9/11 Study Offers Insight Into How Memories Are Formed

The brain's fear center created stronger memories for those nearest Ground Zero.

By E.J. Mundell
HealthDay Reporter
Monday, December 18, 2006; 12:00 AM

Copyright © 2006 ScoutNews, LLC. All rights reserved.

MONDAY, Dec. 18 (HealthDay News) -- Most Americans remember where they were on the morning of Sept. 11, 2001.

But a new brain-scan study suggests that not all those memories were created equally.

"If you were near the World Trade Center, your memories are qualitatively different from other people -- even those who were elsewhere in Manhattan," said lead researcher Elizabeth Phelps, a professor of psychology at New York University.

Specifically, people who were within about two miles of Ground Zero on that day now retain especially vivid, detailed recollections of the scenes and events of that morning -- a kind of recall that experts call "flashbulb memories."

Brain imaging suggests that these memories are especially strong because the amygdala -- a brain area focused on fear and memory -- kicked into high gear as these people watched that morning's catastrophic events unfold.

Nearly all of the study participants who had been in lower Manhattan on 9/11 said they experienced first-hand the sights, sounds and smells of that day. And many said they feared for their own safety.

All of that may have played a role in imprinting these highly potent memories in their brains, Phelps said.

"This isn't unique to 9/11," she added, noting that flashbulb memories can be laid down in any kind of traumatic event, be it personal or very public.

But while other researchers have studied these trauma-linked memories before, "what's different about this is that we could actually look at the brain mechanism behind it," Phelps said.

Her team published its findings in this week's issue of the Proceedings of the National Academy of Sciences.

The findings don't mean that only people who were close to Ground Zero can have stark, detailed memories of that day.

"I think that you can have these memories even if you weren't at the event and not physically threatened yourself," said Dr. David Spiegel, a professor and chairman of psychiatry and behavioral sciences at Stanford University School of Medicine. "But I think what Phelps is showing us is the most extreme and physiologically identifiable version -- it's a matter of degree."