Scientists at the University of Cardiff have identified why it is that amnesia can be caused by damage to either of two quite distinct parts of the brain by studying the role of the fornix, a pathway in the brain.
Although researchers have long known that brain damage in two different regions can harm the ability to recall new events, the problem has been how to determine whether these two regions are functionally linked, said John Aggleton, a professor in the university's psychology school.
Examining people who had undergone surgery that sometimes damages the fornix, he found that those with a damaged fornix did less well on memory tests than those with no damage.
Professor Aggleton also experimented on rats, deliberately damaging their brains in one of the two areas known to cause amnesia. He found that the rats had problems similar to those of people with fornix damage.
"The findings help to explain how brain pathology in quite distinct sites can lead to very similar patterns of memory loss," he said.
People with a damaged fornix have trouble recalling new information, but they have no problems with recognition. This suggests that a different site is responsible for recognition.