Researchers block formation of certain memories in mice

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Ever have one of those days that you just want to forget? The science may be closer than you think to achieving that.

Researchers have successfully blocked mice from remembering specific drug-related memories by targeting molecules in their brains.

For the study, researchers conditioned mice to be able to administer themselves the drug methamphetamine by pressing a lever in a room that looked, smelled and felt different from their typical environments. The idea was if researchers took the mice out of the environment and then brought them back, they would immediately begin to press the lever in order to get more meth due to the conditioning that took place.

"It's closer to what it's like for a substance abuser after rehab," study author Courtney Miller, assistant professor in the department of metabolism and aging and the neuroscience department at Scripps Institute in Fla., told CBSNews.com. "They'll have all these landmines around them that reminds them of the drug abuse."

The mice were then treated with a couple medications that targeted actin, a protein that creates a sort of scaffolding for dendritic spines. Dendritic spines are small bulb-like structures on the surface of cells that are able to get electrochemical signals from other neurons. Without actin, the scaffolding broke down, therefore weakening the the dendritic spines.

The mice were placed back into methamphetamine environment, but after the treatment, they no longer were interested in pressing the lever, suggesting the memories were deleted.

Before you try to sign up for the treatment that sounds like it came out of the 2004 Jim Carrey drama, "Eternal Sunshine of the Spotless Mind," the method only worked on methamphetamine-related remembrances. Mice who were trained to press the lever to get a food they liked -- which happened to be Fruit Loops -- continued to want to press the lever even after they had taken the anti-actin medications.

The study was published online in Biological Psychiatry on Sept. 5.

Miller said the team doesn't know why breaking down actin affects drug-related memories and not other ones. One of their theories is that because methamphetamine spurs on the production of a brain chemical associated with the reward and pleasure centers in the brain called dopamine, the compound may have some effect on actin's structure.

"It's not unreasonable to think if you have these very small (drug-related) memories that they may involve different mechanisms than your run-of-the mill memory," she explained.

Miller hopes that one day they can use the actin method to help people with drug addictions. Part of the problem is there are very few treatments for people with substance abuse disorders.

For people addicted to classical psychostimulants like cocaine and methamphetamine especially, Miller said there is nothing really effective besides behavioral treatment. She foresees that this anti-actin therapy may be able to be used in conjunction with current methods.

"The problem for people who are addicted to a drug is they may stop using the drug, but their whole world is fraught with landmines of their former use," she said. "They would have a fighting chance of resisting relapse (with this therapy)."

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