Summation of responding to CSs and an excitatory test context

Extinction training can make the extinction context a stimulus-specific inhibitor: A potential mechanism of experimental renewal

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.

Occasion setting, inhibition, and the contextual control of extinction in Pavlovian and instrumental (operant) learning

An occasion setter is a stimulus that modulates the ability of another stimulus to control behavior. A rich history of experimental investigation has identified several important properties that define occasion setters and the conditions that give rise to occasion setting. In this paper, we first consider the basic hallmarks of occasion setting in Pavlovian conditioning. We then review research that has examined the mechanisms underlying the crucial role of context in Pavlovian and instrumental extinction. In Pavlovian extinction, evidence suggests that the extinction context can function as a negative occasion setter whose role is to disambiguate the current meaning of the conditioned stimulus; the conditioning context can also function as a positive occasion setter. In operant extinction, in contrast, the extinction context may directly inhibit the response, and the conditioning context can directly excite it. We outline and discuss the key results supporting these distinctions.