Protection from extinction provided by a conditioned inhibitor

Abstract

Three conditioned suppression experiments with rats as subjects investigated the influence of higher order associations in determining the response potential of a target stimulus. In these experiments, a Pavlovian conditioned inhibitor was compounded with the target cue during extinction treatment. In Experiment 1, strong suppression was observed to the target cue that was given extinction treatment in the presence of a conditioned inhibitor, relative to a target that was extinguished with an associatively neutral cue or was extinguished alone, suggestive of enhanced protection from extinction provided by a conditioned inhibitor. This effect was replicated in a sensory preconditioning preparation in Experiment 2; in Experiment 3, in a sensory preconditioning preparation, this protection effect was retroactively attenuated when the conditioned excitor used to train the conditioned inhibitor was extinguished following extinction of the target. This provides evidence that, at least in a sensory preconditioning preparation, stimuli that are only indirectly associated with the target cue can contribute to the response potential of that target.

Figure 1

The extended comparator hypothesis (ECH; Denniston, Savastano, & Miller, 2001). Arrows represent the associations between stimuli. The strengths of the directly and indirectly associated outcome representations are compared in order to determine the strength of responding to the target cue. Ovals depict stimulus representations; rectangles depict physical events; diamonds represent the comparator process. CS, conditioned stimulus; US, unconditioned stimulus.

Figure 2

The extended comparator hypothesis account of the protection from extinction provided by a conditioned inhibitor. X is the target cue, B is the Pavlovian conditioned inhibitor, and A is the excitor used to train the conditioned inhibitor. Heavy lines indicate strong associations. US, unconditioned stimulus.

Figure 3

Experiment 1: Mean times (log sec) to complete 5 cumulative seconds of licking in the presence of the target cue. All the subjects were tested on X alone.

Figure 4

Experiment 2: Mean times (log sec) to complete 5 cumulative seconds of licking in the presence of the target cue. All the subjects were tested on X alone.