Interaction between conflicting memories in the rat: Contextual pretest cuing reverses control of behavior by testing context

Abstract

Two experiments were run in order to investigate the influence of external contextual cues on the interaction between two conflicting memories. Rats were trained, in the same apparatus, on a passive-avoidance task and, 10 min later, on an active-avoidance task, then submitted to a 24-h delayed test (without reinforcement). When contextual cues remained unchanged throughout these three phases, the animals exhibited proactive interference, as shown by longer response latencies than those of control animals that had learned only the active-avoidance task (Experiment 1). When training contexts were made slightly different from one task to the other (by the presence of a continuous tone during either the first or the second task), the animals behaved at subsequent testing in accordance with the response contingencies present in the context exactly similar to the test context; this control of behavior by testing context was demonstrated both when the tone was absent (Experiments 1 and 2) and present (Experiment 2) at testing. A cuing procedure-a 90-sec exposure to the tone in the experimental room 5 min prior to testingled the animals to behave in accordance with the response previously acquired in the presence of the tone (Experiments 1 and 2), exactly in the same way as animals tested in the presence of the tone (Experiment 2). The same cuing treatment was ineffective when administered 1 h before testing (Experiment 2). These results are interpreted in terms of a dual function of contextual cues at the time of retrieval: the general contextual information present during testing or during pretest cuing is assumed to induce concurrent reactivation of both memories. Consequently, the experimentally manipulated contextual cue (the tone) would have a discriminative function, leading the animals to choose between the two equally available representations.The role of contextual cues in retrieval of memories in humans and in other animals has often been demonstrated. Numerous studies with human subjects have shown that retention performance can be disrupted by changing, at the time of testing, some of the external (Godden & Baddeley, 1975;Smith, 1986;Smith, Glenberg, & Bjork, 1978) or internal (see Eich, 1980;Overton, 1985, for reviews) contextual cues that were present at the time of training. These data are in accordance with a multidimensional view of memory-that is, the contention that a memory is composed of a number of attributes corresponding to the target stimuli as well as to surrounding (contextual) stimuli noticed at the time of the training episode (Bower, 1967;Underwood, 1969). These data also support Tulving and Thomson's (1973) "encoding specificity" hypothesis, which assumes that the success of a memory search is a function of the degree of similarity between the retrieval environment and the context in which the target information was originally encoded. Several studies have illustrated the same ideas in the domain of animal memory. These studies have developed two rather different approaches, using either ...

A retrieval cue for extinction attenuates response recovery (renewal) caused by a return to the conditioning context.

“…Context and retention interval effects observed in these different paradigms may also be due to the failure to retrieve a memory corresponding to a particular phase. Consistent with this view, retrieval cues have also been shown to modify performance after context switches in latent inhibition (Gordon & Weaver, 1989) and in discrimination reversal learning (e.g., Dekeyne & Deweer, 1990;Gordon, Mowrer, McGinnis, & McDermott, 1985). A memory retrieval view has considerable potential for integrating the effects of physical context and time in many Pavlovian interference paradigms.…”

Facilitative effect of a pretest exposure to the CS: Analysis and implications for the memory trace

“…More recently, Dekeyne and Deweer (1990), using an interference paradigm, showed that exposure to a contextual tone enhanced retention of the task with which the tone was related when it was delivered 5 min before testing, but not when it was delivered I h before. Furthermore, using the same discriminative avoidance task as that used in the present study, we gave animals either pretest exposure to the experimental context or a series of five footshocks, after a 21-day retention interval.…”

Proactive interference between cues trained with a common outcome in first-order Pavlovian conditioning.

“…Alternatively stated, the difficulty of reducing previously acquired biological significance does not arise in proactive interference. Over the past several years, the concept of proactive interference has been used to explain the results of several instrumental and Pavlovian preparations (e.g., Cohen & Armstrong, 1996; Cohen, Ried, & Chew, 1994; Dekeyne & Deweer, 1990; Friedline, 1995; Holland, 1999); however, although invoking the mechanism, these studies did not systematically examine interference between cues trained apart.…”