Fear Extinction in Rodents

Chun‐hui Chang1, Ewelina Knapska1, Caitlin A. Orsini1, Christine A. Rabinak1, Joshua M. Zimmerman1, Stephen Maren1

1 University of Michigan, Ann Arbor, Michigan
Publication Name:  Current Protocols in Neuroscience
Unit Number:  Unit 8.23
DOI:  10.1002/0471142301.ns0823s47
Online Posting Date:  April, 2009
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Abstract

Pavlovian conditioning paradigms have become important model systems for understanding the neuroscience of behavior. In particular, studies of the extinction of Pavlovian fear responses are yielding important information about the neural substrates of anxiety disorders, such as phobias and post‐traumatic stress disorder (PTSD) in humans. These studies are germane to understanding the neural mechanisms underlying behavioral interventions that suppress fear, including exposure therapy in anxiety disorders. This unit describes detailed behavioral protocols for examining the nature and properties of fear extinction in laboratory rodents. Curr. Protoc. Neurosci. 47:8.23.1‐8.23.17. © 2009 by John Wiley & Sons, Inc.

Keywords: extinction; fear; rat; anxiety; phobia

     
 
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Table of Contents

  • Introduction
  • Strategic Planning
  • Basic Protocol 1: Fear Extinction in Rats
  • Alternate Protocol 1: Context‐Specific Fear Extinction and Renewal
  • Alternate Protocol 2: Spontaneous Recovery of Fear Memory in Rats
  • Alternate Protocol 3: Reinstatement of Fear Memory After Extinction
  • Commentary
  • Literature Cited
  • Figures
  • Tables
     
 
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Materials

Basic Protocol 1: Fear Extinction in Rats

  Materials
  • 1% ammonium and 1% acetic acid solution for cleaning chambers (odors from these solutions are also used to establish unique olfactory contexts)
  • Rats (e.g., adult, male Long‐Evans)
  • Med‐Test software (MED Associates)
  • Shock calibration tool (MED Associates or equivalent) or an oscilloscope with alligator clips
  • A computer that will run MED‐PC software and interface with the chambers for stimulus delivery and data acquisition
  • Decibel meter
  • Load‐cell platforms (see )
  • Observation/conditioning chambers (30 × 24 × 21–cm; MED Associates; see )
  • Video camera mounted on the ceiling of the sound‐attenuating cabinet facing down into the observation chamber (see )
  • White and black plastic boxes
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Figures

  •   FigureFigure 8.23.1 Photographs of typical equipment used for fear conditioning, extinction, and testing. (A) A set of eight experimental chambers (MED Associates) are situated in sound‐attenuating cabinets and located in an isolated room. (B) Components of a typical conditioning chamber and cabinet.
  •   FigureFigure 8.23.2 Representative photographs of each experimental context. The contexts differ not only visually, but also in terms of the olfactory, auditory, tactile, and transport cues (see text for examples of contextual properties that differ for each of the contexts).
  •   FigureFigure 8.23.3 Idealized graphs showing anticipated results of the . Average percentage of freezing during (A) training (conditioning), (B) extinction, and (C) retention testing. Abbreviations: EXT, extinction group; NO‐EXT, no‐extinction control group; pre, baseline freezing before auditory CS.
  •   FigureFigure 8.23.4 Idealized graphs showing anticipated results of . Average percentage of freezing during (A) extinction, (B) context exposure, and (C) retention testing (renewal). Legends: DIFF, ABA group; SAME, AAA group. A non‐extinguished control group (NO‐EXT) is shown for comparison during the retention test.
  •   FigureFigure 8.23.5 Idealized graph showing anticipated results of . Average percentage of freezing during the retention test performed after 1, 14, or 21 days. A non‐extinguished control group (NO‐EXT) is shown for comparison during the retention test.
  •   FigureFigure 8.23.6 Idealized graph showing anticipated results of . Percentage of freezing during the tone retention test in rats tested in the same (SAME) or different (DIFF) context as the one in which reinstatement shock was delivered. An extinguished control group that did not receive reinstatement shocks (NO‐SHOCK) is shown for comparison.

Videos

Literature Cited

Literature Cited
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   Bouton, M.E., Westbrook, R.F., Corcoran, K.A., and Maren, S. 2006. Contextual and temporal modulation of extinction: behavioral and biological mechanisms. Biol. Psychiat. 60:352‐360.
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   Corcoran, K.A. and Maren, S. 2004. Factors regulating the effects of hippocampal inactivation on renewal of conditional fear after extinction. Learn. Mem. 11:598‐603.
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