Comparison between the effects of ethanol and diazepam on spatial working memory in the rat

The present study compared the effects of ethanol and diazepam on a task that allows for the assessment of both spatial working memory and the acquisition of spatial information within each day. During the first trial of each day, subjects were shown the spatial location of a food reward on a six-arm radial-arm maze. During nine subsequent free-choice trials, subjects were reinforced for returning to that same spatial location. The location of the food reward varied across days. Thus, choosing correctly on any given trial required subjects to remember where food had been received during the previous trials of that day. The effects of ethanol and diazepam on working memory were assessed by analyzing the overall number of errors committed during the nine free-choice trials of each day. The effects of ethanol and diazepam on within-day acquisition were assessed by comparing the number of errors committed during the first three trials of each day to the number of errors committed during the last three trials of each day. Ethanol and diazepam both produced dose-dependent increases in working memory errors, and both did so without impairing within-day acquisition. The results of the present study provide further evidence of the similarities between the effects of ethanol and benzodiazepine receptor agonists on learning and memory, and are consistent with the hypothesis that ethanol's potentiation of GABA at GABAA receptors contributes to the learning and memory impairments produced by ethanol.