Can You Rewire Bad Memories to Improve Mental Health?

Have you ever argued with a friend or family member about the details of a past event? My family and I do this often. For example, I remember when my sister was six years old, she got stuck in the mud by the pond in our hometown, and when our father pulled her out, the mud swallowed a rubber 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 a video recording of the past and more reconstructive,” Steve Ramirez, a neuroscientist at Boston University, told ScienceDaily.com. In fact, research from Northwestern University finds that every time you remember a memory, it becomes a little less precise. Over time, some memories become completely inaccurate. For this reason, police and investigators try to get witness statements as quickly as possible; As time passes, a person’s memory becomes less accurate.

False memories are an interesting feature 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 hold the key to solving mental health disorders. “Our million dollar idea is what if a solution to some of these mental disorders already existed in the brain?” asked Ramirez. “And what if memory is a way there?”

The Study: Mapping memories in the brain

In a study published in the journal Nature, BU researchers set out to better understand how memories are stored. Previous studies have shown that memories are stored throughout the brain and that individual memories are actually a network of cells called engrams. (Remember that a memory isn’t a tangible thing. Technically, an engram is a hypothetical construct that helps us define what a memory actually is.) However, scientists don’t know for sure how Memories are stored as engrams and what distinguishes one memory from another.

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

The discoveries don’t stop there. The team also learned that positive and negative memories are most commonly stored in different parts of the hippocampus. They also communicate with other cells in different ways. “Well, there is [potentially] a molecular basis for distinguishing between positive and negative memories in the brain,” Ramirez said. “We now have a number of markers that we know distinguish positive from negative in the hippocampus.”

The Results: The Theory of Rewiring Bad Memories

Knowing that positive memories are physically different from negative ones, the BU researchers wanted to know if they could not only activate but also alter these memories. They ran a series of tests on mice, first creating positive and negative memories in each mouse. (To create a positive memory, the researchers had the mice socialize. To create a negative one, the researchers gave the mice mild but uncomfortable shocks to their feet.) The researchers then injected the mice with colored solutions so they could see individual ones cell pathways.

From there, the BU researchers had each mouse retrieve the negative memory. The team artificially activated a cluster of positive memory cells in the mouse’s brain with laser light. The “noise” of the positive memory overtook the noise of the negative memory. (The negative memory was thus restarted “positively.”) From that point on, the mice had significantly fewer fear responses when recalling the negative memory.

What that means for us

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

Many of us are already using this strategy. (Has anyone ever tried to cheer you up by reminding you of a funny memory?) It’s an easy way to rewrite a sad moment as you experience it — or as you remember it. Also, scientists can build on this research. Who knows? One day there may be a safe medical procedure that could help rewrite bad memories and change mental health history forever.