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Brodersen PJN, Alfonsa H, Krone LB, Blanco-Duque C, Fisk AS, Flaherty SJ, Guillaumin MCC, Huang YG, Kahn MC, McKillop LE, Milinski L, Taylor L, Thomas CW, Yamagata T, Foster RG, Vyazovskiy VV, Akerman CJ. Somnotate: A probabilistic sleep stage classifier for studying vigilance state transitions. PLoS Comput Biol 2024; 20:e1011793. [PMID: 38232122 PMCID: PMC10824458 DOI: 10.1371/journal.pcbi.1011793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 01/29/2024] [Accepted: 01/02/2024] [Indexed: 01/19/2024] Open
Abstract
Electrophysiological recordings from freely behaving animals are a widespread and powerful mode of investigation in sleep research. These recordings generate large amounts of data that require sleep stage annotation (polysomnography), in which the data is parcellated according to three vigilance states: awake, rapid eye movement (REM) sleep, and non-REM (NREM) sleep. Manual and current computational annotation methods ignore intermediate states because the classification features become ambiguous, even though intermediate states contain important information regarding vigilance state dynamics. To address this problem, we have developed "Somnotate"-a probabilistic classifier based on a combination of linear discriminant analysis (LDA) with a hidden Markov model (HMM). First we demonstrate that Somnotate sets new standards in polysomnography, exhibiting annotation accuracies that exceed human experts on mouse electrophysiological data, remarkable robustness to errors in the training data, compatibility with different recording configurations, and an ability to maintain high accuracy during experimental interventions. However, the key feature of Somnotate is that it quantifies and reports the certainty of its annotations. We leverage this feature to reveal that many intermediate vigilance states cluster around state transitions, whereas others correspond to failed attempts to transition. This enables us to show for the first time that the success rates of different types of transition are differentially affected by experimental manipulations and can explain previously observed sleep patterns. Somnotate is open-source and has the potential to both facilitate the study of sleep stage transitions and offer new insights into the mechanisms underlying sleep-wake dynamics.
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Affiliation(s)
- Paul J. N. Brodersen
- Department of Pharmacology, University of Oxford; Mansfield Road, Oxford, United Kingdom
| | - Hannah Alfonsa
- Department of Pharmacology, University of Oxford; Mansfield Road, Oxford, United Kingdom
| | - Lukas B. Krone
- Department of Physiology, Anatomy and Genetics, University of Oxford; Parks Road, United Kingdom
| | - Cristina Blanco-Duque
- Department of Physiology, Anatomy and Genetics, University of Oxford; Parks Road, United Kingdom
| | - Angus S. Fisk
- Nuffield Department of Clinical Neurosciences, University of Oxford; John Radcliffe Hospital, Oxford, United Kingdom
| | - Sarah J. Flaherty
- Department of Physiology, Anatomy and Genetics, University of Oxford; Parks Road, United Kingdom
| | - Mathilde C. C. Guillaumin
- Nuffield Department of Clinical Neurosciences, University of Oxford; John Radcliffe Hospital, Oxford, United Kingdom
- Sleep and Circadian Neuroscience Institute, University of Oxford; Oxford, United Kingdom
- Institute for Neuroscience, Department of Health Sciences and Technology, ETH Zurich; Schwerzenbach, Switzerland
| | - Yi-Ge Huang
- Department of Physiology, Anatomy and Genetics, University of Oxford; Parks Road, United Kingdom
| | - Martin C. Kahn
- Department of Physiology, Anatomy and Genetics, University of Oxford; Parks Road, United Kingdom
| | - Laura E. McKillop
- Department of Physiology, Anatomy and Genetics, University of Oxford; Parks Road, United Kingdom
| | - Linus Milinski
- Department of Physiology, Anatomy and Genetics, University of Oxford; Parks Road, United Kingdom
| | - Lewis Taylor
- Nuffield Department of Clinical Neurosciences, University of Oxford; John Radcliffe Hospital, Oxford, United Kingdom
| | - Christopher W. Thomas
- Department of Physiology, Anatomy and Genetics, University of Oxford; Parks Road, United Kingdom
| | - Tomoko Yamagata
- Nuffield Department of Clinical Neurosciences, University of Oxford; John Radcliffe Hospital, Oxford, United Kingdom
| | - Russell G. Foster
- Sleep and Circadian Neuroscience Institute, University of Oxford; Oxford, United Kingdom
| | - Vladyslav V. Vyazovskiy
- Department of Physiology, Anatomy and Genetics, University of Oxford; Parks Road, United Kingdom
| | - Colin J. Akerman
- Department of Pharmacology, University of Oxford; Mansfield Road, Oxford, United Kingdom
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2
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Traut J, Mengual JP, Meijer EJ, McKillop LE, Alfonsa H, Hoerder-Suabedissen A, Song SH, Fehér KD, Riemann D, Molnar Z, Akerman CJ, Vyazovskiy VV, Krone LB. Effects of clozapine-N-oxide and compound 21 on sleep in laboratory mice. eLife 2023; 12:e84740. [PMID: 36892930 PMCID: PMC9998087 DOI: 10.7554/elife.84740] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 01/03/2023] [Indexed: 03/10/2023] Open
Abstract
Designer receptors exclusively activated by designer drugs (DREADDs) are chemogenetic tools for remote control of targeted cell populations using chemical actuators that bind to modified receptors. Despite the popularity of DREADDs in neuroscience and sleep research, potential effects of the DREADD actuator clozapine-N-oxide (CNO) on sleep have never been systematically tested. Here, we show that intraperitoneal injections of commonly used CNO doses (1, 5, and 10 mg/kg) alter sleep in wild-type male laboratory mice. Using electroencephalography (EEG) and electromyography (EMG) to analyse sleep, we found a dose-dependent suppression of rapid eye movement (REM) sleep, changes in EEG spectral power during non-REM (NREM) sleep, and altered sleep architecture in a pattern previously reported for clozapine. Effects of CNO on sleep could arise from back-metabolism to clozapine or binding to endogenous neurotransmitter receptors. Interestingly, we found that the novel DREADD actuator, compound 21 (C21, 3 mg/kg), similarly modulates sleep despite a lack of back-metabolism to clozapine. Our results demonstrate that both CNO and C21 can modulate sleep of mice not expressing DREADD receptors. This implies that back-metabolism to clozapine is not the sole mechanism underlying side effects of chemogenetic actuators. Therefore, any chemogenetic experiment should include a DREADD-free control group injected with the same CNO, C21, or newly developed actuator. We suggest that electrophysiological sleep assessment could serve as a sensitive tool to test the biological inertness of novel chemogenetic actuators.
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Affiliation(s)
- Janine Traut
- Department of Psychiatry and Psychotherapy, Medical Center - University of Freiburg, Faculty of Medicine, University of FreiburgFreiburgGermany
- Department of Physiology, Anatomy and Genetics, University of OxfordOxfordUnited Kingdom
- Sir Jules Thorn Sleep and Circadian Neuroscience Institute, University of OxfordOxfordUnited Kingdom
| | - Jose Prius Mengual
- Department of Physiology, Anatomy and Genetics, University of OxfordOxfordUnited Kingdom
- Sir Jules Thorn Sleep and Circadian Neuroscience Institute, University of OxfordOxfordUnited Kingdom
- The Kavli Institute for Nanoscience DiscoveryOxfordUnited Kingdom
| | - Elise J Meijer
- Department of Physiology, Anatomy and Genetics, University of OxfordOxfordUnited Kingdom
- Sir Jules Thorn Sleep and Circadian Neuroscience Institute, University of OxfordOxfordUnited Kingdom
- The Kavli Institute for Nanoscience DiscoveryOxfordUnited Kingdom
| | - Laura E McKillop
- Department of Physiology, Anatomy and Genetics, University of OxfordOxfordUnited Kingdom
- Sir Jules Thorn Sleep and Circadian Neuroscience Institute, University of OxfordOxfordUnited Kingdom
| | - Hannah Alfonsa
- Department of Pharmacology, University of OxfordOxfordUnited Kingdom
| | | | - Seo Ho Song
- Department of Psychiatry, Beth Israel Deaconess Medical Center, Harvard Medical SchoolBostonUnited States
| | - Kristoffer D Fehér
- Geneva University Hospitals (HUG), Division of Psychiatric SpecialtiesGenevaSwitzerland
- University Hospital of Psychiatry and Psychotherapy, University of BernBernSwitzerland
| | - Dieter Riemann
- Department of Psychiatry and Psychotherapy, Medical Center - University of Freiburg, Faculty of Medicine, University of FreiburgFreiburgGermany
- Sir Jules Thorn Sleep and Circadian Neuroscience Institute, University of OxfordOxfordUnited Kingdom
| | - Zoltan Molnar
- Department of Physiology, Anatomy and Genetics, University of OxfordOxfordUnited Kingdom
| | - Colin J Akerman
- Department of Pharmacology, University of OxfordOxfordUnited Kingdom
| | - Vladyslav V Vyazovskiy
- Department of Physiology, Anatomy and Genetics, University of OxfordOxfordUnited Kingdom
- Sir Jules Thorn Sleep and Circadian Neuroscience Institute, University of OxfordOxfordUnited Kingdom
- The Kavli Institute for Nanoscience DiscoveryOxfordUnited Kingdom
| | - Lukas B Krone
- Department of Physiology, Anatomy and Genetics, University of OxfordOxfordUnited Kingdom
- Sir Jules Thorn Sleep and Circadian Neuroscience Institute, University of OxfordOxfordUnited Kingdom
- The Kavli Institute for Nanoscience DiscoveryOxfordUnited Kingdom
- University Hospital of Psychiatry and Psychotherapy, University of BernBernSwitzerland
- Centre for Experimental Neurology, University of BernBernSwitzerland
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Parrish RR, MacKenzie-Gray Scott C, Jackson-Taylor T, Grundmann A, McLeod F, Codadu NK, Călin A, Alfonsa H, Wykes RC, Voipio J, Trevelyan AJ. Indirect Effects of Halorhodopsin Activation: Potassium Redistribution, Nonspecific Inhibition, and Spreading Depolarization. J Neurosci 2023; 43:685-692. [PMID: 36639898 PMCID: PMC9899079 DOI: 10.1523/jneurosci.1141-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 11/28/2022] [Accepted: 12/02/2022] [Indexed: 12/14/2022] Open
Abstract
The movement of ions in and out of neurons can exert significant effects on neighboring cells. Here we report several experimentally important consequences of activation of the optogenetic chloride pump, halorhodopsin. We recorded extracellular K+ concentration ([K+]extra) in neocortical brain slices prepared from young adult mice (both sexes) which express halorhodopsin in pyramidal cells. Strong halorhodopsin activation induced a pronounced drop in [K+]extra that persisted for the duration of illumination. Pharmacological blockade of K+ channels reduced the amplitude of this drop, indicating that it represents K+ redistribution into cells during the period of hyperpolarization. Halorhodopsin thus drives the inward movement of both Cl- directly, and K+ secondarily. When the illumination period ended, a rebound surge in extracellular [K+] developed over tens of seconds, partly reflecting the previous inward redistribution of K+, but additionally driven by clearance of Cl- coupled to K+ by the potassium-chloride cotransporter, KCC2. The drop in [K+]extra during light activation leads to a small (2-3 mV) hyperpolarization also of other cells that do not express halorhodopsin. Its activation therefore has both direct and indirect inhibitory effects. Finally, we show that persistent strong activation of halorhodopsin causes cortical spreading depolarizations (CSDs), both in vitro and in vivo This novel means of triggering CSDs is unusual, in that the events can arise during the actual period of illumination, when neurons are being hyperpolarized and [K+]extra is low. We suggest that this fundamentally different experimental model of CSDs will open up new avenues of research to explain how they occur naturally.SIGNIFICANCE STATEMENT Halorhodopsin is a light-activated electrogenic chloride pump, which has been widely used to inhibit neurons optogenetically. Here, we demonstrate three previously unrecognized consequences of its use: (1) intense activation leads to secondary movement of K+ ions into the cells; (2) the resultant drop in extracellular [K+] reduces excitability also in other, nonexpressing cells; and (3) intense persistent halorhodopsin activation can trigger cortical spreading depolarization (CSD). Halorhodopsin-induced CSDs can occur when neurons are hyperpolarized and extracellular [K+] is low. This contrasts with the most widely used experimental models that trigger CSDs with high [K+]. Both models, however, are consistent with the hypothesis that CSDs arise following net inward ionic movement into the principal neuron population.
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Affiliation(s)
- R Ryley Parrish
- Newcastle University Biosciences Institute, Medical School, Newcastle upon Tyne, NE2 4HH, United Kingdom
- Department of Cell Biology and Physiology, Brigham Young University, Provo 84602, Utah
| | | | - Tom Jackson-Taylor
- Newcastle University Biosciences Institute, Medical School, Newcastle upon Tyne, NE2 4HH, United Kingdom
| | - Alex Grundmann
- Newcastle University Biosciences Institute, Medical School, Newcastle upon Tyne, NE2 4HH, United Kingdom
| | - Faye McLeod
- Newcastle University Biosciences Institute, Medical School, Newcastle upon Tyne, NE2 4HH, United Kingdom
| | - Neela K Codadu
- Queen Square Institute of Neurology, University College London, WC1N 3BG, United Kingdom
| | - Alexandru Călin
- Newcastle University Biosciences Institute, Medical School, Newcastle upon Tyne, NE2 4HH, United Kingdom
| | - Hannah Alfonsa
- Newcastle University Biosciences Institute, Medical School, Newcastle upon Tyne, NE2 4HH, United Kingdom
| | - Rob C Wykes
- Nanomedicine Lab, University of Manchester, Manchester, M13 9PL, United Kingdom
- Queen Square Institute of Neurology, University College London, WC1N 3BG, United Kingdom
| | - Juha Voipio
- Faculty of Biological and Environmental Sciences, Molecular and Integrative Biosciences, University of Helsinki, Helsinki, 00014, Finland
| | - Andrew J Trevelyan
- Newcastle University Biosciences Institute, Medical School, Newcastle upon Tyne, NE2 4HH, United Kingdom
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4
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Alfonsa H, Burman RJ, Brodersen PJN, Newey SE, Mahfooz K, Yamagata T, Panayi MC, Bannerman DM, Vyazovskiy VV, Akerman CJ. Intracellular chloride regulation mediates local sleep pressure in the cortex. Nat Neurosci 2023; 26:64-78. [PMID: 36510112 PMCID: PMC7614036 DOI: 10.1038/s41593-022-01214-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 10/25/2022] [Indexed: 12/14/2022]
Abstract
Extended wakefulness is associated with reduced performance and the build-up of sleep pressure. In the cortex, this manifests as changes in network activity. These changes show local variation depending on the waking experience, and their underlying mechanisms represent targets for overcoming the effects of tiredness. Here, we reveal a central role for intracellular chloride regulation, which sets the strength of postsynaptic inhibition via GABAA receptors in cortical pyramidal neurons. Wakefulness results in depolarizing shifts in the equilibrium potential for GABAA receptors, reflecting local activity-dependent processes during waking and involving changes in chloride cotransporter activity. These changes underlie electrophysiological and behavioral markers of local sleep pressure within the cortex, including the levels of slow-wave activity during non-rapid eye movement sleep and low-frequency oscillatory activity and reduced performance levels in the sleep-deprived awake state. These findings identify chloride regulation as a crucial link between sleep-wake history, cortical activity and behavior.
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Affiliation(s)
- Hannah Alfonsa
- Department of Pharmacology, University of Oxford, Oxford, UK.
| | | | | | - Sarah E Newey
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Kashif Mahfooz
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Tomoko Yamagata
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Marios C Panayi
- Department of Experimental Psychology, University of Oxford, Oxford, UK
| | - David M Bannerman
- Department of Experimental Psychology, University of Oxford, Oxford, UK
| | | | - Colin J Akerman
- Department of Pharmacology, University of Oxford, Oxford, UK.
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5
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Traut J, Mengual J, Meijer E, McKillop L, Alfonsa H, Hoerder-Suabedissen A, Song S, Molnár Z, Akerman C, Vyazovskiy V, Krone L. Effects of clozapine-N-oxide and Compound 21 on sleep in laboratory mice. Sleep Med 2022. [DOI: 10.1016/j.sleep.2022.05.056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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6
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Alfonsa H, Lakey JH, Lightowlers RN, Trevelyan AJ. Cl-out is a novel cooperative optogenetic tool for extruding chloride from neurons. Nat Commun 2016; 7:13495. [PMID: 27853135 PMCID: PMC5118542 DOI: 10.1038/ncomms13495] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 10/10/2016] [Indexed: 01/11/2023] Open
Abstract
Chloride regulation affects brain function in many ways, for instance, by dictating the GABAergic reversal potential, and thereby influencing neuronal excitability and spike timing. Consistent with this, there is increasing evidence implicating chloride in a range of neurological conditions. Investigations about these conditions, though, are made difficult by the limited range of tools available to manipulate chloride levels. In particular, there has been no way to actively remove chloride from neurons; we now describe an optogenetic strategy, ‘Cl-out', to do exactly this. Cl-out achieves its effect by the cooperative action of two different component opsins: the proton pump, Archaerhodopsin and a chloride channel opsin. The removal of chloride happens when both are activated together, using Archaerhodopsin as an optical voltage clamp to provide the driving force for chloride removal through the concurrently opened, chloride channels. We further show that this novel optogenetic strategy can reverse an in vitro epileptogenic phenotype. Chloride regulation is important for setting GABAergic reversal potential, though tools to manipulate chloride levels are limited. Here, the authors combine Archaerhodopsin with a chloride channel opsin to generate an optogenetic chloride extrusion strategy, ‘Cl-out', which they demonstrate in hippocampal slices.
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Affiliation(s)
- Hannah Alfonsa
- Institute of Neuroscience, Medical School, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
| | - Jeremy H Lakey
- Institute for Cell and Molecular Biosciences, Medical School, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
| | - Robert N Lightowlers
- Institute for Cell and Molecular Biosciences, Medical School, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
| | - Andrew J Trevelyan
- Institute of Neuroscience, Medical School, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
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