William C. Gordon

Susceptibility of a reactivated memory to the effects of strychnine: a time-dependent phenomenon.

Abstract It was demonstrated in Experiment 1 that the administration of strychnine following memory reactivation results in facilitated retention. Furthermore, this facilitation was shown to decrease as the interval between reactivation and the drug treatment was increased. The retrograde facilitation gradient found in Experiment 1 was shown to have a much shorter duration than the gradient produced by injecting strychnine at various intervals after original learning (Experiment 2). The possibility that reactivation and new learning initiate similar types of memory processing was discussed.

Contextual influences on the interaction between conflicting memories in the rat

Contextual events redundant to the learning, in sequence, of passive and active avoidance were of one type for the former task and of another for the latter. During later testing, these contextual events were found to determine which of these acquired, conflicting dispositions would be manifested in behavior. Mutual interference in retention otherwise seen under similar circumstances seemed subordinate to the influence of the three types of contextual stimuli tested—drug (pentobarbital), compound (the experimental room in which conditioning took place), and a relatively unitary stimulus (a constantly sounding buzzer). The discussion considered the defining characteristics of a “contextual stimulus” and the mechanisms through which contextual events control the manifestation of learned behaviors and alleviation of interference in retention.

Mechanisms for the cueing phenomenon: The addition of the cueing context to the training memory ☆

Abstract A series of three experiments was run to test the hypothesis that when animals are exposed to a cue from prior training, the context in which cueing occurs becomes associated with the training memory. The first experiment demonstrates that when rats are trained to avoid in one context and then are tested in a different context performance is reduced. Experiments 2 and 3 demonstrate that this performance deficit can be alleviated by cueing the rats in the test context prior to testing. The data suggested that the improved performance does not seem to result from the association of the cueing context with a fear response. These results are discussed in relation to the context addition hypothesis.

Dual effects of response blocking following avoidance learning

Abstract It was shown that either enhanced or decreased avoidance responding by rats could be produced by the same response blocking procedure occurring after avoidance training. The particular result produced depended on (1) the duration of the blocking trial and (2) when during the retention interval the blocking trial occurred. Results were interpreted in terms of a memory reactivation explanation and implications for the therapeutic uses of extinction were discussed.

An extinction trial as a reminder treatment following electroconvulsive shock

Animals given electroconvulsive shock (ECS) following active avoidance training were found to exhibit poor retention of the active avoidance response. However, this deficit was alleviated if the animals received an extinction trial for active avoidance prior to retention testing. That the trial was an extinction trial was demonstrated by the fact that exposure to the trial decremented the performance of animals not given ECS after learning. The implications of these findings for explanations of retrograde amnesia are discussed.

Reactivation-induced interference in a short-term retention paradigm

Abstract In Experiment 1 it was demonstrated that interference with a rats retention of a target spatial cue decreases as the interval between prior conflicting cues and the target increases. Experiment 2 showed that interference can occur even when the interstimulus interval is long, if the memory of a conflicting cue is reactivated just prior to exposing an animal to the target cue. A third experiment suggested that these findings could not be easily interpreted in terms of a stimulus satiation effect. The implications of these findings for a trace decay model of short-term retention were discussed.

Age-related differences in electric shock detection and escape thresholds in Sprague-Dawley albino rats.

For both male and female Sprague-Dawley albino rats, shock detection thresholds decreased as a function of age over a range of 90 to 660 days of age. Shock escape thresholds also were found to vary inversely with age. The findings are discussed in light of previous shock threshold experiments and in terms of implications for studies of age-related learning changes.

The alleviation of short-term retention decrements with reactivation☆

Abstract Retention of spatial information by rats was shown to decrease significantly over a 90-sec retention interval. However, this decrement was alleviated significantly when a reactivation or cueing treatment was presented during the 90-sec interval. Further, the rate of forgetting following reactivation was shown to be similar to that which occurs following original information input. The implications of these findings for information loss models of forgetting were discussed.

The Malleability of Memory in Animals

Publisher Summary Empirical evidence for constructive processes in humans was first introduced by Bartlett in 1932. Since that time, numerous investigators have demonstrated that humans tend to distort their memories for events and that these distortions often depend on what additional information already is contained in a persons memory store when the target memory is formed. This chapter discusses the issue of memory malleability in animals. An animals memory of a training experience is not necessarily fixed at the time of learning. The view that the memories of animals are malleable has a number of implications for the study of memory processing in infrahumans. Traditionally, the study of memory retrieval has centered on the relationship between training and testing experiences.

The interaction of memories in the rat: Effects on short-term retention performance

Abstract In four experiments, rats were tested for short-term retention of a target spatial location either with or without prior exposures to alternate spatial locations in a T-maze. In all cases, exposure to alternate locations prior to exposure to the target location impaired retention of the target. This impairment increased as the number of exposures to the alternate location was increased, and the impairment decreased as the interval between alternate and target exposures was increased. In no case was the magnitude of the impairment found to increase as the retention interval was lengthened.