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Mechanisms of fear extinction

Abstract

Excessive fear and anxiety are hallmarks of a variety of disabling anxiety disorders that affect millions of people throughout the world. Hence, a greater understanding of the brain mechanisms involved in the inhibition of fear and anxiety is attracting increasing interest in the research community. In the laboratory, fear inhibition most often is studied through a procedure in which a previously fear conditioned organism is exposed to a fear-eliciting cue in the absence of any aversive event. This procedure results in a decline in conditioned fear responses that is attributed to a process called fear extinction. Extensive empirical work by behavioral psychologists has revealed basic behavioral characteristics of extinction, and theoretical accounts have emphasized extinction as a form of inhibitory learning as opposed to an erasure of acquired fear. Guided by this work, neuroscientists have begun to dissect the neural mechanisms involved, including the regions in which extinction-related plasticity occurs and the cellular and molecular processes that are engaged. The present paper will cover behavioral, theoretical and neurobiological work, and will conclude with a discussion of clinical implications.

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Acknowledgements

We thank Dr Eric Kandel for his many helpful comments and Ms Toni Edwards for her assistance. This research was supported by National Institute of Mental Health grants MH47840, MH57250 and MH59906; the Science and Technology Center (The Center for Behavioral Neuroscience of the National Science Foundation under Agreement No. IBN-9876754); and the Yerkes Base Grant.

Dr Davis has submitted a patent for the use of D-cycloserine for the specific enhancement of learning during psychotherapy and is entitled to royalties from Therapade in the event this invention is commercialized. The terms of these arrangements have been reviewed and approved by Emory University in accordance with its conflict of interest policies.

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Myers, K., Davis, M. Mechanisms of fear extinction. Mol Psychiatry 12, 120–150 (2007). https://doi.org/10.1038/sj.mp.4001939

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Keywords

  • learning
  • memory
  • pavlovian conditioning
  • exposure therapy

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