Amnesia may affect thoughts of the future too

By Amy Norton

NEW YORK (Reuters Health) -Amnesia may not only impair people's memories, but their ability to picture the future as well, scientists reported Monday.

In a study of amnesia patients with damage to a brain structure called the hippocampus, British researchers found that the men generally had difficulty imagining potential future events.

When asked to picture a particular scenario -- visiting a museum or a tropical beach, for example -- the patients were unable to picture a detailed scene. Instead, they saw fragments, like the blue sky of the beach scene or the door and ceiling of the museum hall.

It's long been known that damage to the hippocampus can cause amnesia, according to Dr. Eleanor M. Maguire, a senior research fellow at University College London's Institute of Neurology.

"However, until now it was not known if the difficulties amnesic patients have are restricted to the past, or whether they could imagine future experiences or even imagine fictitious experiences," she told Reuters Health.

Maguire and her colleagues report the findings in the advance online edition of Proceedings of the National Academy of Sciences.

The study included five men with amnesia caused by hippocampal damage and 10 healthy men of a similar age, education and IQ. All were asked to imagine and describe themselves in various situations. They were asked to visualize both common events that could happen -- like the museum and beach scenarios -- and events that would likely occur in the future -- such as holiday or weekend plans.

Compared with their healthy counterparts, men with amnesia had trouble describing both the hypothetical situations and possible future events in their lives.

"The patients reported that they were unable to visualize an experience in their mind's eye, seeing instead just a collection of separate images," Maguire explained.

In that sense, she said, they were "forced to live in the present."

The researchers speculate that a common brain mechanism underlies both memory recall and visualization of imaginary and future events. The hippocampus, Maguire said, may provide the "backdrop," or environmental setting, to which the details of people's experiences are bound.

Beyond amnesia, the findings may help shed light on how the brain's memory system works more generally -- something, Maguire noted, that researchers still know relatively little about.

SOURCE: Proceedings of the National Academy of Sciences Early Edition, January 15, 2006.