Figure 4. Context-dependent extinction of fear in rodents.

Extinction is a form of learning in which a conditional stimulus (CS) is presented alone after conditioning. Such CS-alone presentations decrease the magnitude and frequency of the learned response, and this loss of responding to the CS is context-specific. As a result, a diminished conditioned response to the CS is expressed only in the context in which the extinction occurred, but the response will return (or ‘renew’) in any other context. The figure shows the typical procedure for studying the context-dependence of extinction in rodents. In this procedure, rats are first conditioned to an auditory CS in one context (blue). Subsequently, extinction training to that CS occurs in another context (either the purple or green context), and rats are then tested in a context that is either the same or different as the one in which extinction took place. In this example, the purple context is the same context as extinction for half of the animals but a different context for the other half of the animals.