Lernmechanismen und Entwicklung der Alkoholabhängigkeit: Effekte von Alkohol auf den Erwerb und die Löschung konditionierter Reaktionen

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In the original project supported by the DFG, the effects of alcohol on the acquisition of associations between cues in the environment and rewards {experiment 1), as well as on the extinction of learned associations between cues in the environment and rewards (experiment 2) are studied with moderate to heavy social drinkers. Mechanisms of Pavlovian and instrumental conditioning play an important role in the development and maintenance of alcohol dependence. But although a large body of literature suggests that the glutamatergic neurotransmitter system is critically involved in the acquisition as well as extinction of associations between cues and rewards and the inhibitory effects of acute alcohol on the glutamatergic system are well known, no studies are available to investigate how alcohol influences conditioning in humans. Thus, it is expected that these experiments will help to specify the nature of the learning mechanisms responsible for the acquisition and maintenance of addictive behaviour in humans. At present, experiment 1 is finished and the analyses of the data indicate interesting results. We found that alcohol has no significant influence on the acquisition of appetitive conditioned behaviour as measured by the expectancy of the reward outcome, but impairs the inhibition of the conditioned appetitive response when S- is presented. We currently examine the effects of alcohol on extinction; experiment 2 is in progress. As a consequence of our findings in experiment 1, we want to propose a third experiment to investigate whether this result is restricted to conditioned appetitive behaviour or if it is also present when aversive stimuli are presented. In the original application for the research fellowship this idea was already introduced. As the work progresses it has been clear that it will not be possible to carry out this experiment in the time allocated for the project. Therefore, the extension of the research fellowship would be necessary to allow the investigation of the impact of alcohol on aversive conditioning and response inhibition with the methodology already developed for experiment 1 and 2 and seems to be of special importance when taking into account our findings in experiment 1. Aversive conditioning plays an important role in alcohol dependent patients consuming alcohol due to negative emotional feelings like depression and anxiety and this project would thus provide new data and enhance current knowledge on mechanisms of aversive conditioning in humans.