Can we alter unwanted memories? A recent project by neuroscientist Steve Ramirez and his colleagues offers a fascinating glimpse into the potential to artificially control memories in rodents, offering hope for future treatments for anxiety and depression. This rewritten account, adapted from Ramirez’s “How to Change a Memory” (Princeton University Press, 2025), details the groundbreaking research and its personal significance.
The Weight of Anxiety and the Search for Relief
Feelings like anxiety, though often invisible to others, are an inescapable part of the human experience. We regularly confront stressors – a job interview, an upcoming exam, a first date – and our brains naturally prepare us for various outcomes. While this vigilance is healthy, encouraging preparation and hard work, it can become debilitating when anxiety becomes overwhelming, potentially leading to mental health challenges. The wide range of triggers and experiences that contribute to anxiety underscores the complex and individualized nature of memory, highlighting its crucial role in shaping our emotional state.
Ramirez’s personal journey deeply influenced his research. Witnessing his mother’s struggle with panic attacks spurred him to explore a direct, scientifically-grounded approach to alleviating such debilitating conditions. He and his team aimed to artificially activate positive memories to counteract the symptoms of anxiety and depression.
A Brain-Centric Approach to Memory
The core of the project involved directly influencing the brain to restore balance. Ramirez and his lab partner, Xu Liu, sought to control memories in rodents, drawing inspiration from psychological research on the “undoing effect of positive emotions” by Barbara Fredrickson and colleagues. This research demonstrated that positive emotions can physiologically counteract the negative impacts of stress on the brain and body.
Restoring Balance Through Positive Memories
To test this concept, Ramirez and Liu designed an experiment involving rodents. Animals were placed in a box with two valves: one dispensed sugar water, and the other provided regular water. Typically, rodents show a preference for sugar water, but those exhibiting anxiety- or depression-like behaviors often demonstrate a random preference between the two valves.
The research team’s crucial innovation was to use optogenetics – a technique that uses light to control genetically modified neurons – to reactivate positive memories. By targeting cells in the hippocampus, a region of the brain vital for memory, they could “wake up” these memories. As Ramirez puts it, it was a “fancy, high-tech Proustian madeleine,” evoking the rich recollections of the past.
The effect was remarkable. When the laser stimulated positive memories, the mice perked up, scanning their environment and quickly choosing the valve with sugar water. Within an hour, reactivating positive memories restored the animals’ behavior to a healthy baseline, also triggering brain areas associated with reward and motivation.
Long-Term Benefits and a Path Forward
Further research, led by undergraduate Briana Chen, revealed even more impressive results. Chronically reactivating positive memories twice daily for about a week not only alleviated symptoms of anxiety and depression but also promoted the growth of new cells in the brain, demonstrating both short- and long-term benefits.
Inspired by the Research Domain Criteria (RDoC), a neurocentric approach to mental health treatment, the team envisioned combining their biological findings with cognitive-behavioral therapies to develop more effective interventions.
A Personal Memory and the Power of Connection
Ramirez also draws on personal experience to illustrate the power of positive memories. He recounts a childhood memory with his mother, a pivotal moment where they jointly overcame his fear of heights by jumping into a village pond in El Salvador. This memory, rich in cognitive and emotional components, embodies the potential for memories to reshape our perspectives and provide enduring strength.
Positive memories are some of the most powerful biological tools available in our brains.
Ramirez’s research offers a fascinating glimpse into the possibilities of manipulating memory to improve mental well-being, underscoring the profound connection between memory, emotion, and brain health. Ultimately, the study highlights the potential to harness the brain’s own resources to alleviate suffering and promote resilience
