Chenyang (Leo) Lin, a brain and behavior researcher at Boston University, has always lived far from dense woodlands, growing up in a coastal city in southern China. However, an unforgettable hike in New Hampshire last year exposed him to towering trees and playful squirrels, starkly different from his familiar surroundings. “That was a genuinely new experience for me,” Lin recalls. Interestingly, this hike isn’t the only thing he remembers from that day; he also vividly recalls the chickens he saw along the way.
Lin’s interest in memory formation has led him to profound insights about why certain memories, like those of mundane chickens and exciting squirrels, remain so vivid. His recent study, published on September 24 in Science Advances, reveals how emotionally charged events can help individuals recall moments that might otherwise fade away. It appears that the brain connects related objects and experiences, explaining Lin’s recollection of ordinary farm animals alongside more stimulating wildlife.
Understanding what we remember, and crucially what we forget, has significant implications for students aiming to retain information and therapists working with trauma patients, Lin suggests.
Since the 1990s, research has indicated that combining a weaker memory with a stronger one can reinforce memory retention. This theory, known as “tag and capture,” suggests that everyday memories leave behind neuronal markers that tend to fade within hours. However, the occurrence of a more intense memory shortly after the mundane event triggers a protein rush in the hippocampus and associated neural pathways, effectively linking these weak memories to stronger ones.
To explore this theory, Lin and his research team conducted a diligent experiment involving over 100 participants, who viewed various sequences of animals like aardvarks, hamsters, and sea stars, as well as ordinary tools on a screen. Participants were first shown a series of images and then presented with another set where rewards were attached to their responses. Some participants received a substantial reward for identifying animals while receiving a minimal reward for identifying tools, with others experiencing the reverse.
The next day, participants were unexpectedly tested on their recollection of the images they had viewed the day prior. The findings indicated that both the size of the reward and the type of image played significant roles in memory retention. Those who received a large reward for identifying animals remembered about 50 percent of them, compared to about 45 percent for those with a small reward. Interestingly, big rewards linked to tools did not enhance memory recall for those objects, suggesting initial memories of tools were inherently stronger.
Cognitive neuroscientist Joseph Dunsmoor from The University of Texas at Austin noted that while weak memories are transient, this research is pioneering in demonstrating that these fragile memories are more likely to endure when associated with strong memories. Dunsmoor elaborates, “This illustrates how past experiences can gain new significance.”
Moreover, Lin’s team discovered that participants were generally better at forming new memories following a significant reward, suggesting that heightened arousal and engagement during notable events prime the brain for acquiring new information. This finding opens doors to future applications in both therapeutic settings and educational environments.
Lin envisions a future where therapists can assist trauma survivors in reinforcing everyday memories that precede a traumatic event, potentially mitigating subsequent emotional distress. Furthermore, educators could leverage these insights to enhance memory retention among students, perhaps integrating physical movements or other engaging techniques in learning scenarios.
