Lacunar amnesia

Lacunar amnesia is the loss of memory about one specific event. It is a type of amnesia that leaves a lacuna (a gap) in the record of memory.

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Popular culture

This type of amnesia is used as a plot device in the movie Eternal Sunshine of the Spotless Mind, in which a company (appropriately named Lacuna) offers the service of having a specific person erased from someone's memories by removing all memories of them.

"Scientists believe memories are captured and stored by two separate parts of the brain, the hippocampus, the normal seat of memory, and the amygdala, one of the brain's emotional centers. People incapable of forming long-term memories thanks to hippocampus damage can still form subconscious memories of traumatic events if their amygdala is intact. Someone suffering from the Memento condition would likely have a feeling of general unease encountering a person who had harmed them in the past, though they wouldn't be able to put their finger on why. As the plot of Eternal Sunshine correctly suggests, the brain is designed to preserve emotionally strong memories. Even amnesiacs, under the right circumstances, can remember their past feelings."

"Some scientists now believe that memories effectively get rewritten every time they're activated. Studies on rats suggest that if you block a crucial chemical process during the execution of a learned behavior - pushing a lever to get food, for instance - the learned behavior disappears. The rat stops remembering. Theoretically, if you could block that chemical reaction in a human brain while triggering a specific memory, you could make a targeted erasure. Think of a dreadful fight with your girlfriend while blocking that chemical reaction, and zap! The memory's gone."

Source: Analysis: Concepts in memory-loss movies not so far-fetched, NPR Special; 3/23/2004; Alex Chadwick.