Summary

Polygraphic Recording Procedure for Measuring Sleep in Mice

Published: January 25, 2016
doi:

Summary

The recording of electroencephalogram (EEG) and electromyogram (EMG) in freely behaving mice is a critical step to correlate behavior and physiology with sleep and wakefulness. The experimental protocol described herein provides a cable-based system for acquiring EEG and EMG recordings in mice.

Abstract

Recording of the epidural electroencephalogram (EEG) and electromyogram (EMG) in small animals, like mice and rats, has been pivotal to study the homeodynamics and circuitry of sleep-wake regulation. In many laboratories, a cable-based sleep recording system is used to monitor the EEG and EMG in freely behaving mice in combination with computer software for automatic scoring of the vigilance states on the basis of power spectrum analysis of EEG data. A description of this system is detailed herein. Steel screws are implanted over the frontal cortical area and the parietal area of 1 hemisphere for monitoring EEG signals. In addition, EMG activity is monitored by the bilateral placement of wires in both neck muscles. Non-rapid eye movement (Non-REM; NREM) sleep is characterized by large, slow brain waves with delta activity below 4 Hz in the EEG, whereas a shift from low-frequency delta activity to a rapid low-voltage EEG in the theta range between 6 and 10 Hz can be observed at the transition from NREM to REM sleep. By contrast, wakefulness is identified by low- to moderate-voltage brain waves in the EEG trace and significant EMG activity.

Introduction

Technical advances have often precipitated quantum leaps in the understanding of neurobiological processes. For example, Hans Berger's discovery in 1929 that electrical potentials recorded from the human scalp took the form of sinusoidal waves, the frequency of which was directly related to the level of wakefulness of the subject, led to rapid advances in the understanding of sleep-wake regulation, in both animals and humans alike.1 To this day the electroencephlogram (EEG), in conjunction with the electromyogram (EMG), i.e., electrical activity produced by skeletal muscles, represents the data "backbone" of nearly every experimental and clinical assessment that seeks to correlate behavior and physiology with the activity of cortical neurons in behaving animals, including humans. In most basic sleep research laboratories these EEG recordings are performed by using a cable-based system (Figure 1) wherein acquired data is subjected off-line to pattern and spectrum analysis [e.g., applying a fast Fourier transform (FFT) algorithm] to determine the vigilance state of the subject being recorded.2, 3 Sleep consists of rapid-eye movement (REM) and non-REM (NREM) sleep. REM sleep is characterized by a rapid low-voltage EEG, random eye movement, and muscle atonia, a state in which the muscles are effectively paralyzed. REM sleep is also known as paradoxical sleep, because the brain activity resembles that of wakefulness, whereas the body is largely disconnected from the brain and appears to be in deep sleep. By contrast, motor neurons are stimulated during NREM sleep but there is no eye movement. Human NREM sleep can be divided into 4 stages, whereby stage 4 is called deep sleep or slow-wave sleep and is identified by large, slow brain waves with delta activity between 0.5 – 4 Hz in the EEG. On the other hand, a subdivision between phases of NREM sleep in smaller animals, like rats and mice, has not been established, mostly because they do not have long consolidated periods of sleep as seen in humans.

Over the years, and on the basis of EEG interpretation, several models of sleep-wake regulation, both circuit- and humoral-based, have been proposed. The neural and cellular basis of the need for sleep or, alternatively, "sleep drive," remains unresolved, but has been conceptualized as a homeostatic pressure that builds during the waking period and is dissipated by sleep. One theory is that endogenous somnogenic factors accumulate during wakefulness and that their gradual accumulation is the underpinning of sleep homeostatic pressure. While the first formal hypothesis that sleep is regulated by humoral factors has been credited to Rosenbaum's work published in 18924, it was Ishimori5, 6 and Pieron7 who independently, and over 100 years ago, demonstrated the existence of sleep-promoting chemicals. Both researchers proposed, and indeed proved, that hypnogenic substances or 'hypnotoxins' were present in the cerebral spinal fluid (CSF) of sleep-deprived dogs.8 Over the past century several additional putative hypnogenic substances implicated in the sleep homeostatic process have been identified (for review, see ref. 9), including prostaglandin (PG) D2,10 cytokines,11 adenosine,12 anandamide,13 and the urotensin II peptide.14

Experimental work by Economo15, 16, Moruzzi and Magoun17, and others in the early and mid-20th century produced findings that inspired circuit-based theories of sleep and wakefulness and, to a certain degree, overshadowed the then prevailing humoral theory of sleep. To date, several "circuit models" have been proposed, each informed by data of varying quality and quantity (for review, see ref. 18). One model, for example, proposes that slow-wave sleep is generated through adenosine-mediated inhibition of acetylcholine release from cholinergic neurons in the basal forebrain, an area mainly consisiting of the nucleus of the horizontal limb of the diagonal band of Broca and the substantia inominata.19 Another popular model of sleep/wake regulation describes a flip-flop switch mechanism on the basis of mutually inhibitory interactions between sleep-inducing neurons in the ventrolateral preoptic area and wake-inducing neurons in the hypothalamus and brain stem.18, 20, 21 Moreover, for the switching in and out of REM sleep, a similar reciprocally inhibitory interaction has been proposed for areas in the brain stem, that is the ventral periaqueductal gray, lateral pontine tegmentum, and sublaterodorsal nucleus.22 Collectively, these models have proven valuable heuristics and afforded important interpretative frameworks for studies in sleep research; however, a yet fuller understanding of the molecular mechanisms and circuits regulating the sleep-wake cycle will require a more complete knowledge of its components. The system for polygraphic recording detailed below should aid in this goal.

Protocol

Ethics Statement: Procedures involving animal subjects have been approved by the Institutional Animal Experiment Committee at the University of Tsukuba. 1. Preparation of Electrodes and Cables for EEG/EMG Recordings Prepare EEG/EMG recording electrode according to the following procedure. Note: The electrode is disposable and can be used only for 1 animal. Plan carefully the wiring configuration for all connectors. Place marks on the connectors for the correct orientation. …

Representative Results

Figure 1B illustrates examples of the mouse EEG in the different vigilance states. As shown in Table 1, epochs are classified as NREM sleep if the EEG shows large, slow brain waves with a delta rhythm below 4 Hz and the EMG has only a weak or no signal. Epochs are classified as REM sleep if the EEG shows rapid low-voltage brain waves in the theta range between 6 and 10 Hz and the EMG shows low amplitude. Other epochs should be classified as wakefulness (<…

Discussion

This protocol describes a set-up for EEG/EMG recordings that allows the assessment of sleep and wakefulness under low-noise, cost-effective, and high-throughput conditions. Due to the small size of the EEG/EMG electrode head assembly, this system can be combined with other implants for intra-brain experiments, including optogenetics (optical fiber implantation) or, in conjunction with simultaneous cannula implantation, microinfusion of drugs into the mouse brain.31 Moreover, the design of the electrode head as…

Declarações

The authors have nothing to disclose.

Acknowledgements

We thank Dr. Larry D. Frye for editorial help with this manuscript. This work was supported by Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research 24300129 (to M.L.), 25890005 (to Y.O.) and 26640025 (to Y.T.), the National Agriculture and Food Research Organization (to Y.U.), the World Premier International Research Center Initiative (WPI) from the Ministry of Education, Culture, Sports, Science, and Technology (to Y.O., Y.T., Y.U. and M.L.) and the Nestlé Nutrition Council, Japan (to M.L.).

Materials

4-pin header Hirose A3B-4PA-2DSA(71)
Ampicillin Meiji Seika N/A
Analog-to-digital converter Contec AD16-16U(PCIEV)
Caffeine Sigma C0750
Carbide cutter Minitor B1055
Crimp housing Hirose DF11-4DS-2C
Crimp socket Hirose DF11-30SC
Dental cement (Toughron Rebase) Miki Chemical Product N/A
Epoxy adhesive Konishi #16351
FFC/FPC connector Honda Tsushin Kogyo FFC-10BMEP1(B)
Flat cable Hitachi Cable 20528-ST LF
Instant glue (Aron Alpha A) Toagosei N/A
Meloxicam Boehringer Ingelheim N/A
Pentobarbital Kyoritsu Seiyaku N/A
Signal amplifier Biotex N/A
Sleep recording chamber APL N/A
SleepSign software Kissei Comtec N/A for EEG/EMG recording/analysis
Slip ring Biotex N/A
Stainless steel screw Yamazaki N/A φ1.0×2.0
Stainless steel wire Cooner Wire AS633

Referências

  1. Berger, H. Über das Elektrenkephalogramm des Menschen. Arch. Psych. 87 (1), 527-570 (1929).
  2. Tobler, I., Deboer, T., Fischer, M. Sleep and sleep regulation in normal and prion protein-deficient mice. J. Neurosci. 17 (5), 1869-1879 (1997).
  3. Kohtoh, S., et al. Algorithm for sleep scoring in experimental animals based on fast Fourier transform power spectrum analysis of the electroencephalogram. Sleep Biol. Rhythm. 6 (3), 163-171 (2008).
  4. Rosenbaum, E. . Warum müssen wir schlafen? : eine neue Theorie des Schlafes. , (1892).
  5. Kubota, K. Kuniomi Ishimori and the first discovery of sleep-inducing substances in the brain. Neurosci. Res. 6 (6), 497-518 (1989).
  6. Ishimori, K. True cause of sleep: a hypnogenic substance as evidenced in the brain of sleep-deprived animals. Tokyo Igakkai Zasshi. 23, 429-457 (1909).
  7. Legendre, R., Pieron, H. Recherches sur le besoin de sommeil consécutif à une veille prolongée. Z. Allegem. Physiol. 14, 235-262 (1913).
  8. Inoué, S., Honda, K., Komoda, Y. Sleep as neuronal detoxification and restitution. Behav. Brain. Res. 69 (1-2), 91-96 (1995).
  9. Urade, Y., Hayaishi, O. Prostaglandin D2 and sleep/wake regulation. Sleep Med. Rev. 15 (6), 411-418 (2011).
  10. Ueno, R., Ishikawa, Y., Nakayama, T., Hayaishi, O. Prostaglandin D2 induces sleep when microinjected into the preoptic area of conscious rats. Biochem. Biophys. Res. Commun. 109 (2), 576-582 (1982).
  11. Krueger, J. M., Walter, J., Dinarello, C. A., Wolff, S. M., Chedid, L. Sleep-promoting effects of endogenous pyrogen (interleukin-1). Am. J. Physiol. 246 (6 Pt 2), R994-R999 (1984).
  12. Porkka-Heiskanen, T., et al. Adenosine: a mediator of the sleep-inducing effects of prolonged wakefulness. Science. 276 (5316), 1265-1268 (1997).
  13. Garcia-Garcia, F., Acosta-Pena, E., Venebra-Munoz, A., Murillo-Rodriguez, E. Sleep-inducing factors. CNS Neurol. Disord. Drug. Targets. 8 (4), 235-244 (2009).
  14. Huitron-Resendiz, S., et al. Urotensin II modulates rapid eye movement sleep through activation of brainstem cholinergic neurons. J. Neurosci. 25 (23), 5465-5474 (2005).
  15. Wilkins, R. H., Brody, I. A. Encephalitis lethargica. Arch. Neurol. 18 (3), 324-328 (1968).
  16. von Economo, C. Die encephalitis lethargica. Wien. Klin. Wochenschr. 30, 581-585 (1917).
  17. Moruzzi, G., Magoun, H. W. Brain stem reticular formation and activation of the EEG. Electroencephalogr. Clin. Neurophysiol. 1 (4), 455-473 (1949).
  18. Saper, C. B., Fuller, P. M., Pedersen, N. P., Lu, J., Scammell, T. E. Sleep state switching. Neuron. 68 (6), 1023-1042 (2010).
  19. Jones, B. E., Krnjevic , K., L, D. e. s. c. a. r. r. i. e. s., S, M. i. r. c. e. a. . Progress in Brain Research. 145, 157-169 (2004).
  20. Saper, C. B., Scammell, T. E., Lu, J. Hypothalamic regulation of sleep and circadian rhythms. Nature. 437 (7063), 1257-1263 (2005).
  21. Fort, P., Bassetti, C. L., Luppi, P. H. Alternating vigilance states: new insights regarding neuronal networks and mechanisms. Eur. J. Neurosci. 29 (9), 1741-1753 (2009).
  22. Lu, J., Sherman, D., Devor, M., Saper, C. B. A putative flip-flop switch for control of REM sleep. Nature. 441 (7093), 589-594 (2006).
  23. Paxinos, G., Franklin, K. B. J. . The mouse brain in stereotaxic coordinates. , (2001).
  24. Lazarus, M., et al. Arousal effect of caffeine depends on adenosine A2A receptors in the shell of the nucleus accumbens. J. Neurosci. 31 (27), 10067-10075 (2011).
  25. Huang, Z. L., et al. Adenosine A2A, but not A1, receptors mediate the arousal effect of caffeine. Nat. Neurosci. 8 (7), 858-859 (2005).
  26. Qu, W. M., Huang, Z. L., Xu, X. H., Matsumoto, N., Urade, Y. Dopaminergic D1 and D2 receptors are essential for the arousal effect of modafinil. J. Neurosci. 28 (34), 8462-8469 (2008).
  27. Huang, Z. L., et al. Arousal effect of orexin A depends on activation of the histaminergic system. Proc. Natl. Acad. Sci. USA. 98 (17), 9965-9970 (2001).
  28. Xu, Q., et al. A mouse model mimicking human first night effect for the evaluation of hypnotics. Pharmacol. Biochem. Behav. 116, 129-136 (2014).
  29. Cho, S., et al. Marine polyphenol phlorotannins promote non-rapid eye movement sleep in mice via the benzodiazepine site of the GABAA receptor. Psychopharmacol. 231 (14), 2825-2837 (2014).
  30. Liu, Y. Y., et al. Piromelatine exerts antinociceptive effect via melatonin, opioid, and 5HT1A receptors and hypnotic effect via melatonin receptors in a mouse model of neuropathic pain. Psychopharmacol. 231 (20), 3973-3985 (2014).
  31. Qu, W. M., et al. Lipocalin-type prostaglandin D synthase produces prostaglandin D2 involved in regulation of physiological sleep. Proc. Natl. Acad. Sci. USA. 103 (47), 17949-17954 (2006).

Play Video

Citar este artigo
Oishi, Y., Takata, Y., Taguchi, Y., Kohtoh, S., Urade, Y., Lazarus, M. Polygraphic Recording Procedure for Measuring Sleep in Mice. J. Vis. Exp. (107), e53678, doi:10.3791/53678 (2016).

View Video