Imagine if we could rewrite our most painful memories, turning them into sources of strength. Sounds like science fiction, right? But what if I told you that neuroscientists have already begun to unlock this very power? In this eye-opening excerpt from How to Change a Memory (Princeton University Press, 2025), author and neuroscientist Steve Ramirez takes us on a deeply personal and groundbreaking journey into the heart of memory manipulation. Ramirez and his team discovered a way to artificially control memories in rodents by directly interfacing with their brains, raising a question that’s both thrilling and unsettling: Can we truly change bad memories?
Our brains are wired to prepare us for uncertainty, often juggling multiple outcomes to keep us on our toes. This biological safeguard is healthy—it motivates us to prepare for stressful events. But here’s where it gets controversial: What happens when stress spirals out of control, tipping the scales into mental health disorders? Anxiety, for instance, doesn’t follow a single path; it’s a labyrinth of experiences and memories that converge into a shared feeling. These triggers, unique to each of us, are rooted in our memories. When they disrupt our lives, they’re labeled as mental disorders—a broad classification that often oversimplifies the complexity of the human mind.
As Ramirez entered his final year of graduate school, he was grappling with this very complexity. Amid his own mounting pressures—finishing his thesis, job hunting, and searching for purpose—his mother faced a resurgence of panic attacks, a lifelong battle with anxiety. Her struggles became a turning point for him. And this is the part most people miss: It wasn’t just about understanding anxiety; it was about finding a way to turn off the switch on those debilitating moments. His final project aimed to artificially activate positive memories to combat anxiety and depression, a deeply personal mission to stand by his mother, his superhero.
Teaming up with lab partner Xu Liu, Ramirez sought a brain-centric approach: Could they manipulate memories in rodents to restore behavioral and neuronal balance? Their inspiration came from psychologist Barbara Fredrickson’s influential study, The Undoing Effect of Positive Emotions, which revealed that positive emotions can physiologically counteract the effects of negative ones. For example, stressed participants who watched uplifting movie clips saw their cardiovascular activity return to baseline faster than those who watched neutral or sad clips. But could this work in the brain itself?
Using optogenetics—a technique to control neurons with light—Ramirez and Liu designed an experiment with rodents displaying anxiety- and depression-like behaviors. These rodents, unlike their healthy counterparts, showed no preference for sugar water over regular water in a sucrose preference test. With a click of a button, they activated a deep-blue laser in the rodents’ hippocampi, awakening positive memories. The result was astonishing: The rodents perked up, their behavior shifting instantly as if a wave of motivation rippled through their bodies. Within an hour, their preference for sugar water was restored, and brain regions linked to reward and motivation lit up.
But here’s where it gets even more fascinating: When positive memories were reactivated twice daily for a week, not only did symptoms of anxiety and depression permanently improve, but new brain cells began to grow. Positive memories weren’t just a temporary fix—they had long-term biological benefits. This discovery hinted at a future where memory manipulation could complement cognitive-behavioral therapies for mental disorders.
On a personal note, Ramirez reflects on a cherished memory with his mother—a leap of faith off a cliff in El Salvador. What began as fear transformed into triumph, a memory now rich with positive valence. It’s a testament to the power of shared experiences and the potential of our brains to rewrite our narratives.
But here’s the question that lingers: If we can manipulate memories to alleviate suffering, where do we draw the line? Is it ethical to alter the very fabric of our past? Ramirez invites us to ponder these questions, leaving us with a provocative thought: What if the key to healing lies not in forgetting, but in reimagining?
