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MIT Scientists Use Lasers to Replace Bad Memories with Good Ones in Mice

Massachusetts Institute of Technology scientists have used lasers to replace bad memories with good ones in animal test models.

Nature World News, Aug 28, 2014

Several movies - from the Men in Black franchise to Eternal Sunshine of a Spotless Mind - have shown that someday technology will help us erase bad memories and overwrite them with good ones. Recently, scientists from Netherlands had shown that shock therapy can help alter memories.

Now, MIT scientists say that they have found a way to reverse the emotional association of specific memories. The team demonstrated that it is possible to manipulate brain cells using optogenetics - a method that uses light to regulate brain cell activity.

The researchers said that most memories have emotional connections in the brain. Some events such as a holiday might trigger pleasant emotions such as joy, while others such as death of a loved one leads to feelings of sadness.

Susumu Tonegawa, the Picower Professor of Biology and Neuroscience and an author of the study, believes that someday humans might be able to tinker with these emotional associations.

"In the future, one may be able to develop methods that help people to remember positive memories more strongly than negative ones," said Tonegawa in a news release.

Parts of memories are stored in a brain region called hippocampus, while the associated emotion is kept in the amygdale.

Previous research has shown emotional associations are malleable. In the current study, MIT scientists found the neural circuitry that makes these associations possible.

In the study, male mice were given mild electric shock when the animals ventured into a specific part of the cage. The shocks made the males fear a certain part of the enclosure. To induce good memories, male mice were left with female mice, ABC News reports.

The mice were genetically engineered to have specific brain neurons that can be activated by light. The researchers used lasers to reactivate desired brain cells in the brain.

In the second part of the experiment, the team reversed the emotional association. The researchers activated neurons that were linked to pleasure during a second shock treatment. This changed the brain wiring of the animals and they started associating painful activity with pleasure.

"We could switch the mouse's memory from positive emotions to negative, and negative to positive," Tonegawa said, according to ABC News .

The study is published in the journal Nature.  

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