Researchers Explore Enzyme That Can Both Increase, Decrease Memory

BETHESDA, MD—A new study into the biochemical mechanisms that control memory has added to the hope that someday scientists will be able to strengthen a person’s ability to remember through chemical intervention.

memory-enzyme.jpgNIH-funded researchers at the SUNY Downstate Medical Center in New York City have been experimenting with an enzyme, which can enhance a memory in a rat’s brain weeks after the event generating that memory occurred. Conversely, when this enzyme—PKM-zeta—is decreased, memory can be erased.

This is not the first time researchers have identified enzymes that impact memory. In January, researchers from another NIH-funded study reported that they had identified a naturally-occurring growth factor that significantly boosts memory retention. However, the growth factor’s effect was limited to specific time-limited windows in the memory retention process—right after a memory is formed and right after a memory is retrieved. The factor’s effect during retrieval may become less potent as a memory becomes older.

PKM-zeta seems to have no such limitations, however. In previous studies, researchers trained rats to associate the sweet taste of saccharin with sickness. Thereafter, the rats stayed away from saccharin. But after receiving a chemical that blocked PKM-zeta from the area where long-term memories are stored, the rats began eating saccharin again. This proved that a lack of PKM-zeta could erase memory.

In the newest study, the researchers used a virus to infect the neocortex—the brain’s outer mantle where long-term memories are stored—with PKM-zeta. Rats that received the boost avoided the sickness-inducing foods much better than the control rats.

“This pivotal mechanism could become a target for treatments to help manage debilitating emotional memories in anxiety disorders and for enhancing faltering memories in disorders of aging,” said NIMH Director Thomas R. Insel, MD, in a statement.

The challenge now is to discover how to target the enzyme to specific memories. Currently, the effects of PKM-zeta apply to multiple memories stored in the targeted brain area. Also, it is unknown whether the enzyme is helping with the retrieval of specific memories, or the entire mechanism of memory retrieval as a whole.

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