2007-1-30
This is the VOA Special English Health Report.
Amnesia is a loss of memory. But scientists in Britain have found that it can mean a loss of imagination as well.
They asked amnesia patients in a study to imagine new experiences and then describe them. The researchers say the patients could not describe what they saw in their minds to the same extent as people without memory loss.
Eleanor Maguire at the Wellcome Trust Center for Neuroimaging at University College London was a leader of the study. She says it shows amnesiacs as people trapped in the present. They cannot look back at their past nor ahead to what the future might look like.
The five amnesiacs in the study all had serious damage to the hippocampus. This part of the brain is believed to process experiences into memories. But scientists disagree about the extent to which it also stores memories.
All five amnesiacs were men. They were compared with a control group of ten men who had no injury to their hippocampus.
The researchers asked all of the men in the study to imagine themselves in different situations. For example, they were asked to picture themselves on a sandy beach along a tropical coast -- or in a museum with lots to see.
The men in the control group gave descriptions rich in detail. One man described the heat of the sun on the beach, an old fishing boat on the water and big brown rocks. He described how to his left the beach curved around and became a point with wooden buildings on it. And his description continued.
But the amnesiacs were far more basic in what they saw. One said he could not see anything except the blue of the sky. He could hear seagulls and feel the sand. But when asked if he was seeing this in his mind's eye, he answered: "No, the only thing I can see is blue."
The scientists rated answers based on spatial references -- where objects were described in relation to each other. They also rated answers for any descriptions of people or animals, for sensory descriptions and for emotions or actions.
The control group rated higher in all areas. The amnesiacs rated lower especially in terms of spatial references and emotions. The findings could show that the hippocampus has more to do with imagination and memories than scientists may have ever imagined.
The findings appear in this week's Proceedings of the National Academy of Sciences, in the United States.
And that's the VOA Special English Health Report, written by Caty Weaver. I'm Mario Ritter.