In either case, they drink to create a shift toward a positive state, he said. His mice behave in much the same way. In fact, C57Black6 will drink alcohol in preference to water and if prevented access for a period of time will increase the amount they drink much like what is observed during alcohol relapse for alcoholics, he said. In one of Middaugh's research protocols, mice are conditioned to press a lever for access to alcohol. The lever response produces delivery of a measured amount of ethanol to a fountain from which the mouse can drink.
Computer programs control the number of responses required to obtain each drink.
By determining the maximum number of responses the animal will make for each drink, we have a measure of its reward value. Our experiments have shown that preventing access to alcohol will increase its reward value for mice just as frequently noted for humans, Middaugh said. Future studies will investigate other potential therapeutic agents, he said. Under another research protocol, Pavlovian classical conditioning is used to pair environmental stimuli with alcohol. The environmental stimuli will then elicit approach responses suggesting their reward value.