3.3
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Original Research ARTICLE

Front. Behav. Neurosci., 04 May 2012 | http://dx.doi.org/10.3389/fnbeh.2012.00018

Reinstatement of extinguished fear by an unextinguished conditional stimulus

  • 1 Department of Psychology, University of California at Los Angeles, Los Angeles, CA, USA
  • 2 Department of Psychiatry and Biobehavioral Sciences, University of California at Los Angeles, Los Angeles, CA, USA

Anxiety disorders are often treated using extinction-based exposure therapy, but relapse is common and can occur as a result of reinstatement, whereby an aversive “trigger” can reinstate extinguished fear. Animal models of reinstatement commonly utilize a Pavlovian fear conditioning procedure, in which subjects are first trained to fear a conditional stimulus (CS) by pairing it with an aversive unconditional stimulus (US), and then extinguished by repeated presentations of the CS alone. Reinstatement is typically induced by exposing subjects to an aversive US after extinction, but here we show that exposure to a non-extinguished CS can reinstate conditional fear responding to an extinguished CS, a phenomenon we refer to as “conditional reinstatement” (CRI). Rats were trained to fear two CSs (light and tone) and subsequently underwent extinction training to only one CS (counterbalanced). Presenting the unextinguished CS (but not a novel cue) immediately after extinction reinstated conditional fear responding to the extinguished CS in a test session given 24 h later. These findings indicate that reinstatement of extinguished fear can be triggered by exposure to conditional as well as unconditional aversive stimuli, and this may help to explain why relapse is common following clinical extinction therapy in humans. Further study of CRI using animal models may prove useful for developing refined extinction therapies that are more resistant to reinstatement.

Keywords: reinstatement, fear extinction, fear conditioning

Citation: Halladay LR, Zelikowsky M, Blair HT and Fanselow MS (2012) Reinstatement of extinguished fear by an unextinguished conditional stimulus. Front. Behav. Neurosci. 6:18. doi: 10.3389/fnbeh.2012.00018

Received: 13 February 2012; Paper pending published: 04 April 2012;
Accepted: 13 April 2012; Published online: 04 May 2012.

Edited by:

Martine Ammassari-Teule, Consiglio Nazionale delle Ricerche, Italy

Reviewed by:

Pascale Gisquet-Verrier, Université Paris-Sud, France
Leonardo Restivo, Hospital for Sick Children, Canada

Copyright: © 2012 Halladay, Zelikowsky, Blair and Fanselow. This is an open-access article distributed under the terms of the Creative Commons Attribution Non Commercial License, which permits non-commercial use, distribution, and reproduction in other forums, provided the original authors and source are credited.

*Correspondence: Lindsay R. Halladay, Department of Psychology, University of California at Los Angeles, 1285 Franz Hall, Los Angeles, CA 90095-1563, USA. e-mail: lrhalladay@ucla.edu