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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(More)
Post-traumatic amnesia (PTA) is a transient sequela of closed head injury (CHI). The term PTA has been in clinical use for over half a century, and generally refers to the subacute phase of recovery immediately after unconsciousness following CHI. The duration of PTA predicts functional outcome after CHI, but its pathophysiological mechanism is not known.(More)
Rats were fed every other day (EOD) from 3-21 months of age prior to training in an 8-arm radial maze with retention intervals of 0, 1 or 5 hr imposed between the fourth and fifth choices. Their performance was compared to that of another aged group fed ad lib throughout life prior to radial maze training and to 3 month old controls. Rats fed ad lib until(More)
Male rats were tested in an 8 arm radial maze from 6-26 months of age with 5 hr delay imposed between choices 4 and 5. At 26 months their spatial memory was more accurate than when they were first tested at 6 months and also more accurate than that exhibited by another 5 month old group tested concurrently. However, these old rats acquired a noval spatial(More)
The influence of the centrally active anticholinergic, scopolamine hydrobromide, on working and reference memory was studied in rats tested in a 12-arm radial maze. Both 0.25 and 0.5 mg/kg doses of the drug increased the number of working memory (WM) errors but had no effect on reference memory (RM) errors. A lower dose (0.125 mg/kg) was ineffective, as was(More)
d-Amphetamine injections produce a dose-dependent disruption of performance within a discrete delayed alternation and a spatial delayed matching-to-sample task. Since d-amphetamine in the doses used had no deleterious effects on discrimination performance (no delay condition), it is suggested that d-amphetamine disrupts neuronal activity representing(More)
To assess the effects of amphetamine on working and reference memory rats were trained on a 12-arm radial maze with six arms baited and six arms unbaited until stable performance was achieved. Administration of 2.0 mg/kg d-amphetamine sulfate increased both working and reference memory errors, but only if a 5-min delay was imposed after three successful(More)
A. Markowska, O. Buresová, and J. Bures (1983, Behavioral and Neural Biology, 38, 97-112) argued that the apparent persistence of accurate spatial working memory over delays of several hours arises from the formation of response strategies and the use of olfactory stimuli that develop with extended training at long delays. To test this explanation rats with(More)
Rats with electrodes implanted in dorsal hippocampus were trained to perform a delayed spatial matching-to-sample task on a radial arm maze. Subseizure level electrical stimulation of the dorsal hippocampus applied during the study phase disrupted retention of a specific arm when tested at a 20-min delay but had no effects at 1- and 12-min delays. There(More)
Previous research has suggested that acetylcholine might activate play fighting in juvenile rats through its actions on central muscarinic receptors. To test this hypothesis we evaluated the effects on play fighting by the muscarinic agonists pilocarpine and arecoline given alone or in combination with the muscarinic antagonists scopolamine or(More)