Performance by adult rats in sensory-mediated radial arm maze tasks is not impaired and may be transiently enhanced by chronic exposure to ethanol

The effect of chronic exposure to ethanol on learning and memory was assessed in rats. Adult rats were fed a liquid diet containing ethanol (Et) ad libitum, pair-fed an isocaloric/isonutritious control diet (Ct), or fed lab chow and water (Ch) ad libitum These diets were provided for as long as 28 weeks prior to testing and during the period of behavioral testing. Rats were required to learn a radial arm maze task that depended upon extramaze cues (visual and spatial) or intramaze cues (various odors). Each rat was tested twice daily for 26 days. The number of reference and working memory errors and the time required to successfully navigate the maze (latency) were recorded. Et-fed rats consistently performed the same or better than the Ct-fed or Ch-fed rats. The enhanced behavior was task-specific and transient. The enhancement was observed in rats after 14 or 20 weeks of ethanol exposure, but not in rats exposed to ethanol for 28 weeks, Et-fed rats performed significantly better on the reference memory task in the odor condition of the maze task, whereas their performance in the spatial task was similar to that for the two control groups, Thus, after an extended period of exposure (e.g., 28 weeks), ethanol had no effect on learning and memory. On the other hand, under certain conditions (14 or 20 weeks), ethanol transiently enhanced memory.