Proximity linked to vivid 9/11 memories -study

NEW YORK, Dec 18 (Reuters) A study of people who were in Manhattan on September 11 indicates that personal involvement may be crucial in forming a ''flashbulb memory,'' a memory of a shocking, public event, researchers said today.

The New York University study found that people who were in lower Manhattan -- closer to the Twin Towers -- had, on average, more vivid, detailed memories of the day than those who were in other parts of Manhattan, Elizabeth Phelps, whose laboratory conducted the study, said in a news release.

The concept of ''flashbulb memory'' is based on studies of people's memories of the assassinations of President John Kennedy and other world leaders.

The theory is that the surprising, important nature of these events triggers a mechanism that conserves what occurred at that instant, producing a picture-like representation.

''Our findings on 9/11 memories indicate that personal involvement may be critical in producing memories with the characteristic qualities of flashbulb memories,'' Tali Sharot, the study's lead author, said in the release.

''We think that is because the amygdala, which is known to play a role in enhancing the feeling of remembering for emotional material, is more engaged when these events are experience first-hand,'' Sharot said.

The amygdala is a small, almond-shaped structure in the brain known to mediate emotion's effect on memory.

In the study, the brain activity of 24 people who were in Manhattan on September 11, 2001, was observed using magnetic resonance imaging while they recalled autobiographical memories from the day, along with other distinct, autobiographical events from the summer of 2001.

After the scanning, they were asked to rate their memories for vividness, detail, confidence in accuracy and other factors. They also were asked to write down their memories.

The study was reported in the Proceedings of the National Academy of Sciences.

REUTERS PKS BST0325