Figure 1.

Fear conditioning, extinction, extinction recall and renewal. Fear conditioning contingencies were established on day 1, followed by extinction of the CS+ (to form CS+E). On day 2, extinction recall was tested using re-presentation of the extinguished CS+ (in the absence of shock) interleaved with CS− in the safety context. The propensity for danger context to elicit the return of fear was tested via re-presentation of the extinguished CS+ (again in the absence of shock) interleaved with CS− in the danger context (context that matched initial conditioned fear acquisition).