In the new film ‘Eternal Sunshine of the Spotless Mind’, starring Jim Carrey, two lovers who recently broke up impulsively decide to take a pill that will erase their memories of each other. An interesting premise, though it would be tough to find a scientist who believes it will ever be possible to pinpoint and erase a specific string of memories. It does, however, seem possible to tinker a bit with long-term memories, particularly if they’re associated with strong emotion.

In a 2000 study for instance, New York University researchers trained lab rats to associate a tone with receiving an electric shock. Soon, the rats froze in fear when they simply heard the tone. Then the researchers gave some of the rats a drug that prevented the amygdala–a structure in the brain believed related to the processing of emotions–from making proteins necessary for memory storage. After waiting a few days, researchers played the tone again. Normal rats were still fearful. This time, though, those that had received the drug were not, apparently having forgotten the earlier association.

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