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. Author manuscript; available in PMC: 2009 Apr 13.
Published in final edited form as: Neuropsychopharmacology. 2007 Sep 19;33(1):56–72. doi: 10.1038/sj.npp.1301555

Fig. 1.

Fig. 1

Extinction learning occurs in three phases. Acquisition is characterized by a decrease in conditioned responses to the presentation of a CS without the US. Consolidation is a time-dependent process during which a long-term extinction representation is formed. Retrieval of extinction occurs at a later time, when the CS is re-presented. Good extinction retrieval is characterized by low levels of conditioned responses (green bar), whereas poor extinction retrieval is characterized by high levels of conditioned responses (red bar). Poor retrieval of extinction is normally observed following renewal, reinstatement, spontaneous recovery, or in pathological conditions characterized by extinction failure.