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Can You Rewrite Bad Memories as Good Ones? Scientists Believe This Brave New World Is Near

In this fascinating study, researchers learned to activate positive and negative memories.


Have you ever fought with a friend or a family member over the details of a past event? My family and I do this often. I have a memory, for example, that my sister got stuck in the mud at our hometown pond when she was six years old, and when our dad pulled her out, the mud swallowed a rain boot. My sister insisted that this actually happened on a family trip to Nova Scotia, Canada. We later found out that my sister was right — so why was my false memory so strong?

Memory is less of a video recording of the past, and more reconstructive,” Steve Ramirez, a Boston University neuroscientist, explained to Indeed, Northwestern University research notes that each time you recall a memory, it becomes a little less precise. Over time, some memories become entirely inaccurate. This is the reason police and investigators try to get witness accounts as soon as possible; the more time that passes, the less accurate a person’s memory will be.

False memories are an interesting trait of the human brain, but what if they were turned into a useful tool? Ramirez and a team of Boston University (BU) scientists believe this malleability of memory could be the key to resolving mental health disorders. “Our million-dollar idea is, what if a solution for some of these mental disorders already exists in the brain?” Ramirez asked. “And what if memory is one way of getting there?”

The Study: Mapping Memories in the Brain

In a study published in the journal Nature, BU researchers set out to better understand the storage of memories. Previous studies established that memories are stored throughout the brain, and that individual memories are actually a network of cells called engrams. (Keep in mind that a memory is not a tangible thing. Technically, an engram is a hypothetical construct that helps us to define what a memory actually is.) However, scientists don’t fully know how memories are stored as engrams, and what differentiates one memory from another.

So, the BU researchers worked to uncover the molecular and genetic differences between memories stored in the hippocampus. (The hippocampus is a small but crucial region deep within the brain associated with learning and memory.) They found that emotional memories — such as very happy or very sad ones — are unique when compared to other brain cells. And within those emotional memories, positive and negative memories are physically distinct from each other as well.

The discoveries don’t stop there. The team also learned that positive and negative memories are most often stored in different parts of the hippocampus. Plus, they communicate to other cells using distinct pathways. “So, there’s [potentially] a molecular basis for differentiating between positive and negative memories in the brain,” Ramirez said. “We now have a bunch of markers that we know differentiate positive from negative in the hippocampus.”

The Results: The Theory of Rewiring Bad Memories

With the knowledge that positive memories are physically different from negative ones, the BU researchers wanted to know if they could not only activate these memories, but change them. They performed a series of tests on mice, first creating positive and negative memories in each mouse. (To create a positive memory, the researchers let the mice socialize. To create a negative one, the researchers gave the mice mild but unpleasant shocks to their feet.) Then, the researchers injected the mice’s brains with colored solutions so they could see individual cell pathways.

From there, the BU researchers had each mouse recall the negative memory. As that happened, the team artificially activated a group of positive memory cells in that mouse’s brain with laser light. The “noise” of the positive memory overtook the noise of the negative memory. (So, the negative memory got a “positive” reboot.) From that point on, the mice had significantly reduced fear responses when they recalled the negative memory.

What This Means for Us

At this point in time, scientists cannot artificially activate and change memory cells in humans. The practice would be impractical (the hippocampus is too deep within the brain) and unethical. However, the BU researchers theorize that therapists could apply this strategy to therapy sessions. “You can ask the person, ‘Can you remember something negative, can you remember something positive?'” said Stephanie Grella, lead author and a former postdoctoral fellow in Ramirez’s lab at BU. In effect, asking a patient to remember a positive memory at a very specific time during a session could prove helpful.

This strategy is one many of us already employ. (Has anyone ever tried to cheer you up by reminding you of a funny memory?) It’s a simple way of rewriting a sad moment as you’re living it — or as you’re recalling it. Plus, scientists can build on this research. Who knows? One day, a safe medical procedure may exist that helps rewrite bad memories, changing the history of mental health forever.

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