Brain researchers have found that closeness counts when it comes to how strong our memories are. While everyone remembers where they were on 9-11 when they heard the news of attacks on the World Trade Center, this ScienCentral News video explains how those who were close to the scene formed memories that still provoke the brain's response to danger.
Matthew Swulinski was steps from the World Trade Center on September 11, 2001 when he managed to take a series of haunting photographs. "It was too late for me to run away, it was too late for me to hide anywhere," he recalls. "I was actually standing and waiting for this to be over."
His photos are a physical record of what he experienced that day, but neuroscientist Elizabeth Phelps at New York University and graduate student Tali Sharot, now a post doctoral fellow at University College London, studied people like Swulinski to learn about a different kind of snapshot: the so-called "flashbulb memory," a vivid moment in time that we seem to remember as if it were a photograph.
Roger Brown and James Kulik coined the term “flashbulb memory” in 1977 to describe people’s uncanny ability to recount where they were and what they were doing on November 22, 1963, the moment they heard that John F. Kennedy had been assassinated.
Swulinksi describes his September 11, 2001 experience with extra intensity because he was at Ground Zero. “I remember parts of the building falling around me everywhere. And I was just basically hit by glass– it’s kind of a miracle. And later – that’s the moment I realized that I’m in danger– and after the second plane, I left the area. I was still involved because of the falling towers and the cloud that appeared after that. The clouds actually covered me.”
Brown and Kulik described flashbulb memories as vivid, detailed, and highly accurate. But since then, researchers have challenged several aspects of the supposed uniqueness of flashbulb memories. For instance, while people are confident in their recall, research shows that their supposed flashbulb memories are not necessarily any more accurate than other memories.
What’s Happening in the Brain?
Phelps and Sharot thought 9-11 experiences provided an opportunity to investigate what’s actually happening in the brain, using state-of-the-art technology.
Elizabeth Phelps wih lab manager Ashley Shurick (seated)
“So, that’s what we looked for,” says Phelps, “we looked to see what is the special brain mechanism that’s laying down these very vivid memories that we call flashbulb memories.”
They used functional MRI to scan the brains of people who were close to or distant from Ground Zero as they recalled events of that day compared to other events around that time. The scans revealed that the amygdala, part of the brain that sends us into "fight or flight" mode when we're threatened, lit up only in those who were closest to the World Trade Center on 9-11 as they recalled events of that day.
Satellite imagery: GeoEye
“Those were the people, when we looked at their memories, [who] were more likely to report that they felt threat,” says Phelps. “You know, that they were worried about their safety. The people in Midtown were more likely to say they heard about it on the internet or a colleague came to tell them.”
One role of the amygdala is to respond to danger by signaling the sympathetic nervous system and releasing hormones like adrenaline, making us ready to respond to any threat. The fact that the amygdala is active in remembering emotional events means that to some extent, we relive the experience.
Phelps explains, "What we find is, later on when you retrieve that memory, you don't just retrieve the events that happen, you retrieve part of the emotional experience as well."
Swulinski's experience seems to bear this out. “When I talk to family or friends from time to time and I’m trying to explain what happened to me, what was my experience, I very often have tears in my eyes, so it’s very strong.”
Phelps says the research uncovers some of the basic mechanisms involved in how emotional memories are stored and retrieved in psychologicl disorders like post traumatic stress disorder (PTSD), and may help doctors develop new treatments for patients with PTSD.