LOW-DOSES OF ETHANOL IMPAIR SPATIAL WORKING-MEMORY AND REDUCE HIPPOCAMPAL THETA-ACTIVITY

Low doses of ethanol can alter neural activity in the septohippocampal pathway, a pathway critical for spatial working memory. The present s tudy was designed to determine whether acute ethanol induces impairmen ts in working memory and disrupts septohippocampal function as measure d by the hippocampal theta rhythm. Rats were preoperatively trained on delayed alternation. A within-subject design was used to evaluate the effects of ethanol (0.25, 0.5, 0.75 and 1.0 g/kg, intraperitoneally) on performance 10 min and 90 min after injection as compared with prei njection baseline. Ethanol produced dose-, delay-, and time-dependent impairments in working memory as indicated by a change in choice accur acy in the delayed alternation task. Ethanol did not affect performanc e time, the ability to complete the task, or response bias. Thus, the impairment does not appear to result from a decrement in general perfo rmance, but rather from an impairment in spatial working memory. Hippo campal theta activity was suppressed by ethanol at the same doses, 0.7 5 g/kg and 1.0 g/kg, that impaired working memory. The interaction of ethanol with functions of the septohippocampal pathway are discussed.