Acute ethanol administration impairs spatial performance while facilitating nonspatial performance in rats

Acute ethanol administration produces learning and memory impairments simil ar to those found following lesions to the hippocampal system in rats. For example, both ethanol and hippocampal lesions impair performance on spatial learning and memory tasks while sparing performance on many nonspatial lea rning and memory tasks. Lesions to the hippocampal system can also alter th e nature of the information that the animal uses to guide its behavior, fro m using spatial information to using individual cues. In the present experi ment, rats were trained, while sober, to navigate on an eight-arm radial ar m maze to a specific arm for food reward. During training, the rewarded arm was always in the same specific location and contained well-defined cues. After the rat learned the task, a memory test was conducted under different doses of ethanol (0.0 g/kg [saline control], 1.0, 1.5, or 2.0 g/kg, intrap eritoneal). On the test day the maze was rotated so that the cued arm was 9 0 degrees to the right of its original position. During testing, intact rat s showed a significant bias to approach the place where they had been previ ously rewarded, even though the cue was no longer located there. Acute etha nol administration dose dependently reduced approaches to the rewarded plac e. However, ethanol administration did not result in increases in random ch oices; rather, it resulted in a dose-dependent increase in approaches to th e cued arm, now in a new location. These results extend previous research s howing that acute ethanol administration and lesions to the hippocampal sys tem produce similar effects on learning and memory in rats. (C) 1999 Academ ic Press.