Differential effects of several retrieval cues over time: Evidence for time-dependent reorganization of memory

Abstract

The retention performance following partial training (15 trials) of a brightness-discrimination avoidance task has been shown to fluctuate over time, with a drop in performance 1 h after training (Kamin effect), a long-term spontaneous improvement (LTSl) after 3 days, and long-term spontaneous forgetting after 21 days. The purpose of this paper was to determine ifthese time-dependent modulations of retention performance reflect time-dependent modifications in the organization of the attributes that constitute the memory trace. We studied the relative effectiveness of several pretest cuings on retention performance when they were delivered just before a retention test occurring 1 h, 3 days, or 21 days following initial training. Some cuing treatments were related to a particular training event (conditioned or unconditioned stimulus, experimental context). Compound cuings, composed of two or more training events, were also studied to test a possible additive effect between retrieval cues. To demonstrate time-dependent modifications in the memory trace, a differential effectiveness over time was expected for at least some retrieval cues. The results show that cuing may compensate for performance deficits (1 h or 21 days), but does not further enhance performance when spontaneously improved (3 days). No detectable additive effects of retrieval cues were obtained. However, these results provide information that suggests a time-dependent effectiveness for some cuing treatments. In the last experiment, we investigated this possibility by studying the effects of each of these treatments when delivered after either a J-h or a 21-day retention interval. The results confirm a time-dependent decrease in effectiveness of a pretest exposure to the CS and an increase in effectiveness over time of a pretest exposure to the experimental context or to a well-ordered sequence of events. Such differential retrievability of a partially learned episode according to both the nature of the cues and the length of the retention interval suggests a time-dependent reorganization of memory attributes.

Memory reactivation effects independent of reconsolidation

“…These experiments demonstrated that electrical stimulation of the area shortly before testing again demonstrated a significant reduction in errors in the maze (Sara and Devauges 1988) Several experiments have indicated that a short exposure to specific features of the training episode can compensate for the disruption due to long-term forgetting (Spear and Parsons 1976;Spear et al 1980). The experimental context seems to be a particularly effective reminder to alleviate performance disruption due to longterm forgetting in rats trained in an appetitive or in an aversive discrimination task (Deweer et al 1980;Gisquet-Verrier et al 1989). In these studies, the improvement resulting from the pretest exposure to the retrieval cues is evidenced shortly thereafter (from 0 to 10 min) and is not maintained over time (Gisquet-Verrier 2009).…”

Retrieval and Reconsolidation: Toward a Neurobiology of Remembering

“…Pretest exposure to the experimental context in which discriminative avoidance training had taken place also alleviates forgetting. These experiments compared the effectiveness of the contextual cue and the conditioned stimulus (CS) as reminders and found that pretest priming with the CS facilitated performance at short training to test intervals, whereas the contextual cue was only effective after a long retention interval, when control animals showed considerable forgetting (Gisquet-Verrier and Alexinsky 1986;Gisquet-Verrier et al 1989). (Left) Number of errors at each daily trial during acquisition; (right) retention performance of rats tested 3 weeks after the last training trial.…”

Reactivation of an old memory during sleep and wakefulness

“…The cuing procedure has been widely used in a variety of paradigms, and it still appears to be effective at very long delays after learning (Dekeyne, Deweer, & Sara, 1987;Gatti, Pais, & Weeks, 1975;Gisquet-Verrier, Dekeyne, & Alexinsky, 1989). Thus, it is possible for cuing to reactivate even a longestablished memory.…”