Roles for sleep in memory: insights from the fly

Donlea, Jeffrey M.

doi:10.1016/j.conb.2018.10.006

Cited by 43 publications

(36 citation statements)

References 88 publications

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“…Yet, we lack a fundamental understanding of sleep function [21]. The fly model is a powerful tool to understand sleep regulatory processes and functions [22]. Here, we used the GRASP technique to show that increases in sleep pressure decrease neural-glial interactions between MB neurons and astrocytes.…”

Section: Resultsmentioning

confidence: 99%

Sleep pressure regulates mushroom body neural-glial interactions in Drosophila

Vanderheyden¹,

Dongen²,

Frank³

et al. 2019

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Sleep is a behavior that exists broadly across animal phyla, from flies to humans, and is necessary for normal brain function. Recent studies in both vertebrates and invertebrates have suggested a role for glial cells in sleep regulatory processes. Changes in neural-glial interactions have been shown to be critical for synaptic plasticity and circuit function. Here, we wanted to test the hypothesis that changes in sleep pressure alters neural-glial interactions. In the fruit fly, Drosophila melanogaster, sleep is known to be regulated by mushroom body (MB) circuits. We used the technique GFP Reconstitution Across Synaptic Partners (GRASP) to test whether changes in sleep pressure affect neural-glial interactions between MB neurons and astrocytes, a specialized glial cell type known to regulate sleep in flies and mammals. The MB-astrocyte GRASP signal was reduced after 24 h of sleep deprivation, whereas the signal returned to baseline levels following 72 h of recovery. Social enrichment, which increases sleep drive, similarly reduced the MB-astrocyte GRASP signal. We did not observe any changes in the MB-astrocyte GRASP signal over time-of-day, or following paraquat exposure or starvation. These data suggest that changes in sleep pressure are linked to dynamic changes in neural-glial interactions between astrocytes and neuronal sleep circuits, which are not caused by normal rest-activity cycles or stressors.

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Section: Resultsmentioning

confidence: 99%

Sleep pressure regulates mushroom body neural-glial interactions in Drosophila

Vanderheyden¹,

Dongen²,

Frank³

et al. 2019

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“…The proposed PSD-expansion model may also be relevant to neurons that maintain NREM sleep, except that this circuit would operate "in reverse": Neurons that fire frequently during NREM sleep but tend not to fire during wakefulness may accumulate protein fragments during NREM sleep and destroy them later, during wakefulness. 9) A particularly deep NREM sleep, called a "slow-wave" sleep and defined, in part, by its electroencephalographic features, is up-regulated in cortical regions of the brain that have been recently hyperactive (35). Molecular/mechanistic aspects of a slow-wave NREM sleep are largely unknown.…”

Section: Might Psds Reversibly Expand During Nrem Sleep?mentioning

confidence: 99%

“…3) and other aspects of the FG hypothesis is a tractable challenge, since all proposed conjectures are concrete enough to be falsifiable. If the FG hypothesis proves correct at least in outline, it would imply that the dynamics of intracellular and extracellular protein fragments, in the brain and in other organs, may underlie not only molecular-level roles of sleep but its higher-order functions as well, including the extensively documented role of sleep in learning and memory (34,35). Several lines of evidence indicate that memory and learning involve natural protein fragments, both in mammals and in the Aplysia marine snail (67,70).…”

Section: Might Psds Reversibly Expand During Nrem Sleep?mentioning

confidence: 99%

“…Other suggested causes/functions of sleep tend to be higher-order concepts. They include the synaptic homeostasis hypothesis (33) and extensive evidence for a role of sleep in memory and learning (34,35).If the assumption (it remains an assumption) that the fundamental cause of sleep resides in individual neurons and other…”

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confidence: 99%

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On the cause of sleep: Protein fragments, the concept of sentinels, and links to epilepsy

Varshavsky

2019

Proc. Natl. Acad. Sci. U.S.A.

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The molecular-level cause of sleep is unknown. In 2012, we suggested that the cause of sleep stems from cumulative effects of numerous intracellular and extracellular protein fragments. According to the fragment generation (FG) hypothesis, protein fragments (which are continually produced through nonprocessive cleavages by intracellular, intramembrane, and extracellular proteases) can be beneficial but toxic as well, and some fragments are eliminated slowly during wakefulness. We consider the FG hypothesis and propose that, during wakefulness, the degradation of accumulating fragments is delayed within natural protein aggregates such as postsynaptic densities (PSDs) in excitatory synapses and in other dense protein meshworks, owing to an impeded diffusion of the ∼3,000-kDa 26S proteasome. We also propose that a major function of sleep involves a partial and reversible expansion of PSDs, allowing an accelerated destruction of PSD-localized fragments by the ubiquitin/proteasome system. Expansion of PSDs would alter electrochemistry of synapses, thereby contributing to a decreased neuronal firing during sleep. If so, the loss of consciousness, a feature of sleep, would be the consequence of molecular processes (expansions of protein meshworks) that are required for degradation of protein fragments. We consider the concept of FG sentinels, which signal to sleep-regulating circuits that the levels of fragments are going up. Also discussed is the possibility that protein fragments, which are known to be overproduced during an epileptic seizure, may contribute to postictal sleep and termination of seizures. These and related suggestions, described in the paper, are compatible with current evidence about sleep and lead to testable predictions. fragment | extracellular | intracellular | proteolysis | sleep S leep is universal among mammals and other vertebrates.Animals with much smaller nervous systems, such as insects, also sleep (1-8). Mechanisms that control sleep include circadian circuits, which underlie daily rhythms of sleep and other biological variables (9). However, circadian aspects of sleep do not define it entirely, because sleep has the homeostatic property of becoming longer after sleep deprivation (10, 11). In mammals, birds, and lizards, two alternating modes of sleep have been identified, the non-rapid eye movement (NREM) sleep and the rapid eye movement (REM) sleep (12,13). The depth of NREM sleep is yet another sleep variable. In adult humans, NREM sleep occupies ∼80% of the total sleep time. For recent reviews of sleep, see refs. 14-20.Despite advances in the understanding of neuronal circuits as well as genes, proteins, short peptides, and other compounds that regulate sleep, it is largely unknown why sleep exists and what it is for. Maladaptive aspects of sleep include elevated dangers of predation during sleep, the neglect of territorial defense and foraging for food, and the loss of parental care and mating opportunities. It is unknown what features of sleep did not allow these fitness costs to ca...

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Effects of a combination of Poria Cocos, Ziziphus spinose, and gamma‐aminobutyric acid (GABA) on sleep quality and skin health: A randomized double‐blind placebo‐controlled clinical trial

Hao,

Song,

2024

Food Science & Nutrition

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Sleep is crucial for preserving both physical and mental health, including skin health. Presently, there is a burgeoning interest in the use of herbal and natural ingredients to mitigate the adverse effects of sleep disorders. In this 4‐week, randomized, double‐blind, controlled trial, 70 subjects with sleep disorders were randomly assigned to receive either a placebo or a Poria cocos, Ziziphus spinose, and GABA (PZG) supplement (10 mL per day). Total sleep duration was detected by wrist actigraphy, and sleep quality was assessed by the Pittsburgh Sleep Quality Index (PSQI). Skin conditions were evaluated based on assessments of skin hydration, glossiness elasticity, color, severity of wrinkles, and skin roughness. After 4 weeks, the total sleep duration significantly increased by 12.96% (p = .006) and the PSQI score notably decreased by 59.94% (p = .000) compared to the baseline. Notably, compared to the baseline conditions, skin hydration, radiance, elasticity, firmness, wrinkle severity, and roughness were significantly improved in the PZG group. In addition, the PZG group demonstrated significantly greater improvements than the placebo group in terms of changes from baseline in total sleep duration, PSQI score, skin hydration, wrinkle severity, and skin roughness. The present results demonstrated that the combined intake of herbs and GABA can improve sleep quality and enhance skin health without adverse effects.

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Roles for sleep in memory: insights from the fly

Cited by 43 publications

References 88 publications

Sleep pressure regulates mushroom body neural-glial interactions in Drosophila

Sleep pressure regulates mushroom body neural-glial interactions in Drosophila

On the cause of sleep: Protein fragments, the concept of sentinels, and links to epilepsy

Effects of a combination of Poria Cocos, Ziziphus spinose, and gamma‐aminobutyric acid (GABA) on sleep quality and skin health: A randomized double‐blind placebo‐controlled clinical trial

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