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Van De Poll MN, van Swinderen B. Balancing Prediction and Surprise: A Role for Active Sleep at the Dawn of Consciousness? Front Syst Neurosci 2021; 15:768762. [PMID: 34803618 PMCID: PMC8602873 DOI: 10.3389/fnsys.2021.768762] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 10/08/2021] [Indexed: 11/14/2022] Open
Abstract
The brain is a prediction machine. Yet the world is never entirely predictable, for any animal. Unexpected events are surprising, and this typically evokes prediction error signatures in mammalian brains. In humans such mismatched expectations are often associated with an emotional response as well, and emotional dysregulation can lead to cognitive disorders such as depression or schizophrenia. Emotional responses are understood to be important for memory consolidation, suggesting that positive or negative 'valence' cues more generally constitute an ancient mechanism designed to potently refine and generalize internal models of the world and thereby minimize prediction errors. On the other hand, abolishing error detection and surprise entirely (as could happen by generalization or habituation) is probably maladaptive, as this might undermine the very mechanism that brains use to become better prediction machines. This paradoxical view of brain function as an ongoing balance between prediction and surprise suggests a compelling approach to study and understand the evolution of consciousness in animals. In particular, this view may provide insight into the function and evolution of 'active' sleep. Here, we propose that active sleep - when animals are behaviorally asleep but their brain seems awake - is widespread beyond mammals and birds, and may have evolved as a mechanism for optimizing predictive processing in motile creatures confronted with constantly changing environments. To explore our hypothesis, we progress from humans to invertebrates, investigating how a potential role for rapid eye movement (REM) sleep in emotional regulation in humans could be re-examined as a conserved sleep function that co-evolved alongside selective attention to maintain an adaptive balance between prediction and surprise. This view of active sleep has some interesting implications for the evolution of subjective awareness and consciousness in animals.
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Affiliation(s)
| | - Bruno van Swinderen
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
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2
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Malinowski JE, Scheel D, McCloskey M. Do animals dream? Conscious Cogn 2021; 95:103214. [PMID: 34653784 DOI: 10.1016/j.concog.2021.103214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 07/22/2021] [Accepted: 09/21/2021] [Indexed: 10/20/2022]
Abstract
The understanding of biological functions of sleep has improved recently, including an understanding of the deep evolutionary roots of sleep among animals. However, dreaming as an element of sleep may be particularly difficult to address in non-human animals because in humans dreaming involves a non-wakeful form of awareness typically identified through verbal report. Here, we argue that parallels that exist between the phenomenology, physiology, and sleep behaviors during human dreaming provide an avenue to investigate dreaming in non-human animals. We review three alternative measurements of human dreaming - neural correlates of dreaming, 'replay' of newly-acquired memories, and dream-enacting behaviors - and consider how these may be applied to non-human animal models. We suggest that while animals close in brain structure to humans (such as mammals and birds) may be optimal models for the first two of these measurements, cephalopods, especially octopuses, may be particularly good candidates for the third.
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Affiliation(s)
- J E Malinowski
- School of Psychology, University of East London, Stratford, UK.
| | - D Scheel
- Institute of Culture & Environment, Alaska Pacific University, Anchorage, AK, USA.
| | - M McCloskey
- Institute of Culture & Environment, Alaska Pacific University, Anchorage, AK, USA.
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Osorio-Palacios M, Montiel-Trejo L, Oliver-Domínguez I, Hernández-Falcón J, Mendoza-Ángeles K. Sleep Phases in Crayfish: Relationship Between Brain Electrical Activity and Autonomic Variables. Front Neurosci 2021; 15:694924. [PMID: 34720849 PMCID: PMC8551808 DOI: 10.3389/fnins.2021.694924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 09/16/2021] [Indexed: 11/17/2022] Open
Abstract
In vertebrates like mammals and birds, two types of sleep have been identified: rapid eye movement and non-rapid eye movement sleep. Each one is associated with specific electroencephalogram patterns and is accompanied by variations in cardiac and respiratory frequencies. Sleep has been demonstrated only in a handful of invertebrates, and evidence for different sleep stages remains elusive. Previous results show that crayfish sleeps while lying on one side on the surface of the water, but it is not known if this animal has sleep phases. Heart rate and respiratory frequency are modified by diverse changes in the crayfish environment during wakefulness, and previously, we showed that variations in these variables are present during sleep despite that there are no autonomic anatomical structures described in this animal. Here, we conducted experiments to search for sleep phases in crayfish and the relationships between sleep and cardiorespiratory activity. We used the wavelet transform, grouping analysis with k-means clustering, and principal component analysis, to analyze brain and cardiorespiratory electrical activity. Our results show that (a) crayfish can sleep lying on one side or when it is motionless and (b) the depth of sleep (measured as the power of electroencephalographic activity) changes over time and is accompanied by oscillations in cardiorespiratory signal amplitude and power. Finally, we propose that in crayfish there are at least three phases of sleep.
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Affiliation(s)
- Mireya Osorio-Palacios
- Laboratorio de Redes Neuronales, Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), México City, Mexico
| | | | | | - Jesús Hernández-Falcón
- Laboratorio de Redes Neuronales, Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), México City, Mexico
| | - Karina Mendoza-Ángeles
- Laboratorio de Redes Neuronales, Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), México City, Mexico
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Tierney AJ, MacKillop I, Rosenbloom T, Werner A. Post-feeding behavior in crayfish (Procambarus clarkii): Description of an invertebrate behavioral satiety sequence. Physiol Behav 2019; 213:112720. [PMID: 31639378 DOI: 10.1016/j.physbeh.2019.112720] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 10/01/2019] [Accepted: 10/18/2019] [Indexed: 11/19/2022]
Abstract
Previous studies have demonstrated that food consumption induces the behavioral satiety sequence (BSS) in some animals, a characteristic series of activities which include exploration, grooming, and resting. The BSS, while valuable in assessing the effects of drugs on food intake, has not been widely studied in non-mammalian species. Our experiment examined post-feeding behavior in crayfish using continuous recording of five behaviors: feeding, walking, grooming, leg wave, and quiescence. We found that food intake, but not sham feeding, significantly decreased feeding behavior, increased leg wave, and increased quiescence. Walking and grooming were not significantly altered by food intake. These findings indicate that post-feeding behaviors in crayfish share some characteristics with the mammalian BSS. Detailed descriptions of post-ingestive behavior in invertebrates may contribute to the development of drugs targeting feeding behaviors in medically and economically important species.
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Affiliation(s)
- A J Tierney
- Neuroscience Program, Department of Psychological and Brain Sciences, Colgate University, Hamilton, NY 13346, USA.
| | - I MacKillop
- Neuroscience Program, Department of Psychological and Brain Sciences, Colgate University, Hamilton, NY 13346, USA
| | - T Rosenbloom
- Neuroscience Program, Department of Psychological and Brain Sciences, Colgate University, Hamilton, NY 13346, USA
| | - A Werner
- Neuroscience Program, Department of Psychological and Brain Sciences, Colgate University, Hamilton, NY 13346, USA
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Hernández OH. Circadian rhythms of omitted stimulus potentials in the crayfish brain. BIOL RHYTHM RES 2018. [DOI: 10.1080/09291016.2017.1336885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Oscar Hernando Hernández
- Centro de Investigaciones Biomédicas, Universidad Autónoma de Campeche, San Francisco de Campeche, Campeche, México
- Hospital General de Especialidades “Dr. Javier Buenfil Osorio”, San Francisco de Campeche, Campeche, México
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Oscillatory brain activity in spontaneous and induced sleep stages in flies. Nat Commun 2017; 8:1815. [PMID: 29180766 PMCID: PMC5704022 DOI: 10.1038/s41467-017-02024-y] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 11/01/2017] [Indexed: 12/03/2022] Open
Abstract
Sleep is a dynamic process comprising multiple stages, each associated with distinct electrophysiological properties and potentially serving different functions. While these phenomena are well described in vertebrates, it is unclear if invertebrates have distinct sleep stages. We perform local field potential (LFP) recordings on flies spontaneously sleeping, and compare their brain activity to flies induced to sleep using either genetic activation of sleep-promoting circuitry or the GABAA agonist Gaboxadol. We find a transitional sleep stage associated with a 7–10 Hz oscillation in the central brain during spontaneous sleep. Oscillatory activity is also evident when we acutely activate sleep-promoting neurons in the dorsal fan-shaped body (dFB) of Drosophila. In contrast, sleep following Gaboxadol exposure is characterized by low-amplitude LFPs, during which dFB-induced effects are suppressed. Sleep in flies thus appears to involve at least two distinct stages: increased oscillatory activity, particularly during sleep induction, followed by desynchronized or decreased brain activity. Sleep in mammals comprises physiologically and functionally distinct stages. Here, the authors report a transitional sleep stage in Drosophila associated with 7–10 Hz oscillatory activity that can be obtained through activation of the sleep-promoting neurons of the dorsal fan-shaped body.
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de Bivort BL, van Swinderen B. Evidence for selective attention in the insect brain. CURRENT OPINION IN INSECT SCIENCE 2016; 15:9-15. [PMID: 27436727 DOI: 10.1016/j.cois.2016.02.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 02/10/2016] [Accepted: 02/15/2016] [Indexed: 06/06/2023]
Abstract
The capacity for selective attention appears to be required by any animal responding to an environment containing multiple objects, although this has been difficult to study in smaller animals such as insects. Clear operational characteristics of attention however make study of this crucial brain function accessible to any animal model. Whereas earlier approaches have relied on freely behaving paradigms placed in an ecologically relevant context, recent tethered preparations have focused on brain imaging and electrophysiology in virtual reality environments. Insight into brain activity during attention-like behavior has revealed key elements of attention in the insect brain. Surprisingly, a variety of brain structures appear to be involved, suggesting that even in the smallest brains attention might involve widespread coordination of neural activity.
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Affiliation(s)
- Benjamin L de Bivort
- Center for Brain Science and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Bruno van Swinderen
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia.
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Vorster AP, Born J. Sleep and memory in mammals, birds and invertebrates. Neurosci Biobehav Rev 2015; 50:103-19. [DOI: 10.1016/j.neubiorev.2014.09.020] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 09/24/2014] [Accepted: 09/27/2014] [Indexed: 01/04/2023]
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Hartse KM. Phylogeny in Sleep Medicine. Sleep Med 2015. [DOI: 10.1007/978-1-4939-2089-1_62] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Abstract
STUDY OBJECTIVE To characterize sleep in the marine mollusk, Aplysia californica. DESIGN Animal behavior and activity were assessed using video recordings to measure activity, resting posture, resting place preference, and behavior after rest deprivation. Latencies for behavioral responses were measured for appetitive and aversive stimuli for animals in the wake and rest states. SETTING Circadian research laboratory for Aplysia. PATIENTS OR PARTICIPANTS A. californica from the Pacific Ocean. INTERVENTIONS N/A. MEASUREMENTS AND RESULTS Aplysia rest almost exclusively during the night in a semi-contracted body position with preferential resting locations in the upper corners of their tank. Resting animals demonstrate longer latencies in head orientation and biting in response to a seaweed stimulus and less frequent escape response steps following an aversive salt stimulus applied to the tail compared to awake animals at the same time point. Aplysia exhibit rebound rest the day following rest deprivation during the night, but not after similar handling stimulation during the day. CONCLUSIONS Resting behavior in Aplysia fulfills all invertebrate characteristics of sleep including: (1) a specific sleep body posture, (2) preferred resting location, (3) reversible behavioral quiescence, (4) elevated arousal thresholds for sensory stimuli during sleep, and (5) compensatory sleep rebound after sleep deprivation.
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Affiliation(s)
- Albrecht P.A. Vorster
- Department of Biological Science, Program in Neuroscience, Florida State University, Tallahassee, FL; Present Address: Department of Medical Psychology and Behavioral Neurobiology and Center for Integrative Neuroscience CIN, University of Tübingen, Tübingen, Germany
| | - Harini C. Krishnan
- Department of Biological Science, Program in Neuroscience, Florida State University, Tallahassee, FL
| | - Chiara Cirelli
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI
| | - Lisa C. Lyons
- Department of Biological Science, Program in Neuroscience, Florida State University, Tallahassee, FL
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Michel M, Lyons LC. Unraveling the complexities of circadian and sleep interactions with memory formation through invertebrate research. Front Syst Neurosci 2014; 8:133. [PMID: 25136297 PMCID: PMC4120776 DOI: 10.3389/fnsys.2014.00133] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 07/07/2014] [Indexed: 12/14/2022] Open
Abstract
Across phylogeny, the endogenous biological clock has been recognized as providing adaptive advantages to organisms through coordination of physiological and behavioral processes. Recent research has emphasized the role of circadian modulation of memory in generating peaks and troughs in cognitive performance. The circadian clock along with homeostatic processes also regulates sleep, which itself impacts the formation and consolidation of memory. Thus, the circadian clock, sleep and memory form a triad with ongoing dynamic interactions. With technological advances and the development of a global 24/7 society, understanding the mechanisms underlying these connections becomes pivotal for development of therapeutic treatments for memory disorders and to address issues in cognitive performance arising from non-traditional work schedules. Invertebrate models, such as Drosophila melanogaster and the mollusks Aplysia and Lymnaea, have proven invaluable tools for identification of highly conserved molecular processes in memory. Recent research from invertebrate systems has outlined the influence of sleep and the circadian clock upon synaptic plasticity. In this review, we discuss the effects of the circadian clock and sleep on memory formation in invertebrates drawing attention to the potential of in vivo and in vitro approaches that harness the power of simple invertebrate systems to correlate individual cellular processes with complex behaviors. In conclusion, this review highlights how studies in invertebrates with relatively simple nervous systems can provide mechanistic insights into corresponding behaviors in higher organisms and can be used to outline possible therapeutic options to guide further targeted inquiry.
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Affiliation(s)
- Maximilian Michel
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine Nashville, TN, USA
| | - Lisa C Lyons
- Department of Biological Science, Program in Neuroscience, Florida State University Tallahassee, FL, USA
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Erasing synapses in sleep: is it time to be SHY? Neural Plast 2012; 2012:264378. [PMID: 22530156 PMCID: PMC3317003 DOI: 10.1155/2012/264378] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Accepted: 12/04/2011] [Indexed: 02/04/2023] Open
Abstract
Converging lines of evidence strongly support a role for sleep in brain plasticity. An elegant idea that may explain how sleep accomplishes this role is the "synaptic homeostasis hypothesis (SHY)." According to SHY, sleep promotes net synaptic weakening which offsets net synaptic strengthening that occurs during wakefulness. SHY is intuitively appealing because it relates the homeostatic regulation of sleep to an important function (synaptic plasticity). SHY has also received important experimental support from recent studies in Drosophila melanogaster. There remain, however, a number of unanswered questions about SHY. What is the cellular mechanism governing SHY? How does it fit with what we know about plasticity mechanisms in the brain? In this review, I discuss the evidence and theory of SHY in the context of what is known about Hebbian and non-Hebbian synaptic plasticity. I conclude that while SHY remains an elegant idea, the underlying mechanisms are mysterious and its functional significance unknown.
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Stephenson R, Lewis V. Behavioural evidence for a sleep-like quiescent state in a pulmonate mollusc, Lymnaea stagnalis (Linnaeus). ACTA ACUST UNITED AC 2011; 214:747-56. [PMID: 21307060 DOI: 10.1242/jeb.050591] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The objective of this study was to determine whether the great pond snail, Lymnaea stagnalis, expresses a sleep-like behavioural state. We found that snails spontaneously enter a relatively brief (22±1 min) quiescent state characterized by postural relaxation of the foot, mantle and tentacles, and cessation of radula rasping. Quiescence was reversed ('aroused') by appetitive (sucrose solution) and aversive (tactile) stimuli. Responsiveness to both stimuli was significantly lower in quiescent snails than in active snails. However, tactile stimuli evoked a more sustained defensive response in quiescent snails. Quiescence bouts were consolidated into 'clusters' over an infradian timescale and were only weakly affected by time of day. Clusters contained 7±0.5 bouts, lasted 13±1 h and were separated by long (37±4 h) intervals of almost continuous activity. Analysis of Kaplan-Meier survival curves revealed that the quiescent bout duration was described by an exponential probability distribution (time constant 15±1 min). Active bout duration was described by a bi-exponential probability distribution (time constants 62±4 and 592±48 min). We found no evidence for a 'sleep rebound' mechanism and quiescence expression appeared to be regulated through stochastic processes causing state transitions to resemble a Markovian random walk. We conclude that Lymnaea is a potentially valuable model system for studies of cellular function in sleep.
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Affiliation(s)
- Richard Stephenson
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada.
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Abstract
As bluntly summarized by a psychologist over a century ago, everyone knows what attention is [James (1890). The Principles of Psychology]. Attention describes our capacity to focus perception on one or a group of related stimuli while filtering out irrelevant stimuli. The ease we have in recognizing this astounding capacity in ourselves is matched by a surprising difficulty in identifying it in others, and this is especially the case for measuring attention in other animals. Identifying and measuring attention-like processes in simple animals such as flies requires, to some extent, even more rigor than asking the same question for our closer animal relatives, such as apes and monkeys. This is because flies have completely different brains than humans do, so to study attention in these creatures one must rely purely on operational or behavioral measures rather than comparative neuroanatomy. There is a long history of using sophisticated behavioral paradigms to study visual responses in Drosophila melanogaster, and these studies have often provided early evidence of attention-like processes in flies. More recently, these fly paradigms have been applied to measuring visual attention directly, and the combination of electrophysiology with these preparations has provided insight into how a fly might pay attention. Together with more efficient methods for measuring some aspects of attention, such as stimulus suppression, these approaches should begin to uncover how visual attention might work in a small brain.
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Affiliation(s)
- Bruno van Swinderen
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072 Australia
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