Ambient temperature during torpor affects NREM sleep EEG during arousal episodes in hibernating European ground squirrels

Electroencephalographic slow-wave activity (SWA) in non-rapid eye movement (NREM) sleep is directly related to prior sleep/wake history, with high levels of SWA following extended periods of wake. Therefore, SWA has been thought to reflect the level of accumulated sleep need. The discovery that euthermic intervals between hibernation bouts are spent primarily in sleep and that this sleep is characterized by high and monotonically declining SWA has led to speculation that sleep homeostasis may play a fundamental role in the regulation of the timing of bouts of hibernation and periodic arousals to euthermia. It was proposed that because the SWA profile seen after arousal from hibernation is strikingly similar to what is seen in nonhibernating mammals after extended periods of wakefulness, that hibernating mammals may arouse from hibernation with significant accumulated sleep need. This sleep need may accumulate during hibernation because the low brain temperatures during hibernation may not be compatible with sleep restorative processes. In the present study, golden-mantled ground squirrels were sleep deprived during the first 4 h of interbout euthermia by injection of caffeine (20 mg/kg ip). We predicted that if the SWA peaks after bouts of hibernation reflected a homeostatic response to an accumulated sleep need, sleep deprivation should simply have displaced and possibly augmented the SWA to subsequent recovery sleep. Instead we found that after caffeine-induced sleep deprivation of animals just aroused from hibernation, the anticipated high SWA typical of recovery sleep did not occur. Similar results were found in a study that induced sleep deprivation by gentle handling (19). These findings indicate that the SWA peak immediately after hibernation does not represent homeostatic regulation of NREM sleep, as it normally does after prolonged wakefulness during euthermia, but instead may reflect some other neurological process in the recovery of brain function from an extended period at low temperature.

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

SLEEP ◽

10.1093/sleep/zsaa056.324 ◽

2020 ◽

Vol 43 (Supplement_1) ◽

pp. A124-A124

Author(s):

T Basishvili ◽

M Eliozishvili ◽

T Oniani ◽

T Tchintcharauli ◽

I Sakhelashvili ◽

...

Keyword(s):

Longitudinal Study ◽

Nrem Sleep ◽

Sleep Eeg ◽

Brain Maturation ◽

Adhd Group ◽

Typically Developing ◽

Eeg Activity ◽

Theta Power ◽

Delta Power ◽

Drug Naïve

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

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Effects of central injection of biogenic amines during arousal from hibernation

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1979.236.3.r162 ◽

1979 ◽

Vol 236 (3) ◽

pp. R162-R167 ◽

Cited By ~ 1

Author(s):

J. D. Glass ◽

L. C. Wang

Keyword(s):

Ambient Temperature ◽

Specific Heat ◽

Biogenic Amines ◽

Heat Production ◽

Ground Squirrels ◽

Spermophilus Richardsonii ◽

Simultaneous Measurements ◽

Apparent Specific Heat ◽

Intracerebroventricular Injections ◽

Made In

Simultaneous measurements of heat production (HP) and heat loss (HL) and brain and rectal temperatures were made in Richardon's ground squirrels (Spermophilus richardsonii) rewarming from hibernation at an ambient temperature of 6.0 +/- 0.5 degrees C. Calculations from HP and HL measurements from control animals showed that due to differential rewarming, there was a reduction of apparent specific heat of the animal to 0.59 cal/g. degrees C. This resulted in an energy saving of 30%. Three intracerebroventricular injections of 5-hydroxytryptamine (5-HT) of 56 microgram each at brain temperatures of 10, 20, and 30 degrees C caused initial suppression of HP and a greater overall HL, which resulted in a slower rate of arousal as compared to the controls. Injections of norepinephrine (NE) of 12.5 microgram each at similar brain temperatures caused a greater rate of HP, which resulted in a faster rate of arousal as compared to the controls. The respective actions of 5-HT and NE on thermoregulation during rewarming are similar to those in some euthermic hibernators and nonhibernating species. Our data indicated that these substances evoke thermoregulatory responses during arousal in much the same manner as during normothermia.

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Loss of circadian organization of sleep and wakefulness during hibernation

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00771.2000 ◽

2002 ◽

Vol 282 (4) ◽

pp. R1086-R1095 ◽

Cited By ~ 22

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.

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Parasympathetic influence on heart rate in euthermic and hibernating ground squirrels.

Journal of Experimental Biology ◽

10.1242/jeb.198.4.931 ◽

1995 ◽

Vol 198 (4) ◽

pp. 931-937 ◽

Cited By ~ 4

Author(s):

M B Harris ◽

W K Milsom

Keyword(s):

Heart Rate ◽

Ambient Temperature ◽

Parasympathetic Nervous System ◽

Ground Squirrels ◽

Relative Role ◽

Body Temperatures ◽

Inotropic Effects ◽

Ambient Temperatures ◽

Isolated Hearts ◽

C 32

The relative role of the parasympathetic nervous system during deep hibernation is enigmatic. Conflicting hypotheses exist, and both sides draw support from investigations of vagal influence on the heart. Recent studies have shown cardiac chronotropic and inotropic effects of parasympathetic stimulation and inhibition in isolated hearts and anesthetized animals at hibernating body temperatures. No studies, however, have demonstrated such occurrences in undisturbed deeply hibernating animals. The present study documents respiratory-related alterations in heart rate during euthermia and hibernation at ambient temperatures of 15, 10 and 5 degrees C mediated by parasympathetic influence. During quiet wakefulness, euthermic squirrels breathed continuously and exhibited a 29% acceleration in heart rate during inspiration. During deep undisturbed hibernation, at 15, 10 and 5 degrees C ambient temperature, animals exhibited an episodic breathing pattern and body temperatures were slightly above ambient temperature. At each temperature, heart rate during the respiratory episode was greater than that during the apnea. The magnitude of this ventilatory tachycardia decreased with ambient temperature, being 108% at 15 degrees C, 32% at 10 degrees C and 11.5% at 5 degrees C. Animals exposed to 3% CO2 at 5 degrees C, which significantly increased ventilation, still exhibited an 11.7% increase in heart rate during breathing. Thus, the magnitude of the ventilation tachycardia was independent of the level of ventilation, at least over the range studied. Inhibition of vagus nerve conduction at 5 degrees C was achieved using localized nerve block. This led to an increase in apneic heart rate and abolished the ventilatory tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)

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628 Longitudinal Association between NREM Sleep Depth and Arousability with ADHD and Internalizing Disorders in Adolescence

SLEEP ◽

10.1093/sleep/zsab072.626 ◽

2021 ◽

Vol 44 (Supplement_2) ◽

pp. A246-A247

Author(s):

Anna Ricci ◽

Julio Fernandez-Mendoza ◽

Fan He ◽

Susan Calhoun ◽

Magdy Younes ◽

...

Keyword(s):

Behavioral Disorders ◽

Nrem Sleep ◽

Internalizing Disorders ◽

Developmental Trajectory ◽

Sleep Eeg ◽

Behavioral Disorder ◽

Sleep Depth ◽

Transition To Adolescence ◽

Psychoactive Medications

Abstract Introduction Sleep depth decreases in the transition from childhood to adolescence, even in typically developing (TD) youth. However, it remains unknown whether this developmental trajectory in NREM sleep depth differs across adolescents with psychiatric/behavioral disorders. Methods We analyzed the sleep EEG of 392 subjects aged 5–12 at baseline and 12–22 at follow-up (45.2% female, 23.2% racial/ethnic minority), of whom 246 were TD adolescents (controls), 62 were diagnosed with a psychiatric/behavioral disorder and were taking stimulant, anti-depressant, anxiolytic, sedative and/or anti-psychotic medications, and 84 were un-medicated. NREM sleep depth was measured at both time points using the odds ratio product (ORP), which provides a standardized continuous EEG measure of NREM sleep depth/arousability (higher ORP reflects lighter NREM sleep). General linear models examined mean differences between groups on the percent change in ORP between baseline and follow-up (ΔORP) while adjusting for sex, race/ethnicity, age, BMI and AHI at follow-up, and PSG system, psychiatric/behavioral disorders, psychoactive medications and ORP at baseline as well as time-to-follow-up. Results Overall, medicated (80.4%, 95%CI=66.2–94.6) and un-medicated (66.1%, 95%CI=53.0–79.1) subjects showed a higher ΔORP compared to controls (52.2%, 95%CI=40.0–64.5, p<0.01 and p<0.05, respectively) but did not differ between each other (p=0.134). Specifically, un-medicated subjects with ADHD (n=56) showed a higher ΔORP (77.3%, 95%CI=62.4–92.1) compared to controls (p<0.01), while subjects with ADHD on stimulant medication (n=36) did not differ (66.1%, 95%CI=48.9–93.2) from controls (p=0.268) or from un-medicated ADHD subjects (p=0.303). Subjects with internalizing disorders on psychoactive medications (n=29) showed a higher ΔORP (104.9%, 95%CI=82.8–127.0) compared to controls (p<0.01) and to un-medicated subjects (n=27) with internalizing disorders (60.1%, 95%CI=36.8–83.3, p<0.01), who did not differ from controls (p=0.772). Conclusion The greater increase in ORP in the transition to adolescence in un-medicated youth with ADHD suggests that decreased NREM sleep depth may be a biomarker of the disorder. In contrast, the greater increase in ORP in medicated youth with internalizing disorders suggests that psychoactive medications impact NREM sleep depth in these children as they transition to adolescence. These data have important implications for sleep EEG studies that include medicated and un-medicated youth with comorbid psychiatric disorders. Support (if any) NIH Awards Number R01MH118308, R01HL136587, R01HL97165, R01HL63772, UL1TR000127

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Differential modulation of NREM sleep regulation and EEG topography by chronic sleep restriction in mice

Scientific Reports ◽

10.1038/s41598-019-54790-y ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Bowon Kim ◽

Eunjin Hwang ◽

Robert E. Strecker ◽

Jee Hyun Choi ◽

Youngsoo Kim

Keyword(s):

Nrem Sleep ◽

Brain Regions ◽

Sleep Eeg ◽

Sleep Restriction ◽

Electrode Arrays ◽

Sleep Regulation ◽

Amplitude Analysis ◽

Delta Power ◽

Eeg Topography ◽

Chronic Sleep

AbstractCompensatory elevation in NREM sleep EEG delta power has been typically observed following prolonged wakefulness and widely used as a sleep homeostasis indicator. However, recent evidence in human and rodent chronic sleep restriction (CSR) studies suggests that NREM delta power is not progressively increased despite of accumulated sleep loss over days. In addition, there has been little progress in understanding how sleep EEG in different brain regions responds to CSR. Using novel high-density EEG electrode arrays in the mouse model of CSR where mice underwent 18-h sleep deprivation per day for 5 consecutive days, we performed an extensive analysis of topographical NREM sleep EEG responses to the CSR condition, including period-amplitude analysis of individual slow waves. As previously reported in our analysis of REM sleep responses, we found different patterns of changes: (i) progressive decrease in NREM sleep duration and consolidation, (ii) persistent enhancement in NREM delta power especially in the frontal and parietal regions, and (iii) progressive increases in individual slow wave slope and frontal fast oscillation power. These results suggest that multiple sleep-wake regulatory systems exist in a brain region-specific manner, which can be modulated independently, especially in the CSR condition.

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Characterization of midbrain component of the trigger for arousal from hibernation

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1976.230.2.368 ◽

1976 ◽

Vol 230 (2) ◽

pp. 368-375 ◽

Cited By ~ 19

Author(s):

AL Beckman ◽

E Satinoff ◽

TL Stanton

Keyword(s):

Body Temperature ◽

Ambient Temperature ◽

Reticular Formation ◽

Functional Organization ◽

Ground Squirrels ◽

Anterior Hypothalamus ◽

Midbrain Reticular Formation ◽

Citellus Lateralis ◽

Arousal Mechanism

The ability of the midbrain reticular formation (MRF) to trigger arousal from hibernation and to change body temperature (Tb) during euthermia was tested in golden-mantled ground squirrels (Citellus lateralis). During hibernation (ambient temperature 5-6 degrees C) microinjections of cholinomimetic compounds (acetylcholine and carbachol) triggered full arousal or produced transient increases in Tb in 15 out of 19 tests; MRF microinjections of norepinephrine (NE) and 5-hydroxytryptamine (5-HT), at the same concentrations that produced full arousal when microinjected into the preoptic/anterior hypothalamus (PO/AH) area in previous experiments, has no effect on Tb in 13 out of 16 tests. In experiments on euthermic ground squirrels tested at an ambient temperature of 25 degrees C, MRF microinjections of acetylcholine raised Tb, whereas the monoamines had no significant effects. These results show that cholinoceptive neurons in the MRF can trigger arousal from hibernation and increase Tb during euthermia. The failure of NE and 5-HT to produce any significant effects at the same doses that were reported to be effective in the PO/AH indicates that the functional organization of the MRF portion of the arousal mechanism is different from that reported for the PO/AH.

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