Sleep and EEG Phenotyping in Mice

Géraldine Morgane Mang1, Paul Franken1

1 Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
Publication Name:  Current Protocols in Mouse Biology
Unit Number:   
DOI:  10.1002/9780470942390.mo110126
Online Posting Date:  March, 2012
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Abstract

Although alternative, noninvasive methods are being developed, current research on rodent sleep still almost exclusively relies on recording the electroencephalogram (EEG). EEG provides information about the electrical activity of the brain and is, in combination with the electromyogram (EMG), primarily used to distinguish the different sleep and wake states. This unit describes the technique used to record EEG and EMG signals in freely moving mice, under standard laboratory conditions or specific experimental protocols such as sleep deprivation (SD). In addition to its use to determine behavioral state, the EEG contains a wealth of information concerning rhythmic brain activity that can be extracted using signal analysis tools. We will describe the protocol for implantation of EEG and EMG electrodes, provide examples of experimental designs, and discuss data acquisition and analysis illustrating the type of information that can be obtained from the EEG in mice. Curr. Protoc. Mouse Biol. 2:54‐74 © 2012 by John Wiley & Sons, Inc.

Keywords: EEG; sleep; mice; signal analysis; spectral analysis

     
 
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Table of Contents

  • Introduction
  • Basic Protocol 1: Implantation of EEG and EMG Electrodes
  • Basic Protocol 2: Recording EEG/EMG During Experiment
  • Basic Protocol 3: Data Acquisition
  • Basic Protocol 4: Determining Behavioral State Based on the EEG and EMG Signals (i.e., “Scoring”)
  • Basic Protocol 5: Spectral Analysis
  • Commentary
  • Literature Cited
  • Figures
     
 
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Materials

Basic Protocol 1: Implantation of EEG and EMG Electrodes

  Materials
  • Xylazine (Rompun, 2%, Provet AG; http://www.provet.ch/)
  • Ketamine (Ketasol 100, Graeub Veterinary Products, http://www.graeub.com/)
  • 0.9% (w/v) NaCl
  • 100% ethanol
  • Isoflurane (Isoflurane Attane, Provet AG; http://www.provet.ch/; optional)
  • Ophthalmic gel (e.g., Viscotears, Novartis Pharma AG; http://www.novartis.com)
  • Betadine
  • Adhesive Resin Cement (RelyX ARC Adhesive Resin Cement, 3 M ESPE Dental Products, http://solutions.3msuisse.ch)
  • Dental Cement (e.g., Paladur, Heraeus Kulzer; http://heraeus‐dental.de)
  • Analgesic (e.g., Fynadine, 50 mg/ml)
  • Soldering iron (e.g., Weller WS 81, Distrelec; https://www.distrelec.com/)
  • Stainless steel miniature screws (e.g., Precision Screws and Parts, 303 SS, diameter 1.1 mm, Morris Co.; http://www.morris01550.com/; gold plated by a local gilding/galvanic workshop; the gold plating is not essential to the protocol and stainless‐steel screws can be used as such, but it makes the soldering of the screws easier)
  • Copper electrical wire (Wire‐Wrap AWG30 from Distrelec; https://www.distrelec.com)
  • Gold wire (e.g., Cendres + Métaux SA; http://www.cmsa.ch/)
  • Electric clippers
  • Stereotaxic frame (e.g., Small Animal Stereotaxic System, David Kopf Instruments)
  • Heating pad (e.g., DC Temperature Control System, FHC; http://www.fh‐co.com/)
  • High‐intensity light source (e.g., Fiber‐Lite MI‐150, High Intensity Illuminator, Dolan‐Jenner Industries)
  • Sterilized surgical instrument kit including scissors, forceps, scalpels and clamps
  • Micro drill (e.g., Quetin MOD.CC 1000, Micro Mega; http://www.micro‐mega.com/)
  • Sterile cotton swabs
  • Micro screwdriver ∼1 mm (e.g., Minicraft TS‐6N, Distrelec; https://www.distrelec.com/)
  • Connector (BPHF2‐O6S‐E‐3.2, OHS RoHS; ENA AG; http://www.ena.ch/)
  • Suture (e.g., Ethilon II 5/0, 45 cm, Ethicon Products; http://www.ethicon.com)
NOTE: Although we only very seldom observe signs of infection in mice after surgery, some precautions have to be taken before starting the operation. All instruments should be sterilized before starting and, if necessary, again during the operation (e.g., autoclave or glass beads); the experimenter should wear protective clothes (clean lab coat, sterile gloves, and covering mask) and use a dedicated sterile surgical area.

Basic Protocol 2: Recording EEG/EMG During Experiment

  Materials
  • Mouse with electrodes implanted as described in protocol 1
  • Housing cages (e.g., Charles River Type F1, 30.5 × 18 × 18.4 cm) with food and water ad libitum
  • Electric flat‐ribbon cables (e.g., 510640, Distrelec, https://www.distrelec.com/)
  • Connector 1 and 2 (OHS RoHS ENA AG; http://www.ena.ch/)
  • Commutators with counter balance mechanism (3 M, http://solutions.3msuisse.ch)

Basic Protocol 3: Data Acquisition

  Materials
  • Computer
  • Acquisition hardware which includes an isolation unit, amplifier, AD converter, and filter components (e.g., EMBLA A10, Medcare Flaga; http://www.embla.com)
  • Acquisition software (e.g., Somnologica 3, Medcare Flaga; http://www.embla.com); this acquisition and analysis software automatically performs most of the steps listed in the following protocol

Basic Protocol 4: Determining Behavioral State Based on the EEG and EMG Signals (i.e., “Scoring”)

  Materials
  • Computer for EEG analysis
  • EEG analysis software (e.g., Somnologica 3, Medcare Flaga; http://www.medcare.com)

Basic Protocol 5: Spectral Analysis

  Materials
  • Software to manage the data (e.g., algorithms written in R or Matlab or other programming languages)
  • A statistical analysis tool (e.g., SAS Institute software, version 9.1)
  • Software for graphics (e.g., SigmaPlot 10.0, Systat Software)
NOTE: Most of the EEG recording and analysis software applications such as Somnologica offer the possibility to generate EEG spectra for discrete windows using FFT. Be sure that the chosen 4‐sec windows for scoring state match the windowing of the FFT spectra.
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Figures

Videos

Literature Cited

Literature Cited
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