scholarly journals Hibernation in a primate: does sleep occur?

2016 ◽  
Vol 3 (8) ◽  
pp. 160282 ◽  
Author(s):  
Marina B. Blanco ◽  
Kathrin H. Dausmann ◽  
Sheena L. Faherty ◽  
Peter Klopfer ◽  
Andrew D. Krystal ◽  
...  
Keyword(s):  
Rem Sleep ◽  
Low Voltage ◽  
Ground Squirrels ◽  
Cold Weather ◽  
Close Relative ◽  
Gradual Transition ◽  
Physiological Processes ◽  
Tropical Conditions ◽  
Eeg Recordings ◽  
Torpor Bouts

During hibernation, critical physiological processes are downregulated and thermogenically induced arousals are presumably needed periodically to fulfil those physiological demands. Among the processes incompatible with a hypome tabolic state is sleep. However, one hibernating primate, the dwarf lemur Cheirogaleus medius , experiences rapid eye movement (REM)-like states during hibernation, whenever passively reaching temperatures above 30°C, as occurs when it hibernates in poorly insulated tree hollows under tropical conditions. Here, we report electroencephalographic (EEG) recordings, temperature data and metabolic rates from two related species ( C. crossleyi and C. sibreei ), inhabiting high-altitude rainforests and hibernating underground, conditions that mirror, to some extent, those experienced by temperate hibernators. We compared the physiology of hibernation and spontaneous arousals in these animals to C. medius , as well as the much more distantly related non-primate hibernators, such as Arctic, golden-mantled and European ground squirrels. We observed a number of commonalities with non-primate temperate hibernators including: (i) monotonous ultra-low voltage EEG during torpor bouts in these relatively cold-weather hibernators, (ii) the absence of sleep during torpor bouts, (iii) the occurrence of spontaneous arousals out of torpor, during which sleep regularly occurred, (iv) relatively high early EEG non-REM during the arousal, and (v) a gradual transition to the torpid EEG state from non-REM sleep. Unlike C. medius , our study species did not display sleep-like states during torpor bouts, but instead exclusively exhibited them during arousals. During these short euthermic periods, non-REM as well as REM sleep-like stages were observed. Differences observed between these two species and their close relative, C. medius , for which data have been published, presumably reflect differences in hibernaculum temperature.

scholarly journals Sounding It Out: Auditory Stimulation and Overnight Memory Processing

2021 ◽  
Author(s):  
Marcus O. Harrington ◽  
Scott A. Cairney
Keyword(s):  
Rem Sleep ◽  
Memory Consolidation ◽  
Slow Wave Sleep ◽  
Auditory Stimulation ◽  
Theta Oscillations ◽  
Neural Oscillations ◽  
Healthy Children ◽  
Factors Affecting ◽  
Memory Processing ◽  
Eeg Recordings

Abstract Purpose of Review Auditory stimulation is a technique that can enhance neural oscillations linked to overnight memory consolidation. In this review, we evaluate the impacts of auditory stimulation on the neural oscillations of sleep and associated memory processes in a variety of populations. Recent Findings Cortical EEG recordings of slow-wave sleep (SWS) are characterised by two cardinal oscillations: slow oscillations (SOs) and sleep spindles. Auditory stimulation delivered in SWS enhances SOs and phase-coupled spindle activity in healthy children and adults, children with ADHD, adults with mild cognitive impairment and patients with major depression. Under certain conditions, auditory stimulation bolsters the benefits of SWS for memory consolidation, although further work is required to fully understand the factors affecting stimulation-related memory gains. Recent work has turned to rapid eye movement (REM) sleep, demonstrating that auditory stimulation can be used to manipulate REM sleep theta oscillations. Summary Auditory stimulation enhances oscillations linked to overnight memory processing and shows promise as a technique for enhancing the memory benefits of sleep.

Loss of circadian organization of sleep and wakefulness during hibernation

2002 ◽  
Vol 282 (4) ◽  
pp. R1086-R1095 ◽  
Author(s):  
Jennie E. Larkin ◽  
Paul Franken ◽  
H. Craig Heller
Keyword(s):  
Brain Temperature ◽  
Nrem Sleep ◽  
Wave Activity ◽  
Ground Squirrels ◽  
Ultradian Rhythm ◽  
Organization Of Sleep ◽  
Sleep Homeostasis ◽  
Circadian Organization ◽  
Frequency Components ◽  
Torpor Bouts

We investigated circadian and homeostatic regulation of nonrapid eye movement (NREM) sleep in golden-mantled ground squirrels during euthermic intervals between torpor bouts. Slow-wave activity (SWA; 1–4 Hz) and sigma activity (10–15 Hz) represent the two dominant electroencephalographic (EEG) frequency components of NREM sleep. EEG sigma activity has a strong circadian component in addition to a sleep homeostatic component, whereas SWA mainly reflects sleep homeostasis [Dijk DJ and Czeisler CA. J Neurosci 15: 3526–3538, 1995; Dijk DJ, Shanahan TL, Duffy JF, Ronda JM, and Czeisler CA. J Physiol (Lond) 505: 851–858, 1997]. Animals maintained under constant conditions continued to display circadian rhythms in both sigma activity and brain temperature throughout euthermic intervals, whereas sleep and wakefulness showed no circadian organization. Instead, sleep and wakefulness were distributed according to a 6-h ultradian rhythm. SWA, NREM sleep bout length, and sigma activity responded homeostatically to the ultradian sleep-wake pattern. We suggest that the loss of sleep-wake consolidation in ground squirrels during the hibernation season may be related to the greatly decreased locomotor activity during the hibernation season and may be necessary for maintenance of multiday torpor bouts characteristic of hibernating species.

scholarly journals Resting EEG Measures of Brain Arousal in a Multisite Study of Major Depression

2018 ◽  
Vol 50 (1) ◽  
pp. 3-12 ◽  
Author(s):  
Christine Ulke ◽  
Craig E. Tenke ◽  
Jürgen Kayser ◽  
Christian Sander ◽  
Daniel Böttger ◽  
...  
Keyword(s):  
Low Voltage ◽  
Clinical Care ◽  
The United States ◽  
Alpha Activity ◽  
Healthy Controls ◽  
Significant Group ◽  
Depressed Patients ◽  
Eyes Closed ◽  
Eeg Recordings ◽  
Brain Arousal

Several studies have found upregulated brain arousal during 15-minute EEG recordings at rest in depressed patients. However, studies based on shorter EEG recording intervals are lacking. Here we aimed to compare measures of brain arousal obtained from 2-minute EEGs at rest under eyes-closed condition in depressed patients and healthy controls in a multisite project—Establishing Moderators and Biosignatures of Antidepressant Response for Clinical Care (EMBARC). We expected that depressed patients would show stable and elevated brain arousal relative to controls. Eighty-seven depressed patients and 36 healthy controls from four research sites in the United States were included in the analyses. The Vigilance Algorithm Leipzig (VIGALL) was used for the fully automatic classification of EEG-vigilance stages (indicating arousal states) of 1-second EEG segments; VIGALL-derived measures of brain arousal were calculated. We found that depressed patients scored higher on arousal stability ( Z = −2.163, P = .015) and A stages (dominant alpha activity; P = .027) but lower on B1 stages (low-voltage non-alpha activity, P = .008) compared with healthy controls. No significant group differences were observed in Stage B2/3. In summary, we were able to demonstrate stable and elevated brain arousal during brief 2-minute recordings at rest in depressed patients. Results set the stage for examining the value of these measures for predicting clinical response to antidepressants in the entire EMBARC sample and evaluating whether an upregulated brain arousal is particularly characteristic for responders to antidepressants.

scholarly journals Electrical Stimulation Activates Fibroblasts through the Elevation of Intracellular Free Ca2+: Potential Mechanism of Pelvic Electrical Stimulation Therapy

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Suting Li ◽  
Danhua Lu ◽  
Jianming Tang ◽  
Jie Min ◽  
Ming Hu ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Nuclear Translocation ◽  
Low Voltage ◽  
Second Messenger ◽  
Vaginal Wall ◽  
Downstream Signaling ◽  
Physiological Processes ◽  
L929 Fibroblast ◽  
Intracellular Ca

Ca2+ is an important ion in response to electrical stimulation (ES) and acts as second messenger in the regulation of various physiological processes. Pelvic floor electrical stimulation (PES) is a low-voltage clinical application, available for urinary incontinence (UI) treatment. Fibroblasts, as the main cellular component of vaginal wall and pelvic ligament, play an important role in the maintenance of pelvic health. We studied the effect of ES on fibroblasts in this study. ES was conducted with electrotaxis chambers on L929 fibroblast and the ES parameter was 100 mV/mm×2h. The results showed that ES increased intracellular Ca2+ concentration, promoted the expression of PCNA, CyclinB1, and CyclinD1, and increased the proportion of cells in S and G2 phages. After ES, fibroblasts get activated and proliferated. Besides, BAPTA-AM, a membrane permeated chelator for intracellular free Ca2+, partially inhibited the effect of ES on fibroblasts activation and proliferation promotion. Furthermore, we elucidated that Ca2+, as a second messenger and upstream signal for Smads and Akt signaling, regulated ES-induced nuclear translocation of smad2/3, phosphorylation of smad2/3, Akt, and GSK3β. Finally, we validated the effect of ES on PES mouse model. The results indicated that PES promoted the activation and proliferation of fibroblasts in vivo. In conclusion, we verify that ES can elevate the concentration of intracellular Ca2+ and activate its downstream signaling and then promote the activation of fibroblasts, which may be one of the mechanisms of PES therapy.

scholarly journals Mammalian hibernation as a model of disuse osteoporosis: the effects of physical inactivity on bone metabolism, structure, and strength

2008 ◽  
Vol 295 (6) ◽  
pp. R1999-R2014 ◽  
Author(s):  
Meghan E. McGee-Lawrence ◽  
Hannah V. Carey ◽  
Seth W. Donahue
Keyword(s):  
Bone Loss ◽  
Bone Metabolism ◽  
Bone Structure ◽  
Weight Bearing ◽  
Hormonal Control ◽  
Ground Squirrels ◽  
Valuable Insight ◽  
Physiological Processes ◽  
Skeletal Loading ◽  
Insight Into

Reduced skeletal loading typically leads to bone loss because bone formation and bone resorption become unbalanced. Hibernation is a natural model of musculoskeletal disuse because hibernating animals greatly reduce weight-bearing activity, and therefore, they would be expected to lose bone. Some evidence suggests that small mammals like ground squirrels, bats, and hamsters do lose bone during hibernation, but the mechanism of bone loss is unclear. In contrast, hibernating bears maintain balanced bone remodeling and preserve bone structure and strength. Differences in the skeletal responses of bears and smaller mammals to hibernation may be due to differences in their hibernation patterns; smaller mammals may excrete calcium liberated from bone during periodic arousals throughout hibernation, leading to progressive bone loss over time, whereas bears may have evolved more sophisticated physiological processes to recycle calcium, prevent hypercalcemia, and maintain bone integrity. Investigating the roles of neural and hormonal control of bear bone metabolism could give valuable insight into translating the mechanisms that prevent disuse-induced bone loss in bears into novel therapies for treating osteoporosis.

scholarly journals 0012 REM Sleep in Ostrich Chicks

SLEEP ◽  
2020 ◽  
Vol 43 (Supplement_1) ◽  
pp. A5-A5
Author(s):  
O Lyamin ◽  
V Borshenko ◽  
A Bakhchina ◽  
J Siegel
Keyword(s):  
Rem Sleep ◽  
Slow Wave Sleep ◽  
Low Voltage ◽  
Basic Research ◽  
Early Age ◽  
Unexpected Result ◽  
Sleep State ◽  
Eye Closure ◽  
The Brain ◽  
Nonrem Sleep

Abstract Introduction It was reported that adult ostriches displayed the longest REM sleep episodes (up to 5 min) and more REM sleep (24% of the nighttime) than any other avian species. In all mammals studied so far REM sleep predominates at early age suggesting it promotes development of the brain. The aim of this study was to examine REM sleep in ostrich chicks. Methods EEG, electrooculogram and electromyogram of the neck muscles were recorded in 4 chronically implanted 2–3 month old ostrich chicks over 3 nights. The last night was scored in 4-sec epochs for waking, nonREM and REM sleep. Results NonREM sleep and REM sleep in the ostrich chicks occurred when they were sitting or lying with the head held above the ground or rested on the ground. REM sleep was characterized by distinct rapid eye movements, head drops and eye closure. The amplitude of the EEG during episodes of REM sleep ranged between low voltage EEG, as recorded during quiet waking and high voltage slow waves, as recorded during nonREM sleep EEG. The ostrich chicks spent on average 70.7 + 2.2% of the nighttime in nonREM sleep and 12.3 + 3.9% in REM sleep. The episodes of REM sleep lasted on average 9 + 1 sec and ranged between 4 and 36 sec. Conclusion Similar to adult birds, 2–3 mo old ostrich chicks displayed a “mixed” sleep state which has features of both slow wave sleep / nonREM and REM sleep, as we have described in the platypus and echidna. An unexpected result of this study is the total amount and duration of episodes of REM were considerably smaller than has been reported in adult ostriches. More studies need to be done on the developmental and environmental determinants of REM sleep in the ostrich. Support The Russian Foundation for Basic Research (18-04-01252) and HL148574

scholarly journals Why Are Seizures Rare in Rapid Eye Movement Sleep? Review of the Frequency of Seizures in Different Sleep Stages

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Marcus Ng ◽  
Milena Pavlova
Keyword(s):  
Eye Movement ◽  
Rem Sleep ◽  
Low Voltage ◽  
Sleep Stage ◽  
Sleep Stages ◽  
Seizure Freedom ◽  
Rapid Eye Movement ◽  
Focal Seizures ◽  
Generalized Seizures ◽  
Interictal Discharges

Since the formal characterization of sleep stages, there have been reports that seizures may preferentially occur in certain phases of sleep. Through ascending cholinergic connections from the brainstem, rapid eye movement (REM) sleep is physiologically characterized by low voltage fast activity on the electroencephalogram, REMs, and muscle atonia. Multiple independent studies confirm that, in REM sleep, there is a strikingly low proportion of seizures (~1% or less). We review a total of 42 distinct conventional and intracranial studies in the literature which comprised a net of 1458 patients. Indexed to duration, we found that REM sleep was the most protective stage of sleep against focal seizures, generalized seizures, focal interictal discharges, and two particular epilepsy syndromes. REM sleep had an additional protective effect compared to wakefulness with an average 7.83 times fewer focal seizures, 3.25 times fewer generalized seizures, and 1.11 times fewer focal interictal discharges. In further studies REM sleep has also demonstrated utility in localizing epileptogenic foci with potential translation into postsurgical seizure freedom. Based on emerging connectivity data in sleep, we hypothesize that the influence of REM sleep on seizures is due to a desynchronized EEG pattern which reflects important connectivity differences unique to this sleep stage.

Accelerated reproductive development in juvenile male ground squirrels fed a high-fat diet

1992 ◽  
Vol 262 (4) ◽  
pp. R644-R650 ◽  
Author(s):  
J. Dark ◽  
N. F. Ruby ◽  
G. N. Wade ◽  
P. Licht ◽  
I. Zucker
Keyword(s):  
High Fat Diet ◽  
Average Duration ◽  
Reproductive Development ◽  
Ground Squirrels ◽  
Plasma Testosterone ◽  
Juvenile Male ◽  
High Fat ◽  
Reproductive Condition ◽  
Juvenile Males ◽  
Torpor Bouts

Male golden-mantled ground squirrels held at 23 degrees C were fed high-fat (HF) or standard (chow) diets. In December, ambient temperature was reduced to 6 degrees C, food was removed, and frequency and duration of torpor bouts were monitored continuously by radiotelemetry. Reproductive condition and body composition were assessed upon terminal arousal in the spring. Juvenile males fed the HF diet weighed more than chow-fed controls before and throughout the hibernation season and had significantly greater lipid masses at terminal arousal. Testes masses and plasma testosterone concentrations were substantially higher in HF than in chow-fed juveniles. The accelerated reproductive development of fatter squirrels was not contingent upon increases in the total number of days spent in torpor, number of torpor bouts, or the average duration of each arousal from torpor. Access to the HF diet had no effect on body mass, adiposity, or reproductive status of adult male ground squirrels in spring. Threshold levels of white adipose tissue and associated differences in availability of metabolic fuels may be permissive for testicular growth during the hibernation season. Juveniles exceed this threshold only when fed the HF diet.

Sleep and hibernation in ground squirrels (Citellus spp): electrophysiological observations

1977 ◽  
Vol 233 (5) ◽  
pp. R213-R221 ◽  
Author(s):  
J. M. Walker ◽  
S. F. Glotzbach ◽  
R. J. Berger ◽  
H. C. Heller
Keyword(s):  
Rem Sleep ◽  
Slow Wave Sleep ◽  
Dark Period ◽  
Total Sleep Time ◽  
Brain Temperature ◽  
Sleep Time ◽  
Light Period ◽  
Ground Squirrels ◽  
Sleep Stages ◽  
Electroencephalogram Eeg

Electroencephalogram (EEG), electrooculogram, electromyogram, and electrocardiogram were recorded from ground squirrels (Citellus beldingi and C. lateralis) during the summer and also during the hibernation season. Summer recordings revealed that the animals spent an average of 66% of the 24-h period asleep (49% of the 12-h light period and 84% of the 12-h dark period); 19% of the total sleep time (TST) consisted of rapid-eye-movement (REM) sleep, and 81% of TST consisted of slow-wave sleep (SWS). Recordings obtained during the hibernation season showed that hibernation was entered through sleep, but the distribution of sleep states was different than in euthermic sleep. During the early entrance when brain temperature (Tbr) was between 35 and 25 degrees C, the animals were asleep 88% of the time, but only 10% of the TST was spent in REM sleep. The EEG amplitude declined with decreased Tbr so that classical sleep stages could not be identified below a Tbr of 25 degrees C. The frequency of the EEG increased as Tbr decreased; but activity in the 0–4 cycles/s band occupied the majority of the record even at a Tbr of 10 degrees C. Below a Tbr of 10 degrees C the EEG was isoelectric except for intermittent bursts of spindles. It was concluded from these and other results that the entrance into hibernation represents an extension of the thermoregulatory adjustments that occur during SWS.

scholarly journals P.128 Quantitative EEG Detects REM Sleep Microstructure

2021 ◽  
Vol 48 (s3) ◽  
pp. S56-S56
Author(s):  
D Toutant ◽  
M Ng
Keyword(s):  
Eye Movements ◽  
Rem Sleep ◽  
Quantitative Eeg ◽  
Artifact Reduction ◽  
Proof Of Concept ◽  
Rapid Eye Movement Sleep ◽  
Artifact Detection ◽  
Eeg Recordings ◽  
Sleep Microstructure ◽  
Epilepsy Monitoring

Background: Rapid eye movement sleep (REM) is divided into phasic and tonic microstates. Phasic REM is defined by presence of REMs with reportedly greater antiepileptic effect. We assessed whether quantitative EEG (QEEG) software can detect REM microstates. Methods: We applied artifact reduction and detection trends from QEEG software (Persyst 14) on 18 patients undergoing 30 day-night high density EEG recordings in the epilepsy monitoring unit. We identified phasic REM as 10-second epochs of previously human-scored REM that demonstrated presence of either vertical or horizontal eye movements on the QEEG artifact detection panel. Remaining epochs were identified as tonic REM. Results: Out of 91.2 average minutes of REM (range 24.5-167.5) per recording, a mean of 2.5% (range 0-18.9%) demonstrated eye movements intensive enough for QEEG artifact detection to be identified as phasic REM. On average, only 40% (range 0-500%) of eye movements per recording was flagged as vertical. Conclusions: These findings provide proof-of-concept that QEEG can automatically assess REM microstructure by readily detecting phasic and tonic REM. These findings also confirm that most REMs are horizontal. Having the ability to easily and automatically detect phasic versus tonic REM can help further future studies examining the antiepileptic effect of REM sleep.

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