Biomedical subjects

J R Rush

Publications and source records attributed to J R Rush.

4 recordsLinked to original sources

PubMed1985

Spatial memory in rats: electroconvulsive shock selectively disrupts working memory but spares reference memory.

In two experiments rats were trained until they displayed highly accurate spatial memories when a 4-h delay was imposed between the to-be-remembered event (TBRE) and the retention test in a 12-arm radial maze. If the procedure tested only working memory (WM) electronvulsive shock (ECS) 2 h after the TBRE produced amnesia but ECS immediately after the TBRE was ineffective. If the testing procedure also involved a reference memory (RM) component, ECS degraded WM regardless of whether it was given 0 or 2 h after the TBRE. RM was not affected. With either training procedure administering ECS 2 h before the TBRE was ineffective. Thus, in the radial maze truly old spatial RM was immune to disruption by ECS while more recent WM was vulnerable. Possible explanations of the data are presented.

Animals↗

PubMed1983

Spatial working memory in rats: effects of monoaminergic antagonists.

To assess the possible involvement of the monoaminergic neurotransmitters norepinephrine, dopamine and serotonin in the maintenance of spatial working memory rats were treated with antagonists 0 or 2 hr after completing the first 4 choices in an 8 arm maze. Haloperidol (0.25-1 mg/kg), when administered 2 hr after Choice 4, produced a small but consistent impairment in performance on retention tests given 5 hr after the first 4 choices. This deficit closely resembled natural forgetting in terms of the type of errors committed. By contrast, haloperidol in the same doses given 0 hr after Choice 4 or 3 hr before the first 4 choices did not affect retention. Likewise treatment with propranolol (10-20 mg/kg), phentolamine (5-20 mg/kg) or methysergide (5-15 mg/kg) did not impair spatial memory, regardless of when these drugs were injected within the session. Evidently dopaminergic neuronal systems are important in the maintenance of normal spatial working memory.

Animals↗

PubMed1983

Retention deficit after d-amphetamine treatment: memory defect or performance change?

Retention deficits in discrete trial delayed alternation and delayed matching to sample tasks following administration of d-amphetamine have been interpreted to support the view that arousal facilitates the decay of information from shortterm memory (STM) (Kesner, 1973). But since amphetamine causes numerous changes in performance, alternative explanations of the deficit are also plausible. In an attempt to separate drug effects on memory from those on performance, the effects of d-amphetamine on spatial memory in the radial maze were studied in rats. The unusually long span of accurate working memory in this setting permits drug administration within the retention interval as well as prior to the to-be-remembered event (TBRE). In rats tested at a 5-hr retention interval d-amphetamine (2 mg/kg) disrupted retention when given 0.5 hr before or 4.5 hr after the TBRE, but the same treatment 0 or 2 hr after the TBRE or 3 hr before the TBRE was without effect. At a 5-hr retention interval 3 mg/kg d-amphetamine impaired performance if given 2 hr after the TBRE, but not when given 0 hr after the TBRE or 3 hr before the TBRE. However, when the retention interval was lengthened to 7 hr, administering 3 mg/kg d-amphetamine 2 hr after the TBRE did not disrupt performance. The effects of d-amphetamine on spatial memory are best explained in terms of the well established effects of the drug on motor activity and appetite. Similar changes in performance may account for the "memory" impairments observed after amphetamine treatment in other tasks.

Animals↗

PubMed1982

Scopolamine does not disrupt spatial working memory in rats.

The importance of cholinergic systems for spatial working memory was examined by injecting scopolamine at varying times during a 5 hr-long retention interval imposed between the rat's fourth and fifth choices in an 8 arm maze. Regardless of whether or not the testing procedure required the rats to adopt a spatial solution for the task, scopolamine (1.0-5.0 mg/kg) did not impair retention in a manner that was suggestive of an effect on working memory. Modest deficits observed in some conditions appeared to result from drug effects on performance. Previous findings of impaired acquisition of accurate spatial behavior by scopolamine-treated rats evidently reflect an influence of the drug on physiological systems other than those necessary to maintain working memory for spatial information.

Animals↗