Extinction training can make the extinction context a stimulusspecific inhibitor: a potential mechanism of experimental renewal

Abstract

Renewal is the recovery of extinguished responding to a conditioned stimulus when testing occurs outside the extinction context. Renewal has been explained as the extinction context becoming a negative occasion setter during extinction. However, other mechanisms may contribute. Two recent studies showed (a) after extinction of a discrete cue, the extinction context can serve as a conditioned inhibitor, and (b) in some circumstances operational extinction of a conditioned inhibitor can reduce inhibition with respect to a transfer excitor while retaining inhibition with respect to the excitor used in inhibitory training. Here we examine the potential contribution of these phenomena to renewal. In the present experiment, all rats received fear-conditioning with a target cue in one context and extinction of that cue in a second context. Then half of the subjects received massive extinction of the extinction context (i.e., 24 h) while the other half received only handling. Finally, some subjects in each condition were tested for responding to the target cue in the extinction context, others in a second familiar context, and yet others in a third transfer context in which another fear cue had been extinguished. The results showed ABC renewal independent of whether subjects had or had not received context extinction. However, transfer of the inhibitory potential of the extinction context was observed only in subjects that did not receive context extinction. These results suggest an extinction context can serve as a stimulus-specific conditioned inhibitor, thereby contributing to renewal by decreasing responding to the target cue in an ABB control condition.