical and practical interests. In the second part, the time-domain analysis of a slow-wave coplanar waveguide is presented.

The Fate of Incoming Stimuli during NREM Sleep is Determined by Spindles and the Phase of the Slow Oscillation.

PubMed

Schabus, Manuel; Dang-Vu, Thien Thanh; Heib, Dominik Philip Johannes; Boly, Mélanie; Desseilles, Martin; Vandewalle, Gilles; Schmidt, Christina; Albouy, Geneviève; Darsaud, Annabelle; Gais, Steffen; Degueldre, Christian; Balteau, Evelyne; Phillips, Christophe; Luxen, André; Maquet, Pierre

2012-01-01

The present study aimed at identifying the neurophysiological responses associated with auditory stimulation during non-rapid eye movement (NREM) sleep using simultaneous electroencephalography (EEG)/functional magnetic resonance imaging (fMRI) recordings. It was reported earlier that auditory stimuli produce bilateral activation in auditory cortex, thalamus, and caudate during both wakefulness and NREM sleep. However, due to the spontaneous membrane potential fluctuations cortical responses may be highly variable during NREM. Here we now examine the modulation of cerebral responses to tones depending on the presence or absence of sleep spindles and the phase of the slow oscillation. Thirteen healthy young subjects were scanned successfully during stage 2-4 NREM sleep in the first half of the night in a 3 T scanner. Subjects were not sleep-deprived and sounds were post hoc classified according to (i) the presence of sleep spindles or (ii) the phase of the slow oscillation during (±300 ms) tone delivery. These detected sounds were then entered as regressors of interest in fMRI analyses. Interestingly wake-like responses - although somewhat altered in size and location - persisted during NREM sleep, except during present spindles (as previously published in Dang-Vu et al., 2011) and the negative going phase of the slow oscillation during which responses became less consistent or even absent. While the phase of the slow oscillation did not alter brain responses in primary sensory cortex, it did modulate responses at higher cortical levels. In addition EEG analyses show a distinct N550 response to tones during the presence of light sleep spindles and suggest that in deep NREM sleep the brain is more responsive during the positive going slope of the slow oscillation. The presence of short temporal windows during which the brain is open to external stimuli is consistent with the fact that even during deep sleep meaningful events can be detected. Altogether, our

Increased Sleep Depth in Developing Neural Networks: New Insights from Sleep Restriction in Children

PubMed Central

Kurth, Salome; Dean, Douglas C.; Achermann, Peter; O’Muircheartaigh, Jonathan; Huber, Reto; Deoni, Sean C. L.; LeBourgeois, Monique K.

2016-01-01

Brain networks respond to sleep deprivation or restriction with increased sleep depth, which is quantified as slow-wave activity (SWA) in the sleep electroencephalogram (EEG). When adults are sleep deprived, this homeostatic response is most pronounced over prefrontal brain regions. However, it is unknown how children’s developing brain networks respond to acute sleep restriction, and whether this response is linked to myelination, an ongoing process in childhood that is critical for brain development and cortical integration. We implemented a bedtime delay protocol in 5- to 12-year-old children to obtain partial sleep restriction (1-night; 50% of their habitual sleep). High-density sleep EEG was assessed during habitual and restricted sleep and brain myelin content was obtained using mcDESPOT magnetic resonance imaging. The effect of sleep restriction was analyzed using statistical non-parametric mapping with supra-threshold cluster analysis. We observed a localized homeostatic SWA response following sleep restriction in a specific parieto-occipital region. The restricted/habitual SWA ratio was negatively associated with myelin water fraction in the optic radiation, a developing fiber bundle. This relationship occurred bilaterally over parieto-temporal areas and was adjacent to, but did not overlap with the parieto-occipital region showing the most pronounced homeostatic SWA response. These results provide evidence for increased sleep need in posterior neural networks in children. Sleep need in parieto-temporal areas is related to myelin content, yet it remains speculative whether age-related myelin growth drives the fading of the posterior homeostatic SWA response during the transition to adulthood. Whether chronic insufficient sleep in the sensitive period of early life alters the anatomical generators of deep sleep slow-waves is an important unanswered question. PMID:27708567

Sleeping on the rubber-hand illusion: Memory reactivation during sleep facilitates multisensory recalibration.

PubMed

Honma, Motoyasu; Plass, John; Brang, David; Florczak, Susan M; Grabowecky, Marcia; Paller, Ken A

2016-01-01

Plasticity is essential in body perception so that physical changes in the body can be accommodated and assimilated. Multisensory integration of visual, auditory, tactile, and proprioceptive signals contributes both to conscious perception of the body's current state and to associated learning. However, much is unknown about how novel information is assimilated into body perception networks in the brain. Sleep-based consolidation can facilitate various types of learning via the reactivation of networks involved in prior encoding or through synaptic down-scaling. Sleep may likewise contribute to perceptual learning of bodily information by providing an optimal time for multisensory recalibration. Here we used methods for targeted memory reactivation (TMR) during slow-wave sleep to examine the influence of sleep-based reactivation of experimentally induced alterations in body perception. The rubber-hand illusion was induced with concomitant auditory stimulation in 24 healthy participants on 3 consecutive days. While each participant was sleeping in his or her own bed during intervening nights, electrophysiological detection of slow-wave sleep prompted covert stimulation with either the sound heard during illusion induction, a counterbalanced novel sound, or neither. TMR systematically enhanced feelings of bodily ownership after subsequent inductions of the rubber-hand illusion. TMR also enhanced spatial recalibration of perceived hand location in the direction of the rubber hand. This evidence for a sleep-based facilitation of a body-perception illusion demonstrates that the spatial recalibration of multisensory signals can be altered overnight to stabilize new learning of bodily representations. Sleep-based memory processing may thus constitute a fundamental component of body-image plasticity.

Surface Current Density Mapping for Identification of Gastric Slow Wave Propagation

PubMed Central

Bradshaw, L. A.; Cheng, L. K.; Richards, W. O.; Pullan, A. J.

2009-01-01

The magnetogastrogram records clinically relevant parameters of the electrical slow wave of the stomach noninvasively. Besides slow wave frequency, gastric slow wave propagation velocity is a potentially useful clinical indicator of the state of health of gastric tissue, but it is a difficult parameter to determine from noninvasive bioelectric or biomagnetic measurements. We present a method for computing the surface current density (SCD) from multichannel magnetogastrogram recordings that allows computation of the propagation velocity of the gastric slow wave. A moving dipole source model with hypothetical as well as realistic biomagnetometer parameters demonstrates that while a relatively sparse array of magnetometer sensors is sufficient to compute a single average propagation velocity, more detailed information about spatial variations in propagation velocity requires higher density magnetometer arrays. Finally, the method is validated with simultaneous MGG and serosal EMG measurements in a porcine subject. PMID:19403355

Uncovering representations of sleep-associated hippocampal ensemble spike activity

NASA Astrophysics Data System (ADS)

Chen, Zhe; Grosmark, Andres D.; Penagos, Hector; Wilson, Matthew A.

2016-08-01

Pyramidal neurons in the rodent hippocampus exhibit spatial tuning during spatial navigation, and they are reactivated in specific temporal order during sharp-wave ripples observed in quiet wakefulness or slow wave sleep. However, analyzing representations of sleep-associated hippocampal ensemble spike activity remains a great challenge. In contrast to wake, during sleep there is a complete absence of animal behavior, and the ensemble spike activity is sparse (low occurrence) and fragmental in time. To examine important issues encountered in sleep data analysis, we constructed synthetic sleep-like hippocampal spike data (short epochs, sparse and sporadic firing, compressed timescale) for detailed investigations. Based upon two Bayesian population-decoding methods (one receptive field-based, and the other not), we systematically investigated their representation power and detection reliability. Notably, the receptive-field-free decoding method was found to be well-tuned for hippocampal ensemble spike data in slow wave sleep (SWS), even in the absence of prior behavioral measure or ground truth. Our results showed that in addition to the sample length, bin size, and firing rate, number of active hippocampal pyramidal neurons are critical for reliable representation of the space as well as for detection of spatiotemporal reactivated patterns in SWS or quiet wakefulness.

Modulation of somatosensory evoked potentials during wake-sleep states and spike-wave discharges in the rat.

PubMed

Shaw, Fu-Zen; Lee, Su-Ying; Chiu, Ted H

2006-03-01

To clarify the cortical evoked responses in the primary somatosensory cortex of the rat under states of waking, slow-wave sleep (SWS), paradoxical sleep (PS), and spike-wave discharges (SWDs), which are associated with absence seizure. Somatosensory evoked potentials (SEPs) in response to single- and paired-pulse stimulations under waking, SWS, PS, and SWDs were compared. SEPs to a single-pulse stimulus with regard to cortical spikes of sleep spindles and SWDs were also evaluated. Twenty Long Evans rats. Single- and paired-pulse innocuous electrical stimulations were applied to the tail of rats with chronically implanted electrodes in the primary somatosensory cortex and neck muscle under waking, SWS, PS, and SWDs. SEPs displayed distinct patterns under waking/PS and SWS/SWDs. The short-latency P1-N1 wave of the SEP was severely impeded during SWDs but not in other states. Reduction of the P1-N1 magnitude to the second stimulus of the paired-pulse stimulus for interstimulus intervals of < or = 300 milliseconds appeared in waking and PS states, but the decrease occurred only at particular interstimulus intervals under SWS. Interestingly, augmentation was found under SWDs. Moreover, cyclic augmentation of the P1-N1 magnitude was associated with spindle spikes, but cyclic reduction was observed with SWD spikes. Changes in SEPs are not only behavior dependent, but also phase locked onto ongoing brain activity. Distinct short-term plasticity of SEPs during sleep spindles or SWDs may merit further studies for seizure control and tactile information processing.

Voluntary Sleep Loss in Rats.

PubMed

Oonk, Marcella; Krueger, James M; Davis, Christopher J

2016-07-01

Animal sleep deprivation (SDEP), in contrast to human SDEP, is involuntary and involves repeated exposure to aversive stimuli including the inability of the animal to control the waking stimulus. Therefore, we explored intracranial self-stimulation (ICSS), an operant behavior, as a method for voluntary SDEP in rodents. Male Sprague-Dawley rats were implanted with electroencephalography/electromyography (EEG/EMG) recording electrodes and a unilateral bipolar electrode into the lateral hypothalamus. Rats were allowed to self-stimulate, or underwent gentle handling-induced SDEP (GH-SDEP), during the first 6 h of the light phase, after which they were allowed to sleep. Other rats performed the 6 h ICSS and 1 w later were subjected to 6 h of noncontingent stimulation (NCS). During NCS the individual stimulation patterns recorded during ICSS were replayed. After GH-SDEP, ICSS, or NCS, time in nonrapid eye movement (NREM) sleep and rapid eye movement (REM) sleep increased. Further, in the 24 h after SDEP, rats recovered all of the REM sleep lost during SDEP, but only 75% to 80% of the NREM sleep lost, regardless of the SDEP method. The magnitude of EEG slow wave responses occurring during NREM sleep also increased after SDEP treatments. However, NREM sleep EEG slow wave activity (SWA) responses were attenuated following ICSS, compared to GH-SDEP and NCS. We conclude that ICSS and NCS can be used to sleep deprive rats. Changes in rebound NREM sleep EEG SWA occurring after ICSS, NCS, and GH-SDEP suggest that nonspecific effects of the SDEP procedure differentially affect recovery sleep phenotypes. © 2016 Associated Professional Sleep Societies, LLC.

Altered slow wave activity in major depressive disorder with hypersomnia: a high density EEG pilot study

PubMed Central

Plante, David T.; Landsness, Eric C.; Peterson, Michael J.; Goldstein, Michael R.; Wanger, Tim; Guokas, Jeff J.; Tononi, Giulio; Benca, Ruth M.

2012-01-01

Hypersomnolence in major depressive disorder (MDD) plays an important role in the natural history of the disorder, but the basis of hypersomnia in MDD is poorly understood. Slow wave activity (SWA) has been associated with sleep homeostasis, as well as sleep restoration and maintenance, and may be altered in MDD. Therefore, we conducted a post-hoc study that utilized high density electroencephalography (hdEEG) to test the hypothesis that MDD subjects with hypersomnia (HYS+) would have decreased SWA relative to age and sex-matched MDD subjects without hypersomnia (HYS−) and healthy controls (n=7 for each group). After correcting for multiple comparisons using statistical non-parametric mapping, HYS+ subjects demonstrated significantly reduced parieto-occipital all-night SWA relative to HYS− subjects. Our results suggest hypersomnolence may be associated with topographic reductions in SWA in MDD. Further research using adequately powered prospective design is indicated to confirm these findings. PMID:22512951

Sleep pattern and locomotor activity are impaired by doxorubicin in non-tumor-bearing rats.

PubMed

Lira, Fabio Santos; Esteves, Andrea Maculano; Pimentel, Gustavo Duarte; Rosa, José Cesar; Frank, Miriam Kannebley; Mariano, Melise Oliveira; Budni, Josiane; Quevedo, João; Santos, Ronaldo Vagner Dos; de Mello, Marco Túlio

2016-01-01

We sought explore the effects of doxorubicin on sleep patterns and locomotor activity. To investigate these effects, two groups were formed: a control group and a Doxorubicin (DOXO) group. Sixteen rats were randomly assigned to either the control or DOXO groups. The sleep patterns were examined by polysomnographic recording and locomotor activity was evaluated in an open-field test. In the light period, the total sleep time and slow wave sleep were decreased, while the wake after sleep onset and arousal were increased in the DOXO group compared with the control group (p<0.05). In the dark period, the total sleep time, arousal, and slow wave sleep were increased, while the wake after sleep onset was decreased in the DOXO group compared with the control group (p<0.05). Moreover, DOXO induced a decrease of crossing and rearing numbers when compared control group (p<0.05). Therefore, our results suggest that doxorubicin induces sleep pattern impairments and reduction of locomotor activity.

Beta EEG reflects sensory processing in active wakefulness and homeostatic sleep drive in quiet wakefulness.

PubMed

Grønli, Janne; Rempe, Michael J; Clegern, William C; Schmidt, Michelle; Wisor, Jonathan P

2016-06-01

Markers of sleep drive (<10 Hz; slow-wave activity and theta) have been identified in the course of slow-wave sleep and wakefulness. So far, higher frequencies in the waking electroencephalogram have not been examined thoroughly as a function of sleep drive. Here, electroencephalogram dynamics were measured in epochs of active wake (wake characterized by high muscle tone) or quiet wake (wake characterized by low muscle tone). It was hypothesized that the higher beta oscillations (15-35 Hz, measured by local field potential and electroencephalography) represent fundamentally different processes in active wake and quiet wake. In active wake, sensory stimulation elevated beta activity in parallel with gamma (80-90 Hz) activity, indicative of cognitive processing. In quiet wake, beta activity paralleled slow-wave activity (1-4 Hz) and theta (5-8 Hz) in tracking sleep need. Cerebral lactate concentration, a measure of cerebral glucose utilization, increased during active wake whereas it declined during quiet wake. Mathematical modelling of state-dependent dynamics of cortical lactate concentration was more precisely predictive when quiet wake and active wake were included as two distinct substates rather than a uniform state of wakefulness. The extent to which lactate concentration declined in quiet wake and increased in active wake was proportionate to the amount of beta activity. These data distinguish quiet wake from active wake. Quiet wake, particularly when characterized by beta activity, is permissive to metabolic and electrophysiological changes that occur in slow-wave sleep. These data urge further studies on state-dependent beta oscillations across species. © 2016 European Sleep Research Society.

The new wave-ring helical (WRH) slow-wave structure for traveling wave tube amplifiers

NASA Astrophysics Data System (ADS)

Panahi, Nasser; Saviz, S.; Ghorannevis, M.

2017-12-01

In this paper, the new slow-wave structure called wave-ring helix to enhance the power of the traveling wave tubes is introduced. In this new structure, without increasing the length and radius of the helix, the wave motion path can be increased to radiofrequency wave in phase with the electron beam. The results show that in the special frequency range the output power and gain are greater than conventional helix. In this paper, optimization results are presented in cold and hot tests on the new structure. The software CST is used in S-band frequency range.

Update of sleep alterations in depression

PubMed Central

Medina, Andrés Barrera; Lechuga, DeboraYoaly Arana; Escandón, Oscar Sánchez; Moctezuma, Javier Velázquez

2014-01-01

Sleep disturbances in depression are up to 70%. Patients frequently have difficulty in falling asleep, frequent awakenings during the night and non-restorative sleep. Sleep abnormalities in depression are mainly characterized by increased rapid eye movement (REM) sleep and reduced slow wave sleep. Among the mechanisms of sleep disturbances in depression are hyperactivation of the hypothalamic-pituitary-adrenal axis, CLOCK gene polymorphism and primary sleep disorders. The habenula is a structure regulating the activities of monoaminergic neurons in the brain. The hyperactivation of the habenula has also been implicated, together with sleep disturbances, in depression. The presence of depression in primary sleep disorders is common. Sleep disturbances treatment include pharmacotherapy or Cognitive Behavioral Therapy. PMID:26483922

Brain extracellular glucose assessed by voltammetry throughout the rat sleep-wake cycle.

PubMed

Netchiporouk, L; Shram, N; Salvert, D; Cespuglio, R

2001-04-01

In the present study, cortical extracellular levels of glucose were monitored for the first time throughout the sleep-wake states of the freely moving rat. For this purpose, polygraphic recordings (electroencephalogram of the fronto-occipital cortices and electromyogram of the neck muscles) were achieved in combination with differential normal pulse voltammetry (DNPV) using a specific glucose sensor. Data obtained reveal that the basal extracellular glucose concentration in the conscious rat is 0.59 +/- 0.3 m M while under chloral hydrate anaesthesia (0.4 g/kg, i.p.) it increases up to 180% of its basal concentration. Regarding the sleep-wake cycle, the existence of spontaneous significant variations in the mean glucose level during slow-wave sleep (SWS = +13%) and paradoxical sleep (PS = -11%) compared with the waking state (100%) is also reported. It is to be noticed that during long periods of active waking, glucose level tends towards a decrease that becomes significant after 15 min (active waking = -32%). On the contrary, during long episodes of slow-wave sleep, it tends towards an increase which becomes significant after 12 min (SWS = +28%). It is suggested that voltammetric techniques using enzymatic biosensors are useful tools allowing direct glucose measurements in the freely moving animal. On the whole, paradoxical sleep is pointed out as a state highly dependent on the availability of energy and slow-wave sleep as a period of energy saving.

SLOW MAGNETOACOUSTIC WAVES OBSERVED ABOVE A QUIET-SUN REGION IN A DARK CAVITY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu Jiajia; Zhou Zhenjun; Wang Yuming

Waves play a crucial role in diagnosing the plasma properties of various structures in the solar corona and coronal heating. Slow magnetoacoustic (MA) waves are one of the important types of magnetohydrodynamic waves. In past decades, numerous slow MA waves were detected above active regions and coronal holes, but were rarely found elsewhere. Here, we investigate a 'tornado'-like structure consisting of quasi-periodic streaks within a dark cavity at about 40-110 Mm above a quiet-Sun region on 2011 September 25. Our analysis reveals that these streaks are actually slow MA wave trains. The properties of these wave trains, including phase speed,more » compression ratio, and kinetic energy density, are similar to those of the reported slow MA waves, except that the period of these waves is about 50 s, much shorter than the typical reported values (3-5 minutes).« less

Sleep Reduces False Memory in Healthy Older Adults

PubMed Central

Lo, June C.; Sim, Sam K. Y.; Chee, Michael W. L.

2014-01-01

Study Objectives: To investigate the effects of post-learning sleep and sleep architecture on false memory in healthy older adults. Design: Balanced, crossover design. False memory was induced using the Deese-Roediger-McDermott (DRM) paradigm and assessed following nocturnal sleep and following a period of daytime wakefulness. Post-learning sleep structure was evaluated using polysomnography (PSG). Setting: Sleep research laboratory. Participants: Fourteen healthy older adults from the Singapore-Longitudinal Aging Brain Study (mean age ± standard deviation = 66.6 ± 4.1 y; 7 males). Measurements and Results: At encoding, participants studied lists of words that were semantically related to non-presented critical lures. At retrieval, they made “remember”/“know” and “new” judgments. Compared to wakefulness, post-learning sleep was associated with reduced “remember” responses, but not “know” responses to critical lures. In contrast, there were no significant differences in the veridical recognition of studied words, false recognition of unrelated distractors, discriminability, or response bias between the sleep and the wake conditions. More post-learning slow wave sleep was associated with greater reduction in false memory. Conclusions: In healthy older adults, sleep facilitates the reduction in false memory without affecting veridical memory. This benefit correlates with the amount of slow wave sleep in the post-learning sleep episode. Citation: Lo JC; Sim SK; Chee MW. Sleep reduces false memory in healthy older adults. SLEEP 2014;37(4):665-671. PMID:24744453

Voluntary Sleep Loss in Rats

PubMed Central

Oonk, Marcella; Krueger, James M.; Davis, Christopher J.

2016-01-01

Study Objectives: Animal sleep deprivation (SDEP), in contrast to human SDEP, is involuntary and involves repeated exposure to aversive stimuli including the inability of the animal to control the waking stimulus. Therefore, we explored intracranial self-stimulation (ICSS), an operant behavior, as a method for voluntary SDEP in rodents. Methods: Male Sprague-Dawley rats were implanted with electroencephalography/electromyography (EEG/EMG) recording electrodes and a unilateral bipolar electrode into the lateral hypothalamus. Rats were allowed to self-stimulate, or underwent gentle handling-induced SDEP (GH-SDEP), during the first 6 h of the light phase, after which they were allowed to sleep. Other rats performed the 6 h ICSS and 1 w later were subjected to 6 h of noncontingent stimulation (NCS). During NCS the individual stimulation patterns recorded during ICSS were replayed. Results: After GH-SDEP, ICSS, or NCS, time in nonrapid eye movement (NREM) sleep and rapid eye movement (REM) sleep increased. Further, in the 24 h after SDEP, rats recovered all of the REM sleep lost during SDEP, but only 75% to 80% of the NREM sleep lost, regardless of the SDEP method. The magnitude of EEG slow wave responses occurring during NREM sleep also increased after SDEP treatments. However, NREM sleep EEG slow wave activity (SWA) responses were attenuated following ICSS, compared to GH-SDEP and NCS. Conclusions: We conclude that ICSS and NCS can be used to sleep deprive rats. Changes in rebound NREM sleep EEG SWA occurring after ICSS, NCS, and GH-SDEP suggest that nonspecific effects of the SDEP procedure differentially affect recovery sleep phenotypes. Citation: Oonk M, Krueger JM, Davis CJ. Voluntary sleep loss in rats. SLEEP 2016;39(7):1467–1479. PMID:27166236

Astrocytic modulation of sleep homeostasis and cognitive consequences of sleep loss.

PubMed

Halassa, Michael M; Florian, Cedrick; Fellin, Tommaso; Munoz, James R; Lee, So-Young; Abel, Ted; Haydon, Philip G; Frank, Marcos G

2009-01-29

Astrocytes modulate neuronal activity by releasing chemical transmitters via a process termed gliotransmission. The role of this process in the control of behavior is unknown. Since one outcome of SNARE-dependent gliotransmission is the regulation of extracellular adenosine and because adenosine promotes sleep, we genetically inhibited the release of gliotransmitters and asked if astrocytes play an unsuspected role in sleep regulation. Inhibiting gliotransmission attenuated the accumulation of sleep pressure, assessed by measuring the slow wave activity of the EEG during NREM sleep, and prevented cognitive deficits associated with sleep loss. Since the sleep-suppressing effects of the A1 receptor antagonist CPT were prevented following inhibition of gliotransmission and because intracerebroventricular delivery of CPT to wild-type mice mimicked the transgenic phenotype, we conclude that astrocytes modulate the accumulation of sleep pressure and its cognitive consequences through a pathway involving A1 receptors.

Reconstruction of gastric slow wave from finger photoplethysmographic signal using radial basis function neural network.

PubMed

Mohamed Yacin, S; Srinivasa Chakravarthy, V; Manivannan, M

2011-11-01

Extraction of extra-cardiac information from photoplethysmography (PPG) signal is a challenging research problem with significant clinical applications. In this study, radial basis function neural network (RBFNN) is used to reconstruct the gastric myoelectric activity (GMA) slow wave from finger PPG signal. Finger PPG and GMA (measured using Electrogastrogram, EGG) signals were acquired simultaneously at the sampling rate of 100 Hz from ten healthy subjects. Discrete wavelet transform (DWT) was used to extract slow wave (0-0.1953 Hz) component from the finger PPG signal; this slow wave PPG was used to reconstruct EGG. A RBFNN is trained on signals obtained from six subjects in both fasting and postprandial conditions. The trained network is tested on data obtained from the remaining four subjects. In the earlier study, we have shown the presence of GMA information in finger PPG signal using DWT and cross-correlation method. In this study, we explicitly reconstruct gastric slow wave from finger PPG signal by the proposed RBFNN-based method. It was found that the network-reconstructed slow wave provided significantly higher (P < 0.0001) correlation (≥ 0.9) with the subject's EGG slow wave than the correlation obtained (≈0.7) between the PPG slow wave from DWT and the EEG slow wave. Our results showed that a simple finger PPG signal can be used to reconstruct gastric slow wave using RBFNN method.

Declarative Memory Consolidation: Mechanisms Acting during Human Sleep

ERIC Educational Resources Information Center

Gais, Steffen; Born, Jan

2004-01-01

Of late, an increasing number of studies have shown a strong relationship between sleep and memory. Here we summarize a series of our own studies in humans supporting a beneficial influence of slow-wave sleep (SWS) on declarative memory formation, and try to identify some mechanisms that might underlie this influence. Specifically, these…

[EFFECTS OF ELECTRICAL STIMULATION OF NUCLEUS RETICULARIS PONTIS ORALIS ON THE SLEEP-WAKING STATES IN KRUSHINSKII-MOLODKINA STRAIN RATS].

PubMed

Vataev, S I; Malgina, N A; Oganesyan, G A

2015-07-01

The effects of electrical stimulation of nucleus reticularis pontis oralis on the behavior and brain electrical activity during all phases of the sleep-waking cycle was studied in Krushinskii-Molodkina strain rats, which have an inherited predisposition to audiogenic seizures. Electrical stimulation with 7 Hz frequency in the deep stage of slow-wave sleep cause appearance the fast-wave sleep. Similar stimulation during fast-wave sleep periods did not effects on the electrographic patterns and EEG spectral characteristics of hippocampus, visual, auditory and somatocnen nrnrenc nf the cnrtey ThPe sfimul1stinns did nnt break a fast-wave sleenhut increased almost twice due the duration of these sleep episodes. After electrical stimulation by same frequency during the wakeftlness and superficial slow-wave sleep states, the patterns and spectral characteristics of brain electrical activity in rats showed no significant changes as compared with controls. The results of this study indicate that the state of the animals sleep-waking cycle at the time of stimulation is a critical variable that influences the responses which are induced by electrical stimulation of the nucleus reticularis pontis oralis.

Interobserver variability in recognizing arousal in respiratory sleep disorders.

PubMed

Drinnan, M J; Murray, A; Griffiths, C J; Gibson, G J

1998-08-01

Daytime sleepiness is a common consequence of repeated arousal in obstructive sleep apnea (OSA). Arousal indices are sometimes used to make decisions on treatment, but there is no evidence that arousals are detected similarly even by experienced observers. Using the American Sleep Disorders Association (ASDA) definition of arousal in terms of the accompanying electroencephalogram (EEG) changes, we have quantified interobserver agreement for arousal scoring and identified factors affecting it. Ten patients with suspected OSA were studied; three representative EEG events during each of light, slow-wave, and rapid-eye-movement (REM) sleep were extracted from each record (90 events total) and evaluated by experts in 14 sleep laboratories. Observers differed (ANOVA, p < 0.001) in the number of events scored as arousal (totals ranged from 23 to 53 of the 90 events). Overall agreement was moderate (kappa = 0.47), but it was best for events during slow-wave sleep, moderate for REM, and poor for light sleep (kappa = 0.60, 0.52, and 0.28, respectively). Agreement was unrelated to arousal duration. We conclude that the ASDA definition of arousal is only moderately repeatable. Account should be taken of this variability when results from different centers are compared.

Determining attenuation properties of interfering fast and slow ultrasonic waves in cancellous bone.

PubMed

Nelson, Amber M; Hoffman, Joseph J; Anderson, Christian C; Holland, Mark R; Nagatani, Yoshiki; Mizuno, Katsunori; Matsukawa, Mami; Miller, James G

2011-10-01

Previous studies have shown that interference between fast waves and slow waves can lead to observed negative dispersion in cancellous bone. In this study, the effects of overlapping fast and slow waves on measurements of the apparent attenuation as a function of propagation distance are investigated along with methods of analysis used to determine the attenuation properties. Two methods are applied to simulated data that were generated based on experimentally acquired signals taken from a bovine specimen. The first method uses a time-domain approach that was dictated by constraints imposed by the partial overlap of fast and slow waves. The second method uses a frequency-domain log-spectral subtraction technique on the separated fast and slow waves. Applying the time-domain analysis to the broadband data yields apparent attenuation behavior that is larger in the early stages of propagation and decreases as the wave travels deeper. In contrast, performing frequency-domain analysis on the separated fast waves and slow waves results in attenuation coefficients that are independent of propagation distance. Results suggest that features arising from the analysis of overlapping two-mode data may represent an alternate explanation for the previously reported apparent dependence on propagation distance of the attenuation coefficient of cancellous bone. © 2011 Acoustical Society of America

Determining attenuation properties of interfering fast and slow ultrasonic waves in cancellous bone

PubMed Central

Nelson, Amber M.; Hoffman, Joseph J.; Anderson, Christian C.; Holland, Mark R.; Nagatani, Yoshiki; Mizuno, Katsunori; Matsukawa, Mami; Miller, James G.

2011-01-01

Previous studies have shown that interference between fast waves and slow waves can lead to observed negative dispersion in cancellous bone. In this study, the effects of overlapping fast and slow waves on measurements of the apparent attenuation as a function of propagation distance are investigated along with methods of analysis used to determine the attenuation properties. Two methods are applied to simulated data that were generated based on experimentally acquired signals taken from a bovine specimen. The first method uses a time-domain approach that was dictated by constraints imposed by the partial overlap of fast and slow waves. The second method uses a frequency-domain log-spectral subtraction technique on the separated fast and slow waves. Applying the time-domain analysis to the broadband data yields apparent attenuation behavior that is larger in the early stages of propagation and decreases as the wave travels deeper. In contrast, performing frequency-domain analysis on the separated fast waves and slow waves results in attenuation coefficients that are independent of propagation distance. Results suggest that features arising from the analysis of overlapping two-mode data may represent an alternate explanation for the previously reported apparent dependence on propagation distance of the attenuation coefficient of cancellous bone. PMID:21973378

Differential effects of sodium oxybate and baclofen on EEG, sleep, neurobehavioral performance, and memory.

PubMed

Vienne, Julie; Lecciso, Gianpaolo; Constantinescu, Irina; Schwartz, Sophie; Franken, Paul; Heinzer, Raphaël; Tafti, Mehdi

2012-08-01

Sodium oxybate (SO) is a GABAβ agonist used to treat the sleep disorder narcolepsy. SO was shown to increase slow wave sleep (SWS) and EEG delta power (0.75-4.5 Hz), both indexes of NREM sleep (NREMS) intensity and depth, suggesting that SO enhances recuperative function of NREM. We investigated whether SO induces physiological deep sleep. SO was administered before an afternoon nap or before the subsequent experimental night in 13 healthy volunteers. The effects of SO were compared to baclofen (BAC), another GABAβ receptor agonist, to assess the role of GABAβ receptors in the SO response. As expected, a nap significantly decreased sleep need and intensity the subsequent night. Both drugs reversed this nap effect on the subsequent night by decreasing sleep latency and increasing total sleep time, SWS during the first NREMS episode, and EEG delta and theta (0.75-7.25 Hz) power during NREMS. The SO-induced increase in EEG delta and theta power was, however, not specific to NREMS and was also observed during REM sleep (REMS) and wakefulness. Moreover, the high levels of delta power during a nap following SO administration did not affect delta power the following night. SO and BAC taken before the nap did not improve subsequent psychomotor performance and subjective alertness, or memory consolidation. Finally, SO and BAC strongly promoted the appearance of sleep onset REM periods. The SO-induced EEG slow waves seem not to be functionally similar to physiological slow waves. Our findings also suggest a role for GABAβ receptors in REMS generation.

Objective daytime sleepiness in patients with somnambulism or sleep terrors.

PubMed

Lopez, Régis; Jaussent, Isabelle; Dauvilliers, Yves

2014-11-25

To objectively measure daytime sleepiness and to assess for clinical and polysomnographic determinants of mean sleep latency in adult patients with somnambulism (sleepwalking [SW]) or sleep terrors (ST) compared with controls. Thirty drug-free adult patients with primary SW or ST, and age-, sex-, and body mass index-matched healthy controls underwent a standardized clinical interview, completed questionnaires including the Epworth Sleepiness Scale, and underwent one night of video polysomnography followed by the Multiple Sleep Latency Test (MSLT). Excessive daytime sleepiness defined as Epworth Sleepiness Scale score >10 was reported in 66.7% of patients and 6.7% of controls. The temporal pattern of sleep latencies in individual MSLT trials differed between patients and controls, with progressive increased sleep latency in patients across the trials in contrast to a "U curve" for controls. We did not find between-group differences regarding the mean sleep latency on the 5 MSLT trials, but did observe reduced sleep latencies in patients for the first 2 trials. Despite increased slow-wave sleep disruptions found in patients (i.e, more micro-arousals and hypersynchronous high-voltage delta waves arousals), we did not find polysomnographic characteristic differences when comparing sleepy patients for either subjective or objective daytime sleepiness on the MSLT compared with alert patients. Excessive daytime sleepiness is a common complaint in subjects with SW or ST and shorter sleep latencies in the early morning hours. Despite an increased slow-wave sleep fragmentation found in these patients, we did not identify any association with the level of daytime sleepiness. © 2014 American Academy of Neurology.

Sleep and breathing in high altitude pulmonary edema susceptible subjects at 4,559 meters.

PubMed

Nussbaumer-Ochsner, Yvonne; Schuepfer, Nicole; Ursprung, Justyna; Siebenmann, Christoph; Maggiorini, Marco; Bloch, Konrad E

2012-10-01

Susceptible subjects ascending rapidly to high altitude develop pulmonary edema (HAPE). We evaluated whether HAPE leads to sleep and breathing disturbances that are alleviated by dexamethasone. Double-blind, randomized, placebo-controlled trial with open-label extension. One night in sleep laboratory at 490 m, 2 nights in mountain hut at 4,559 m. 21 HAPE susceptibles. Dexamethasone 2 × 8 mg/d, either 24 h prior to ascent and at 4,559 m (dex-early), or started on day 2 at 4,559 m only (dex-late). Polysomnography, questionnaires on sleep and acute mountain sickness. Polysomnographies at 490 m were normal. In dex-late (n = 12) at 4,559 m, night 1 and 3, median oxygen saturation was 71% and 80%, apnea/hypopnea index 91.3/h and 9.6/h. In dex-early (n = 9), corresponding values were 78% and 79%, and 85.3/h and 52.3/h (P < 0.05 vs. 490 m, all instances). In dex-late, ascending from 490 m to 4,559 m (night 1), sleep efficiency decreased from 91% to 65%, slow wave sleep from 20% to 8% (P < 0.05, both instances). In dex-early, corresponding sleep efficiencies were 96% and 95%, slow wave sleep 18% and 9% (P < 0.05). From night 1 to 3, sleep efficiency remained unchanged in both groups while slow wave sleep increased to 20% in dex-late (P < 0.01). Compared to dex-early, initial AMS scores in dex-late were higher but improved during stay at altitude. HAPE susceptibles ascending rapidly to high altitude experience pronounced nocturnal hypoxemia, and reduced sleep efficiency and deep sleep. Dexamethasone taken before ascent prevents severe hypoxemia and sleep disturbances, while dexamethasone taken 24 h after arrival at 4,559 m increases oxygenation and deep sleep.

Effect of Local Thermal Equilibrium Misbalance on Long-wavelength Slow Magnetoacoustic Waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakariakov, V. M.; Afanasyev, A. N.; Kumar, S.

Evolution of slow magnetoacoustic waves guided by a cylindrical magnetic flux tube that represents a coronal loop or plume, is modeled accounting for the effects of finite gas pressure, weak nonlinearity, dissipation by thermal conduction and viscosity, and the misbalance between the cooling by optically thin radiation and unspecified heating of the plasma. An evolutionary equation of the Burgers–Malthus type is derived. It is shown that the cooling/heating misbalance, determined by the derivatives of the combined radiative cooling and heating function, with respect to the density, temperature, and magnetic field at the thermal equilibrium affect the wave rather strongly. Thismore » effect may either cause additional damping, or counteract it, or lead to the gradual amplification of the wave. In the latter case, the coronal plasma acts as an active medium for the slow magnetoacoustic waves. The effect of the cooling/heating misbalance could be important for coronal slow waves, and could be responsible for certain discrepancies between theoretical results and observations, in particular, the increased or decreased damping lengths and times, detection of the waves at certain heights only, and excitation of compressive oscillations. The results obtained open up a possibility for the diagnostics of the coronal heating function by slow magnetoacoustic waves.« less

Narcolepsy type 1 and hypersomnia associated with a psychiatric disorder show different slow wave activity dynamics.

PubMed

Walacik-Ufnal, Ewa; Piotrowska, Anna Justyna; Wołyńczyk-Gmaj, Dorota; Januszko, Piotr; Gmaj, Bartłomiej; Ufnal, Marcin; Kabat, Marek; Wojnar, Marcin

2017-01-01

The aim of the study was to compare electrophysiological parameters of night sleep in narcolepsy type 1 and hypersomnia associated with a psychiatric disorder. Fortyfour patients: 15 with narcolepsy type 1, 14 with hypersomnia associated with a psychiatric disorder and 15 age- and sex-matched controls participated in the study. The study subjects filled in the Athens Insomnia Scale (AIS) and the Beck Depression Inventory (BDI). The severity of daytime sleepiness was quantified subjectively using the Epworth Sleepiness Scale (ESS) and the Stanford Sleepiness Scale (SSS), and objectively using the Multiple Sleep Latency Test (MSLT). All subjects underwent polysomnography (PSG) on the two consecutive nights. The data from the second night was analysed. The slow wave activity (SWA, 1-4 Hz) was calculated for the three consecutive sleep cycles, and topographic delta power maps were plotted. In contrast to narcoleptics, psychiatric hypersomniacs had undisturbed nocturnal sleep, high sleep efficiency, normal non-rapid eye movement (NREM) and rapid eye movement (REM) sleep proportions, normal REM latency and sleep latencies on MSLT and PSG. The subjective and objective sleepiness was significantly higher in narcolepsy group than in psychiatric hypersomnia group. In all the study groups SWA was the most prominent in frontal areas, while the greatest between-group differences were found in the central areas. There were significant differences between the groups in SWA in the second NREM episode. The highest SWA was observed in the hypersomnia group, while the lowest in the narcolepsy group. Psychiatric hypersomniacs and controls did not differ in the SWA exponential decline over consecutive NREM episodes, whereas narcoleptics exhibited a steeper dissipation of sleep pressure from the first to the second NREM episode. In conclusion, narcolepsy type1 and hypersomnia associated with psychiatric disorder differ in the SWA dynamics. Narcoleptics presented with the altered

Comparing the Robustness of High-Frequency Traveling-Wave Tube Slow-Wave Circuits

NASA Technical Reports Server (NTRS)

Chevalier, Christine T.; Wilson, Jeffrey D.; Kory, Carol L.

2007-01-01

A three-dimensional electromagnetic field simulation software package was used to compute the cold-test parameters, phase velocity, on-axis interaction impedance, and attenuation, for several high-frequency traveling-wave tube slow-wave circuit geometries. This research effort determined the effects of variations in circuit dimensions on cold-test performance. The parameter variations were based on the tolerances of conventional micromachining techniques.

Estimation of Delta Wave by Mutual Information of Heartbeat During Sleep

NASA Astrophysics Data System (ADS)

Kurihara, Yosuke; Watanabe, Kajiro; Kobayashi, Kazuyuki; Tanaka, Hiroshi

The quality of sleep is evaluated based on the sleep stages judged by R-K method or the manual of American Academy of Sleep Medicine. The brainwaves, eye movements, and chin EMG of sleeping subjects are used for the judgment. These methods above, however, require some electrodes to be attached to the head and the face to obtain the brainwaves, eye movements, and chin EMG, thus making the measurements troublesome to be held on a daily basis. If non-invasive measurements of brainwaves, eye movements, and chin EMG are feasible, or their equivalent data can be estimated through other bio-signals, the monitoring of the quality of daily sleeps, which influences the health condition, will be easy. In this paper, we discuss the appearance rate of delta wave occurrences, which is deeply related with the depth of sleep, can be estimated based on the average amount of mutual information calculated by pulse wave signals and body movements measured non-invasively by the pneumatic method. As a result, the root mean square error between the appearance rate of delta wave occurrences measured with a polysomnography and the estimated delta pulse was 14.93%.

Relationship between delta power and the electrocardiogram-derived cardiopulmonary spectrogram: possible implications for assessing the effectiveness of sleep.

PubMed

Thomas, Robert Joseph; Mietus, Joseph E; Peng, Chung-Kang; Guo, Dan; Gozal, David; Montgomery-Downs, Hawley; Gottlieb, Daniel J; Wang, Cheng-Yen; Goldberger, Ary L

2014-01-01

The physiologic relationship between slow-wave activity (SWA) (0-4 Hz) on the electroencephalogram (EEG) and high-frequency (0.1-0.4 Hz) cardiopulmonary coupling (CPC) derived from electrocardiogram (ECG) sleep spectrograms is not known. Because high-frequency CPC appears to be a biomarker of stable sleep, we tested the hypothesis that that slow-wave EEG power would show a relatively fixed-time relationship to periods of high-frequency CPC. Furthermore, we speculated that this correlation would be independent of conventional nonrapid eye movement (NREM) sleep stages. We analyzed selected datasets from an archived polysomnography (PSG) database, the Sleep Heart Health Study I (SHHS-I). We employed the cross-correlation technique to measure the degree of which 2 signals are correlated as a function of a time lag between them. Correlation analyses between high-frequency CPC and delta power (computed both as absolute and normalized values) from 3150 subjects with an apnea-hypopnea index (AHI) of ≤5 events per hour of sleep were performed. The overall correlation (r) between delta power and high-frequency coupling (HFC) power was 0.40±0.18 (P=.001). Normalized delta power provided improved correlation relative to absolute delta power. Correlations were somewhat reduced in the second half relative to the first half of the night (r=0.45±0.20 vs r=0.34±0.23). Correlations were only affected by age in the eighth decade. There were no sex differences and only small racial or ethnic differences were noted. These results support a tight temporal relationship between slow wave power, both within and outside conventional slow wave sleep periods, and high frequency cardiopulmonary coupling, an ECG-derived biomarker of "stable" sleep. These findings raise mechanistic questions regarding the cross-system integration of neural and cardiopulmonary control during sleep. Copyright © 2013 Elsevier B.V. All rights reserved.

Slow oscillations orchestrating fast oscillations and memory consolidation.

PubMed

Mölle, Matthias; Born, Jan

2011-01-01

Slow-wave sleep (SWS) facilitates the consolidation of hippocampus-dependent declarative memory. Based on the standard two-stage memory model, we propose that memory consolidation during SWS represents a process of system consolidation which is orchestrated by the neocortical <1Hz electroencephalogram (EEG) slow oscillation and involves the reactivation of newly encoded representations and their subsequent redistribution from temporary hippocampal to neocortical long-term storage sites. Indeed, experimental induction of slow oscillations during non-rapid eye movement (non-REM) sleep by slowly alternating transcranial current stimulation distinctly improves consolidation of declarative memory. The slow oscillations temporally group neuronal activity into up-states of strongly enhanced neuronal activity and down-states of neuronal silence. In a feed-forward efferent action, this grouping is induced not only in the neocortex but also in other structures relevant to consolidation, namely the thalamus generating 10-15Hz spindles, and the hippocampus generating sharp wave-ripples, with the latter well known to accompany a replay of newly encoded memories taking place in hippocampal circuitries. The feed-forward synchronizing effect of the slow oscillation enables the formation of spindle-ripple events where ripples and accompanying reactivated hippocampal memory information become nested into the single troughs of spindles. Spindle-ripple events thus enable reactivated memory-related hippocampal information to be fed back to neocortical networks in the excitable slow oscillation up-state where they can induce enduring plastic synaptic changes underlying the effective formation of long-term memories. Copyright © 2011 Elsevier B.V. All rights reserved.

Sleep and Plasticity in Schizophrenia

PubMed Central

Sprecher, Kate E.; Ferrarelli, Fabio

2016-01-01

Schizophrenia is a devastating mental illness with a worldwide prevalence of approximately 1 %. Although the clinical features of the disorder were described over one hundred years ago, its neurobiology is still largely elusive despite several decades of research. Schizophrenia is associated with marked sleep disturbances and memory impairment. Above and beyond altered sleep architecture, sleep rhythms including slow waves and spindles are disrupted in schizophrenia. In the healthy brain, these rhythms reflect and participate in plastic processes during sleep. This chapter discusses evidence that schizophrenia patients exhibit dysfunction of sleep-mediated plasticity on a behavioral, cellular, and molecular level and offers suggestions on how the study of sleeping brain activity can shed light on the pathophysiological mechanisms of the disorder. PMID:25608723

Investigation of Slow-wave Activity Saturation during Surgical Anesthesia Reveals a Signature of Neural Inertia in Humans.

PubMed

Warnaby, Catherine E; Sleigh, Jamie W; Hight, Darren; Jbabdi, Saad; Tracey, Irene

2017-10-01

Previously, we showed experimentally that saturation of slow-wave activity provides a potentially individualized neurophysiologic endpoint for perception loss during anesthesia. Furthermore, it is clear that induction and emergence from anesthesia are not symmetrically reversible processes. The observed hysteresis is potentially underpinned by a neural inertia mechanism as proposed in animal studies. In an advanced secondary analysis of 393 individual electroencephalographic data sets, we used slow-wave activity dose-response relationships to parameterize slow-wave activity saturation during induction and emergence from surgical anesthesia. We determined whether neural inertia exists in humans by comparing slow-wave activity dose responses on induction and emergence. Slow-wave activity saturation occurs for different anesthetics and when opioids and muscle relaxants are used during surgery. There was wide interpatient variability in the hypnotic concentrations required to achieve slow-wave activity saturation. Age negatively correlated with power at slow-wave activity saturation. On emergence, we observed abrupt decreases in slow-wave activity dose responses coincident with recovery of behavioral responsiveness in ~33% individuals. These patients are more likely to have lower power at slow-wave activity saturation, be older, and suffer from short-term confusion on emergence. Slow-wave activity saturation during surgical anesthesia implies that large variability in dosing is required to achieve a targeted potential loss of perception in individual patients. A signature for neural inertia in humans is the maintenance of slow-wave activity even in the presence of very-low hypnotic concentrations during emergence from anesthesia.

Accurate Cold-Test Model of Helical TWT Slow-Wave Circuits

NASA Technical Reports Server (NTRS)

Kory, Carol L.; Dayton, James A., Jr.

1997-01-01

Recently, a method has been established to accurately calculate cold-test data for helical slow-wave structures using the three-dimensional electromagnetic computer code, MAFIA. Cold-test parameters have been calculated for several helical traveling-wave tube (TWT) slow-wave circuits possessing various support rod configurations, and results are presented here showing excellent agreement with experiment. The helical models include tape thickness, dielectric support shapes and material properties consistent with the actual circuits. The cold-test data from this helical model can be used as input into large-signal helical TWT interaction codes making it possible, for the first time, to design a complete TWT via computer simulation.

Changes in processing of masked stimuli across early- and late-night sleep: a study on behavior and brain potentials.

PubMed

Verleger, Rolf; Schuknecht, Simon-Vitus; Jaśkowski, Piotr; Wagner, Ullrich

2008-11-01

Sleep has proven to support the memory consolidation in many tasks including learning of perceptual skills. Explicit, conscious types of memory have been demonstrated to benefit particularly from slow-wave sleep (SWS), implicit, non-conscious types particularly from rapid eye movement (REM) sleep. By comparing the effects of early-night sleep, rich in SWS, and late-night sleep, rich in REM sleep, we aimed to separate the contribution of these two sleep stages in a metacontrast masking paradigm in which explicit and implicit aspects in perceptual learning could be assessed separately by stimulus identification and priming, respectively. We assumed that early sleep intervening between two sessions of task performance would specifically support stimulus identification, while late sleep would specifically support priming. Apart from overt behavior, event-related EEG potentials (ERPs) were measured to record the cortical mechanisms associated with behavioral changes across sleep. In contrast to our hypothesis, late-night sleep appeared to be more important for changes of behavior, both for stimulus identification, which tended to improve across late-night sleep, and for priming, with the increase of errors induced by masked stimuli correlating with the duration of REM sleep. ERP components proved sensitive to presence of target shapes in the masked stimuli and to their priming effects. Of these components, the N2 component, indicating processing of conflict, became larger across early-night sleep and was related to the duration of S4 sleep, the deepest substage of SWS containing particularly high portions of EEG slow waves. These findings suggest that sleep promotes perceptual learning primarily by its REM sleep portion, but indirectly also by way of improved action monitoring supported by deep slow-wave sleep.

Differential Effects of Sodium Oxybate and Baclofen on EEG, Sleep, Neurobehavioral Performance, and Memory

PubMed Central

Vienne, Julie; Lecciso, Gianpaolo; Constantinescu, Irina; Schwartz, Sophie; Franken, Paul; Heinzer, Raphaël; Tafti, Mehdi

2012-01-01

Study Objectives: Sodium oxybate (SO) is a GABAB agonist used to treat the sleep disorder narcolepsy. SO was shown to increase slow wave sleep (SWS) and EEG delta power (0.75-4.5 Hz), both indexes of NREM sleep (NREMS) intensity and depth, suggesting that SO enhances recuperative function of NREM. We investigated whether SO induces physiological deep sleep. Design: SO was administered before an afternoon nap or before the subsequent experimental night in 13 healthy volunteers. The effects of SO were compared to baclofen (BAC), another GABAB receptor agonist, to assess the role of GABAB receptors in the SO response. Measurements and Results: As expected, a nap significantly decreased sleep need and intensity the subsequent night. Both drugs reversed this nap effect on the subsequent night by decreasing sleep latency and increasing total sleep time, SWS during the first NREMS episode, and EEG delta and theta (0.75-7.25 Hz) power during NREMS. The SO-induced increase in EEG delta and theta power was, however, not specific to NREMS and was also observed during REM sleep (REMS) and wakefulness. Moreover, the high levels of delta power during a nap following SO administration did not affect delta power the following night. SO and BAC taken before the nap did not improve subsequent psychomotor performance and subjective alertness, or memory consolidation. Finally, SO and BAC strongly promoted the appearance of sleep onset REM periods. Conclusions: The SO-induced EEG slow waves seem not to be functionally similar to physiological slow waves. Our findings also suggest a role for GABAB receptors in REMS generation. Citation: Vienne J; Lecciso G; Constantinescu I; Schwartz S; Franken P; Heinzer R; Tafti M. Differential effects of sodium oxybate and baclofen on EEG, sleep, neurobehavioral performance, and memory. SLEEP 2012;35(8):1071–1084. PMID:22851803

The temporal structure of behaviour and sleep homeostasis.

PubMed

Vyazovskiy, Vladyslav V; Tobler, Irene

2012-01-01

The amount and architecture of vigilance states are governed by two distinct processes, which occur at different time scales. The first, a slow one, is related to a wake/sleep dependent homeostatic Process S, which occurs on a time scale of hours, and is reflected in the dynamics of NREM sleep EEG slow-wave activity. The second, a fast one, is manifested in a regular alternation of two sleep states--NREM and REM sleep, which occur, in rodents, on a time scale of ~5-10 minutes. Neither the mechanisms underlying the time constants of these two processes--the slow one and the fast one, nor their functional significance are understood. Notably, both processes are primarily apparent during sleep, while their potential manifestation during wakefulness is obscured by ongoing behaviour. Here, we find, in mice provided with running wheels, that the two sleep processes become clearly apparent also during waking at the level of behavior and brain activity. Specifically, the slow process was manifested in the total duration of waking periods starting from dark onset, while the fast process was apparent in a regular occurrence of running bouts during the waking periods. The dynamics of both processes were stable within individual animals, but showed large interindividual variability. Importantly, the two processes were not independent: the periodic structure of waking behaviour (fast process) appeared to be a strong predictor of the capacity to sustain continuous wakefulness (slow process). The data indicate that the temporal organization of vigilance states on both the fast and the slow time scales may arise from a common neurophysiologic mechanism.

Sleep instability and cognitive status in drug-resistant epilepsies.

PubMed

Pereira, Alessandra Marques; Bruni, Oliviero; Ferri, Raffaele; Nunes, Magda Lahorgue

2012-05-01

The aims of this study were to evaluate the sleep habits of children with drug resistant epilepsy and to correlate sleep abnormalities with epilepsy and level of intelligence. Twenty five subjects with drug resistant epilepsy (14 males, age range 2-16.4 years) were recruited for this study. A control group was formed by 23 normal children. Two instruments to assess sleep habits were administered to the patients with epilepsy: a questionnaire on sleep habits (to preschool children) and a questionnaire on sleep behavior (for children aged more than seven years old); a cognitive test (Wechsler Intelligence Scale for Children-WISC) was also performed. Patients underwent a complete polysomnographic study and sleep parameters, including CAP, were analyzed and correlated according to cognitive-behavioral measures in children with epilepsy. Children with drug-resistant epilepsy and severe mental retardation showed sleep abnormalities such as low sleep efficiency, high percentage of wakefulness after sleep onset, reduced slow wave sleep, and reduced REM sleep. Sleep microstructure evaluated by means of CAP analysis showed a decrease in A1 index during N3 in patients with more severe cognitive impairment. Children with epilepsy and cognitive impairment (n=10) had higher Sleep Behavior Questionnaire for Children (SBQC) total scores (65.60 ± 18.56) compared to children with epilepsy and normal IQ (50.00 ± 10.40), p<0.05. Children with drug-resistant epilepsy have a greater incidence of sleep problems regarding qualitative aspects, macrostructure, and CAP. The decrease of CAP rate and of A1, mainly during slow wave sleep (associated to REM sleep reduction), might represent a sleep microstructural pattern of intellectual disability. Copyright © 2012 Elsevier B.V. All rights reserved.

No effect of odor-induced memory reactivation during REM sleep on declarative memory stability

PubMed Central

Cordi, Maren J.; Diekelmann, Susanne; Born, Jan; Rasch, Björn

2014-01-01

Memory reactivations in hippocampal brain areas are critically involved in memory consolidation processes during sleep. In particular, specific firing patterns of hippocampal place cells observed during learning are replayed during subsequent sleep and rest in rodents. In humans, experimentally inducing hippocampal memory reactivations during slow-wave sleep (but not during wakefulness) benefits consolidation and immediately stabilizes declarative memories against future interference. Importantly, spontaneous hippocampal replay activity can also be observed during rapid eye movement (REM) sleep and some authors have suggested that replay during REM sleep is related to processes of memory consolidation. However, the functional role of reactivations during REM sleep for memory stability is still unclear. Here, we reactivated memories during REM sleep and examined its consequences for the stability of declarative memories. After 3 h of early, slow-wave sleep (SWS) rich sleep, 16 healthy young adults learned a 2-D object location task in the presence of a contextual odor. During subsequent REM sleep, participants were either re-exposed to the odor or to an odorless vehicle, in a counterbalanced within subject design. Reactivation was followed by an interference learning task to probe memory stability after awakening. We show that odor-induced memory reactivation during REM sleep does not stabilize memories against future interference. We propose that the beneficial effect of reactivation during sleep on memory stability might be critically linked to processes characterizing SWS including, e.g., slow oscillatory activity, sleep spindles, or low cholinergic tone, which are required for a successful redistribution of memories from medial temporal lobe regions to neocortical long-term stores. PMID:25225474

Enhanced traveling wave amplification of co-planar slow wave structure by extended phase-matching

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palm, Andrew; Sirigiri, Jagadishwar; Shin, Young-Min, E-mail: yshin@niu.edu

2015-09-15

The electron beam co-propagating with slow waves in a staggered double grating array (SDGA) efficiently amplifies millimeter and sub-millimeter waves over a wide spectrum. Our theoretical and numerical analyses show that the power amplification in the fundamental passband is enhanced by the extended beam-wave phase-matching. Particle-in-cell simulations on the SDGA slow wave structure, designed with 10.4 keV and 50–100 mA sheet beam, indicate that maintaining beam-wave synchronization along the entire length of the circuit improves the gain by 7.3% leading to a total gain of 28 dB, corresponding to 62 W saturated power at the middle of operating band, and a 3-dB bandwidthmore » of 7 GHz with 10.5% at V-band (73.5 GHz center frequency) with saturated peak power reaching 80 W and 28 dB at 71 GHz. These results also show a reasonably good agreement with analytic calculations based on Pierce small signal gain theory.« less

Modeling aircraft noise induced sleep disturbance

NASA Astrophysics Data System (ADS)

McGuire, Sarah M.

One of the primary impacts of aircraft noise on a community is its disruption of sleep. Aircraft noise increases the time to fall asleep, the number of awakenings, and decreases the amount of rapid eye movement and slow wave sleep. Understanding these changes in sleep may be important as they could increase the risk for developing next-day effects such as sleepiness and reduced performance and long-term health effects such as cardiovascular disease. There are models that have been developed to predict the effect of aircraft noise on sleep. However, most of these models only predict the percentage of the population that is awakened. Markov and nonlinear dynamic models have been developed to predict an individual's sleep structure during the night. However, both of these models have limitations. The Markov model only accounts for whether an aircraft event occurred not the noise level or other sound characteristics of the event that may affect the degree of disturbance. The nonlinear dynamic models were developed to describe normal sleep regulation and do not have a noise effects component. In addition, the nonlinear dynamic models have slow dynamics which make it difficult to predict short duration awakenings which occur both spontaneously and as a result of nighttime noise exposure. The purpose of this research was to examine these sleep structure models to determine how they could be altered to predict the effect of aircraft noise on sleep. Different approaches for adding a noise level dependence to the Markov Model was explored and the modified model was validated by comparing predictions to behavioral awakening data. In order to determine how to add faster dynamics to the nonlinear dynamic sleep models it was necessary to have a more detailed sleep stage classification than was available from visual scoring of sleep data. An automatic sleep stage classification algorithm was developed which extracts different features of polysomnography data including the

Sleep and Breathing in High Altitude Pulmonary Edema Susceptible Subjects at 4,559 Meters

PubMed Central

Nussbaumer-Ochsner, Yvonne; Schuepfer, Nicole; Ursprung, Justyna; Siebenmann, Christoph; Maggiorini, Marco; Bloch, Konrad E.

2012-01-01

Study objectives: Susceptible subjects ascending rapidly to high altitude develop pulmonary edema (HAPE). We evaluated whether HAPE leads to sleep and breathing disturbances that are alleviated by dexamethasone. Design: Double-blind, randomized, placebo-controlled trial with open-label extension. Setting: One night in sleep laboratory at 490 m, 2 nights in mountain hut at 4,559 m. Participants: 21 HAPE susceptibles. Intervention: Dexamethasone 2 × 8 mg/d, either 24 h prior to ascent and at 4,559 m (dex-early), or started on day 2 at 4,559 m only (dex-late). Measurements: Polysomnography, questionnaires on sleep and acute mountain sickness. Results: Polysomnographies at 490 m were normal. In dex-late (n = 12) at 4,559 m, night 1 and 3, median oxygen saturation was 71% and 80%, apnea/hypopnea index 91.3/h and 9.6/h. In dex-early (n = 9), corresponding values were 78% and 79%, and 85.3/h and 52.3/h (P < 0.05 vs. 490 m, all instances). In dex-late, ascending from 490 m to 4,559 m (night 1), sleep efficiency decreased from 91% to 65%, slow wave sleep from 20% to 8% (P < 0.05, both instances). In dex-early, corresponding sleep efficiencies were 96% and 95%, slow wave sleep 18% and 9% (P < 0.05). From night 1 to 3, sleep efficiency remained unchanged in both groups while slow wave sleep increased to 20% in dex-late (P < 0.01). Compared to dex-early, initial AMS scores in dex-late were higher but improved during stay at altitude. Conclusions: HAPE susceptibles ascending rapidly to high altitude experience pronounced nocturnal hypoxemia, and reduced sleep efficiency and deep sleep. Dexamethasone taken before ascent prevents severe hypoxemia and sleep disturbances, while dexamethasone taken 24 h after arrival at 4,559 m increases oxygenation and deep sleep. Citation: Nussbaumer-Ochsner Y; Schuepfer N; Ursprung J; Siebenmann C; Maggiorini M; Bloch KE. Sleep and breathing in high altitude pulmonary edema susceptible subjects at 4,559 meters. SLEEP 2012;35(10):1413-1421. PMID

Catechol-O-Methyltransferase Val158Met Polymorphism Associates with Individual Differences in Sleep Physiologic Responses to Chronic Sleep Loss

PubMed Central

Goel, Namni; Banks, Siobhan; Lin, Ling; Mignot, Emmanuel; Dinges, David F.

2011-01-01

Background The COMT Val158Met polymorphism modulates cortical dopaminergic catabolism, and predicts individual differences in prefrontal executive functioning in healthy adults and schizophrenic patients, and associates with EEG differences during sleep loss. We assessed whether the COMT Val158Met polymorphism was a novel marker in healthy adults of differential vulnerability to chronic partial sleep deprivation (PSD), a condition distinct from total sleep loss and one experienced by millions on a daily and persistent basis. Methodology/Principal Findings 20 Met/Met, 64 Val/Met, and 45 Val/Val subjects participated in a protocol of two baseline 10h time in bed (TIB) nights followed by five consecutive 4 h TIB nights. Met/Met subjects showed differentially steeper declines in non-REM EEG slow-wave energy (SWE)—the putative homeostatic marker of sleep drive—during PSD, despite comparable baseline SWE declines. Val/Val subjects showed differentially smaller increases in slow-wave sleep and smaller reductions in stage 2 sleep during PSD, and had more stage 1 sleep across nights and a shorter baseline REM sleep latency. The genotypes, however, did not differ in performance across various executive function and cognitive tasks and showed comparable increases in subjective and physiological sleepiness in response to chronic sleep loss. Met/Met genotypic and Met allelic frequencies were higher in whites than African Americans. Conclusions/Significance The COMT Val158Met polymorphism may be a genetic biomarker for predicting individual differences in sleep physiology—but not in cognitive and executive functioning—resulting from sleep loss in a healthy, racially-diverse adult population of men and women. Beyond healthy sleepers, our results may also provide insight for predicting sleep loss responses in patients with schizophrenia and other psychiatric disorders, since these groups repeatedly experience chronically-curtailed sleep and demonstrate COMT

Comparison of a single-channel EEG sleep study to polysomnography

PubMed Central

Lucey, Brendan P.; McLeland, Jennifer S.; Toedebusch, Cristina D.; Boyd, Jill; Morris, John C.; Landsness, Eric C.; Yamada, Kelvin; Holtzman, David M.

2016-01-01

Summary An accurate home sleep study to assess electroencephalography (EEG)-based sleep stages and EEG power would be advantageous for both clinical and research purposes, such as for longitudinal studies measuring changes in sleep stages over time. The purpose of this study was to compare sleep scoring of a single-channel EEG recorded simultaneously on the forehead against attended polysomnography. Participants were recruited from both a clinical sleep center and a longitudinal research study investigating cognitively-normal aging and Alzheimer's disease. Analysis for overall epoch-by-epoch agreement found strong and substantial agreement between the single-channel EEG compared to polysomnography (kappa=0.67). Slow wave activity in the frontal regions was also similar when comparing the single-channel EEG device to polysomnography. As expected, stage N1 showed poor agreement (sensitivity 0.2) due to lack of occipital electrodes. Other sleep parameters such as sleep latency and REM onset latency had decreased agreement. Participants with disrupted sleep consolidation, such as from obstructive sleep apnea, also had poor agreement. We suspect that disagreement in sleep parameters between the single-channel EEG and polysomnography is partially due to altered waveform morphology and/or poorer signal quality in the single-channel derivation. Our results show that single-channel EEG provides comparable results to polysomnography in assessing REM, combined stages N2 and N3 sleep, and several other parameters including frontal slow wave activity. The data establish that single-channel EEG can be a useful research tool. PMID:27252090

Excessive sleep need following traumatic brain injury: a case-control study of 36 patients.

PubMed

Sommerauer, Michael; Valko, Philipp O; Werth, Esther; Baumann, Christian R

2013-12-01

Increased sleep need following traumatic brain injury, referred to in this study as post-traumatic pleiosomnia, is common, but so far its clinical impact and therapeutic implications have not been characterized. We present a case-control study of 36 patients with post-traumatic pleiosomnia, defined by an increased sleep need of at least 2 h per 24 h after traumatic brain injury, compared to 36 controls. We assessed detailed history, sleep-activity patterns with sleep logs and actigraphy, nocturnal sleep with polysomnography and daytime sleep propensity with multiple sleep latency tests. Actigraphy recordings revealed that traumatic brain injury (TBI) patients had longer estimated sleep durations than controls (10.8 h per 24 h, compared to 7.3 h). When using sleep logs, TBI patients underestimated their sleep need. During nocturnal sleep, patients had higher amounts of slow-wave sleep than controls (20 versus 13.8%). Multiple sleep latency tests revealed excessive daytime sleepiness in 15 patients (42%), and 10 of them had signs of chronic sleep deprivation. We conclude that post-traumatic pleiosomnia may be even more frequent than reported previously, because affected patients often underestimate their actual sleep need. Furthermore, these patients exhibit an increase in slow-wave sleep which may reflect recovery mechanisms, intrinsic consequences of diffuse brain damage or relative sleep deprivation. © 2013 European Sleep Research Society.

Sex differences in objective measures of sleep in post-traumatic stress disorder and healthy control subjects.

PubMed

Richards, Anne; Metzler, Thomas J; Ruoff, Leslie M; Inslicht, Sabra S; Rao, Madhu; Talbot, Lisa S; Neylan, Thomas C

2013-12-01

A growing literature shows prominent sex effects for risk for post-traumatic stress disorder and associated medical comorbid burden. Previous research indicates that post-traumatic stress disorder is associated with reduced slow wave sleep, which may have implications for overall health, and abnormalities in rapid eye movement sleep, which have been implicated in specific post-traumatic stress disorder symptoms, but most research has been conducted in male subjects. We therefore sought to compare objective measures of sleep in male and female post-traumatic stress disorder subjects with age- and sex-matched control subjects. We used a cross-sectional, 2 × 2 design (post-traumatic stress disorder/control × female/male) involving83 medically healthy, non-medicated adults aged 19-39 years in the inpatient sleep laboratory. Visual electroencephalographic analysis demonstrated that post-traumatic stress disorder was associated with lower slow wave sleep duration (F(3,82)  = 7.63, P = 0.007) and slow wave sleep percentage (F(3,82)  = 6.11, P = 0.016). There was also a group × sex interaction effect for rapid eye movement sleep duration (F(3,82)  = 4.08, P = 0.047) and rapid eye movement sleep percentage (F(3,82)  = 4.30, P = 0.041), explained by greater rapid eye movement sleep in post-traumatic stress disorder females compared to control females, a difference not seen in male subjects. Quantitative electroencephalography analysis demonstrated that post-traumatic stress disorder was associated with lower energy in the delta spectrum (F(3,82)  = 6.79, P = 0.011) in non-rapid eye movement sleep. Slow wave sleep and delta findings were more pronounced in males. Removal of post-traumatic stress disorder subjects with comorbid major depressive disorder, who had greater post-traumatic stress disorder severity, strengthened delta effects but reduced rapid eye movement effects to non-significance. These findings support previous evidence that post

Shifting from Implicit to Explicit Knowledge: Different Roles of Early- and Late-Night Sleep

ERIC Educational Resources Information Center

Yordanova, Juliana; Kolev, Vasil; Verleger, Rolf; Bataghva, Zhamak; Born, Jan; Wagner, Ullrich

2008-01-01

Sleep has been shown to promote the generation of explicit knowledge as indicated by the gain of insight into previously unrecognized task regularities. Here, we explored whether this generation of explicit knowledge depends on pre-sleep implicit knowledge, and specified the differential roles of slow-wave sleep (SWS) vs. rapid eye movement (REM)…

Emotional bias of sleep-dependent processing shifts from negative to positive with aging.

PubMed

Jones, Bethany J; Schultz, Kurt S; Adams, Sydney; Baran, Bengi; Spencer, Rebecca M C

2016-09-01

Age-related memory decline has been proposed to result partially from impairments in memory consolidation over sleep. However, such decline may reflect a shift toward selective processing of positive information with age rather than impaired sleep-related mechanisms. In the present study, young and older adults viewed negative and neutral pictures or positive and neutral pictures and underwent a recognition test after sleep or wake. Subjective emotional reactivity and affect were also measured. Compared with waking, sleep preserved valence ratings and memory for positive but not negative pictures in older adults and negative but not positive pictures in young adults. In older adults, memory for positive pictures was associated with slow wave sleep. Furthermore, slow wave sleep predicted positive affect in older adults but was inversely related to positive affect in young adults. These relationships were strongest for older adults with high memory for positive pictures and young adults with high memory for negative pictures. Collectively, these results indicate preserved but selective sleep-dependent memory processing with healthy aging that may be biased to enhance emotional well-being. Copyright © 2016 Elsevier Inc. All rights reserved.

[The ultradian rhythm of sleep: diverse relations with pituitary and adrenal hormones].

PubMed

Brandenberger, G

2003-11-01

We evaluated the relationship between the ultradian rhythm of sleep and the secretory episodes of pituitary-adrenal hormones. Prolactin (PRL) and TSH exhibited opposite phase relationships with delta waves, PRL increasing and TSH decreasing when delta waves developed. Delta waves never increased together with an increase in cortisol secretion. They oscillated independently from each other throughout the 24 hour period, but when they were present at the same time, they oscillated in opposing phases. Concerning growth hormone (GH), its major peak which occurred shortly after sleep onset in association with the first slow wave sleep episode was blunted during sleep deprivation. However, this blunting was compensated during the day, so that the amount of GH secreted during a 24-hr period was similar whether or not a person had slept during the night. The physiological significance and the clinical implications of the various relationships of the endocrine systems with sleep are poorly known.

Coffee, caffeine, and sleep: A systematic review of epidemiological studies and randomized controlled trials.

PubMed

Clark, Ian; Landolt, Hans Peter

2017-02-01

Caffeine is the most widely consumed psychoactive substance in the world. It is readily available in coffee and other foods and beverages, and is used to mitigate sleepiness, enhance performance, and treat apnea in premature infants. This review systematically explores evidence from epidemiological studies and randomized controlled trials as to whether coffee and caffeine have deleterious effects on sleep. Caffeine typically prolonged sleep latency, reduced total sleep time and sleep efficiency, and worsened perceived sleep quality. Slow-wave sleep and electroencephalographic (EEG) slow-wave activity were typically reduced, whereas stage-1, wakefulness, and arousals were increased. Dose- and timing-response relationships were established. The sleep of older adults may be more sensitive to caffeine compared to younger adults. Pronounced individual differences are also present in young people, and genetic studies isolated functional polymorphisms of genes implicated in adenosine neurotransmission and metabolism contributing to individual sensitivity to sleep disruption by caffeine. Most studies were conducted in male adults of Western countries, which limits the generalizability of the findings. Given the importance of good sleep for general health and functioning, longitudinal investigations aimed at establishing possible causal relationships among coffee- and caffeine-induced changes in sleep quality and health development are warranted. Copyright © 2016 Elsevier Ltd. All rights reserved.

Improved Visualization of Gastrointestinal Slow Wave Propagation Using a Novel Wavefront-Orientation Interpolation Technique.

PubMed

Mayne, Terence P; Paskaranandavadivel, Niranchan; Erickson, Jonathan C; OGrady, Gregory; Cheng, Leo K; Angeli, Timothy R

2018-02-01

High-resolution mapping of gastrointestinal (GI) slow waves is a valuable technique for research and clinical applications. Interpretation of high-resolution GI mapping data relies on animations of slow wave propagation, but current methods remain as rudimentary, pixelated electrode activation animations. This study aimed to develop improved methods of visualizing high-resolution slow wave recordings that increases ease of interpretation. The novel method of "wavefront-orientation" interpolation was created to account for the planar movement of the slow wave wavefront, negate any need for distance calculations, remain robust in atypical wavefronts (i.e., dysrhythmias), and produce an appropriate interpolation boundary. The wavefront-orientation method determines the orthogonal wavefront direction and calculates interpolated values as the mean slow wave activation-time (AT) of the pair of linearly adjacent electrodes along that direction. Stairstep upsampling increased smoothness and clarity. Animation accuracy of 17 human high-resolution slow wave recordings (64-256 electrodes) was verified by visual comparison to the prior method showing a clear improvement in wave smoothness that enabled more accurate interpretation of propagation, as confirmed by an assessment of clinical applicability performed by eight GI clinicians. Quantitatively, the new method produced accurate interpolation values compared to experimental data (mean difference 0.02 ± 0.05 s) and was accurate when applied solely to dysrhythmic data (0.02 ± 0.06 s), both within the error in manual AT marking (mean 0.2 s). Mean interpolation processing time was 6.0 s per wave. These novel methods provide a validated visualization platform that will improve analysis of high-resolution GI mapping in research and clinical translation.

Precipitating factors of somnambulism: impact of sleep deprivation and forced arousals.

PubMed

Pilon, Mathieu; Montplaisir, Jacques; Zadra, Antonio

2008-06-10

Experimental attempts to induce sleepwalking with forced arousals during slow-wave sleep (SWS) have yielded mixed results in children and have not been investigated in adult patients. We hypothesized that the combination of sleep deprivation and external stimulation would increase the probability of inducing somnambulistic episodes in sleepwalkers recorded in the sleep laboratory. The main goal of this study was to assess the effects of forced arousals from auditory stimuli (AS) in adult sleepwalkers and control subjects during normal sleep and following post-sleep deprivation recovery sleep. Ten sleepwalkers and 10 controls were investigated. After a baseline night, participants were presented with AS at predetermined sleep stages either during normal sleep or recovery sleep following 25 hours of sleep deprivation. One week later, the conditions with AS were reversed. No somnambulistic episodes were induced in controls. When compared to the effects of AS during sleepwalkers' normal sleep, the presentation of AS during sleepwalkers' recovery sleep significantly increased their efficacy in experimentally inducing somnambulistic events and a significantly greater proportion of sleepwalkers (100%) experienced at least one induced episode during recovery SWS as compared to normal SWS (30%). There was no significant difference between the mean intensity of AS that induced episodes during sleepwalkers' SWS and the mean intensity of AS that awakened sleepwalkers and controls from SWS. Sleep deprivation and forced arousals during slow-wave sleep can induce somnambulistic episodes in predisposed adults. The results highlight the potential value of this protocol in establishing a video-polysomnographically based diagnosis for sleepwalking.

Every slow-wave impulse is associated with motor activity of the human stomach.

PubMed

Hocke, Michael; Schöne, Ulrike; Richert, Hendryk; Görnert, Peter; Keller, Jutta; Layer, Peter; Stallmach, Andreas

2009-04-01

Using a newly developed high-resolution three-dimensional magnetic detector system (3D-MAGMA), we observed periodical movements of a small magnetic marker in the human stomach at the typical gastric slow-wave frequency, that is 3 min(-1). Thus we hypothesized that each gastric slow wave induces a motor response that is not strong enough to be detected by conventional methods. Electrogastrographies (EGG, Medtronic, Minneapolis, MN) for measurement of gastric slow waves and 3D-MAGMA (Innovent, Jena, Germany) measurements were simultaneously performed in 21 healthy volunteers (10 men, 40.4+/-13.6 yr; 11 women, 35.8+/-11.6 yr). The 3D-MAGMA system contains 27 highly sensitive magnetic field sensors that are able to locate a magnetic pill inside a human body with an accuracy of +/-5 mm or less in position and +/-2 degrees in orientation at a frequency of 50 Hz. Gastric transit time of the magnetic marker ranged from 19 to 154 min. The mean dominant EGG frequency while the marker was in the stomach was 2.87+/-0.15 cpm. The mean dominant 3D-MAGMA frequency during this interval was nearly identical; that is, 2.85+/-0.15 movements per minute. We observed a strong linear correlation between individual dominant EGG and 3D-MAGMA frequency (R=0.66, P=0.0011). Our findings suggest that each gastric slow wave induces a minute contraction that is too small to be detected by conventional motility investigations but can be recorded by the 3D-MAGMA system. The present slow-wave theory that assumes that the slow wave is a pure electrical signal should be reconsidered.

Non-thermal continuous and modulated electromagnetic radiation fields effects on sleep EEG of rats☆

PubMed Central

Mohammed, Haitham S.; Fahmy, Heba M.; Radwan, Nasr M.; Elsayed, Anwar A.

2012-01-01

In the present study, the alteration in the sleep EEG in rats due to chronic exposure to low-level non-thermal electromagnetic radiation was investigated. Two types of radiation fields were used; 900 MHz unmodulated wave and 900 MHz modulated at 8 and 16 Hz waves. Animals has exposed to radiation fields for 1 month (1 h/day). EEG power spectral analyses of exposed and control animals during slow wave sleep (SWS) and rapid eye movement sleep (REM sleep) revealed that the REM sleep is more susceptible to modulated radiofrequency radiation fields (RFR) than the SWS. The latency of REM sleep increased due to radiation exposure indicating a change in the ultradian rhythm of normal sleep cycles. The cumulative and irreversible effect of radiation exposure was proposed and the interaction of the extremely low frequency radiation with the similar EEG frequencies was suggested. PMID:25685416

Frontal predominance of a relative increase in sleep delta and theta EEG activity after sleep loss in humans

NASA Technical Reports Server (NTRS)

Cajochen, C.; Foy, R.; Dijk, D. J.; Czeisler, C. A. (Principal Investigator)

1999-01-01

The effect of sleep deprivation (40 h) on topographic and temporal aspects of electroencephalographic (EEG) activity during sleep was investigated by all night spectral analysis in six young volunteers. The sleep-deprivation-induced increase of EEG power density in the delta and theta frequencies (1-7 Hz) during nonREM sleep, assessed along the antero-posterior axis (midline: Fz, Cz, Pz, Oz), was significantly larger in the more frontal derivations (Fz, Cz) than in the more parietal derivations (Pz, Oz). This frequency-specific frontal predominance was already present in the first 30 min of recovery sleep, and dissipated in the course of the 8-h sleep episode. The data demonstrate that the enhancement of slow wave EEG activity during sleep following extended wakefulness is most pronounced in frontal cortical areas.

The multiple time scales of sleep dynamics as a challenge for modelling the sleeping brain.

PubMed

Olbrich, Eckehard; Claussen, Jens Christian; Achermann, Peter

2011-10-13

A particular property of the sleeping brain is that it exhibits dynamics on very different time scales ranging from the typical sleep oscillations such as sleep spindles and slow waves that can be observed in electroencephalogram (EEG) segments of several seconds duration over the transitions between the different sleep stages on a time scale of minutes to the dynamical processes involved in sleep regulation with typical time constants in the range of hours. There is an increasing body of work on mathematical and computational models addressing these different dynamics, however, usually considering only processes on a single time scale. In this paper, we review and present a new analysis of the dynamics of human sleep EEG at the different time scales and relate the findings to recent modelling efforts pointing out both the achievements and remaining challenges.

Prolonged enhancement of REM sleep produced by carbachol microinjection into the amygdala.

PubMed

Calvo, J M; Simón-Arceo, K; Fernández-Mas, R

1996-01-31

The effect on sleep organization of carbachol microinjected into different amygdaloid nuclei was analysed in 12 cats. Single carbachol doses of 8 micrograms in 0.50 microliter saline were delivered unilaterally or bilaterally into the central, basal, lateral or basolateral amygdaloid nucleus. Carbachol administration into the central nucleus induced a prolonged (5 days) enhancement of both REM sleep and its preceeding slow wave sleep episodes with PGO waves (sommeil phasique a ondes lentes, SPHOL), which was more pronounced following bilateral than unilateral carbachol administration. However, neither SPHOL nor REM sleep changes were produced by administration of carbachol into the other amygdaloid nuclei. We conclude that cholinergic activation of the central amygdaloid nucleus produces a long-term facilitation of REM sleep occurrence.

Polysomnographic study of nocturnal sleep in idiopathic hypersomnia without long sleep time.

PubMed

Pizza, Fabio; Ferri, Raffaele; Poli, Francesca; Vandi, Stefano; Cosentino, Filomena I I; Plazzi, Giuseppe

2013-04-01

We investigated nocturnal sleep abnormalities in 19 patients with idiopathic hypersomnia without long sleep time (IH) in comparison with two age- and sex- matched control groups of 13 normal subjects (C) and of 17 patients with narcolepsy with cataplexy (NC), the latter considered as the extreme of excessive daytime sleepiness (EDS). Sleep macro- and micro- (i.e. cyclic alternating pattern, CAP) structure as well as quantitative analysis of EEG, of periodic leg movements during sleep (PLMS), and of muscle tone during REM sleep were compared across groups. IH and NC patients slept more than C subjects, but IH showed the highest levels of sleep fragmentation (e.g. awakenings), associated with a CAP rate higher than NC during lighter sleep stages and lower than C during slow wave sleep respectively, and with the highest relative amount of A3 and the lowest of A1 subtypes. IH showed a delta power in between C and NC groups, whereas muscle tone and PLMS had normal characteristics. A peculiar profile of microstructural sleep abnormalities may contribute to sleep fragmentation and, possibly, EDS in IH. © 2012 European Sleep Research Society.

Optimizing sleep/wake schedules in space: Sleep during chronic nocturnal sleep restriction with and without diurnal naps

NASA Astrophysics Data System (ADS)

Mollicone, Daniel J.; Van Dongen, Hans P. A.; Dinges, David F.

2007-02-01

Effective sleep/wake schedules for space operations must balance severe time constraints with allocating sufficient time for sleep in order to sustain high levels of neurobehavioral performance. Developing such schedules requires knowledge about the relationship between scheduled "time in bed" (TIB) and actual physiological sleep obtained. A ground-based laboratory study in N=93 healthy adult subjects was conducted to investigate physiological sleep obtained in a range of restricted sleep schedules. Eighteen different conditions with restricted nocturnal anchor sleep, with and without diurnal naps, were examined in a response surface mapping paradigm. Sleep efficiency was found to be a function of total TIB per 24 h regardless of how the sleep was divided among nocturnal anchor sleep and diurnal nap sleep periods. The amounts of sleep stages 1+2 and REM showed more complex relationships with the durations of the anchor and nap sleep periods, while slow-wave sleep was essentially preserved among the different conditions of the experiment. The results of the study indicated that when sleep was chronically restricted, sleep duration was largely unaffected by whether the sleep was placed nocturnally or split between nocturnal anchor sleep periods and daytime naps. Having thus assessed that split-sleep schedules are feasible in terms of obtaining physiological sleep, further research will reveal whether these schedules and the associated variations in the distribution of sleep stages may be advantageous in mitigating neurobehavioral performance impairment in the face of limited time for sleep.

Independent associations between fatty acids and sleep quality among obese patients with obstructive sleep apnoea syndrome.

PubMed

Papandreou, Christopher

2013-10-01

The aim of this study was to examine the relationships between gluteal adipose tissue fatty acids and sleep quality in obese patients with obstructive sleep apnoea syndrome after controlling for possible confounders. Sixty-three patients with obstructive sleep apnoea syndrome based on overnight attended polysomnography were included. Gluteal adipose tissue fatty acids were analysed by gas chromatography. Anthropometric measurements were carried out. Depressive symptoms were assessed by the Zung Self-rating Depression Scale. Saturated fatty acids were positively related to total sleep time, sleep efficiency and rapid eye movement sleep. Significant positive associations were found between polyunsaturated fatty acids and sleep efficiency and rapid eye movement sleep. Moreover, n-3 fatty acids were positively associated with sleep efficiency, slow wave sleep and rapid eye movement sleep. This study revealed independent associations between certain gluteal adipose tissue fatty acids and sleep quality after controlling for age, gender, obesity, obstructive sleep apnoea syndrome indices and Zung Self-rating Depression Scale scores in patients with moderate to severe obstructive sleep apnoea syndrome. © 2013 European Sleep Research Society.

Changes in Processing of Masked Stimuli across Early- and Late-Night Sleep: A Study on Behavior and Brain Potentials

ERIC Educational Resources Information Center

Verleger, Rolf; Schuknecht, Simon-Vitus; Jaskowski, Piotr; Wagner, Ullrich

2008-01-01

Sleep has proven to support the memory consolidation in many tasks including learning of perceptual skills. Explicit, conscious types of memory have been demonstrated to benefit particularly from slow-wave sleep (SWS), implicit, non-conscious types particularly from rapid eye movement (REM) sleep. By comparing the effects of early-night sleep,…

Cellular and chemical neuroscience of mammalian sleep.

PubMed

Datta, Subimal

2010-05-01

Extraordinary strides have been made toward understanding the complexities and regulatory mechanisms of sleep over the past two decades thanks to the help of rapidly evolving technologies. At its most basic level, mammalian sleep is a restorative process of the brain and body. Beyond its primary restorative purpose, sleep is essential for a number of vital functions. Our primary research interest is to understand the cellular and molecular mechanisms underlying the regulation of sleep and its cognitive functions. Here I will reflect on our own research contributions to 50 years of extraordinary advances in the neurobiology of slow-wave sleep (SWS) and rapid eye movement (REM) sleep regulation. I conclude this review by suggesting some potential future directions to further our understanding of the neurobiology of sleep. Copyright 2010 Elsevier B.V. All rights reserved.

Sleeping on the motor engram: The multifaceted nature of sleep-related motor memory consolidation.

PubMed

King, Bradley R; Hoedlmoser, Kerstin; Hirschauer, Franziska; Dolfen, Nina; Albouy, Genevieve

2017-09-01

For the past two decades, it has generally been accepted that sleep benefits motor memory consolidation processes. This notion, however, has been challenged by recent studies and thus the sleep and motor memory story is equivocal. Currently, and in contrast to the declarative memory domain, a comprehensive overview and synthesis of the effects of post-learning sleep on the behavioral and neural correlates of motor memory consolidation is not available. We therefore provide an extensive review of the literature in order to highlight that sleep-dependent motor memory consolidation depends upon multiple boundary conditions, including particular features of the motor task, the recruitment of relevant neural substrates (and the hippocampus in particular), as well as the specific architecture of the intervening sleep period (specifically, sleep spindle and slow wave activity). For our field to continue to advance, future research must consider the multifaceted nature of sleep-related motor memory consolidation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Shock Formation and Energy Dissipation of Slow Magnetosonic Waves in Coronal Plumes

NASA Technical Reports Server (NTRS)

Cuntz, M.; Suess, S. T.

2003-01-01

We study the shock formation and energy dissipation of slow magnetosonic waves in coronal plumes. The wave parameters and the spreading function of the plumes as well as the base magnetic field strength are given by empirical constraints mostly from SOHO/UVCS. Our models show that shock formation occurs at low coronal heights, i.e., within 1.3 bun, depending on the model parameters. In addition, following analytical estimates, we show that scale height of energy dissipation by the shocks ranges between 0.15 and 0.45 Rsun. This implies that shock heating by slow magnetosonic waves is relevant at most heights, even though this type of waves is apparently not a solely operating energy supply mechanism.

Evidence of Biot Slow Waves in Electroseismic Measurementss on Laboratory-Scale

NASA Astrophysics Data System (ADS)

Devi, M. S.

2015-12-01

Electroseismic methods which are the opposite of seismo-electric methods have only been little investigated up to now especially in the near surface scale. These methods can generate the solid-fluid relative movement induced by the electric potential in fluid-filled porous media. These methods are the response of electro-osmosis due to the presence of the electrical double layer. Laboratory experiments and numerical simulations of electroseismic studies have been performed. Electroseismic measurements conducted in micro glass beads saturated with demineralized water. Pair of 37 x 37 mm square aluminium grids with 2 mm of aperture and 4 mm of spacing is used as the electric dipole that connected to the electric power source with the voltage output 150 V. A laser doppler vibrometer is the system used to measure velocity of vibrating objects during measurements by placing a line of reflective paper on the surface of media that scattered back a helium-neon laser. The results in homogeneous media shows that the compressional waves induced by an electric signal. We confirm that the results are not the effects of thermal expansion. We also noticed that there are two kinds of the compressional waves are recorded: fast and slow P-waves. The latter, Biot slow waves, indicate the dominant amplitude. Moreover, we found that the transition frequency (ωc) of Biot slow waves depends on mechanical parameters such as porosity and permeability. The ωc is not affected when varying conductivity of the fluid from 25 - 320 μS/cm, although the amplitude slightly changed. For the results in two layer media by placing a sandstone as a top layer shows that a large amount of transmission seismic waves (apparently as Biot slow waves) rather than converted electromagnetic-to-seismic waves. These properties have also been simulated with full waveform numerical simulations relying on Pride's (1994) using our computer code (Garambois & Dietrich, 2002). If it is true that the electric source in

Enhanced Slow-Wave EEG Activity and Thermoregulatory Impairment following the Inhibition of the Lateral Hypothalamus in the Rat

PubMed Central

Cerri, Matteo; Vecchio, Flavia Del; Mastrotto, Marco; Luppi, Marco; Martelli, Davide; Perez, Emanuele; Tupone, Domenico; Zamboni, Giovanni; Amici, Roberto

2014-01-01

Neurons within the lateral hypothalamus (LH) are thought to be able to evoke behavioural responses that are coordinated with an adequate level of autonomic activity. Recently, the acute pharmacological inhibition of LH has been shown to depress wakefulness and promote NREM sleep, while suppressing REM sleep. These effects have been suggested to be the consequence of the inhibition of specific neuronal populations within the LH, i.e. the orexin and the MCH neurons, respectively. However, the interpretation of these results is limited by the lack of quantitative analysis of the electroencephalographic (EEG) activity that is critical for the assessment of NREM sleep quality and the presence of aborted NREM-to-REM sleep transitions. Furthermore, the lack of evaluation of the autonomic and thermoregulatory effects of the treatment does not exclude the possibility that the wake-sleep changes are merely the consequence of the autonomic, in particular thermoregulatory, changes that may follow the inhibition of LH neurons. In the present study, the EEG and autonomic/thermoregulatory effects of a prolonged LH inhibition provoked by the repeated local delivery of the GABAA agonist muscimol were studied in rats kept at thermoneutral (24°C) and at a low (10°C) ambient temperature (Ta), a condition which is known to depress sleep occurrence. Here we show that: 1) at both Tas, LH inhibition promoted a peculiar and sustained bout of NREM sleep characterized by an enhancement of slow-wave activity with no NREM-to-REM sleep transitions; 2) LH inhibition caused a marked transitory decrease in brain temperature at Ta 10°C, but not at Ta 24°C, suggesting that sleep changes induced by LH inhibition at thermoneutrality are not caused by a thermoregulatory impairment. These changes are far different from those observed after the short-term selective inhibition of either orexin or MCH neurons, suggesting that other LH neurons are involved in sleep-wake modulation. PMID:25398141

Sleep spindles in humans: insights from intracranial EEG and unit recordings

PubMed Central

Andrillon, Thomas; Nir, Yuval; Staba, Richard J.; Ferrarelli, Fabio; Cirelli, Chiara; Tononi, Giulio; Fried, Itzhak

2012-01-01

Sleep spindles are an electroencephalographic (EEG) hallmark of non-rapid eye movement (NREM) sleep and are believed to mediate many sleep-related functions, from memory consolidation to cortical development. Spindles differ in location, frequency, and association with slow waves, but whether this heterogeneity may reflect different physiological processes and potentially serve different functional roles remains unclear. Here we utilized a unique opportunity to record intracranial depth EEG and single-unit activity in multiple brain regions of neurosurgical patients to better characterize spindle activity in human sleep. We find that spindles occur across multiple neocortical regions, and less frequently also in the parahippocampal gyrus and hippocampus. Most spindles are spatially restricted to specific brain regions. In addition, spindle frequency is topographically organized with a sharp transition around the supplementary motor area between fast (13-15Hz) centroparietal spindles often occurring with slow wave up-states, and slow (9-12Hz) frontal spindles occurring 200ms later on average. Spindle variability across regions may reflect the underlying thalamocortical projections. We also find that during individual spindles, frequency decreases within and between regions. In addition, deeper sleep is associated with a reduction in spindle occurrence and spindle frequency. Frequency changes between regions, during individual spindles, and across sleep may reflect the same phenomenon, the underlying level of thalamocortical hyperpolarization. Finally, during spindles neuronal firing rates are not consistently modulated, although some neurons exhibit phase-locked discharges. Overall, anatomical considerations can account well for regional spindle characteristics, while variable hyperpolarization levels can explain differences in spindle frequency. PMID:22159098

Convectively coupled equatorial waves within the MJO during CINDY/DYNAMO: slow Kelvin waves as building blocks

NASA Astrophysics Data System (ADS)

Kikuchi, Kazuyoshi; Kiladis, George N.; Dias, Juliana; Nasuno, Tomoe

2018-06-01

This study examines the relationship between the MJO and convectively coupled equatorial waves (CCEWs) during the CINDY2011/DYNAMO field campaign using satellite-borne infrared radiation data, in order to better understand the interaction between convection and the large-scale circulation. The spatio-temporal wavelet transform (STWT) enables us to document the convective signals within the MJO envelope in terms of CCEWs in great detail, through localization of space-time spectra at any given location and time. Three MJO events that occurred in October, November, and December 2011 are examined. It is, in general, difficult to find universal relationships between the MJO and CCEWs, implying that MJOs are diverse in terms of the types of disturbances that make up its convective envelope. However, it is found in all MJO events that the major convective body of the MJO is made up mainly by slow convectively coupled Kelvin waves. These Kelvin waves have relatively fast phase speeds of 10-13 m s-1 outside of, and slow phase speeds of 8-9 m s-1 within the MJO. Sometimes even slower eastward propagating signals with 3-5 m s-1 phase speed show up within the MJO, which, as well as the slow Kelvin waves, appear to comprise major building blocks of the MJO. It is also suggested that these eastward propagating waves often occur coincident with n = 1 WIG waves, which is consistent with the schematic model from Nakazawa in 1988. Some practical aspects that facilitate use of the STWT are also elaborated upon and discussed.

Cortical firing and sleep homeostasis.

PubMed

Vyazovskiy, Vladyslav V; Olcese, Umberto; Lazimy, Yaniv M; Faraguna, Ugo; Esser, Steve K; Williams, Justin C; Cirelli, Chiara; Tononi, Giulio

2009-09-24

The need to sleep grows with the duration of wakefulness and dissipates with time spent asleep, a process called sleep homeostasis. What are the consequences of staying awake on brain cells, and why is sleep needed? Surprisingly, we do not know whether the firing of cortical neurons is affected by how long an animal has been awake or asleep. Here, we found that after sustained wakefulness cortical neurons fire at higher frequencies in all behavioral states. During early NREM sleep after sustained wakefulness, periods of population activity (ON) are short, frequent, and associated with synchronous firing, while periods of neuronal silence are long and frequent. After sustained sleep, firing rates and synchrony decrease, while the duration of ON periods increases. Changes in firing patterns in NREM sleep correlate with changes in slow-wave activity, a marker of sleep homeostasis. Thus, the systematic increase of firing during wakefulness is counterbalanced by staying asleep.

Sleep, sport, and the brain.

PubMed

Halson, Shona L; Juliff, Laura E

2017-01-01

The recognition that sleep is one of the foundations of athlete performance is increasing both in the elite athlete arena as well as applied performance research. Sleep, as identified through sleep deprivation and sleep extension investigations, has a role in performance, illness, injury, metabolism, cognition, memory, learning, and mood. Elite athletes have been identified as having poorer quality and quantity of sleep in comparison to the general population. This is likely the result on training times, competition stress/anxiety, muscle soreness, caffeine use, and travel. Sleep, in particular slow wave sleep, provides a restorative function to the body to recover from prior wakefulness and fatigue by repairing processes and restoring energy. In addition, research in the general population is highlighting the importance of sleep on neurophysiology, cognitive function, and mood which may have implications for elite athlete performance. It is thus increased understanding of both the effects of sleep deprivation and potential mechanisms of influence on performance that may allow scientists and practitioners to positively influence sleep in athletes and ultimately maximize performances. © 2017 Elsevier B.V. All rights reserved.

Effect of oxcarbazepine on sleep architecture.

PubMed

Ayala-Guerrero, Fructuoso; Mexicano, Graciela; González, Valentín; Hernandez, Mario

2009-07-01

The most common side effects following administration of antiepileptic drugs involve alterations in sleep architecture and varying degrees of daytime sleepiness. Oxcarbazepine is a drug that is approved as monotherapy for the treatment of partial seizures and generalized tonic-clonic seizures. However, there is no information about its effects on sleep pattern organization; therefore, the objective of this work was to analyze such effects. Animals (Wistar rats) exhibited three different behavioral and electrophysiological states of vigilance: wakefulness, slow wave sleep (SWS), and rapid eye movement (REM) sleep. Oral treatment with oxcarbazepine (100 mg/kg) produced an increment in total sleep time throughout the recording period. This increment involved both SWS and REM sleep. Mean duration of the REM sleep phase was not affected. In contrast, the frequency of this sleep phase increased significantly across the 10-hour period. REM sleep latency shortened significantly. Results obtained in this work indicate that oxcarbazepine's acute effects point to hypnotic properties.

Sleep-enhancing effects of far-infrared radiation in rats

NASA Astrophysics Data System (ADS)

Honda, K.; Inoué, S.

1988-06-01

Unrestrained male rats continuously exposed to far-infrared radiation exhibited a significant increase in slow wave sleep (SWS) during the light period but not in the dark period. The change was largely due to the elevated occurrence of SWS episodes but not to the prolongation of their duration. Paradoxical sleep was not affected throughout the observation period except for a significant decrease at the end of the dark period. Thus the far-infrared radiation exerted a sleep modulatory effect closely related to the circadian activity-rest cycle.

Clustering of Ca2+ transients in interstitial cells of Cajal defines slow wave duration

PubMed Central

Drumm, Bernard T.; Hennig, Grant W.; Battersby, Matthew J.; Sung, Tae Sik

2017-01-01

Interstitial cells of Cajal (ICC) in the myenteric plexus region (ICC-MY) of the small intestine are pacemakers that generate rhythmic depolarizations known as slow waves. Slow waves depend on activation of Ca2+-activated Cl− channels (ANO1) in ICC, propagate actively within networks of ICC-MY, and conduct to smooth muscle cells where they generate action potentials and phasic contractions. Thus, mechanisms of Ca2+ regulation in ICC are fundamental to the motor patterns of the bowel. Here, we characterize the nature of Ca2+ transients in ICC-MY within intact muscles, using mice expressing a genetically encoded Ca2+ sensor, GCaMP3, in ICC. Ca2+ transients in ICC-MY display a complex firing pattern caused by localized Ca2+ release events arising from multiple sites in cell somata and processes. Ca2+ transients are clustered within the time course of slow waves but fire asynchronously during these clusters. The durations of Ca2+ transient clusters (CTCs) correspond to slow wave durations (plateau phase). Simultaneous imaging and intracellular electrical recordings revealed that the upstroke depolarization of slow waves precedes clusters of Ca2+ transients. Summation of CTCs results in relatively uniform Ca2+ responses from one slow wave to another. These Ca2+ transients are caused by Ca2+ release from intracellular stores and depend on ryanodine receptors as well as amplification from IP3 receptors. Reduced extracellular Ca2+ concentrations and T-type Ca2+ channel blockers decreased the number of firing sites and firing probability of Ca2+ transients. In summary, the fundamental electrical events of small intestinal muscles generated by ICC-MY depend on asynchronous firing of Ca2+ transients from multiple intracellular release sites. These events are organized into clusters by Ca2+ influx through T-type Ca2+ channels to sustain activation of ANO1 channels and generate the plateau phase of slow waves. PMID:28592421

The actions of dihydroxyphenylalanine and dihydroxyphenylserine on the sleep-wakefulness cycle of the rat after peripheral decarboxylase inhibition.

PubMed Central

Altier, H; Moldes, M; Monti, J M

1975-01-01

1. The actions of dihydroxyphenylalanine (DOPA) and dihydroxyphenylserine (DOPS) were assessed on the sleep-wakefulness cycle of male Wistar rats. 2. In comparative studies the extracerebral decarboxylase was inhibited with serinetrihydroxybenzylhydrazide (RO 4-4602) before injection of DOPA or DOPS. 3. DOPA (80-160 mg/kg, i.p.) with or without previous inhibition of the peripheral decarboxylase gave rise to an initial significant increase of slow wave activity, which may be related to a release of 5-hydroxytryptamine. 4. During the subsequent 8 h sessions, DOPA significantly decreased slow wave sleep and rapid eye movement sleep (REM) and increased wakefulness. 5. DOPS (80-160 mg/kg, i.p.) did not significantly modify the sleep-wakefulness cycle apart from a decrease of the latency for the first REM episode after 160 mg/kg in the RO 4-4602 pretreated animals. PMID:166716

Circumferential and functional re-entry of in vivo slow-wave activity in the porcine small intestine.

PubMed

Angeli, T R; O'Grady, G; Du, P; Paskaranandavadivel, N; Pullan, A J; Bissett, I P; Cheng, L K

2013-05-01

Slow-waves modulate the pattern of small intestine contractions. However, the large-scale spatial organization of intestinal slow-wave pacesetting remains uncertain because most previous studies have had limited resolution. This study applied high-resolution (HR) mapping to evaluate intestinal pacesetting mechanisms and propagation patterns in vivo. HR serosal mapping was performed in anesthetized pigs using flexible arrays (256 electrodes; 32 × 8; 4 mm spacing), applied along the jejunum. Slow-wave propagation patterns, frequencies, and velocities were calculated. Slow-wave initiation sources were identified and analyzed by animation and isochronal activation mapping. Analysis comprised 32 recordings from nine pigs (mean duration 5.1 ± 3.9 min). Slow-wave propagation was analyzed, and a total of 26 sources of slow-wave initiation were observed and classified as focal pacemakers (31%), sites of functional re-entry (23%) and circumferential re-entry (35%), or indeterminate sources (11%). The mean frequencies of circumferential and functional re-entry were similar (17.0 ± 0.3 vs 17.2 ± 0.4 cycle min(-1) ; P = 0.5), and greater than that of focal pacemakers (12.7 ± 0.8 cycle min(-1) ; P < 0.001). Velocity was anisotropic (12.9 ± 0.7 mm s(-1) circumferential vs 9.0 ± 0.7 mm s(-1) longitudinal; P < 0.05), contributing to the onset and maintenance of re-entry. This study has shown multiple patterns of slow-wave initiation in the jejunum of anesthetized pigs. These results constitute the first description and analysis of circumferential re-entry in the gastrointestinal tract and functional re-entry in the in vivo small intestine. Re-entry can control the direction, pattern, and frequency of slow-wave propagation, and its occurrence and functional significance merit further investigation. © 2013 Blackwell Publishing Ltd.

Sleep in schizophrenia: A systematic review and meta-analysis of polysomnographic findings in case-control studies.

PubMed

Chan, Man-Sum; Chung, Ka-Fai; Yung, Kam-Ping; Yeung, Wing-Fai

2017-04-01

Polysomnographic studies have been performed to examine the sleep abnormalities in schizophrenia, but the results are inconsistent. An updated systematic review, meta-analysis, and moderator analysis was conducted. Major databases were searched without language restriction from 1968 to January 2014. Data were analyzed using the random-effects model and summarized using the Hedges's g. Thirty-one studies with 574 patients and 515 healthy controls were evaluated. Limited by the number of studies and a lack of patient-level data, moderator analysis was restricted to medication status, duration of medication withdrawal, and illness duration. We showed that patients with schizophrenia have significantly shorter total sleep time, longer sleep onset latency, more wake time after sleep onset, lower sleep efficiency, and decreased stage 4 sleep, slow wave sleep, and duration and latency of rapid eye movement sleep compared to healthy controls. The findings on delta waves and sleep spindles were inconsistent. Moderator analysis could not find any abnormalities in sleep architecture in medication-naïve patients. Patients with antipsychotic withdrawal for longer than eight weeks were shown to have less sleep architectural abnormalities, compared to shorter duration of withdrawal, but the abnormalities in sleep continuity were similar. Slow wave sleep deficit was found in patients with schizophrenia for more than three years, while sleep onset latency was increased in medication-naïve, medication-withdrawn, and medicated patients. Our study showed that polysomnographic abnormalities are present in schizophrenia. Illness duration, medication status, and duration of medication withdrawal are several of the clinical factors that contribute to the heterogeneity between studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Conventional, Bayesian, and Modified Prony's methods for characterizing fast and slow waves in equine cancellous bone

PubMed Central

Groopman, Amber M.; Katz, Jonathan I.; Holland, Mark R.; Fujita, Fuminori; Matsukawa, Mami; Mizuno, Katsunori; Wear, Keith A.; Miller, James G.

2015-01-01

Conventional, Bayesian, and the modified least-squares Prony's plus curve-fitting (MLSP + CF) methods were applied to data acquired using 1 MHz center frequency, broadband transducers on a single equine cancellous bone specimen that was systematically shortened from 11.8 mm down to 0.5 mm for a total of 24 sample thicknesses. Due to overlapping fast and slow waves, conventional analysis methods were restricted to data from sample thicknesses ranging from 11.8 mm to 6.0 mm. In contrast, Bayesian and MLSP + CF methods successfully separated fast and slow waves and provided reliable estimates of the ultrasonic properties of fast and slow waves for sample thicknesses ranging from 11.8 mm down to 3.5 mm. Comparisons of the three methods were carried out for phase velocity at the center frequency and the slope of the attenuation coefficient for the fast and slow waves. Good agreement among the three methods was also observed for average signal loss at the center frequency. The Bayesian and MLSP + CF approaches were able to separate the fast and slow waves and provide good estimates of the fast and slow wave properties even when the two wave modes overlapped in both time and frequency domains making conventional analysis methods unreliable. PMID:26328678

Adolescent Changes in Homeostatic Regulation of EEG Activity in the Delta and Theta Frequency Bands during NREM Sleep

PubMed Central

Campbell, Ian G.; Darchia, Nato; Higgins, Lisa M.; Dykan, Igor V.; Davis, Nicole M.; de Bie, Evan; Feinberg, Irwin

2011-01-01

Study Objectives: Slow wave EEG activity in NREM sleep decreases by more than 60% between ages 10 and 20 years. Slow wave EEG activity also declines across NREM periods (NREMPs) within a night, and this decline is thought to represent the dynamics of sleep homeostasis. We used longitudinal data to determine whether these homeostatic dynamics change across adolescence. Design: All-night sleep EEG was recorded semiannually for 6 years. Setting: EEG was recorded with ambulatory recorders in the subjects' homes. Participants: Sixty-seven subjects in 2 cohorts, one starting at age 9 and one starting at age 12 years. Measurements and Results: For NREM delta (1-4 Hz) and theta (4-8 Hz) EEG, we tested whether the proportion of spectral energy contained in the first NREMP changes with age. We also tested for age changes in the parameters of the process S exponential decline. For both delta and theta, the proportion of energy in the first NREMP declined significantly across ages 9 to 18 years. Process S parameters SWA0 and TWA0, respectively, represent slow wave (delta) activity and theta wave activity at the beginning of the night. SWA0 and TWA0 declined significantly (P < 0.0001) across ages 9 to 18. Conclusions: These declines indicate that the intensity of the homeostatic or restorative processes at the beginning of sleep diminished across adolescence. We propose that this change in sleep regulation is caused by the synaptic pruning that occurs during adolescent brain maturation. Citation: Campbell IG; Darchia N; Higgins LM; Dykan IV; Davis NM; de Bie E; Feinberg I. Adolescent changes in homeostatic regulation of EEG activity in the delta and theta frequency bands during NREM sleep. SLEEP 2011;34(1):83-91. PMID:21203377

Slow waves in microchannel metal waveguides and application to particle acceleration

NASA Astrophysics Data System (ADS)

Steinhauer, L. C.; Kimura, W. D.

2003-06-01

Conventional metal-wall waveguides support waveguide modes with phase velocities exceeding the speed of light. However, for infrared frequencies and guide dimensions of a fraction of a millimeter, one of the waveguide modes can have a phase velocity equal to or less than the speed of light. Such a metal microchannel then acts as a slow-wave structure. Furthermore, if it is a transverse magnetic mode, the electric field has a component along the direction of propagation. Therefore, a strong exchange of energy can occur between a beam of charged particles and this slow-waveguide mode. Moreover, the energy exchange can be sustained over a distance limited only by the natural damping of the wave. This makes the microchannel metal waveguide an attractive possibility for high-gradient electron laser acceleration because the wave can be directly energized by a long-wavelength laser. Indeed the frequency of CO2 lasers lies at a fortuitous wavelength that produces a strong laser-particle interaction in a channel of reasonable macroscopic size (e.g., ˜0.6 mm). The dispersion properties including phase velocity and damping for the slow wave are developed. The performance and other issues related to laser accelerator applications are discussed.

Endothelial function and sleep: associations of flow-mediated dilation with perceived sleep quality and rapid eye movement (REM) sleep.

PubMed

Cooper, Denise C; Ziegler, Michael G; Milic, Milos S; Ancoli-Israel, Sonia; Mills, Paul J; Loredo, José S; Von Känel, Roland; Dimsdale, Joel E

2014-02-01

Endothelial function typically precedes clinical manifestations of cardiovascular disease and provides a potential mechanism for the associations observed between cardiovascular disease and sleep quality. This study examined how subjective and objective indicators of sleep quality relate to endothelial function, as measured by brachial artery flow-mediated dilation (FMD). In a clinical research centre, 100 non-shift working adults (mean age: 36 years) completed FMD testing and the Pittsburgh Sleep Quality Index, along with a polysomnography assessment to obtain the following measures: slow wave sleep, percentage rapid eye movement (REM) sleep, REM sleep latency, total arousal index, total sleep time, wake after sleep onset, sleep efficiency and apnea-hypopnea index. Bivariate correlations and follow-up multiple regressions examined how FMD related to subjective (i.e., Pittsburgh Sleep Quality Index scores) and objective (i.e., polysomnography-derived) indicators of sleep quality. After FMD showed bivariate correlations with Pittsburgh Sleep Quality Index scores, percentage REM sleep and REM latency, further examination with separate regression models indicated that these associations remained significant after adjustments for sex, age, race, hypertension, body mass index, apnea-hypopnea index, smoking and income (Ps < 0.05). Specifically, as FMD decreased, scores on the Pittsburgh Sleep Quality Index increased (indicating decreased subjective sleep quality) and percentage REM sleep decreased, while REM sleep latency increased (Ps < 0.05). Poorer subjective sleep quality and adverse changes in REM sleep were associated with diminished vasodilation, which could link sleep disturbances to cardiovascular disease. © 2013 European Sleep Research Society.

Resting-state slow wave power, healthy aging and cognitive performance.

PubMed

Vlahou, Eleni L; Thurm, Franka; Kolassa, Iris-Tatjana; Schlee, Winfried

2014-05-29

Cognitive functions and spontaneous neural activity show significant changes over the life-span, but the interrelations between age, cognition and resting-state brain oscillations are not well understood. Here, we assessed performance on the Trail Making Test and resting-state magnetoencephalographic (MEG) recordings from 53 healthy adults (18-89 years old) to investigate associations between age-dependent changes in spontaneous oscillatory activity and cognitive performance. Results show that healthy aging is accompanied by a marked and linear decrease of resting-state activity in the slow frequency range (0.5-6.5 Hz). The effects of slow wave power on cognitive performance were expressed as interactions with age: For older (>54 years), but not younger participants, enhanced delta and theta power in temporal and central regions was positively associated with perceptual speed and executive functioning. Consistent with previous work, these findings substantiate further the important role of slow wave oscillations in neurocognitive function during healthy aging.

Slow-Mode MHD Wave Penetration into a Coronal Null Point due to the Mode Transmission

NASA Astrophysics Data System (ADS)

Afanasyev, Andrey N.; Uralov, Arkadiy M.

2016-11-01

Recent observations of magnetohydrodynamic oscillations and waves in solar active regions revealed their close link to quasi-periodic pulsations in flaring light curves. The nature of that link has not yet been understood in detail. In our analytical modelling we investigate propagation of slow magnetoacoustic waves in a solar active region, taking into account wave refraction and transmission of the slow magnetoacoustic mode into the fast one. The wave propagation is analysed in the geometrical acoustics approximation. Special attention is paid to the penetration of waves in the vicinity of a magnetic null point. The modelling has shown that the interaction of slow magnetoacoustic waves with the magnetic reconnection site is possible due to the mode transmission at the equipartition level where the sound speed is equal to the Alfvén speed. The efficiency of the transmission is also calculated.

Critical evaluation of the effect of valerian extract on sleep structure and sleep quality.

PubMed

Donath, F; Quispe, S; Diefenbach, K; Maurer, A; Fietze, I; Roots, I

2000-03-01

A carefully designed study assessed the short-term (single dose) and long-term (14 days with multiple dosage) effects of a valerian extract on both objective and subjective sleep parameters. The investigation was performed as a randomised, double-blind, placebo-controlled, cross-over study. Sixteen patients (4 male, 12 female) with previously established psychophysiological insomnia (ICSD-code 1.A.1.), and with a median age of 49 (range: 22 to 55), were included in the study. The main inclusion criteria were reported primary insomnia according to ICSD criteria, which was confirmed by polysomnographic recording, and the absence of acute diseases. During the study, the patients underwent 8 polysomnographic recordings: i.e., 2 recordings (baseline and study night) at each time point at which the short and long-term effects of placebo and valerian were tested. The target variable of the study was sleep efficiency. Other parameters describing objective sleep structure were the usual features of sleep-stage analysis, based on the rules of Rechtschaffen and Kales (1968), and the arousal index (scored according to ASDA criteria, 1992) as a sleep microstructure parameter. Subjective parameters such as sleep quality, morning feeling, daytime performance, subjectively perceived duration of sleep latency, and sleep period time were assessed by means of questionnaires. After a single dose of valerian, no effects on sleep structure and subjective sleep assessment were observed. After multiple-dose treatment, sleep efficiency showed a significant increase for both the placebo and the valerian condition in comparison with baseline polysomnography. We confirmed significant differences between valerian and placebo for parameters describing slow-wave sleep. In comparison with the placebo, slow-wave sleep latency was reduced after administration of valerian (21.3 vs. 13.5 min respectively, p<0.05). The SWS percentage of time in bed (TIB) was increased after long-term valerian

KINETIC SIMULATION OF SLOW MAGNETOSONIC WAVES AND QUASI-PERIODIC UPFLOWS IN THE SOLAR CORONA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruan, Wenzhi; He, Jiansen; Tu, Chuanyi

Quasi-periodic disturbances of emission-line parameters are frequently observed in the corona. These disturbances propagate upward along the magnetic field with speeds of ∼100 km s{sup −1}. This phenomenon has been interpreted as evidence of the propagation of slow magnetosonic waves or has been argued to be a signature of intermittent outflows superposed on the background plasmas. Here we aim to present a new “wave + flow” model to interpret these observations. In our scenario, the oscillatory motion is a slow-mode wave, and the flow is associated with a beam created by the wave–particle interaction owing to Landau resonance. With themore » help of a kinetic model, we simulate the propagation of slow-mode waves and the generation of beam flows. We find that weak periodic beam flows can be generated by to Landau resonance in the solar corona, and the phase with the strongest blueward asymmetry is ahead of that with the strongest blueshift by about 1/4 period. We also find that the slow wave damps to the level of 1/ e after the transit time of two wave periods, owing to Landau damping and Coulomb collisions in our simulation. This damping timescale is similar to that resulting from thermal conduction in the MHD regime. The beam flow is weakened/attenuated with increasing wave period and decreasing wave amplitude since Coulomb collisions become more and more dominant over the wave action. We suggest that this “wave + flow” kinetic model provides an alternative explanation for the observed quasi-periodic propagating perturbations in various parameters in the solar corona.« less

Sleep and wakefulness in somnambulism: a spectral analysis study.

PubMed

Guilleminault, C; Poyares, D; Aftab, F A; Palombini, L; Abat, F

2001-08-01

The sleep structure and the dynamics of EEG slow-wave activity (SWA) were investigated in 12 young adults and age- and gender-matched controls. Polysomnography was performed in subjects with well-documented chronic sleepwalking and in matched controls. Blinded visual scoring was performed using the international criteria from the Rechtschaffen and Kales atlas [A manual of standardized technology, techniques and scoring systems for sleep stages of human subjects. Los Angeles: UCLA Brain Information Service, Brain Research Institute, 1968.] and by determining the presence of microarousals as defined in the American Sleep Disorders Association (ASDA) atlas [Sleep 15 (1992) 173.]. An evaluation of SWA overnight was performed on total nocturnal sleep to determine if a difference existed between groups of subjects, since sleepwalking usually originates with slow-wave sleep. Investigation of the delta power in successive nonoverlapping 4-second windows in the 32 seconds just prior to EMG activity associated with a confusional arousal was also conducted. One central EEG lead was used for all analyses. Somnambulistic individuals experienced more disturbed sleep than controls during the first NREM-REM sleep cycle. They had a higher number of ASDA arousals and presented lower peak of SWA during the first cycle that led to a lower SWA decline overnight. When the investigation focused on the short segment immediately preceding a confusional arousal, they presented an important increase in the relative power of low delta (0.75-2 Hz) just prior to the confusional arousal. Sleepwalkers undergo disturbed nocturnal sleep at the beginning of the night. The increased power of low delta just prior to the confusional arousal experienced may not be related to Stages 3-4 NREM sleep. We hypothesize that it may be translated as a cortical reaction to brain activation.

Analysis of sleep parameters in patients with obstructive sleep apnea studied in a hospital vs. a hotel-based sleep center.

PubMed

Hutchison, Kimberly N; Song, Yanna; Wang, Lily; Malow, Beth A

2008-04-15

Polysomnography is associated with changes in sleep architecture called the first-night effect. This effect is believed to result from sleeping in an unusual environment and the technical equipment used to study sleep. Sleep experts hope to decrease this variable by providing a more familiar, comfortable atmosphere for sleep testing through hotel-based sleep centers. In this study, we compared the sleep parameters of patients studied in our hotel-based and hospital-based sleep laboratories. We retrospectively reviewed polysomnograms completed in our hotel-based and hospital-based sleep laboratories from August 2003 to July 2005. All patients were undergoing evaluation for obstructive sleep apnea. Hospital-based patients were matched for age and apnea-hypopnea index with hotel-based patients. We compared the sleep architecture changes associated with the first-night effect in the two groups. The associated conditions and symptoms listed on the polysomnography referral forms are also compared. No significant differences were detected between the two groups in sleep onset latency, sleep efficiency, REM sleep latency, total amount of slow wave sleep (NREM stages 3 and 4), arousal index, and total stage 1 sleep. This pilot study failed to show a difference in sleep parameters associated with the first-night effect in patients undergoing sleep studies in our hotel and hospital-based sleep laboratories. Future studies need to compare the first-night effect in different sleep disorders, preferably in multi-night recordings.

Simultaneous realization of slow and fast acoustic waves using a fractal structure of Koch curve.

PubMed

Ding, Jin; Fan, Li; Zhang, Shu-Yi; Zhang, Hui; Yu, Wei-Wei

2018-01-24

An acoustic metamaterial based on a fractal structure, the Koch curve, is designed to simultaneously realize slow and fast acoustic waves. Owing to the multiple transmitting paths in the structure resembling the Koch curve, the acoustic waves travelling along different paths interfere with each other. Therefore, slow waves are created on the basis of the resonance of a Koch-curve-shaped loop, and meanwhile, fast waves even with negative group velocities are obtained due to the destructive interference of two acoustic waves with opposite phases. Thus, the transmission of acoustic wave can be freely manipulated with the Koch-curve shaped structure.

Sex differences in sleep pattern of rats in an experimental model of osteoarthritis.

PubMed

Silva, Andressa; Araujo, Paula; Zager, Adriano; Tufik, Sergio; Andersen, Monica Levy

2011-07-01

Osteoarthritis (OA) is a major healthcare burden with increasing incidence, and is characterised by the degeneration of articular cartilage. OA is associated with chronic pain and sleep disturbance. The current study examined and compared the long-term effects of chronic articular pain on sleep patterns between female and male rats in an experimental model of OA. Rats were implanted with electrodes for electrocorticography and electromyography and assigned to control, sham or OA groups. OA was induced by the intra-articular administration of (2 mg) monosodium iodoacetate into the left knee joint in male and female rats (at estrus and diestrus phases). Sleep was monitored at days 1, 10, 15, 20 and 28 after iodoacetate injection during light and dark periods. The results showed that the overall sleep architecture changed in both sexes. These alterations occurred during the light and dark periods, began on D1 and persisted until the end of the study. OA rats, regardless of sex, showed a fragmented sleep pattern with reduced sleep efficiency, slow-wave sleep and paradoxical sleep, and fewer paradoxical sleep bouts. However, the males showed lower sleep efficiency and reduced slow-wave sleep compared to females during the dark period. Additionally, OA affected the hormonal levels in male rats, as testosterone levels were reduced in comparison to the control and sham groups. In females, progesterone and estradiol remained unchanged throughout the study. Our results suggest that the chronic model of OA influenced the sleep patterns in both sexes. However, males appeared to be more affected. Copyright © 2010. Published by Elsevier Ltd.

Selective neuronal lapses precede human cognitive lapses following sleep deprivation.

PubMed

Nir, Yuval; Andrillon, Thomas; Marmelshtein, Amit; Suthana, Nanthia; Cirelli, Chiara; Tononi, Giulio; Fried, Itzhak

2017-12-01

Sleep deprivation is a major source of morbidity with widespread health effects, including increased risk of hypertension, diabetes, obesity, heart attack, and stroke. Moreover, sleep deprivation brings about vehicle accidents and medical errors and is therefore an urgent topic of investigation. During sleep deprivation, homeostatic and circadian processes interact to build up sleep pressure, which results in slow behavioral performance (cognitive lapses) typically attributed to attentional thalamic and frontoparietal circuits, but the underlying mechanisms remain unclear. Recently, through study of electroencephalograms (EEGs) in humans and local field potentials (LFPs) in nonhuman primates and rodents it was found that, during sleep deprivation, regional 'sleep-like' slow and theta (slow/theta) waves co-occur with impaired behavioral performance during wakefulness. Here we used intracranial electrodes to record single-neuron activities and LFPs in human neurosurgical patients performing a face/nonface categorization psychomotor vigilance task (PVT) over multiple experimental sessions, including a session after full-night sleep deprivation. We find that, just before cognitive lapses, the selective spiking responses of individual neurons in the medial temporal lobe (MTL) are attenuated, delayed, and lengthened. These 'neuronal lapses' are evident on a trial-by-trial basis when comparing the slowest behavioral PVT reaction times to the fastest. Furthermore, during cognitive lapses, LFPs exhibit a relative local increase in slow/theta activity that is correlated with degraded single-neuron responses and with baseline theta activity. Our results show that cognitive lapses involve local state-dependent changes in neuronal activity already present in the MTL.

Do Older Adults Need Sleep? A Review of Neuroimaging, Sleep, and Aging Studies.

PubMed

Scullin, Michael K

2017-09-01

Sleep habits, sleep physiology, and sleep disorders change with increasing age. However, there is a longstanding debate regarding whether older adults need sleep to maintain health and daily functioning (reduced-sleep-need view). An alternative possibility is that all older adults need sleep, but that many older adults have lost the ability to obtain restorative sleep (reduced-sleep-ability view). Prior research using behavioral and polysomnography outcomes has not definitively disentangled the reduced-sleep-need and reduced-sleep-ability views. Therefore, this review examines the neuroimaging literature to determine whether age-related changes in sleep cause-or are caused by-age-related changes in brain structure, function, and pathology. In middle-aged and older adults, poorer sleep quality, greater nighttime hypoxia, and shorter sleep duration related to cortical thinning in frontal regions implicated in slow wave generation, in frontoparietal networks implicated in cognitive control, and in hippocampal regions implicated in memory consolidation. Furthermore, poor sleep quality was associated with higher amyloid burden and decreased connectivity in the default mode network, a network that is disrupted in the pathway to Alzheimer's disease. All adults need sleep, but cortical thinning and amyloidal deposition with advancing age may weaken the brain's ability to produce restorative sleep. Therefore, sleep in older adults may not always support identical functions for physical, mental, and cognitive health as in young adults.

Functional Anatomy of Non-REM Sleep

PubMed Central

de Andrés, Isabel; Garzón, Miguel; Reinoso-Suárez, Fernando

2011-01-01

The state of non-REM sleep (NREM), or slow wave sleep, is associated with a synchronized EEG pattern in which sleep spindles and/or K complexes and high-voltage slow wave activity (SWA) can be recorded over the entire cortical surface. In humans, NREM is subdivided into stages 2 and 3–4 (presently named N3) depending on the proportions of each of these polygraphic events. NREM is necessary for normal physical and intellectual performance and behavior. An overview of the brain structures involved in NREM generation shows that the thalamus and the cerebral cortex are absolutely necessary for the most significant bioelectric and behavioral events of NREM to be expressed; other structures like the basal forebrain, anterior hypothalamus, cerebellum, caudal brain stem, spinal cord and peripheral nerves contribute to NREM regulation and modulation. In NREM stage 2, sustained hyperpolarized membrane potential levels resulting from interaction between thalamic reticular and projection neurons gives rise to spindle oscillations in the membrane potential; the initiation and termination of individual spindle sequences depends on corticothalamic activities. Cortical and thalamic mechanisms are also involved in the generation of EEG delta SWA that appears in deep stage 3–4 (N3) NREM; the cortex has classically been considered to be the structure that generates this activity, but delta oscillations can also be generated in thalamocortical neurons. NREM is probably necessary to normalize synapses to a sustainable basal condition that can ensure cellular homeostasis. Sleep homeostasis depends not only on the duration of prior wakefulness but also on its intensity, and sleep need increases when wakefulness is associated with learning. NREM seems to ensure cell homeostasis by reducing the number of synaptic connections to a basic level; based on simple energy demands, cerebral energy economizing during NREM sleep is one of the prevalent hypotheses to explain NREM homeostasis

High Resolution Topography of Age-Related Changes in Non-Rapid Eye Movement Sleep Electroencephalography

PubMed Central

Sprecher, Kate E.; Riedner, Brady A.; Smith, Richard F.; Tononi, Giulio; Davidson, Richard J.; Benca, Ruth M.

2016-01-01

Sleeping brain activity reflects brain anatomy and physiology. The aim of this study was to use high density (256 channel) electroencephalography (EEG) during sleep to characterize topographic changes in sleep EEG power across normal aging, with high spatial resolution. Sleep was evaluated in 92 healthy adults aged 18–65 years old using full polysomnography and high density EEG. After artifact removal, spectral power density was calculated for standard frequency bands for all channels, averaged across the NREM periods of the first 3 sleep cycles. To quantify topographic changes with age, maps were generated of the Pearson’s coefficient of the correlation between power and age at each electrode. Significant correlations were determined by statistical non-parametric mapping. Absolute slow wave power declined significantly with increasing age across the entire scalp, whereas declines in theta and sigma power were significant only in frontal regions. Power in fast spindle frequencies declined significantly with increasing age frontally, whereas absolute power of slow spindle frequencies showed no significant change with age. When EEG power was normalized across the scalp, a left centro-parietal region showed significantly less age-related decline in power than the rest of the scalp. This partial preservation was particularly significant in the slow wave and sigma bands. The effect of age on sleep EEG varies substantially by region and frequency band. This non-uniformity should inform the design of future investigations of aging and sleep. This study provides normative data on the effect of age on sleep EEG topography, and provides a basis from which to explore the mechanisms of normal aging as well as neurodegenerative disorders for which age is a risk factor. PMID:26901503

Effects of aging on sleep structure throughout adulthood: a population-based study.

PubMed

Moraes, Walter; Piovezan, Ronaldo; Poyares, Dalva; Bittencourt, Lia Rita; Santos-Silva, Rogerio; Tufik, Sergio

2014-04-01

Although many studies have shown the evolution of sleep parameters across the lifespan, not many have included a representative sample of the general population. The objective of this study was to describe age-related changes in sleep structure, sleep respiratory parameters and periodic limb movements of the adult population of São Paulo. We selected a representative sample of the city of São Paulo, Brazil that included both genders and an age range of 20-80 years. Pregnant and lactating women, people with physical or mental impairments that prevent self-care and people who work every night were not included. This sample included 1024 individuals who were submitted to polysomnography and structured interviews. We subdivided our sample into five-year age groups. One-way analysis of variance was used to compare age groups. Pearson product-moment was used to evaluate correlation between age and sleep parameters. Total sleep time, sleep efficiency, percentage of rapid eye movement (REM) sleep and slow wave sleep showed a significant age-related decrease (P<0.05). WASO (night-time spent awake after sleep onset), arousal index, sleep latency, REM sleep latency, and the percentage of stages 1 and 2 showed a significant increase (P<0.05). Furthermore, apnea-hypopnea index increased and oxygen saturation decreased with age. The reduction in the percentage of REM sleep significantly correlated with age in women, whereas the reduction in the percentage of slow wave sleep correlated with age in men. The periodic limb movement (PLM) index increased with age in men and women. Sleep structure and duration underwent significant alterations throughout the aging process in the general population. There was an important correlation between age, sleep respiratory parameters and PLM index. In addition, men and women showed similar trends but with different effect sizes. Copyright © 2014 Elsevier B.V. All rights reserved.

African Genetic Ancestry is Associated with Sleep Depth in Older African Americans

PubMed Central

Halder, Indrani; Matthews, Karen A.; Buysse, Daniel J.; Strollo, Patrick J.; Causer, Victoria; Reis, Steven E.; Hall, Martica H.

2015-01-01

Study Objectives: The mechanisms that underlie differences in sleep characteristics between European Americans (EA) and African Americans (AA) are not fully known. Although social and psychological processes that differ by race are possible mediators, the substantial heritability of sleep characteristics also suggests genetic underpinnings of race differences. We hypothesized that racial differences in sleep phenotypes would show an association with objectively measured individual genetic ancestry in AAs. Design: Cross sectional. Setting: Community-based study. Participants: Seventy AA adults (mean age 59.5 ± 6.7 y; 62% female) and 101 EAs (mean age 60.5 ± 7 y, 39% female). Measurements and Results: Multivariate tests were used to compare the Pittsburgh Sleep Quality Index (PSQI) and in-home polysomnographic measures of sleep duration, sleep efficiency, apnea-hypopnea index (AHI), and indices of sleep depth including percent visually scored slow wave sleep (SWS) and delta EEG power of EAs and AAs. Sleep duration, efficiency, and sleep depth differed significantly by race. Individual % African ancestry (%AF) was measured in AA subjects using a panel of 1698 ancestry informative genetic markers and ranged from 10% to 88% (mean 67%). Hierarchical linear regression showed that higher %AF was associated with lower percent SWS in AAs (β (standard error) = −4.6 (1.5); P = 0.002), and explained 11% of the variation in SWS after covariate adjustment. A similar association was observed for delta power. No association was observed for sleep duration and efficiency. Conclusion: African genetic ancestry is associated with indices of sleep depth in African Americans. Such an association suggests that part of the racial differences in slow-wave sleep may have genetic underpinnings. Citation: Halder I, Matthews KA, Buysse DJ, Strollo PJ, Causer V, Reis SE, Hall MH. African genetic ancestry is associated with sleep depth in older African Americans. SLEEP 2015;38(8):1185–1193

Muramyl Peptide-Enhanced Sleep: Pharmacological Optimization of Performance.

DTIC Science & Technology

1987-06-01

cycle of 12 h:12 h was maintained, light from 0600 to 1800 h. Food and water were available ad libitum. At the top of the chamber, a BRS/LVE electrical...and temperture in cat. Sleep Res. 16: 150, 1987. 108. Swanson, J. Studies on gonococcus infection. xii. Colony color and opacity variants of...Methods) received infusion. The major effectof increasing Ta to 27°C was to increase duration of slow wave sleep during the entire 6-hour recording

Arousal from sleep - The physiological and subjective effects of a 15 dB/A/ reduction in aircraft flyover noise

NASA Technical Reports Server (NTRS)

Levere, T. E.; Davis, N.

1977-01-01

The present research was concerned with whether or not a 15 dB(A) reduction in overall noise level would lessen the sleep disturbing properties of jet aircraft flyover noise and, if less disturbing, whether this would be subjectively appreciated by the sleeping individual. The results indicate that a reduction of 15 dB (A) does result in less sleep disruption but only during sleep characterized by fast-wave electroencephalographic activity. During sleep characterized by slow-wave electroencephalographic activity, such a reduction in the sleep-disturbing properties of jet aircraft noise has little effect. Moreover, even when effective during fast-wave sleep, the decreased arousal produced by the lower noise levels is not subjectively appreciated by the individual in terms of his estimate of the quality of his night's sleep. Thus, reducing the overall noise level of jet aircraft flyovers by some 15 dB(A), is, at best, minimally beneficial to sleep.

Experimental and Automated Analysis Techniques for High-resolution Electrical Mapping of Small Intestine Slow Wave Activity

PubMed Central

Angeli, Timothy R; O'Grady, Gregory; Paskaranandavadivel, Niranchan; Erickson, Jonathan C; Du, Peng; Pullan, Andrew J; Bissett, Ian P

2013-01-01

Background/Aims Small intestine motility is governed by an electrical slow wave activity, and abnormal slow wave events have been associated with intestinal dysmotility. High-resolution (HR) techniques are necessary to analyze slow wave propagation, but progress has been limited by few available electrode options and laborious manual analysis. This study presents novel methods for in vivo HR mapping of small intestine slow wave activity. Methods Recordings were obtained from along the porcine small intestine using flexible printed circuit board arrays (256 electrodes; 4 mm spacing). Filtering options were compared, and analysis was automated through adaptations of the falling-edge variable-threshold (FEVT) algorithm and graphical visualization tools. Results A Savitzky-Golay filter was chosen with polynomial-order 9 and window size 1.7 seconds, which maintained 94% of slow wave amplitude, 57% of gradient and achieved a noise correction ratio of 0.083. Optimized FEVT parameters achieved 87% sensitivity and 90% positive-predictive value. Automated activation mapping and animation successfully revealed slow wave propagation patterns, and frequency, velocity, and amplitude were calculated and compared at 5 locations along the intestine (16.4 ± 0.3 cpm, 13.4 ± 1.7 mm/sec, and 43 ± 6 µV, respectively, in the proximal jejunum). Conclusions The methods developed and validated here will greatly assist small intestine HR mapping, and will enable experimental and translational work to evaluate small intestine motility in health and disease. PMID:23667749

Choline acetyltransferase expression during periods of behavioral activity and across natural sleep-wake states in the basal forebrain.

PubMed

Greco, M A; McCarley, R W; Shiromani, P J

1999-01-01

The present study examined whether the expression of the messenger RNA encoding the protein responsible for acetylcholine synthesis is associated with sleep-wakefulness. Choline acetyltransferase messenger RNA levels were analysed using a semi-quantitative assay in which reverse transcription was coupled to complementary DNA amplification using the polymerase chain reaction. To examine the relationship between steady-state messenger RNA and behavioral activity, rats were killed during the day (4.00 p.m.) or night (4.00 a.m.), and tissue from the vertical and horizontal limbs of the diagonal bands of Broca was analysed. Choline acetyltransferase messenger RNA levels were higher during the day than during the night. The second study examined more closely the association between choline acetyltransferase messenger RNA levels and individual bouts of wakefulness, slow-wave sleep or rapid eye movement sleep. Choline acetyltransferase messenger RNA levels were low during wakefulness, intermediate in slow-wave sleep and high during rapid eye movement sleep. In contrast, protein activity, measured at a projection site of cholinergic neurons of the basal forebrain, was higher during wakefulness than during sleep. These findings suggest that choline acetyltransferase protein and messenger RNA levels exhibit an inverse relationship during sleep and wakefulness. The increased messenger RNA expression during sleep is consistent with a restorative function of sleep.

Electrocardiogram-Based Sleep Spectrogram Measures of Sleep Stability and Glucose Disposal in Sleep Disordered Breathing

PubMed Central

Pogach, Melanie S.; Punjabi, Naresh M.; Thomas, Neil; Thomas, Robert J.

2012-01-01

Study Objectives: Sleep disordered breathing (SDB) is independently associated with insulin resistance, glucose intolerance, and type 2 diabetes mellitus. Experimental sleep fragmentation has been shown to impair insulin sensitivity. Conventional electroencephalogram (EEG)-based sleep-quality measures have been inconsistently associated with indices of glucose metabolism. This analysis explored associations between glucose metabolism and an EEG-independent measure of sleep quality, the sleep spectrogram, which maps coupled oscillations of heart-rate variability and electrocardiogram (ECG)-derived respiration. The method allows improved characterization of the quality of stage 2 non-rapid eye movement (NREM) sleep. Design: Cross-sectional study. Setting: N/A. Participants: Nondiabetic subjects with and without SDB (n = 118) underwent the frequently sampled intravenous glucose tolerance test (FSIVGTT) and a full-montage polysomnogram. The sleep spectrogram was generated from ECG collected during polysomnography. Interventions: N/A. Measurements and Results: Standard polysomnographic stages (stages 1, 2, 3+4, and rapid eye movement [REM]) were not associated with the disposition index (DI) derived from the FSIVGTT. In contrast, spectrographic high-frequency coupling (a marker of stable or “effective” sleep) duration was associated with increased, and very-low-frequency coupling (a marker of wake/REM/transitions) associated with reduced DI. This relationship was noted after adjusting for age, sex, body mass index, slow wave sleep, total sleep time, stage 1, the arousal index, and the apnea-hypopnea index. Conclusions: ECG-derived sleep-spectrogram measures of sleep quality are associated with alterations in glucose-insulin homeostasis. This alternate mode of estimating sleep quality could improve our understanding of sleep and sleep-breathing effects on glucose metabolism. Citation: Pogach MS; Punjabi NM; Thomas N; Thomas RJ. Electrocardiogram-based sleep

Novel high-gain, improved-bandwidth, finned-ladder V-band Traveling-Wave Tube slow-wave circuit design

NASA Technical Reports Server (NTRS)

Kory, Carol L.; Wilson, Jeffrey D.

1994-01-01

The V-band frequency range of 59-64 GHz is a region of the millimeter-wave spectrum that has been designated for inter-satellite communications. As a first effort to develop a high-efficiency V-band Traveling-Wave Tube (TWT), variations on a ring-plane slow-wave circuit were computationally investigated to develop an alternative to the more conventional ferruled coupled-cavity circuit. The ring-plane circuit was chosen because of its high interaction impedance, large beam aperture, and excellent thermal dissipation properties. Despite these advantages, however, low bandwidth and high voltage requirements have, until now, prevented its acceptance outside the laboratory. In this paper, the three-dimensional electrodynamic simulation code MAFIA (solution of MAxwell's Equation by the Finite-Integration-Algorithm) is used to investigate methods of increasing the bandwidth and lowering the operating voltage of the ring-plane circuit. Calculations of frequency-phase dispersion, beam on-axis interaction impedance, attenuation and small-signal gain per wavelength were performed for various geometric variations and loading distributions of the ring-plane TWT slow-wave circuit. Based on the results of the variations, a circuit termed the finned-ladder TWT slow-wave circuit was designed and is compared here to the scaled prototype ring-plane and a conventional ferruled coupled-cavity TWT circuit over the V-band frequency range. The simulation results indicate that this circuit has a much higher gain, significantly wider bandwidth, and a much lower voltage requirement than the scaled ring-plane prototype circuit, while retaining its excellent thermal dissipation properties. The finned-ladder circuit has a much larger small-signal gain per wavelength than the ferruled coupled-cavity circuit, but with a moderate sacrifice in bandwidth.

Morvan's syndrome and the sustained absence of all sleep rhythms for months or years: An hypothesis.

PubMed

Touzet, Claude

2016-09-01

Despite the predation costs, sleep is ubiquitous in the animal realm. Humans spend a third of their life sleeping, and the quality of sleep has been related to co-morbidity, Alzheimer disease, etc. Excessive wakefulness induces rapid changes in cognitive performances, and it is claimed that one could die of sleep deprivation as quickly as by absence of water. In this context, the fact that a few people are able to go without sleep for months, even years, without displaying any cognitive troubles requires explanations. Theories ascribing sleep to memory consolidation are unable to explain such observations. It is not the case of the theory of sleep as the hebbian reinforcement of the inhibitory synapses (ToS-HRIS). Hebbian learning (Long Term Depression - LTD) guarantees that an efficient inhibitory synapse will lose its efficiency just because it is efficient at avoiding the activation of the post-synaptic neuron. This erosion of the inhibition is replenished by hebbian learning (Long Term Potentiation - LTP) when pre and post-synaptic neurons are active together - which is exactly what happens with the travelling depolarization waves of the slow-wave sleep (SWS). The best documented cases of months-long insomnia are reports of patients with Morvan's syndrome. This syndrome has an autoimmune cause that impedes - among many things - the potassium channels of the post-synaptic neurons, increasing LTP and decreasing LTD. We hypothesize that the absence of inhibitory efficiency erosion during wakefulness (thanks to a decrease of inhibitory LTD) is the cause for an absence of slow-wave sleep (SWS), which results also in the absence of REM sleep. Copyright © 2016 Elsevier Ltd. All rights reserved.

Postoperative changes in sleep-disordered breathing and sleep architecture in patients with obstructive sleep apnea.

PubMed

Chung, Frances; Liao, Pu; Yegneswaran, Balaji; Shapiro, Colin M; Kang, Weimin

2014-02-01

Anesthetics, analgesics, and surgery may profoundly affect sleep architecture and aggravate sleep-related breathing disturbances. The authors hypothesized that patients with preoperative polysomnographic evidence of obstructive sleep apnea (OSA) would experience greater changes in these parameters than patients without OSA. After obtaining approvals from the Institutional Review Boards, consented patients underwent portable polysomnography preoperatively and on postoperative nights (N) 1, 3, 5, and 7 at home or in hospital. The primary and secondary outcome measurements were polysomnographic parameters of sleep-disordered breathing and sleep architecture. Of the 58 patients completed the study, 38 patients had OSA (apnea hypopnea index [AHI] >5) with median preoperative AHI of 18 events per hour and 20 non-OSA patients had median preoperative AHI of 2. AHI was increased after surgery in both OSA and non-OSA patients (P < 0.05), with peak increase on postoperative N3 (OSA vs. non-OSA, 29 [14, 57] vs. 8 [2, 18], median [25th, 75th percentile], P < 0.05). Hypopnea index accounted for 72% of the postoperative increase in AHI. The central apnea index was low (median = 0) but was significantly increased on postoperative N1 in only non-OSA patients. Sleep efficiency, rapid eye movement sleep, and slow-wave sleep were decreased on N1 in both groups, with gradual recovery. Postoperatively, sleep architecture was disturbed and AHI was increased in both OSA and non-OSA patients. Although the disturbances in sleep architecture were greatest on postoperative N1, breathing disturbances during sleep were greatest on postoperative N3.

Effect of short-term acclimatization to high altitude on sleep and nocturnal breathing.

PubMed

Nussbaumer-Ochsner, Yvonne; Ursprung, Justyna; Siebenmann, Christoph; Maggiorini, Marco; Bloch, Konrad E

2012-03-01

Objective physiologic data on sleep and nocturnal breathing at initial exposure and during acclimatization to high altitude are scant. We tested the hypothesis that acute exposure to high altitude induces quantitative and qualitative changes in sleep and that these changes are partially reversed with acclimatization. Prospective observation. One night in a sleep laboratory at 490 meters, the first and the third night in a mountain hut at 4559 meters. Sixteen healthy mountaineers. Altitude exposure. Polysomnography, questionnaire evaluation of sleep and acute mountain sickness. Compared to 490 m, median nocturnal oxygen saturation decreased during the 1st night at 4559 m from 96% to 67%, minute ventilation increased from 4.4 to 6.3 L/min, and the apnea-hypopnea index increased from 0.1 to 60.9/h; correspondingly, sleep efficiency decreased from 93% to 69%, and slow wave sleep from 18% to 6% (P < 0.05, all instances). During the 3rd night at 4559 m, oxygen saturation was 71%, slow wave sleep 11% (P < 0.05 vs. 1st night, both instances) and the apnea/hypopnea index was 86.5/h (P = NS vs. 1st night). Symptoms of AMS and of disturbed sleep were significantly reduced in the morning after the 3rd vs. the 1st night at 4559 m. In healthy mountaineers ascending rapidly to high altitude, sleep quality is initially impaired but improves with acclimatization in association with improved oxygen saturation, while periodic breathing persists. Therefore, high altitude sleep disturbances seem to be related predominantly to hypoxemia rather than to periodic breathing.

After Being Challenged by a Video Game Problem, Sleep Increases the Chance to Solve It

PubMed Central

Beijamini, Felipe; Pereira, Sofia Isabel Ribeiro; Cini, Felipe Augusto; Louzada, Fernando Mazzilli

2014-01-01

In the past years many studies have demonstrated the role of sleep on memory consolidation. It is known that sleeping after learning a declarative or non-declarative task, is better than remaining awake. Furthermore, there are reports of a possible role for dreams in consolidation of declarative memories. Other studies have reported the effect of naps on memory consolidation. With similar protocols, another set of studies indicated that sleep has a role in creativity and problem-solving. Here we hypothesised that sleep can increase the likelihood of solving problems. After struggling to solve a video game problem, subjects who took a nap (n = 14) were almost twice as likely to solve it when compared to the wake control group (n = 15). It is interesting to note that, in the nap group 9 out 14 subjects engaged in slow-wave sleep (SWS) and all solved the problem. Surprisingly, we did not find a significant involvement of Rapid Eye Movement (REM) sleep in this task. Slow-wave sleep is believed to be crucial for the transfer of memory-related information to the neocortex and implement intentions. Sleep can benefit problem-solving through the generalisation of newly encoded information and abstraction of the gist. In conclusion, our results indicate that sleep, even a nap, can potentiate the solution of problems that involve logical reasoning. Thus, sleep's function seems to go beyond memory consolidation to include managing of everyday-life events. PMID:24416219

After being challenged by a video game problem, sleep increases the chance to solve it.

PubMed

Beijamini, Felipe; Pereira, Sofia Isabel Ribeiro; Cini, Felipe Augusto; Louzada, Fernando Mazzilli

2014-01-01

In the past years many studies have demonstrated the role of sleep on memory consolidation. It is known that sleeping after learning a declarative or non-declarative task, is better than remaining awake. Furthermore, there are reports of a possible role for dreams in consolidation of declarative memories. Other studies have reported the effect of naps on memory consolidation. With similar protocols, another set of studies indicated that sleep has a role in creativity and problem-solving. Here we hypothesised that sleep can increase the likelihood of solving problems. After struggling to solve a video game problem, subjects who took a nap (n = 14) were almost twice as likely to solve it when compared to the wake control group (n = 15). It is interesting to note that, in the nap group 9 out 14 subjects engaged in slow-wave sleep (SWS) and all solved the problem. Surprisingly, we did not find a significant involvement of Rapid Eye Movement (REM) sleep in this task. Slow-wave sleep is believed to be crucial for the transfer of memory-related information to the neocortex and implement intentions. Sleep can benefit problem-solving through the generalisation of newly encoded information and abstraction of the gist. In conclusion, our results indicate that sleep, even a nap, can potentiate the solution of problems that involve logical reasoning. Thus, sleep's function seems to go beyond memory consolidation to include managing of everyday-life events.

Giant amplification in degenerate band edge slow-wave structures interacting with an electron beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Othman, Mohamed A. K.; Veysi, Mehdi; Capolino, Filippo

2016-03-15

We propose a new amplification regime based on a synchronous operation of four degenerate electromagnetic (EM) modes in a slow-wave structure and the electron beam, referred to as super synchronization. These four EM modes arise in a Fabry-Pérot cavity when degenerate band edge (DBE) condition is satisfied. The modes interact constructively with the electron beam resulting in superior amplification. In particular, much larger gains are achieved for smaller beam currents compared to conventional structures based on synchronization with only a single EM mode. We demonstrate giant gain scaling with respect to the length of the slow-wave structure compared to conventionalmore » Pierce type single mode traveling wave tube amplifiers. We construct a coupled transmission line model for a loaded waveguide slow-wave structure exhibiting a DBE, and investigate the phenomenon of giant gain via super synchronization using the Pierce model generalized to multimode interaction.« less

TeO2 slow surface acoustic wave Bragg cell

NASA Astrophysics Data System (ADS)

Yao, Shi-Kay

1991-08-01

A newly discovered slow acoustic surface wave (SAW) on a (-110) cut TeO2 surface is reported focusing on its properties studied using a PC based numerical method. It is concluded that the slow SAW is rather tolerant to crystal surface orientation errors and has unusually deep penetration of its shear component into the thickness of substrate, about 47 wavelengths for a half amplitude point. The deep shear field is considered to be beneficial for surface acoustooptic interaction with free propagating focused laser beams. Rotation of the substrate about the z-axis makes it possible to adjust a slow SAW velocity with the potential advantage of trading acoustic velocity for less acoustic attenuation. Wider-bandwidth long signal processing time Bragg cells may be feasible utilizing this trade-off. The slow SAW device is characterized by an extremely low power consumption which might be useful for compact portable or avionics signal processing equipment applications.

Sleep in the Cape Mole Rat: A Short-Sleeping Subterranean Rodent.

PubMed

Kruger, Jean-Leigh; Gravett, Nadine; Bhagwandin, Adhil; Bennett, Nigel C; Archer, Elizabeth K; Manger, Paul R

2016-01-01

The Cape mole rat Georychus capensis is a solitary subterranean rodent found in the western and southern Cape of South Africa. This approximately 200-gram bathyergid rodent shows a nocturnal circadian rhythm, but sleep in this species is yet to be investigated. Using telemetric recordings of the electroencephalogram (EEG) and electromyogram (EMG) in conjunction with video recordings, we were able to show that the Cape mole rat, like all other rodents, has sleep periods composed of both rapid eye movement (REM) and slow-wave (non-REM) sleep. These mole rats spent on average 15.4 h awake, 7.1 h in non-REM sleep and 1.5 h in REM sleep each day. Cape mole rats sleep substantially less than other similarly sized terrestrial rodents but have a similar percentage of total sleep time occupied by REM sleep. In addition, the duration of both non-REM and REM sleep episodes was markedly shorter in the Cape mole rat than has been observed in terrestrial rodents. Interestingly, these features (total sleep time and episode duration) are similar to those observed in another subterranean bathyergid mole rat, i.e. Fukomys mechowii. Thus, there appears to be a bathyergid type of sleep amongst the rodents that may be related to their environment and the effect of this on their circadian rhythm. Investigating further species of bathyergid mole rats may fully define the emerging picture of sleep in these subterranean African rodents. © 2016 S. Karger AG, Basel.

Normal sleep on mechanical ventilation in adult patients with congenital central alveolar hypoventilation (Ondine's curse syndrome).

PubMed

Attali, Valérie; Straus, Christian; Pottier, Michel; Buzare, Marie-Annick; Morélot-Panzini, Capucine; Arnulf, Isabelle; Similowski, Thomas

2017-01-23

The purpose of this study was to describe the sleep structure (especially slow wave sleep) in adults with congenital central hypoventilation syndrome (CCHS), a rare genetic disease due to mutations in the PHOX2B gene. Fourteen patients aged 23 (19.0; 24.8) years old (median [1 rst -3rd quartiles]) with CCHS underwent a sleep interview and night-time attended polysomnography with their ventilatory support. Their sleep variables were compared to those collected in 15 healthy control subjects matched for age, sex and body mass index. The latency to N3 sleep was shorter in patients (26.3 min [24.0; 30.1]) than in controls (49.5 min [34.3; 66.9]; P = 0.005), and sleep onset latency tended to be shorter in patients (14.0 min [7.0; 20.5]) than in controls (33.0 min [18.0; 49.0]; P = 0.052). Total sleep time, sleep stage percentages, sleep fragmentation as well as respiratory and movement index were within normal ranges and not different between groups. Normal sleep in adult patients with CCHS and adequate ventilator support indicates that the PHOX2 gene mutations do not affect brain sleep networks. Consequently, any complaint of disrupted sleep should prompt clinicians to look for the usual causes of sleep disorders, primarily inadequate mechanical ventilation. Shorter N3 latency may indicate a higher need for slow wave sleep, to compensate for the abnormal respiratory-related cortical activity during awake quiet breathing observed in patients with CCH.

Low Activity Microstates During Sleep.

PubMed

Miyawaki, Hiroyuki; Billeh, Yazan N; Diba, Kamran

2017-06-01

To better understand the distinct activity patterns of the brain during sleep, we observed and investigated periods of diminished oscillatory and population spiking activity lasting for seconds during non-rapid eye movement (non-REM) sleep, which we call "LOW" activity sleep. We analyzed spiking and local field potential (LFP) activity of hippocampal CA1 region alongside neocortical electroencephalogram (EEG) and electromyogram (EMG) in 19 sessions from four male Long-Evans rats (260-360 g) during natural wake/sleep across the 24-hr cycle as well as data from other brain regions obtained from http://crcns.org.1,2. LOW states lasted longer than OFF/DOWN states and were distinguished by a subset of "LOW-active" cells. LOW activity sleep was preceded and followed by increased sharp-wave ripple activity. We also observed decreased slow-wave activity and sleep spindles in the hippocampal LFP and neocortical EEG upon LOW onset, with a partial rebound immediately after LOW. LOW states demonstrated activity patterns consistent with sleep but frequently transitioned into microarousals and showed EMG and LFP differences from small-amplitude irregular activity during quiet waking. Their likelihood decreased within individual non-REM epochs yet increased over the course of sleep. By analyzing data from the entorhinal cortex of rats,1 as well as the hippocampus, the medial prefrontal cortex, the postsubiculum, and the anterior thalamus of mice,2 obtained from http://crcns.org, we confirmed that LOW states corresponded to markedly diminished activity simultaneously in all of these regions. We propose that LOW states are an important microstate within non-REM sleep that provide respite from high-activity sleep and may serve a restorative function. © Sleep Research Society 2017. Published by Oxford University Press [on behalf of the Sleep Research Society].

Looking for a precursor of spontaneous Sleep Slow Oscillations in human sleep: The role of the sigma activity

PubMed Central

Allegrini, Paolo; Bedini, Remo; Bergamasco, Massimo; Laurino, Marco; Sebastiani, Laura; Gemignani, Angelo

2016-01-01

Sleep Slow Oscillations (SSOs), paradigmatic EEG markers of cortical bistability (alternation between cellular downstates and upstates), and sleep spindles, paradigmatic EEG markers of thalamic rhythm, are two hallmarks of sleeping brain. Selective thalamic lesions are reportedly associated to reductions of spindle activity and its spectrum ~14 Hz (sigma), and to alterations of SSO features. This apparent, parallel behavior suggests that thalamo-cortical entrainment favors cortical bistability. Here we investigate temporally-causal associations between thalamic sigma activity and shape, topology, and dynamics of SSOs. We recorded sleep EEG and studied whether spatio-temporal variability of SSO amplitude, negative slope (synchronization in downstate falling) and detection rate are driven by cortical-sigma-activity expression (12–18 Hz), in 3 consecutive 1 s-EEG-epochs preceding each SSO event (Baselines). We analyzed: (i) spatial variability, comparing maps of baseline sigma power and of SSO features, averaged over the first sleep cycle; (ii) event-by-event shape variability, computing for each electrode correlations between baseline sigma power and amplitude/slope of related SSOs; (iii) event-by-event spreading variability, comparing baseline sigma power in electrodes showing an SSO event with the homologous ones, spared by the event. The scalp distribution of baseline sigma power mirrored those of SSO amplitude and slope; event-by-event variability in baseline sigma power was associated with that in SSO amplitude in fronto-central areas; within each SSO event, electrodes involved in cortical bistability presented higher baseline sigma activity than those free of SSO. In conclusion, spatio-temporal variability of thalamocortical entrainment, measured by background sigma activity, is a reliable estimate of the cortical proneness to bistability. PMID:26003553

[Microinjections of heat shock protein 70 kDa into the nucleus reticularis pontis oralis induce inhibition of rapid eye movement sleep in pigeons].

PubMed

Gusel'nikova, E A; Pastukhov, Iu F

2008-03-01

Recently it was indicated that microinjections of heat shock proteins 70 kDa (Hsp70) into the third ventricle of brain in pigeons results in an increase in the duration of slow wave sleep and a decrease in somato-visceral indices. It is suggested that Hsp70 effect may be related to GABA(A) receptors activation in the preoptic area of the hypothalamus. However, what transmitter mechanisms of activation are related to the removal effect (in 2-3 hrs) of rapid eye movement sleep inhibition still remains poorly understood. To solve this problem in the present study, microinjections of Hsp70 into the Nucleus reticularis pontis oralis (NRPO) were done. It is well known that cholinergic neurons of the NRPO are crucial for rapid eye movement sleep generation. The data show that Hsp70 produces more early (for first two hrs) a decrease in number of episodes and total time of rapid eye movement sleep, a diminution of electroencephalogram (EEG) power spectra in the 9-14 Hz band, a decrease in contractile muscle activity and brain temperature. It is suggested that Hsp70 effects are realized due to activation of GABA(A) receptors in the NRPO and induced inhibition of cholinergic mechanisms of rapid eye movement sleep triggering. The microinjections of Hsp70 into the NRPO increase the slow wave sleep total time with long latency (for 8-12 hrs). This effect may be related to influence of Hsp70 on neurons population, which are responsible for slow wave sleep maintenance outside the NRPO.

Analysis of Sleep Parameters in Patients with Obstructive Sleep Apnea Studied in a Hospital vs. a Hotel-Based Sleep Center

PubMed Central

Hutchison, Kimberly N.; Song, Yanna; Wang, Lily; Malow, Beth A.

2008-01-01

Background: Polysomnography is associated with changes in sleep architecture called the first-night effect. This effect is believed to result from sleeping in an unusual environment and the technical equipment used to study sleep. Sleep experts hope to decrease this variable by providing a more familiar, comfortable atmosphere for sleep testing through hotel-based sleep centers. In this study, we compared the sleep parameters of patients studied in our hotel-based and hospital-based sleep laboratories. Methods: We retrospectively reviewed polysomnograms completed in our hotel-based and hospital-based sleep laboratories from August 2003 to July 2005. All patients were undergoing evaluation for obstructive sleep apnea. Hospital-based patients were matched for age and apnea-hypopnea index with hotel-based patients. We compared the sleep architecture changes associated with the first-night effect in the two groups. The associated conditions and symptoms listed on the polysomnography referral forms are also compared. Results: No significant differences were detected between the two groups in sleep onset latency, sleep efficiency, REM sleep latency, total amount of slow wave sleep (NREM stages 3 and 4), arousal index, and total stage 1 sleep. Conclusions: This pilot study failed to show a difference in sleep parameters associated with the first-night effect in patients undergoing sleep studies in our hotel and hospital-based sleep laboratories. Future studies need to compare the first-night effect in different sleep disorders, preferably in multi-night recordings. Citation: Hutchison KN; Song Y; Wang L; Malow BA. Analysis of sleep parameters in patients with obstructive sleep apnea studied in a hospital vs. A hotel-based sleep center. J Clin Sleep Med 2008;4(2):119–122. PMID:18468309