ECS effects: Evidence supporting state-dependent learning in rats.

Abstract

Two experiments were conducted to test specific predictions of the statedependency hypothesis concerning the effects of electroconvulsive shock (ECS) on learning. Rats received a single fear-conditioning trial followed 24 hr. later by one of the following treatments: noncontingent footshock (NCFS), NCFS and ECS, or just ECS. Modification of fear conditioning by the various treatments was assessed by a drink-latency measure 24 and 96 hr. posttreatment. Experiment 1 demonstrated "amnesia" during the 24-hr, test and recovery of memory during the 96-hr, test by NCFS-ECS subjects. Experiment 2 showed that extinction training presented 24 hr. after NCFS-ECS treatment was not retained when testing occurred 96 hr. after this treatment. Results of both experiments clearly indicated that the combination of footshock and ECS can produce state-dependent learning. These data indicate that experiments that have used procedures involving footshock followed closely by ECS to demonstrate the disruption of memory formation as a consequence of ECS are also subject to a state-dependency interpretation.

Recovery of memory after reminder: Evidence for two forms of retrieval deficit induced by ECS

“…Reminder was ineffective in restoring memory in TFS/ECS subjects when administered 24 h after the training-trial footshock and ECS (Experiment I). This result is consistent with earlier reports (DeVietti et aI, 1973;DeVietti & Larson, 1971;DeVietti et aI, 1974;Mayse & DeVietti, 1971) indicating that footshock and ECS result in a dissociation of learning measurable 24 h later.…”

“…The very high degree of memory recovery displayed Larson, 1971;DeVietti et aI, 1974;Mayse & DeVietti, 1974). This finding of a high degree of memory recovery resulting from reminder treatment administered to subjects showing strong amnesia is consistent with the retrieval failure aspect of the dissociation/retrieval failure hypothesis.…”

“…Subjects were 58 male Long-Evans rats from the Central Washington State Psychology animal colony and aged 90-120 days at the beginning of the experiment. The apparatus has been described in detail elsewhere (DeVietti & Larson, 1971). Two identical chambers were used for fear conditioning and testing.…”

“…A recently advanced notion in this regard (DeVietti, Holliday, & Larson, 1973), which can be called the dissociation/retrieval failure hypothesis, holds that ECS, following a training-trial footshock, results in two forms of memory retrieval deficit. In this view, one retrieval deficit appears as a relatively weak amnesia from which memory recovers spontaneously and may be likened to the memory deficit observed in dissociation of learning or state-dependency research (DeVietti & Larson, 1971;Mayse & DeVietti, 1971). The other retrieval deficit appears as a relatively permanent amnesia, yielding memory only to reminder (Lewis et ai, 1968;Miller & Springer, 1972;Quartermain et ai, 1970).…”

ECS-induced amnesia: Retention function consistent with state dependency predictions

“…This state dependency view has received support largely from experiments which have administered footshock and ECS a day or more following training, with retention tested at several intervals posttreatment. This paradigm has consistently demonstrated a transient amnesia resulting from footshock ECS (DeVietti, Holliday, & Larson, 1973;DeVietti & Larson, 1971;DeVietti, Mayse, & Morris, in press). However, the evidence that the state dependency effect acts to influence the amnesia induced in the typical ECS paradigm, i.e., when ECS follows a training trial footshock, is less than compelling.…”