It turns out that a common cause of amnesia also prevents its victims from imagining the future, forcing them to live only in the present, researchers report in Tuesday's issue of Proceedings of the National Academy of Sciences.
Researchers at the Wellcome Trust Centre for Neuroimaging, University College London, studied people with damage to the hippocampus, part of the brain that is crucial in learning and memory.
While damage to the hippocampus has long been known to cause amnesia, the team led by Dr. Eleanor Maguire wondered if there were other affects.
So they asked the patients to imagine and describe plausible situations in such locations as the beach, a bar or in the forest. They also asked them to imagine a future meeting with a friend or a Christmas party.
"We found that the role played by the hippocampus in processing memory was far broader than merely reliving past experiences," Maguire said in a statement. "It also seems to support the ability to imagine any kind of experience including possible future events. In that sense, people with damage to the hippocampus are forced to live in the present."
"Furthermore, the patients reported that they were unable to visualize the whole experience in their mind's eye, seeing instead just a collection of separate images," she said.
The findings may indicate that the hippocampus provides the context or setting to visualize images both past and present, the researchers suggested.