A team of Duke University neuroscientists has found that the place a memory is processed in the brain determines whether it is a true or false memory.
These findings, published in the latest issue of the Journal of Neuroscience, could help understand memory changes that accompany normal aging or even lead to early diagnosis of Alzheimer's disease.
Information retrieved from memory is processed in two specific regions of the brain, each of which focuses on a different aspect of a past event, according Roberto Cabeza, lead author of the study.
The medial temporal lobe (MTL) focuses on specific facts about the event, while the frontal parietal network (FPN) processes the global gist of the event.
"Human memory, isn't completely right all the time," said Cabeza. "There are many occasions when people feel strongly about past events, even though they might not have occurred."
During brain scans, Cabeza found that volunteers who were highly confident in memories that were indeed true showed increased activity in the fact-oriented MTL region.
On the other hand, volunteers who showed high confidence in memories that turned out to be false exhibited increased activity in the impressionistic FPN.
The people drawing from this area of the brain recalled the gist or general idea of the event and, while they felt confident about their memories, they were often mistaken since they could not recall the details of the memory.
These findings, coupled with the findings of other studies, can help explain what happens to the human brain as it ages, Cabeza said.
"Specific memories don't last forever, but what ends up lasting are not specific details, but more general or global impressions," Cabeza said.
"Past studies have shown that as normal brains age, they tend to lose the ability to recollect specifics faster than they lose the ability recall impressions. However, patients with Alzheimer's disease tend to lose both types of memories equally, which may prove to be a tool for early diagnosis."
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