Effects of chronic alcohol consumption on spatial reference and working memory tasks.

The aim of this work was to determine the spatial memory impairments induced by chronic alcohol consumption in rats. The alcoholization process began on the 21st postnatal day and alcohol concentrations were gradually increased to reach a concentration of 20% that was maintained for 4 mon. Behavioral tests were performed in the Morris Water Maze (MWM). The first study assessed the effects of chronic alcohol intake on two reference memory tasks (a place learning with multiple trials and a new place learning carried out in the same experimental context). Alcohol-treated animals presented no overall impairment in their ability to process spatial information. Deficits were restricted to reduced behavioral flexibility in spatial strategies. The second study assessed working memory in two tasks in which information about platform location was only valid for one trial. In the first working memory task, the animals had to perform one trial per day and in the second task they were submitted to four trials per day. At the end of the second experiment, all animals were trained in a visual-cued task. In the second experiment, the most important deficits in alcohol-treated animals occur in spatial working memory tasks, and this impairment was independent of the intertrial interval used. In the second spatial working memory task, performance of the alcohol-treated animals in the earlier trials affected their performance in subsequent trials, suggesting that a process of proactive interference had taken place. The visual-cued task demonstrated that these behavioral impairments were produced without visuoperceptive impairments.