scholarly journals Global field synchronization reveals rapid eye movement sleep as most synchronized brain state in the human EEG

2016 ◽  
Vol 3 (10) ◽  
pp. 160201 ◽  
Author(s):  
Peter Achermann ◽  
Thomas Rusterholz ◽  
Roland Dürr ◽  
Thomas König ◽  
Leila Tarokh

Sleep is characterized by a loss of consciousness, which has been attributed to a breakdown of functional connectivity between brain regions. Global field synchronization (GFS) can estimate functional connectivity of brain processes. GFS is a frequency-dependent measure of global synchronicity of multi-channel EEG data. Our aim was to explore and extend the hypothesis of disconnection during sleep by comparing GFS spectra of different vigilance states. The analysis was performed on eight healthy adult male subjects. EEG was recorded during a baseline night, a recovery night after 40 h of sustained wakefulness and at 3 h intervals during the 40 h of wakefulness. Compared to non-rapid eye movement (NREM) sleep, REM sleep showed larger GFS values in all frequencies except in the spindle and theta bands, where NREM sleep showed a peak in GFS. Sleep deprivation did not affect GFS spectra in REM and NREM sleep. Waking GFS values were lower compared with REM and NREM sleep except for the alpha band. Waking alpha GFS decreased following sleep deprivation in the eyes closed condition only. Our surprising finding of higher synchrony during REM sleep challenges the view of REM sleep as a desynchronized brain state and may provide insight into the function of REM sleep.

SLEEP ◽  
2019 ◽  
Vol 43 (6) ◽  
Author(s):  
Sjoerd J van Hasselt ◽  
Maria Rusche ◽  
Alexei L Vyssotski ◽  
Simon Verhulst ◽  
Niels C Rattenborg ◽  
...  

Abstract Most of our knowledge about the regulation and function of sleep is based on studies in a restricted number of mammalian species, particularly nocturnal rodents. Hence, there is still much to learn from comparative studies in other species. Birds are interesting because they appear to share key aspects of sleep with mammals, including the presence of two different forms of sleep, i.e. non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. We examined sleep architecture and sleep homeostasis in the European starling, using miniature dataloggers for electroencephalogram (EEG) recordings. Under controlled laboratory conditions with a 12:12 h light–dark cycle, the birds displayed a pronounced daily rhythm in sleep and wakefulness with most sleep occurring during the dark phase. Sleep mainly consisted of NREM sleep. In fact, the amount of REM sleep added up to only 1~2% of total sleep time. Animals were subjected to 4 or 8 h sleep deprivation to assess sleep homeostatic responses. Sleep deprivation induced changes in subsequent NREM sleep EEG spectral qualities for several hours, with increased spectral power from 1.17 Hz up to at least 25 Hz. In contrast, power below 1.17 Hz was decreased after sleep deprivation. Sleep deprivation also resulted in a small compensatory increase in NREM sleep time the next day. Changes in EEG spectral power and sleep time were largely similar after 4 and 8 h sleep deprivation. REM sleep was not noticeably compensated after sleep deprivation. In conclusion, starlings display signs of NREM sleep homeostasis but the results do not support the notion of important REM sleep functions.


2015 ◽  
Vol 113 (7) ◽  
pp. 2742-2752 ◽  
Author(s):  
Daniel Abásolo ◽  
Samantha Simons ◽  
Rita Morgado da Silva ◽  
Giulio Tononi ◽  
Vladyslav V. Vyazovskiy

Understanding the dynamics of brain activity manifested in the EEG, local field potentials (LFP), and neuronal spiking is essential for explaining their underlying mechanisms and physiological significance. Much has been learned about sleep regulation using conventional EEG power spectrum, coherence, and period-amplitude analyses, which focus primarily on frequency and amplitude characteristics of the signals and on their spatio-temporal synchronicity. However, little is known about the effects of ongoing brain state or preceding sleep-wake history on the nonlinear dynamics of brain activity. Recent advances in developing novel mathematical approaches for investigating temporal structure of brain activity based on such measures, as Lempel-Ziv complexity (LZC) can provide insights that go beyond those obtained with conventional techniques of signal analysis. Here, we used extensive data sets obtained in spontaneously awake and sleeping adult male laboratory rats, as well as during and after sleep deprivation, to perform a detailed analysis of cortical LFP and neuronal activity with LZC approach. We found that activated brain states—waking and rapid eye movement (REM) sleep are characterized by higher LZC compared with non-rapid eye movement (NREM) sleep. Notably, LZC values derived from the LFP were especially low during early NREM sleep after sleep deprivation and toward the middle of individual NREM sleep episodes. We conclude that LZC is an important and yet largely unexplored measure with a high potential for investigating neurophysiological mechanisms of brain activity in health and disease.


1992 ◽  
Vol 72 (1) ◽  
pp. 100-109 ◽  
Author(s):  
J. B. Neilly ◽  
N. B. Kribbs ◽  
G. Maislin ◽  
A. I. Pack

To assess the effects of selective sleep loss on ventilation during recovery sleep, we deprived 10 healthy young adult humans of rapid-eye-movement (REM) sleep for 48 h and compared ventilation measured during the recovery night with that measured during the baseline night. At a later date we repeated the study using awakenings during non-rapid-eye-movement (NREM) sleep at the same frequency as in REM sleep deprivation. Neither intervention produced significant changes in average minute ventilation during presleep wakefulness, NREM sleep, or the first REM sleep period. By contrast, both interventions resulted in an increased frequency of breaths, in which ventilation was reduced below the range for tonic REM sleep, and in an increased number of longer episodes, in which ventilation was reduced during the first REM sleep period on the recovery night. The changes after REM sleep deprivation were largely due to an increase in the duration of the REM sleep period with an increase in the total phasic activity and, to a lesser extent, to changes in the relationship between ventilatory components and phasic eye movements. The changes in ventilation after partial NREM sleep deprivation were associated with more pronounced changes in the relationship between specific ventilatory components and eye movement density, whereas no change was observed in the composition of the first REM sleep period. These findings demonstrate that sleep deprivation leads to changes in ventilation during subsequent REM sleep.


2015 ◽  
Author(s):  
Sudhansu Chokroverty

Recent research has generated an enormous fund of knowledge about the neurobiology of sleep and wakefulness. Sleeping and waking brain circuits can now be studied by sophisticated neuroimaging techniques that map different areas of the brain during different sleep states and stages. Although the exact biologic functions of sleep are not known, sleep is essential, and sleep deprivation leads to impaired attention and decreased performance. Sleep is also believed to have restorative, conservative, adaptive, thermoregulatory, and consolidative functions. This review discusses the physiology of sleep, including its two independent states, rapid eye movement (REM) and non–rapid eye movement (NREM) sleep, as well as functional neuroanatomy, physiologic changes during sleep, and circadian rhythms. The classification and diagnosis of sleep disorders are discussed generally. The diagnosis and treatment of the following disorders are described: obstructive sleep apnea syndrome, narcolepsy-cataplexy sydrome, idiopathic hypersomnia, restless legs syndrome (RLS) and periodic limb movements in sleep, circadian rhythm sleep disorders, insomnias, nocturnal frontal lobe epilepsy, and parasomnias. Sleep-related movement disorders and the relationship between sleep and psychiatric disorders are also discussed. Tables describe behavioral and physiologic characteristics of states of awareness, the international classification of sleep disorders, common sleep complaints, comorbid insomnia disorders, causes of excessive daytime somnolence, laboratory tests to assess sleep disorders, essential diagnostic criteria for RLS and Willis-Ekbom disease, and drug therapy for insomnia. Figures include polysomnographic recording showing wakefulness in an adult; stage 1, 2, and 3 NREM sleep in an adult; REM sleep in an adult; a patient with sleep apnea syndrome; a patient with Cheyne-Stokes breathing; a patient with RLS; and a patient with dream-enacting behavior; schematic sagittal section of the brainstem of the cat; schematic diagram of the McCarley-Hobson model of REM sleep mechanism; the Lu-Saper “flip-flop” model; the Luppi model to explain REM sleep mechanism; and a wrist actigraph from a man with bipolar disorder. This review contains 14 highly rendered figures, 8 tables, 115 references, and 5 MCQs.


1995 ◽  
Vol 268 (6) ◽  
pp. R1456-R1463 ◽  
Author(s):  
T. Porkka-Heiskanen ◽  
S. E. Smith ◽  
T. Taira ◽  
J. H. Urban ◽  
J. E. Levine ◽  
...  

Noradrenergic locus ceruleus neurons are most active during waking and least active during rapid eye movement (REM) sleep. We expected REM sleep deprivation (REMSD) to increase norepinephrine utilization and activate the tyrosine hydroxylase (TH) gene critical for norepinephrine production. Male Wistar rats were deprived of REM sleep with the platform method. Rats were decapitated after 8, 24, or 72 h on small (REMSD) or large (control) platforms or after 8 or 24 h of rebound sleep after 72 h of the platform treatment. During the first 24 h, norepinephrine concentration, measured by high-performance liquid chromatography/electrochemical detection, was lower in the neocortex, hippocampus, and posterior hypothalamus in REMSD rats than in large-platform controls. After 72 h of REMSD, TH mRNA, measured by in situ hybridization, was increased in the locus ceruleus and norepinephrine concentrations were increased. Polygraphy showed that small-platform treatment caused effective and selective REMSD. Serum corticosterone measurement by radioimmunoassay indicated that the differences found in norepinephrine and TH mRNA were not due to differences in stress between the treatments. The novel finding of sleep deprivation-specific increase in TH gene expression indicates an important mechanism of adjusting to sleep deprivation.


2015 ◽  
Author(s):  
Sudhansu Chokroverty

Recent research has generated an enormous fund of knowledge about the neurobiology of sleep and wakefulness. Sleeping and waking brain circuits can now be studied by sophisticated neuroimaging techniques that map different areas of the brain during different sleep states and stages. Although the exact biologic functions of sleep are not known, sleep is essential, and sleep deprivation leads to impaired attention and decreased performance. Sleep is also believed to have restorative, conservative, adaptive, thermoregulatory, and consolidative functions. This review discusses the physiology of sleep, including its two independent states, rapid eye movement (REM) and non–rapid eye movement (NREM) sleep, as well as functional neuroanatomy, physiologic changes during sleep, and circadian rhythms. The classification and diagnosis of sleep disorders are discussed generally. The diagnosis and treatment of the following disorders are described: obstructive sleep apnea syndrome, narcolepsy-cataplexy sydrome, idiopathic hypersomnia, restless legs syndrome (RLS) and periodic limb movements in sleep, circadian rhythm sleep disorders, insomnias, nocturnal frontal lobe epilepsy, and parasomnias. Sleep-related movement disorders and the relationship between sleep and psychiatric disorders are also discussed. Tables describe behavioral and physiologic characteristics of states of awareness, the international classification of sleep disorders, common sleep complaints, comorbid insomnia disorders, causes of excessive daytime somnolence, laboratory tests to assess sleep disorders, essential diagnostic criteria for RLS and Willis-Ekbom disease, and drug therapy for insomnia. Figures include polysomnographic recording showing wakefulness in an adult; stage 1, 2, and 3 NREM sleep in an adult; REM sleep in an adult; a patient with sleep apnea syndrome; a patient with Cheyne-Stokes breathing; a patient with RLS; and a patient with dream-enacting behavior; schematic sagittal section of the brainstem of the cat; schematic diagram of the McCarley-Hobson model of REM sleep mechanism; the Lu-Saper “flip-flop” model; the Luppi model to explain REM sleep mechanism; and a wrist actigraph from a man with bipolar disorder. This review contains 14 highly rendered figures, 8 tables, 115 references, and 5 MCQs.


SLEEP ◽  
2021 ◽  
Author(s):  
Andreas Brink-Kjær ◽  
Matteo Cesari ◽  
Friederike Sixel-Döring ◽  
Brit Mollenhauer ◽  
Claudia Trenkwalder ◽  
...  

Abstract Study objectives Patients diagnosed with isolated rapid eye movement (REM) sleep behavior disorder (iRBD) and Parkinson’s disease (PD) have altered sleep stability reflecting neurodegeneration in brainstem structures. We hypothesize that neurodegeneration alters the expression of cortical arousals in sleep. Methods We analyzed polysomnography data recorded from 88 healthy controls (HC), 22 iRBD patients, 82 de novo PD patients without RBD and 32 with RBD (PD+RBD). These patients were also investigated at a 2-year follow-up. Arousals were analyzed using a previously validated automatic system, which used a central EEG lead, electrooculography, and chin electromyography. Multiple linear regression models were fitted to compare group differences at baseline and change to follow-up for arousal index (ArI), shifts in electroencephalographic signals associated with arousals, and arousal chin muscle tone. The regression models were adjusted for known covariates affecting the nature of arousal. Results In comparison to HC, patients with iRBD and PD+RBD showed increased ArI during REM sleep and their arousals showed a significantly lower shift in α-band power at arousals and a higher muscle tone during arousals. In comparison to HC, the PD patients were characterized by a decreased ArI in NREM sleep at baseline. ArI during NREM sleep decreased further at the 2-year follow-up, although not significantly Conclusions Patients with PD and iRBD present with abnormal arousal characteristics as scored by an automated method. These abnormalities are likely to be caused by neurodegeneration of the reticular activation system due to alpha-synuclein aggregation.


SLEEP ◽  
2020 ◽  
Author(s):  
Jun-Sang Sunwoo ◽  
Kwang Su Cha ◽  
Jung-Ick Byun ◽  
Jin-Sun Jun ◽  
Tae-Joon Kim ◽  
...  

Abstract Study Objectives We investigated electroencephalographic (EEG) slow oscillations (SOs), sleep spindles (SSs), and their temporal coordination during nonrapid eye movement (NREM) sleep in patients with idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD). Methods We analyzed 16 patients with video-polysomnography-confirmed iRBD (age, 65.4 ± 6.6 years; male, 87.5%) and 10 controls (age, 62.3 ± 7.5 years; male, 70%). SSs and SOs were automatically detected during stage N2 and N3. We analyzed their characteristics, including density, frequency, duration, and amplitude. We additionally identified SO-locked spindles and examined their phase distribution and phase locking with the corresponding SO. For inter-group comparisons, we used the independent samples t-test or Wilcoxon rank-sum test, as appropriate. Results The SOs of iRBD patients had significantly lower amplitude, longer duration (p = 0.005 for both), and shallower slope (p < 0.001) than those of controls. The SS power of iRBD patients was significantly lower than that of controls (p = 0.002), although spindle density did not differ significantly. Furthermore, SO-locked spindles of iRBD patients prematurely occurred during the down-to-up-state transition of SOs, whereas those of controls occurred at the up-state peak of SOs (p = 0.009). The phase of SO-locked spindles showed a positive correlation with delayed recall subscores (p = 0.005) but not with tonic or phasic electromyography activity during REM sleep. Conclusions In this study, we found abnormal EEG oscillations during NREM sleep in patients with iRBD. The impaired temporal coupling between SOs and SSs may reflect early neurodegenerative changes in iRBD.


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