The erasure of specific long term memories has been regulated to being a common plot point in Hollywood blockbusters, like Eternal Sunshine of the Spotless Mind. However according to a recent press release by the Weizmann Institute of Science, scientists have managed to erase specific long term memories in mice, suggesting that the view of how the memory works may be flawed, and someday select memory modification could be possible.
The common analogy used for memory is that of a clay tablet, with memories being recorded onto it. However, researchers at Weizmann Institute’s Neurobiology Department believe that making long term memories is a much more complicated process. They believe that a small molecular ‘machine’ must run constantly to allow people to access their memories. The researchers found by stopping the molecules in mice, it erased long term memories.
The study began with the researchers training mice to avoid specific tastes. After the mice were consistently avoiding the forbidden food, the researchers injected a drug that blocks a protein in the part of the brain associated with taste memory. Earlier research had suggested that this protein was part of the ‘memory machine’. After a single treatment of the drug, the mice did not remember to avoid the food.
Scientists think that the protein that was blocked, PKMzeta, is an enzyme that functions as a bridge between nerve cells. It must remain active to keep the bridge. This is often accomplished by learning, which stimulates the PKMzeta. By stopping the PKMzeta from working, it also erased the long term memories.
The use of the drug to erase the food memories in the mice worked a month after the memories had been formed. This length of time is comparable to years in a human life span. The mice in the study showed no indication that they regained any of the lost memories; even several weeks after the protein had been injected. However, the drug most likely erased all of the memories stored in the taste center of the brain, not just specifically learned memories.
By stopping the molecules from working, the learned memories created by the mice were lost forever. The researchers at Weizmann Institute’s Neurobiology Department believe this proves that long term memories require an ongoing process, which the brain both runs and fuels.
This breakthrough in understanding how memories work could lead to medications and other treatments that improve memory or stabilize deteriorating memory.
Weizmann Institute of Science, “Memory Machine.” Eurekalert. URL:(http://www.eurekalert.org/pub_releases/2007-08/wios-mm081507.php)