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Rayan A, Agarwal A, Samanta A, Severijnen E, van der Meij J, Genzel L. Sleep scoring in rodents: Criteria, automatic approaches and outstanding issues. Eur J Neurosci 2024; 59:526-553. [PMID: 36479908 DOI: 10.1111/ejn.15884] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 11/01/2022] [Accepted: 11/23/2022] [Indexed: 12/13/2022]
Abstract
There is nothing we spend as much time on in our lives as we do sleeping, which makes it even more surprising that we currently do not know why we need to sleep. Most of the research addressing this question is performed in rodents to allow for invasive, mechanistic approaches. However, in contrast to human sleep, we currently do not have shared and agreed upon standards on sleep states in rodents. In this article, we present an overview on sleep stages in humans and rodents and a historical perspective on the development of automatic sleep scoring systems in rodents. Further, we highlight specific issues in rodent sleep that also call into question some of the standards used in human sleep research.
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Affiliation(s)
- Abdelrahman Rayan
- Donders Institute for Brain, Cognition, and Behavior, Radboud University, Nijmegen, The Netherlands
| | - Anjali Agarwal
- Donders Institute for Brain, Cognition, and Behavior, Radboud University, Nijmegen, The Netherlands
| | - Anumita Samanta
- Donders Institute for Brain, Cognition, and Behavior, Radboud University, Nijmegen, The Netherlands
| | - Eva Severijnen
- Donders Institute for Brain, Cognition, and Behavior, Radboud University, Nijmegen, The Netherlands
| | - Jacqueline van der Meij
- Donders Institute for Brain, Cognition, and Behavior, Radboud University, Nijmegen, The Netherlands
| | - Lisa Genzel
- Donders Institute for Brain, Cognition, and Behavior, Radboud University, Nijmegen, The Netherlands
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Libourel PA, Lee WY, Achin I, Chung H, Kim J, Massot B, Rattenborg NC. Nesting chinstrap penguins accrue large quantities of sleep through seconds-long microsleeps. Science 2023; 382:1026-1031. [PMID: 38033080 DOI: 10.1126/science.adh0771] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 10/05/2023] [Indexed: 12/02/2023]
Abstract
Microsleeps, the seconds-long interruptions of wakefulness by eye closure and sleep-related brain activity, are dangerous when driving and might be too short to provide the restorative functions of sleep. If microsleeps do fulfill sleep functions, then animals faced with a continuous need for vigilance might resort to this sleep strategy. We investigated electroencephalographically defined sleep in wild chinstrap penguins, at sea and while nesting in Antarctica, constantly exposed to an egg predator and aggression from other penguins. The penguins nodded off >10,000 times per day, engaging in bouts of bihemispheric and unihemispheric slow-wave sleep lasting on average only 4 seconds, but resulting in the accumulation of >11 hours of sleep for each hemisphere. The investment in microsleeps by successfully breeding penguins suggests that the benefits of sleep can accrue incrementally.
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Affiliation(s)
- P-A Libourel
- Neuroscience Research Center of Lyon, Bron, France
| | - W Y Lee
- Korea Polar Research Institute, Incheon, Republic of Korea
| | - I Achin
- Neuroscience Research Center of Lyon, Bron, France
| | - H Chung
- Korea Polar Research Institute, Incheon, Republic of Korea
| | - J Kim
- Cheongju Zoo, Cheongju, Republic of Korea
| | - B Massot
- Lyon Institute of Nanotechnology, Villeurbanne, France
| | - N C Rattenborg
- Avian Sleep Group, Max Planck Institute for Biological Intelligence, Seewiesen, Germany
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3
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Libourel PA, Lesku JA. Sleep: Hemispheres fight for dominance. Curr Biol 2023; 33:R729-R732. [PMID: 37433277 DOI: 10.1016/j.cub.2023.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/13/2023]
Abstract
A new study shows that bearded dragons have a peculiar way to coordinate sleep state changes between brain hemispheres. The hemisphere that acts first imposes its activity on the other during their REM sleep-like state.
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Affiliation(s)
- Paul-Antoine Libourel
- Université Claude Bernard Lyon 1, CNRS, INSERM, Centre de Recherche en Neurosciences de Lyon CRNL U1028 UMR5292, SLEEP Team, F-69500, Bron, France.
| | - John A Lesku
- Sleep Ecophysiology Group, School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne 3086, Australia.
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4
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Fenk LA, Riquelme JL, Laurent G. Interhemispheric competition during sleep. Nature 2023; 616:312-318. [PMID: 36949193 PMCID: PMC10097603 DOI: 10.1038/s41586-023-05827-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 02/10/2023] [Indexed: 03/24/2023]
Abstract
Our understanding of the functions and mechanisms of sleep remains incomplete, reflecting their increasingly evident complexity1-3. Likewise, studies of interhemispheric coordination during sleep4-6 are often hard to connect precisely to known sleep circuits and mechanisms. Here, by recording from the claustra of sleeping bearded dragons (Pogona vitticeps), we show that, although the onsets and offsets of Pogona rapid-eye-movement (REMP) and slow-wave sleep are coordinated bilaterally, these two sleep states differ markedly in their inter-claustral coordination. During slow-wave sleep, the claustra produce sharp-wave ripples independently of one another, showing no coordination. By contrast, during REMP sleep, the potentials produced by the two claustra are precisely coordinated in amplitude and time. These signals, however, are not synchronous: one side leads the other by about 20 ms, with the leading side switching typically once per REMP episode or in between successive episodes. The leading claustrum expresses the stronger activity, suggesting bilateral competition. This competition does not occur directly between the two claustra or telencephalic hemispheres. Rather, it occurs in the midbrain and depends on the integrity of a GABAergic (γ-aminobutyric-acid-producing) nucleus of the isthmic complex, which exists in all vertebrates and is known in birds to underlie bottom-up attention and gaze control. These results reveal that a winner-take-all-type competition exists between the two sides of the brain of Pogona, which originates in the midbrain and has precise consequences for claustrum activity and coordination during REMP sleep.
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Affiliation(s)
- Lorenz A Fenk
- Max Planck Institute for Brain Research, Frankfurt, Germany.
| | - Juan Luis Riquelme
- Max Planck Institute for Brain Research, Frankfurt, Germany
- School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Gilles Laurent
- Max Planck Institute for Brain Research, Frankfurt, Germany.
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Rattenborg NC, Ungurean G. The evolution and diversification of sleep. Trends Ecol Evol 2023; 38:156-170. [PMID: 36411158 DOI: 10.1016/j.tree.2022.10.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 10/17/2022] [Accepted: 10/24/2022] [Indexed: 11/19/2022]
Abstract
The evolutionary origins of sleep and its sub-states, rapid eye movement (REM) and non-REM (NREM) sleep, found in mammals and birds, remain a mystery. Although the discovery of a single type of sleep in jellyfish suggests that sleep evolved much earlier than previously thought, it is unclear when and why sleep diversified into multiple types of sleep. Intriguingly, multiple types of sleep have recently been found in animals ranging from non-avian reptiles to arthropods to cephalopods. Although there are similarities between these states and those found in mammals and birds, notable differences also exist. The diversity in the way sleep is expressed confounds attempts to trace the evolution of sleep states, but also serves as a rich resource for exploring the functions of sleep.
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Affiliation(s)
- Niels C Rattenborg
- Max Planck Institute for Biological Intelligence (in foundation), Seewiesen, Germany.
| | - Gianina Ungurean
- Max Planck Institute for Biological Intelligence (in foundation), Seewiesen, Germany
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6
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Temperature-robust rapid eye movement and slow wave sleep in the lizard Laudakia vulgaris. Commun Biol 2022; 5:1310. [PMID: 36446903 PMCID: PMC9709036 DOI: 10.1038/s42003-022-04261-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 11/15/2022] [Indexed: 11/30/2022] Open
Abstract
During sleep our brain switches between two starkly different brain states - slow wave sleep (SWS) and rapid eye movement (REM) sleep. While this two-state sleep pattern is abundant across birds and mammals, its existence in other vertebrates is not universally accepted, its evolutionary emergence is unclear and it is undetermined whether it is a fundamental property of vertebrate brains or an adaptation specific to homeotherms. To address these questions, we conducted electrophysiological recordings in the Agamid lizard, Laudakia vulgaris during sleep. We found clear signatures of two-state sleep that resemble the mammalian and avian sleep patterns. These states switched periodically throughout the night with a cycle of ~90 seconds and were remarkably similar to the states previously reported in Pogona vitticeps. Interestingly, in contrast to the high temperature sensitivity of mammalian states, state switches were robust to large variations in temperature. We also found that breathing rate, micro-movements and eye movements were locked to the REM state as they are in mammals. Collectively, these findings suggest that two-state sleep is abundant across the agamid family, shares physiological similarity to mammalian sleep, and can be maintain in poikilothems, increasing the probability that it existed in the cold-blooded ancestor of amniotes.
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Omond SET, Hale MW, Lesku JA. Neurotransmitters of sleep and wakefulness in flatworms. Sleep 2022; 45:zsac053. [PMID: 35554581 PMCID: PMC9216492 DOI: 10.1093/sleep/zsac053] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 02/27/2022] [Indexed: 12/02/2022] Open
Abstract
STUDY OBJECTIVES Sleep is a prominent behavioral and biochemical state observed in all animals studied, including platyhelminth flatworms. Investigations into the biochemical mechanisms associated with sleep-and wakefulness-are important for understanding how these states are regulated and how that regulation changed with the evolution of new types of animals. Unfortunately, beyond a handful of vertebrates, such studies on invertebrates are rare. METHODS We investigated the effect of seven neurotransmitters, and one pharmacological compound, that modulate either sleep or wakefulness in mammals, on flatworms (Girardia tigrina). Flatworms were exposed via ingestion and diffusion to four neurotransmitters that promote wakefulness in vertebrates (acetylcholine, dopamine, glutamate, histamine), and three that induce sleep (adenosine, GABA, serotonin) along with the H1 histamine receptor antagonist pyrilamine. Compounds were administered over concentrations spanning three to five orders of magnitude. Flatworms were then transferred to fresh water and video recorded for analysis. RESULTS Dopamine and histamine decreased the time spent inactive and increased distance traveled, consistent with their wake-promoting effect in vertebrates and fruit flies; pyrilamine increased restfulness and GABA showed a nonsignificant trend towards promoting restfulness in a dose-dependent manner, in agreement with their sleep-inducing effect in vertebrates, fruit flies, and Hydra. Similar to Hydra, acetylcholine, glutamate, and serotonin, but also adenosine, had no apparent effect on flatworm behavior. CONCLUSIONS These data demonstrate the potential of neurotransmitters to regulate sleep and wakefulness in flatworms and highlight the conserved action of some neurotransmitters across species.
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Affiliation(s)
- Shauni E T Omond
- School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, Australia
| | - Matthew W Hale
- School of Psychology and Public Health, La Trobe University, Melbourne, Australia
| | - John A Lesku
- School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, Australia
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Rial RV, Canellas F, Akaârir M, Rubiño JA, Barceló P, Martín A, Gamundí A, Nicolau MC. The Birth of the Mammalian Sleep. BIOLOGY 2022; 11:biology11050734. [PMID: 35625462 PMCID: PMC9138988 DOI: 10.3390/biology11050734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 05/05/2022] [Indexed: 11/16/2022]
Abstract
Simple Summary Mammals evolved from reptiles as a consequence of an evolutionary bottleneck. Some diurnal reptiles extended their activity, first to twilight and then to the entire dark time. This forced the change of the visual system. Pursuing maximal sensitivity, they abandoned the filters protecting the eyes against the dangerous diurnal light, which, in turn, forced immobility in lightproof burrows during light time. This was the birth of the mammalian sleep. Then, the Cretacic-Paleogene extinction of dinosaurs leaved free the diurnal niche and allowed the expansion of a few early mammals to diurnal life and the high variability of sleep traits. On the other hand, we propose that the idling rest is a state showing homeostatic regulation. Therefore, the difference between behavioral rest and wakeful idling is rather low: both show quiescence, raised sensory thresholds, reversibility, specific sleeping-resting sites and body positions, it is a pleasing state, and both are dependent of circadian and homeostatic regulation. Indeed, the most important difference is the unconsciousness of sleep and the consciousness of wakeful idling. Thus, we propose that sleep is a mere upgrade of the wakeful rest, and both may have the same function: guaranteeing rest during a part of the daily cycle. Abstract Mammals evolved from small-sized reptiles that developed endothermic metabolism. This allowed filling the nocturnal niche. They traded-off visual acuity for sensitivity but became defenseless against the dangerous daylight. To avoid such danger, they rested with closed eyes in lightproof burrows during light-time. This was the birth of the mammalian sleep, the main finding of this report. Improved audition and olfaction counterweighed the visual impairments and facilitated the cortical development. This process is called “The Nocturnal Evolutionary Bottleneck”. Pre-mammals were nocturnal until the Cretacic-Paleogene extinction of dinosaurs. Some early mammals returned to diurnal activity, and this allowed the high variability in sleeping patterns observed today. The traits of Waking Idleness are almost identical to those of behavioral sleep, including homeostatic regulation. This is another important finding of this report. In summary, behavioral sleep seems to be an upgrade of Waking Idleness Indeed, the trait that never fails to show is quiescence. We conclude that the main function of sleep consists in guaranteeing it during a part of the daily cycle.
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Affiliation(s)
- Rubén V. Rial
- Laboratori de Neurofisiologia del Son i dels Ritmes Biològics, Grup de Recerca Neurofisiologia del Son i Ritmes Biològics, Department of Biologia, Universitat de les Illes Balears, Ctra Valldemossa, km 7.5, 07122 Palma de Mallorca, Illes Balears, Spain; (F.C.); (M.A.); (J.A.R.); (P.B.); (A.M.); (A.G.); (M.C.N.)
- IdISBa, Institut d’Investigació Sanitària de les Illes Balears, Hospital Son Espases, 07120 Palma de Mallorca, Illes Balears, Spain
- IUNICS, Institut Universitari d’Investigació en Ciències de la Salut, Hospital Universitary Son Espases, 07120 Palma de Mallorca, Illes Balears, Spain
- Correspondence: ; Tel.: +34-971-173-147; Fax: +34-971-173-184
| | - Francesca Canellas
- Laboratori de Neurofisiologia del Son i dels Ritmes Biològics, Grup de Recerca Neurofisiologia del Son i Ritmes Biològics, Department of Biologia, Universitat de les Illes Balears, Ctra Valldemossa, km 7.5, 07122 Palma de Mallorca, Illes Balears, Spain; (F.C.); (M.A.); (J.A.R.); (P.B.); (A.M.); (A.G.); (M.C.N.)
- IdISBa, Institut d’Investigació Sanitària de les Illes Balears, Hospital Son Espases, 07120 Palma de Mallorca, Illes Balears, Spain
- IUNICS, Institut Universitari d’Investigació en Ciències de la Salut, Hospital Universitary Son Espases, 07120 Palma de Mallorca, Illes Balears, Spain
| | - Mourad Akaârir
- Laboratori de Neurofisiologia del Son i dels Ritmes Biològics, Grup de Recerca Neurofisiologia del Son i Ritmes Biològics, Department of Biologia, Universitat de les Illes Balears, Ctra Valldemossa, km 7.5, 07122 Palma de Mallorca, Illes Balears, Spain; (F.C.); (M.A.); (J.A.R.); (P.B.); (A.M.); (A.G.); (M.C.N.)
- IdISBa, Institut d’Investigació Sanitària de les Illes Balears, Hospital Son Espases, 07120 Palma de Mallorca, Illes Balears, Spain
- IUNICS, Institut Universitari d’Investigació en Ciències de la Salut, Hospital Universitary Son Espases, 07120 Palma de Mallorca, Illes Balears, Spain
| | - José A. Rubiño
- Laboratori de Neurofisiologia del Son i dels Ritmes Biològics, Grup de Recerca Neurofisiologia del Son i Ritmes Biològics, Department of Biologia, Universitat de les Illes Balears, Ctra Valldemossa, km 7.5, 07122 Palma de Mallorca, Illes Balears, Spain; (F.C.); (M.A.); (J.A.R.); (P.B.); (A.M.); (A.G.); (M.C.N.)
- IdISBa, Institut d’Investigació Sanitària de les Illes Balears, Hospital Son Espases, 07120 Palma de Mallorca, Illes Balears, Spain
- IUNICS, Institut Universitari d’Investigació en Ciències de la Salut, Hospital Universitary Son Espases, 07120 Palma de Mallorca, Illes Balears, Spain
| | - Pere Barceló
- Laboratori de Neurofisiologia del Son i dels Ritmes Biològics, Grup de Recerca Neurofisiologia del Son i Ritmes Biològics, Department of Biologia, Universitat de les Illes Balears, Ctra Valldemossa, km 7.5, 07122 Palma de Mallorca, Illes Balears, Spain; (F.C.); (M.A.); (J.A.R.); (P.B.); (A.M.); (A.G.); (M.C.N.)
- IdISBa, Institut d’Investigació Sanitària de les Illes Balears, Hospital Son Espases, 07120 Palma de Mallorca, Illes Balears, Spain
- IUNICS, Institut Universitari d’Investigació en Ciències de la Salut, Hospital Universitary Son Espases, 07120 Palma de Mallorca, Illes Balears, Spain
| | - Aida Martín
- Laboratori de Neurofisiologia del Son i dels Ritmes Biològics, Grup de Recerca Neurofisiologia del Son i Ritmes Biològics, Department of Biologia, Universitat de les Illes Balears, Ctra Valldemossa, km 7.5, 07122 Palma de Mallorca, Illes Balears, Spain; (F.C.); (M.A.); (J.A.R.); (P.B.); (A.M.); (A.G.); (M.C.N.)
- IdISBa, Institut d’Investigació Sanitària de les Illes Balears, Hospital Son Espases, 07120 Palma de Mallorca, Illes Balears, Spain
- IUNICS, Institut Universitari d’Investigació en Ciències de la Salut, Hospital Universitary Son Espases, 07120 Palma de Mallorca, Illes Balears, Spain
| | - Antoni Gamundí
- Laboratori de Neurofisiologia del Son i dels Ritmes Biològics, Grup de Recerca Neurofisiologia del Son i Ritmes Biològics, Department of Biologia, Universitat de les Illes Balears, Ctra Valldemossa, km 7.5, 07122 Palma de Mallorca, Illes Balears, Spain; (F.C.); (M.A.); (J.A.R.); (P.B.); (A.M.); (A.G.); (M.C.N.)
- IdISBa, Institut d’Investigació Sanitària de les Illes Balears, Hospital Son Espases, 07120 Palma de Mallorca, Illes Balears, Spain
- IUNICS, Institut Universitari d’Investigació en Ciències de la Salut, Hospital Universitary Son Espases, 07120 Palma de Mallorca, Illes Balears, Spain
| | - M. Cristina Nicolau
- Laboratori de Neurofisiologia del Son i dels Ritmes Biològics, Grup de Recerca Neurofisiologia del Son i Ritmes Biològics, Department of Biologia, Universitat de les Illes Balears, Ctra Valldemossa, km 7.5, 07122 Palma de Mallorca, Illes Balears, Spain; (F.C.); (M.A.); (J.A.R.); (P.B.); (A.M.); (A.G.); (M.C.N.)
- IdISBa, Institut d’Investigació Sanitària de les Illes Balears, Hospital Son Espases, 07120 Palma de Mallorca, Illes Balears, Spain
- IUNICS, Institut Universitari d’Investigació en Ciències de la Salut, Hospital Universitary Son Espases, 07120 Palma de Mallorca, Illes Balears, Spain
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Kelly ML, Collins SP, Lesku JA, Hemmi JM, Collin SP, Radford CA. Energy conservation characterizes sleep in sharks. Biol Lett 2022; 18:20210259. [PMID: 35259943 PMCID: PMC8915397 DOI: 10.1098/rsbl.2021.0259] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Sharks represent the earliest group of jawed vertebrates and as such, they may provide original insight for understanding the evolution of sleep in more derived animals. Unfortunately, beyond a single behavioural investigation, very little is known about sleep in these ancient predators. As such, recordings of physiological indicators of sleep in sharks have never been reported. Reduced energy expenditure arising from sustained restfulness and lowered metabolic rate during sleep have given rise to the hypothesis that sleep plays an important role for energy conservation. To determine whether this idea applies also to sharks, we compared metabolic rates of draughtsboard sharks (Cephaloscyllium isabellum) during periods ostensibly thought to be sleep, along with restful and actively swimming sharks across a 24 h period. We also investigated behaviours that often characterize sleep in other animals, including eye closure and postural recumbency, to establish relationships between physiology and behaviour. Overall, lower metabolic rate and a flat body posture reflect sleep in draughtsboard sharks, whereas eye closure is a poorer indication of sleep. Our results support the idea for the conservation of energy as a function of sleep in these basal vertebrates.
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Affiliation(s)
- Michael L Kelly
- School of Life Sciences, La Trobe University, Melbourne, Australia
| | - Selwyn P Collins
- Institute of Marine Science, Leigh Marine Laboratory, The University of Auckland, Auckland, New Zealand
| | - John A Lesku
- School of Life Sciences, La Trobe University, Melbourne, Australia
| | - Jan M Hemmi
- School of Biological Sciences, The University of Western Australia, Perth, Australia.,Oceans Institute, The University of Western Australia, Perth, Australia
| | - Shaun P Collin
- School of Life Sciences, La Trobe University, Melbourne, Australia.,Oceans Institute, The University of Western Australia, Perth, Australia.,Oceans Graduate School, The University of Western Australia, Perth, Australia
| | - Craig A Radford
- Institute of Marine Science, Leigh Marine Laboratory, The University of Auckland, Auckland, New Zealand
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10
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Jaggard JB, Wang GX, Mourrain P. Non-REM and REM/paradoxical sleep dynamics across phylogeny. Curr Opin Neurobiol 2021; 71:44-51. [PMID: 34583217 PMCID: PMC8719594 DOI: 10.1016/j.conb.2021.08.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 08/24/2021] [Accepted: 08/26/2021] [Indexed: 12/14/2022]
Abstract
All animals carefully studied sleep, suggesting that sleep as a behavioral state exists in all animal life. Such evolutionary maintenance of an otherwise vulnerable period of environmental detachment suggests that sleep must be integral in fundamental biological needs. Despite over a century of research, the knowledge of what sleep does at the tissue, cellular or molecular levels remain cursory. Currently, sleep is defined based on behavioral criteria and physiological measures rather than at the cellular or molecular level. Physiologically, sleep has been described as two main states, non-rapid eye moment (NREM) and REM/paradoxical sleep (PS), which are defined in the neocortex by synchronous oscillations and paradoxical wake-like activity, respectively. For decades, these two sleep states were believed to be defining characteristics of only mammalian and avian sleep. Recent work has revealed slow oscillation, silencing, and paradoxical/REM-like activities in reptiles, fish, flies, worms, and cephalopods suggesting that these sleep dynamics and associated physiological states may have emerged early in animal evolution. Here, we discuss these recent developments supporting the conservation of neural dynamics (silencing, oscillation, paradoxical activity) of sleep states across phylogeny.
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Affiliation(s)
- James B Jaggard
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA
| | - Gordon X Wang
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA; Wu Tsai Neuroscience Institute, Stanford University, Stanford, CA, USA
| | - Philippe Mourrain
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA; INSERM 1024, Ecole Normale Supérieure, Paris, France.
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11
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Osorio-Forero A, Cardis R, Vantomme G, Guillaume-Gentil A, Katsioudi G, Devenoges C, Fernandez LMJ, Lüthi A. Noradrenergic circuit control of non-REM sleep substates. Curr Biol 2021; 31:5009-5023.e7. [PMID: 34648731 DOI: 10.1016/j.cub.2021.09.041] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 08/09/2021] [Accepted: 09/15/2021] [Indexed: 12/13/2022]
Abstract
To understand what makes sleep vulnerable in disease, it is useful to look at how wake-promoting mechanisms affect healthy sleep. Wake-promoting neuronal activity is inhibited during non-rapid-eye-movement sleep (NREMS). However, sensory vigilance persists in NREMS in animals and humans, suggesting that wake promotion could remain functional. Here, we demonstrate that consolidated mouse NREMS is a brain state with recurrent fluctuations of the wake-promoting neurotransmitter noradrenaline on the ∼50-s timescale in the thalamus. These fluctuations occurred around mean noradrenaline levels greater than the ones of quiet wakefulness, while noradrenaline (NA) levels declined steeply in REMS. They coincided with a clustering of sleep spindle rhythms in the forebrain and with heart-rate variations, both of which are correlates of sensory arousability. We addressed the origins of these fluctuations by using closed-loop optogenetic locus coeruleus (LC) activation or inhibition timed to moments of low and high spindle activity during NREMS. We could suppress, lock, or entrain sleep-spindle clustering and heart-rate variations, suggesting that both fore- and hindbrain-projecting LC neurons show coordinated infraslow activity variations in natural NREMS. Noradrenergic modulation of thalamic, but not cortical, circuits was required for sleep-spindle clustering and involved NA release into primary sensory and reticular thalamic nuclei that activated both α1- and β-adrenergic receptors to cause slowly decaying membrane depolarizations. Noradrenergic signaling by LC constitutes a vigilance-promoting mechanism that renders mammalian NREMS vulnerable to disruption on the close-to-minute timescale through sustaining thalamocortical and autonomic sensory arousability. VIDEO ABSTRACT.
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Affiliation(s)
- Alejandro Osorio-Forero
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - Romain Cardis
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - Gil Vantomme
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - Aurélie Guillaume-Gentil
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - Georgia Katsioudi
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - Christiane Devenoges
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - Laura M J Fernandez
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - Anita Lüthi
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland.
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12
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Mohanty NP, Wagener C, Herrel A, Thaker M. The ecology of sleep in non-avian reptiles. Biol Rev Camb Philos Soc 2021; 97:505-526. [PMID: 34708504 DOI: 10.1111/brv.12808] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 10/10/2021] [Accepted: 10/18/2021] [Indexed: 01/10/2023]
Abstract
Sleep is ubiquitous in the animal kingdom and yet displays considerable variation in its extent and form in the wild. Ecological factors, such as predation, competition, and microclimate, therefore are likely to play a strong role in shaping characteristics of sleep. Despite the potential for ecological factors to influence various aspects of sleep, the ecological context of sleep in non-avian reptiles remains understudied and without systematic direction. In this review, we examine multiple aspects of reptilian sleep, including (i) habitat selection (sleep sites and their spatio-temporal distribution), (ii) individual-level traits, such as behaviour (sleep postures), morphology (limb morphometrics and body colour), and physiology (sleep architecture), as well as (iii) inter-individual interactions (intra- and inter-specific). Throughout, we discuss the evidence of predation, competition, and thermoregulation in influencing sleep traits and the possible evolutionary consequences of these sleep traits for reptile sociality, morphological specialisation, and habitat partitioning. We also review the ways in which sleep ecology interacts with urbanisation, biological invasions, and climate change. Overall, we not only provide a systematic evaluation of the conceptual and taxonomic biases in the existing literature on reptilian sleep, but also use this opportunity to organise the various ecological hypotheses for sleep characteristics. By highlighting the gaps and providing a prospectus of research directions, our review sets the stage for understanding sleep ecology in the natural world.
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Affiliation(s)
- Nitya P Mohanty
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore, 560 012, India
| | - Carla Wagener
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Stellenbosch, Western Cape, 7600, South Africa
| | - Anthony Herrel
- Département Adaptations du Vivant, MECADEV UMR7179 CNRS/MNHN, Paris, France
| | - Maria Thaker
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore, 560 012, India
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13
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A probabilistic model for the ultradian timing of REM sleep in mice. PLoS Comput Biol 2021; 17:e1009316. [PMID: 34432801 PMCID: PMC8423363 DOI: 10.1371/journal.pcbi.1009316] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 09/07/2021] [Accepted: 07/29/2021] [Indexed: 11/19/2022] Open
Abstract
A salient feature of mammalian sleep is the alternation between rapid eye movement (REM) and non-REM (NREM) sleep. However, how these two sleep stages influence each other and thereby regulate the timing of REM sleep episodes is still largely unresolved. Here, we developed a statistical model that specifies the relationship between REM and subsequent NREM sleep to quantify how REM sleep affects the following NREM sleep duration and its electrophysiological features in mice. We show that a lognormal mixture model well describes how the preceding REM sleep duration influences the amount of NREM sleep till the next REM sleep episode. The model supports the existence of two different types of sleep cycles: Short cycles form closely interspaced sequences of REM sleep episodes, whereas during long cycles, REM sleep is first followed by an interval of NREM sleep during which transitions to REM sleep are extremely unlikely. This refractory period is characterized by low power in the theta and sigma range of the electroencephalogram (EEG), low spindle rate and frequent microarousals, and its duration proportionally increases with the preceding REM sleep duration. Using our model, we estimated the propensity for REM sleep at the transition from NREM to REM sleep and found that entering REM sleep with higher propensity resulted in longer REM sleep episodes with reduced EEG power. Compared with the light phase, the buildup of REM sleep propensity was slower during the dark phase. Our data-driven modeling approach uncovered basic principles underlying the timing and duration of REM sleep episodes in mice and provides a flexible framework to describe the ultradian regulation of REM sleep in health and disease.
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14
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Medeiros SLDS, Paiva MMMD, Lopes PH, Blanco W, Lima FDD, Oliveira JBCD, Medeiros IG, Sequerra EB, de Souza S, Leite TS, Ribeiro S. Cyclic alternation of quiet and active sleep states in the octopus. iScience 2021; 24:102223. [PMID: 33997665 PMCID: PMC8101055 DOI: 10.1016/j.isci.2021.102223] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 12/22/2020] [Accepted: 02/18/2021] [Indexed: 12/27/2022] Open
Abstract
Previous observations suggest the existence of ‘Active sleep’ in cephalopods. To investigate in detail the behavioral structure of cephalopod sleep, we video-recorded four adult specimens of Octopus insularis and quantified their distinct states and transitions. Changes in skin color and texture and movements of eyes and mantle were assessed using automated image processing tools, and arousal threshold was measured using sensory stimulation. Two distinct states unresponsive to stimulation occurred in tandem. The first was a ‘Quiet sleep’ state with uniformly pale skin, closed pupils, and long episode durations (median 415.2 s). The second was an ‘Active sleep’ state with dynamic skin patterns of color and texture, rapid eye movements, and short episode durations (median 40.8 s). ‘Active sleep’ was periodic (60% of recurrences between 26 and 39 min) and occurred mostly after ‘Quiet sleep’ (82% of transitions). These results suggest that cephalopods have an ultradian sleep cycle analogous to that of amniotes. Octopus has ‘Quiet’ and ‘Active sleep’, with different episode duration and periodicity States differ on arousal thresholds, skin color and texture, and eye and mantle movement The results suggest that octopus has a sleep cycle analogous to that of amniotes
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Affiliation(s)
- Sylvia Lima de Souza Medeiros
- Brain Institute, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
- Graduate Program in Psychobiology, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
- Graduate Program in Neuroscience, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
| | - Mizziara Marlen Matias de Paiva
- Brain Institute, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
- Graduate Program in Neuroscience, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
| | - Paulo Henrique Lopes
- Computer Science Department, State University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
- Graduate Program in Bioinformatics, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
| | - Wilfredo Blanco
- Computer Science Department, State University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
- Bioinformatics Multidisciplinary Environment, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
- Graduate Program in Bioinformatics, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
| | - Françoise Dantas de Lima
- Department of Ecology and Zoology, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | | | - Inácio Gomes Medeiros
- Brain Institute, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
- Graduate Program in Bioinformatics, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
| | - Eduardo Bouth Sequerra
- Brain Institute, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
| | - Sandro de Souza
- Brain Institute, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
- Bioinformatics Multidisciplinary Environment, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
- Graduate Program in Bioinformatics, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
| | - Tatiana Silva Leite
- Department of Ecology and Zoology, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Sidarta Ribeiro
- Brain Institute, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
- Graduate Program in Psychobiology, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
- Graduate Program in Neuroscience, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
- Corresponding author
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15
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Yamazaki R, Toda H, Libourel PA, Hayashi Y, Vogt KE, Sakurai T. Evolutionary Origin of Distinct NREM and REM Sleep. Front Psychol 2021; 11:567618. [PMID: 33381062 PMCID: PMC7767968 DOI: 10.3389/fpsyg.2020.567618] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Accepted: 11/25/2020] [Indexed: 11/13/2022] Open
Abstract
Sleep is mandatory in most animals that have the nervous system and is universally observed in model organisms ranging from the nematodes, zebrafish, to mammals. However, it is unclear whether different sleep states fulfill common functions and are driven by shared mechanisms in these different animal species. Mammals and birds exhibit two obviously distinct states of sleep, i.e., non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep, but it is unknown why sleep should be so segregated. Studying sleep in other animal models might give us clues that help solve this puzzle. Recent studies suggest that REM sleep, or ancestral forms of REM sleep might be found in non-mammalian or -avian species such as reptiles. These observations suggest that REM sleep and NREM sleep evolved earlier than previously thought. In this review, we discuss the evolutionary origin of the distinct REM/NREM sleep states to gain insight into the mechanistic and functional reason for these two different types of sleep.
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Affiliation(s)
- Risa Yamazaki
- CNRS UMR 5292, INSERM U1028, Centre de Recherche en Neurosciences de Lyon, Université Claude Bernard Lyon 1, Bron, France
| | - Hirofumi Toda
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Japan
| | - Paul-Antoine Libourel
- CNRS UMR 5292, INSERM U1028, Centre de Recherche en Neurosciences de Lyon, Université Claude Bernard Lyon 1, Bron, France
| | - Yu Hayashi
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Japan.,Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Kaspar E Vogt
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Japan
| | - Takeshi Sakurai
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Japan.,Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
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16
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Ju X, Wang S, Yan P, Zhu C, Hu X, Dong J, Tan Z. Rapid Eye Movement Sleep Deprivation Combined With Fluoxetine Protects Against Depression-Induced Damage and Apoptosis in Rat Hippocampi via A1 Adenosine Receptor. Front Psychiatry 2021; 12:599399. [PMID: 34335318 PMCID: PMC8322534 DOI: 10.3389/fpsyt.2021.599399] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 05/26/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Rapid eye movement sleep deprivation (REMSD) and fluoxetine affect depression, yet the detailed molecular mechanisms were not clear. Methods: Rat depression chronic unpredictable stress was constructed, and the body weight of rats was measured. The efficacy of REMSD and fluoxetine on the pleasure experience, exploration, and cognition of rats with depression was determined by the Sucrose preference test, the open field test, and Morris water task, respectively. The effects of REMSD and fluoxetine on depression-induced damage and apoptosis in rat hippocampi were detected using hematoxylin-eosin staining and terminal transferase-mediated biotin 2'-deoxyuridine, 5'-triphosphate nick end labeling. A1 adenosine receptor content was measured by immunohistochemistry. Relative expressions of the A1 adenosine receptor, proteins related to apoptosis (B Bcl-2-associated X protein; B-cell lymphoma 2), phosphoinositide 3-kinase, P38 mitogen-activated protein kinase, cFos, and adenosine deaminase RNA specific two were quantified by quantitative real-time polymerase chain reaction and Western blot as needed. Results: Depression decreased rat weight. REMSD combined with fluoxetine increased body weight, prompted rat behavior, alleviated depression-induced damage, attenuated apoptosis, and promoted A1 adenosine receptor level in rat hippocampi. Furthermore, the combined therapy upregulated expressions of A1 adenosine receptor, B-cell lymphoma 2, and phosphoinositide 3-kinase but downregulated those of B-cell lymphoma 2-associated X protein, P38 mitogen-activated protein kinase, cFos, and adenosine deaminase RNA specific 2 in the hippocampi of rats with depression. Conclusion:REMSD combined with fluoxetine protected rats against depression-induced damage and apoptosis in the hippocampus via the A1 adenosine receptor, providing a possible treatment strategy for depression.
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Affiliation(s)
- Xuan Ju
- Psychiatric Department, Hangzhou Seventh People's Hospital, Mental Health Center of Zhejiang University School of Medicine, Hangzhou, China
| | - Shengdong Wang
- Molecular Biology Laboratory, Hangzhou Seventh People's Hospital, Mental Health Center of Zhejiang University School of Medicine, Hangzhou, China
| | - Pan Yan
- Molecular Biology Laboratory, Hangzhou Seventh People's Hospital, Mental Health Center of Zhejiang University School of Medicine, Hangzhou, China
| | - Chunyan Zhu
- Psychiatric Department, Hangzhou Seventh People's Hospital, Mental Health Center of Zhejiang University School of Medicine, Hangzhou, China
| | - Xiwen Hu
- Psychiatric Department, Hangzhou Seventh People's Hospital, Mental Health Center of Zhejiang University School of Medicine, Hangzhou, China
| | - Jiezheng Dong
- Psychiatric Department, Hangzhou Seventh People's Hospital, Mental Health Center of Zhejiang University School of Medicine, Hangzhou, China
| | - Zhonglin Tan
- Psychiatric Department, Hangzhou Seventh People's Hospital, Mental Health Center of Zhejiang University School of Medicine, Hangzhou, China
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17
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Canavan SV, Margoliash D. Budgerigars have complex sleep structure similar to that of mammals. PLoS Biol 2020; 18:e3000929. [PMID: 33201883 PMCID: PMC7707536 DOI: 10.1371/journal.pbio.3000929] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 12/01/2020] [Accepted: 10/08/2020] [Indexed: 12/13/2022] Open
Abstract
Birds and mammals share specialized forms of sleep including slow wave sleep (SWS) and rapid eye movement sleep (REM), raising the question of why and how specialized sleep evolved. Extensive prior studies concluded that avian sleep lacked many features characteristic of mammalian sleep, and therefore that specialized sleep must have evolved independently in birds and mammals. This has been challenged by evidence of more complex sleep in multiple songbird species. To extend this analysis beyond songbirds, we examined a species of parrot, the sister taxon to songbirds. We implanted adult budgerigars (Melopsittacus undulatus) with electroencephalogram (EEG) and electrooculogram (EOG) electrodes to evaluate sleep architecture, and video monitored birds during sleep. Sleep was scored with manual and automated techniques, including automated detection of slow waves and eye movements. This can help define a new standard for how to score sleep in birds. Budgerigars exhibited consolidated sleep, a pattern also observed in songbirds, and many mammalian species, including humans. We found that REM constituted 26.5% of total sleep, comparable to humans and an order of magnitude greater than previously reported. Although we observed no spindles, we found a clear state of intermediate sleep (IS) similar to non-REM (NREM) stage 2. Across the night, SWS decreased and REM increased, as observed in mammals and songbirds. Slow wave activity (SWA) fluctuated with a 29-min ultradian rhythm, indicating a tendency to move systematically through sleep states as observed in other species with consolidated sleep. These results are at variance with numerous older sleep studies, including for budgerigars. Here, we demonstrated that lighting conditions used in the prior budgerigar study-and commonly used in older bird studies-dramatically disrupted budgerigar sleep structure, explaining the prior results. Thus, it is likely that more complex sleep has been overlooked in a broad range of bird species. The similarities in sleep architecture observed in mammals, songbirds, and now budgerigars, alongside recent work in reptiles and basal birds, provide support for the hypothesis that a common amniote ancestor possessed the precursors that gave rise to REM and SWS at one or more loci in the parallel evolution of sleep in higher vertebrates. We discuss this hypothesis in terms of the common plan of forebrain organization shared by reptiles, birds, and mammals.
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Affiliation(s)
- Sofija V. Canavan
- Committee on Computational Neuroscience, University of Chicago, Chicago, Illinois, United States of America
- Medical Scientist Training Program, University of Chicago, Chicago, Illinois, United States of America
| | - Daniel Margoliash
- Committee on Computational Neuroscience, University of Chicago, Chicago, Illinois, United States of America
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois, United States of America
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18
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Comparative Perspectives that Challenge Brain Warming as the Primary Function of REM Sleep. iScience 2020; 23:101696. [PMID: 33196022 PMCID: PMC7644584 DOI: 10.1016/j.isci.2020.101696] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 09/17/2020] [Accepted: 10/14/2020] [Indexed: 01/04/2023] Open
Abstract
Rapid eye movement (REM) sleep is a paradoxical state of wake-like brain activity occurring after non-REM (NREM) sleep in mammals and birds. In mammals, brain cooling during NREM sleep is followed by warming during REM sleep, potentially preparing the brain to perform adaptively upon awakening. If brain warming is the primary function of REM sleep, then it should occur in other animals with similar states. We measured cortical temperature in pigeons and bearded dragons, lizards that exhibit NREM-like sleep and REM-like sleep with brain activity resembling wakefulness. In pigeons, cortical temperature decreased during NREM sleep and increased during REM sleep. However, brain temperature did not increase when dragons switched from NREM-like to REM-like sleep. Our findings indicate that brain warming is not a universal outcome of sleep states characterized by wake-like activity, challenging the hypothesis that their primary function is to warm the brain in preparation for wakefulness. In many mammals, the brain cools during non-REM sleep and warms during REM sleep Pigeons exhibit similar changes in cortical temperature during non-REM and REM sleep Brain temperature does not increase during REM-like sleep in bearded dragon lizards Brain warming is not a universal outcome of sleep states with wake-like brain activity
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19
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Aulsebrook AE, Connelly F, Johnsson RD, Jones TM, Mulder RA, Hall ML, Vyssotski AL, Lesku JA. White and Amber Light at Night Disrupt Sleep Physiology in Birds. Curr Biol 2020; 30:3657-3663.e5. [PMID: 32707063 DOI: 10.1016/j.cub.2020.06.085] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 06/22/2020] [Accepted: 06/24/2020] [Indexed: 12/11/2022]
Abstract
Artificial light at night can disrupt sleep in humans [1-4] and other animals [5-10]. A key mechanism for light to affect sleep is via non-visual photoreceptors that are most sensitive to short-wavelength (blue) light [11]. To minimize effects of artificial light on sleep, many electronic devices shift from white (blue-rich) to amber (blue-reduced) light in the evening. Switching outdoor lighting from white to amber might also benefit wildlife [12]. However, whether these two colors of light affect sleep similarly in different animals remains poorly understood. Here we show, by measuring brain activity, that both white and amber lighting disrupt sleep in birds but that the magnitude of these effects differs between species. When experimentally exposed to light at night at intensities typical of urban areas, domestic pigeons (Columba livia) and wild-caught Australian magpies (Cracticus tibicen tyrannica) slept less, favored non-rapid eye movement (NREM) sleep over REM sleep, slept less intensely, and had more fragmented sleep compared to when lights were switched off. In pigeons, these disruptive effects on sleep were similar for white and amber lighting. For magpies, however, amber light had less impact on sleep. Our results demonstrate that amber lighting can minimize sleep disruption in some birds but that this benefit may not be universal. VIDEO ABSTRACT.
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Affiliation(s)
- Anne E Aulsebrook
- School of BioSciences, The University of Melbourne, Melbourne, VIC 3010, Australia; School of Life Sciences, La Trobe University, Melbourne, VIC 3086, Australia.
| | - Farley Connelly
- School of BioSciences, The University of Melbourne, Melbourne, VIC 3010, Australia; School of Life Sciences, La Trobe University, Melbourne, VIC 3086, Australia.
| | - Robin D Johnsson
- School of Life Sciences, La Trobe University, Melbourne, VIC 3086, Australia
| | - Therésa M Jones
- School of BioSciences, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Raoul A Mulder
- School of BioSciences, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Michelle L Hall
- School of BioSciences, The University of Melbourne, Melbourne, VIC 3010, Australia; Bush Heritage Australia, Melbourne, VIC 3000, Australia; School of Biological Sciences, The University of Western Australia, Perth, WA 6009, Australia
| | - Alexei L Vyssotski
- Institute of Neuroinformatics, University of Zurich and ETH Zurich, Zurich 8006, Switzerland
| | - John A Lesku
- School of Life Sciences, La Trobe University, Melbourne, VIC 3086, Australia
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20
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Park SH, Weber F. Neural and Homeostatic Regulation of REM Sleep. Front Psychol 2020; 11:1662. [PMID: 32793050 PMCID: PMC7385183 DOI: 10.3389/fpsyg.2020.01662] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Accepted: 06/18/2020] [Indexed: 12/11/2022] Open
Abstract
Rapid eye movement (REM) sleep is a distinct, homeostatically controlled brain state characterized by an activated electroencephalogram (EEG) in combination with paralysis of skeletal muscles and is associated with vivid dreaming. Understanding how REM sleep is controlled requires identification of the neural circuits underlying its initiation and maintenance, and delineation of the homeostatic processes regulating its expression on multiple timescales. Soon after its discovery in humans in 1953, the pons was demonstrated to be necessary and sufficient for the generation of REM sleep. But, especially within the last decade, researchers have identified further neural populations in the hypothalamus, midbrain, and medulla that regulate REM sleep by either promoting or suppressing this brain state. The discovery of these populations was greatly facilitated by the availability of novel technologies for the dissection of neural circuits. Recent quantitative models integrate findings about the activity and connectivity of key neurons and knowledge about homeostatic mechanisms to explain the dynamics underlying the recurrence of REM sleep. For the future, combining quantitative with experimental approaches to directly test model predictions and to refine existing models will greatly advance our understanding of the neural and homeostatic processes governing the regulation of REM sleep.
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Affiliation(s)
| | - Franz Weber
- Department of Neuroscience, Perelman School of Medicine, Chronobiology and Sleep Institute, University of Pennsylvania, Philadelphia, PA, United States
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21
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Kelly ML, Spreitzenbarth S, Kerr CC, Hemmi JM, Lesku JA, Radford CA, Collin SP. Behavioural sleep in two species of buccal pumping sharks (Heterodontus portusjacksoni and Cephaloscyllium isabellum). J Sleep Res 2020; 30:e13139. [PMID: 32672393 DOI: 10.1111/jsr.13139] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 06/23/2020] [Accepted: 06/23/2020] [Indexed: 11/28/2022]
Abstract
Sleep is known to occur in most, if not all, animals studied thus far. Recent studies demonstrate the presence of sleep in flatworms and jellyfish, suggesting that this behaviour evolved early in the evolution of animals. Sharks are the earliest known extant, jawed vertebrates and may play an important role in understanding the evolutionary history of sleep in vertebrates, and yet, it is unknown whether they sleep. The Port Jackson (Heterodontus portusjacksoni) and draughtsboard (Cephaloscyllium isabellum) sharks are both benthic, buccal pumping species and remain motionless for extended periods of time. Whether these periods of prolonged inactivity represent sleep or quiet wakefulness is unknown. A key criterion for separating sleep from other quiescent states is an increased arousal threshold. We show here that inactive sharks of both species require significantly higher levels of electric stimulation before they show a visible response. Sharks deprived of rest, however, show no significant compensatory increase in restfulness during their normal active period following enforced swimming. Nonetheless, increased arousal thresholds in inactive animals suggest that these two species of shark sleep - the first such demonstration for members of this group of vertebrates. Further research, including electrophysiological studies, on these and other sharks, is required for a comprehensive understanding of sleep in cartilaginous fishes.
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Affiliation(s)
- Michael L Kelly
- School of Biological Sciences, The University of Western Australia, Perth, Australia.,Oceans Institute, The University of Western Australia, Perth, Australia.,Oceans Graduate School, The University of Western Australia, Perth, Australia
| | - Stefan Spreitzenbarth
- Leigh Marine Laboratory, Institute of Marine Science, The University of Auckland, Auckland, New Zealand
| | - Caroline C Kerr
- School of Life Sciences, La Trobe University, Melbourne, Australia
| | - Jan M Hemmi
- School of Biological Sciences, The University of Western Australia, Perth, Australia.,Oceans Institute, The University of Western Australia, Perth, Australia
| | - John A Lesku
- School of Life Sciences, La Trobe University, Melbourne, Australia
| | - Craig A Radford
- Leigh Marine Laboratory, Institute of Marine Science, The University of Auckland, Auckland, New Zealand
| | - Shaun P Collin
- Oceans Institute, The University of Western Australia, Perth, Australia.,Oceans Graduate School, The University of Western Australia, Perth, Australia.,School of Life Sciences, La Trobe University, Melbourne, Australia
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22
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Kashiwagi M, Hayashi Y. The existence of two states of sleep as a common trait in various animals and its molecular and neuronal mechanisms. CURRENT OPINION IN PHYSIOLOGY 2020. [DOI: 10.1016/j.cophys.2020.03.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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23
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Libourel PA, Barrillot B. Is there REM sleep in reptiles? A key question, but still unanswered. CURRENT OPINION IN PHYSIOLOGY 2020. [DOI: 10.1016/j.cophys.2020.01.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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24
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Ungurean G, van der Meij J, Rattenborg NC, Lesku JA. Evolution and plasticity of sleep. CURRENT OPINION IN PHYSIOLOGY 2020. [DOI: 10.1016/j.cophys.2019.12.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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25
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van der Meij J, Ungurean G, Rattenborg NC, Beckers GJL. Evolution of sleep in relation to memory – a birds’ brain view. Curr Opin Behav Sci 2020. [DOI: 10.1016/j.cobeha.2019.12.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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26
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Lyons DG, Rihel J. Sleep Circuits and Physiology in Non-Mammalian Systems. CURRENT OPINION IN PHYSIOLOGY 2020; 15:245-255. [PMID: 34738047 DOI: 10.1016/j.cophys.2020.03.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Research over the last 20 years has firmly established the existence of sleep states across the animal kingdom. Work in non-mammalian animal models such as nematodes, fruit flies, and zebrafish has now uncovered many evolutionarily conserved aspects of sleep physiology and regulation, including shared circuit architecture, homeostatic and circadian control elements, and principles linking sleep physiology to function. Non-mammalian sleep research is now shedding light on fundamental aspects of the genetic and neuronal circuit regulation of sleep, with direct implications for the understanding of how sleep is regulated in mammals.
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Affiliation(s)
- Declan G Lyons
- Department of Cell and Developmental Biology, University College London, United Kingdom, WC1E 6BT
| | - Jason Rihel
- Department of Cell and Developmental Biology, University College London, United Kingdom, WC1E 6BT
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27
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McGaugh SE, Passow CN, Jaggard JB, Stahl BA, Keene AC. Unique transcriptional signatures of sleep loss across independently evolved cavefish populations. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2020; 334:497-510. [PMID: 32351033 DOI: 10.1002/jez.b.22949] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 01/28/2020] [Accepted: 04/04/2020] [Indexed: 12/12/2022]
Abstract
Animals respond to sleep loss with compensatory rebound sleep, and this is thought to be critical for the maintenance of physiological homeostasis. Sleep duration varies dramatically across animal species, but it is not known whether evolutionary differences in sleep duration are associated with differences in sleep homeostasis. The Mexican cavefish, Astyanax mexicanus, has emerged as a powerful model for studying the evolution of sleep. While eyed surface populations of A. mexicanus sleep approximately 8 hr each day, multiple blind cavefish populations have converged on sleep patterns that total as little as 2 hr each day, providing the opportunity to examine whether the evolution of sleep loss is accompanied by changes in sleep homeostasis. Here, we examine the behavioral and molecular response to sleep deprivation across four independent populations of A. mexicanus. Our behavioral analysis indicates that surface fish and all three cavefish populations display robust recovery sleep during the day following nighttime sleep deprivation, suggesting sleep homeostasis remains intact in cavefish. We profiled transcriptome-wide changes associated with sleep deprivation in surface fish and cavefish. While the total number of differentially expressed genes was not greater for the surface population, the surface population exhibited the highest number of uniquely differentially expressed genes than any other population. Strikingly, a majority of the differentially expressed genes are unique to individual cave populations, suggesting unique expression responses are exhibited across independently evolved cavefish populations. Together, these findings suggest sleep homeostasis is intact in cavefish despite a dramatic reduction in overall sleep duration.
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Affiliation(s)
- Suzanne E McGaugh
- Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, Minnesota
| | - Courtney N Passow
- Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, Minnesota
| | - James Brian Jaggard
- Department of Biological Sciences, Florida Atlantic University, Jupiter, Florida
| | - Bethany A Stahl
- Department of Biological Sciences, Florida Atlantic University, Jupiter, Florida
| | - Alex C Keene
- Department of Biological Sciences, Florida Atlantic University, Jupiter, Florida
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Abstract
For many decades, sleep researchers have sought to determine which species 'have' rapid eye movement (REM) sleep. In doing so, they relied predominantly on a template derived from the expression of REM sleep in the adults of a small number of mammalian species. Here, we argue for a different approach that focuses less on a binary decision about haves and have nots, and more on the diverse expression of REM sleep components over development and across species. By focusing on the components of REM sleep and discouraging continued reliance on a restricted template, we aim to promote a richer and more biologically grounded developmental-comparative approach that spans behavioral, physiological, neural, and ecological domains.
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Affiliation(s)
- Mark S Blumberg
- Department of Psychological and Brain Sciences, Iowa Neuroscience Institute, University of Iowa, Iowa City, IA 52242, USA.
| | - John A Lesku
- School of Life Sciences, La Trobe University, Melbourne 3086, Australia
| | - Paul-Antoine Libourel
- Neurosciences Research Center of Lyon, CNRS UMR5292, INSERM U1028, University Claude Bernard Lyon 1 Neurocampus, 95 Boulevard Pinel, 69675 BRON, France
| | - Markus H Schmidt
- Department of Neurology, Bern University Hospital (Inselspital), University of Bern, Freiburgstrasse 18, 3010 Bern, Switzerland; Ohio Sleep Medicine Institute, 4975 Bradenton Avenue, Dublin, OH 43017, USA
| | - Niels C Rattenborg
- Avian Sleep Group, Max Planck Institute for Ornithology, Haus 5, Seewiesen 82319, Germany.
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29
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Kelly M, Collin S, Hemmi J, Lesku J. Evidence for Sleep in Sharks and Rays: Behavioural, Physiological, and Evolutionary Considerations. BRAIN, BEHAVIOR AND EVOLUTION 2019; 94:37-50. [DOI: 10.1159/000504123] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 10/14/2019] [Indexed: 11/19/2022]
Abstract
Sleep is widespread across the animal kingdom. However, most comparative sleep data exist for terrestrial vertebrates, with much less known about sleep in amphibians, bony fishes, and invertebrates. There is an absence of knowledge on sleep in cartilaginous fishes. Sharks and rays are amongst the earliest vertebrates, and may hold clues to the evolutionary history of sleep and sleep states found in more derived animals, such as mammals and birds. Here, we review the literature concerning activity patterns, sleep behaviour, and electrophysiological evidence for sleep in cartilaginous (and bony) fishes following an exhaustive literature search that found more than 80 relevant studies in laboratory and field environments. Evidence for sleep in sharks and rays that respire without swimming is preliminary; evidence for sleep in continuously swimming fishes is currently absent. We discuss ways in which the latter group might sleep concurrent with sustained movement, and conclude with suggestions for future studies in order to provide more comprehensive data on when, how, and why sharks and rays sleep.
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Blum ID, Wu MN. Sleep: Slow Waves Quiet the Fly’s Mind. Curr Biol 2019; 29:R1129-R1131. [DOI: 10.1016/j.cub.2019.09.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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31
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Pennartz CMA, Farisco M, Evers K. Indicators and Criteria of Consciousness in Animals and Intelligent Machines: An Inside-Out Approach. Front Syst Neurosci 2019; 13:25. [PMID: 31379521 PMCID: PMC6660257 DOI: 10.3389/fnsys.2019.00025] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 06/24/2019] [Indexed: 01/02/2023] Open
Abstract
In today's society, it becomes increasingly important to assess which non-human and non-verbal beings possess consciousness. This review article aims to delineate criteria for consciousness especially in animals, while also taking into account intelligent artifacts. First, we circumscribe what we mean with "consciousness" and describe key features of subjective experience: qualitative richness, situatedness, intentionality and interpretation, integration and the combination of dynamic and stabilizing properties. We argue that consciousness has a biological function, which is to present the subject with a multimodal, situational survey of the surrounding world and body, subserving complex decision-making and goal-directed behavior. This survey reflects the brain's capacity for internal modeling of external events underlying changes in sensory state. Next, we follow an inside-out approach: how can the features of conscious experience, correlating to mechanisms inside the brain, be logically coupled to externally observable ("outside") properties? Instead of proposing criteria that would each define a "hard" threshold for consciousness, we outline six indicators: (i) goal-directed behavior and model-based learning; (ii) anatomic and physiological substrates for generating integrative multimodal representations; (iii) psychometrics and meta-cognition; (iv) episodic memory; (v) susceptibility to illusions and multistable perception; and (vi) specific visuospatial behaviors. Rather than emphasizing a particular indicator as being decisive, we propose that the consistency amongst these indicators can serve to assess consciousness in particular species. The integration of scores on the various indicators yields an overall, graded criterion for consciousness, somewhat comparable to the Glasgow Coma Scale for unresponsive patients. When considering theoretically derived measures of consciousness, it is argued that their validity should not be assessed on the basis of a single quantifiable measure, but requires cross-examination across multiple pieces of evidence, including the indicators proposed here. Current intelligent machines, including deep learning neural networks (DLNNs) and agile robots, are not indicated to be conscious yet. Instead of assessing machine consciousness by a brief Turing-type of test, evidence for it may gradually accumulate when we study machines ethologically and across time, considering multiple behaviors that require flexibility, improvisation, spontaneous problem-solving and the situational conspectus typically associated with conscious experience.
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Affiliation(s)
- Cyriel M. A. Pennartz
- Department of Cognitive and Systems Neuroscience, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, Netherlands
- Research Priority Area, Brain and Cognition, University of Amsterdam, Amsterdam, Netherlands
| | - Michele Farisco
- Centre for Research Ethics and Bioethics, Uppsala University, Uppsala, Sweden
- Biogem, Biology and Molecular Genetics Institute, Ariano Irpino, Italy
| | - Kathinka Evers
- Centre for Research Ethics and Bioethics, Uppsala University, Uppsala, Sweden
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Abstract
REM sleep is a paradoxical state accompanied by suspended thermoregulation that is preferentially expressed under optimal ambient temperatures. Komagata and colleagues now demonstrate that activity in hypothalamic melanin concentrating hormone neurons is essential for the temperature-dependent modulation of REM sleep.
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Affiliation(s)
- Gianina Ungurean
- CRNL, SLEEP Team, UMR 5292 CNRS/U1028 INSERM, Université Claude Bernard Lyon 1, Lyon, F-69372, France; Avian Sleep Group, Max Planck Institute for Ornithology, Eberhard-Gwinner-Strasse 5, 82319 Seewiesen, Germany
| | - Niels C Rattenborg
- Avian Sleep Group, Max Planck Institute for Ornithology, Eberhard-Gwinner-Strasse 5, 82319 Seewiesen, Germany.
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Rattenborg NC, van der Meij J, Beckers GJL, Lesku JA. Local Aspects of Avian Non-REM and REM Sleep. Front Neurosci 2019; 13:567. [PMID: 31231182 PMCID: PMC6560081 DOI: 10.3389/fnins.2019.00567] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 05/17/2019] [Indexed: 12/12/2022] Open
Abstract
Birds exhibit two types of sleep that are in many respects similar to mammalian rapid eye movement (REM) and non-REM (NREM) sleep. As in mammals, several aspects of avian sleep can occur in a local manner within the brain. Electrophysiological evidence of NREM sleep occurring more deeply in one hemisphere, or only in one hemisphere – the latter being a phenomenon most pronounced in dolphins – was actually first described in birds. Such asymmetric or unihemispheric NREM sleep occurs with one eye open, enabling birds to visually monitor their environment for predators. Frigatebirds primarily engage in this form of sleep in flight, perhaps to avoid collisions with other birds. In addition to interhemispheric differences in NREM sleep intensity, the intensity of NREM sleep is homeostatically regulated in a local, use-depended manner within each hemisphere. Furthermore, the intensity and temporo-spatial distribution of NREM sleep-related slow waves varies across layers of the avian hyperpallium – a primary visual area – with the slow waves occurring first in, and propagating through and outward from, thalamic input layers. Slow waves also have the greatest amplitude in these layers. Although most research has focused on NREM sleep, there are also local aspects to avian REM sleep. REM sleep-related reductions in skeletal muscle tone appear largely restricted to muscles involved in maintaining head posture. Other local aspects of sleep manifest as a mixture of features of NREM and REM sleep occurring simultaneously in different parts of the neuroaxis. Like monotreme mammals, ostriches often exhibit brainstem-mediated features of REM sleep (muscle atonia and REMs) while the hyperpallium shows EEG slow waves typical of NREM sleep. Finally, although mice show slow waves in thalamic input layers of primary sensory cortices during REM sleep, this is not the case in the hyperpallium of pigeons, suggesting that this phenomenon is not a universal feature of REM sleep. Collectively, the local aspects of sleep described in birds and mammals reveal that wakefulness, NREM sleep, and REM sleep are not always discrete states.
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Affiliation(s)
- Niels C Rattenborg
- Avian Sleep Group, Max Planck Institute for Ornithology, Seewiesen, Germany
| | | | - Gabriël J L Beckers
- Cognitive Neurobiology and Helmholtz Institute, Utrecht University, Utrecht, Netherlands
| | - John A Lesku
- School of Life Sciences, La Trobe University, Melbourne, VIC, Australia
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Iglesias TL, Boal JG, Frank MG, Zeil J, Hanlon RT. Cyclic nature of the REM sleep-like state in the cuttlefish Sepia officinalis. ACTA ACUST UNITED AC 2019; 222:jeb.174862. [PMID: 30446538 DOI: 10.1242/jeb.174862] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 11/08/2018] [Indexed: 01/23/2023]
Abstract
Sleep is a state of immobility characterized by three key criteria: an increased threshold of arousal, rapid reversal to an alert state and evidence of homeostatic 'rebound sleep' in which there is an increase in the time spent in this quiescent state following sleep deprivation. Common European cuttlefish, Sepia officinalis, show states of quiescence during which they meet the last two of these three criteria, yet also show spontaneous bursts of arm and eye movements that accompany rapid changes in chromatophore patterns in the skin. Here, we report that this rapid eye movement sleep-like (REMS-like) state is cyclic in nature. Iterations of the REMS-like state last 2.42±0.22 min (mean±s.e.m.) and alternate with 34.01±1.49 min of the quiescent sleep-like state for durations lasting 176.89±36.71 min. We found clear evidence that this REMS-like state (i) occurs in animals younger than previously reported; (ii) follows an ultradian pattern; (iii) includes intermittent dynamic chromatophore patterning, representing fragments of normal patterning seen in the waking state for a wide range of signaling and camouflage; and (iv) shows variability in the intensity of expression of these skin patterns between and within individuals. These data suggest that cephalopods, which are mollusks with an elaborate brain and complex behavior, possess a sleep-like state that resembles behaviorally the vertebrate REM sleep state, although the exact nature and mechanism of this form of sleep may differ from that of vertebrates.
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Affiliation(s)
- Teresa L Iglesias
- Animal Behavior Graduate Group, University of California Davis, Davis, CA 95616, USA .,Physics and Biology Unit, Okinawa Institute of Science and Technology, Okinawa 904-0412, Japan
| | - Jean G Boal
- Department of Biology, Millersville University, Lancaster, PA 17551, USA
| | - Marcos G Frank
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University-Spokane, Health Sciences Building 280M, 412 E Spokane Falls Blvd, Spokane, WA 99202, USA
| | - Jochen Zeil
- Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
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