It is critical to survival the ability to distinguish between a dangerous and a safe context. A place with aversive connotations generates a fear memory associated to a context; however, when the same place becomes safe, after reexposure, an extinction memory is generated (LeDoux, 2000). Therefore, both the fear and the extinction memory are evoked by the same context, and after some time, the fear memory usually persists and overcomes the extinction memory (Sotres-Bayon et al., 2006; Ji and Maren, 2007). This phenomenon, designated as spontaneous recovery of fear, is an increasing problem for those patients who are treating the emotional outcomes of previous traumatic events as in the Post-traumatic stress disorder (PTSD)(Andero and Ressler,
