Contextual control of inhibition with reinforcement: Adaptation and timing mechanisms.

Abstract

Four experiments with rats studied the effects of switching the context after Pavlovian conditioning. In three conditioned suppression experiments, a large number of conditioning trials created "inhibition with reinforcement" (IWR), in which fear of the conditional stimulus (CS) reached a maximum and then declined despite continued CS-unconditional stimulus pairings. When IWR occurred, a context switch augmented fear of the CS; IWR and augmentation were highly correlated. Neither IWR nor augmentation resulted from inhibition of delay (IOD): In conditioned suppression, IWR and augmentation occurred without IOD (Experiment 3), and in appetitive conditioning (Experiment 4), IOD occurred without IWR or augmentation. IWR may occur in conditioned suppression because the animal adapts to fear of the CS in a context-specific manner. The authors discuss several implications.

The dual role of the context in postpeak performance decrements resulting from extended training

“…Superficially, the observations of Experiment 1 are inconsistent with the results of Bouton et al (2008) and Pickens et al (2009), because we observed a reliable PPD effect outside of the training context, whereas the results of Bouton et al and Pickens et al suggested that recovery from the PPD is observed when the test is conducted outside of the physical or temporal context of training. As mentioned in the introduction, Urcelay and Miller's (2010) observations become relevant for the present discussion because a comparison of the parameters used in Experiment 1 with those used by Bouton et al and Pickens et al shows that they were indeed widely different.…”

“…In particular, we assessed whether this effect could be observed when testing was conducted outside the training context, a finding that would contrast with the results by Bouton et al (2008) showing recovery from the PPD when the test is conducted outside of the context of PPD training. Four groups of rats received 5, 10, 20, or 50 pairings of a clicker with a mild footshock.…”

“…Within this framework, the competitive role of the training context can be inferred during tests of the target stimulus in a neutral context; otherwise, the putative associative strength of the context would be expected to summate with responding to the target stimulus. A consequence of this analysis is that, according to the comparator hypothesis, the PPD will be observed better when the target is tested outside rather than inside the training context, where it was observed by Bouton et al (2008; see also Pickens et al, 2009).…”

“…In particular, we were interested in assessing the influence of contextual cues after extended training, which is known to result in a decrease from peak responding achieved with fewer trials (Pavlov, 1927). In a recent example of this postpeak performance deficit (PPD), using an aversively motivated task with rats as subjects, Bouton, Frohardt, Sunsay, Waddell, and Morris (2008) observed that with extended training, conditioned responding decreased in a context-dependent manner (i.e., the decrease was observed only in the training context), suggesting that the context played a modulatory role. Their interpretation of these findings was that subjects seem to develop "some kind of inhibition or adaptation process" that diminishes the effectiveness of footshock as an unconditioned stimulus (US) and that the habituation is context specific (Bouton et al, 2008, p. 234).…”

“…Critically, we hypothesized that these opposite effects were caused by the use of different spacings of training trials (Urcelay & Milller, 2010), so that test context was orthogonal to training with massed trials (as in Exp. 1) or with widely spaced trials (approximating those used by Bouton et al, 2008, andPickens et al, 2009). These two prior experiments agreed in suggesting that the PPD is context dependent, but they were constrained by the parameters used during training.…”