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Something to Remember

May 17, 2011

(Ivanhoe Newswire) — According to a Johns Hopkins neuroscientist the trouble with our aging brains is that they’re unable to process new information, such was where the keys are or new names, as “new” because the brain pathways leading to the hippocampus — the area of the brain that stores memories — become degraded over time. As a result, our brains cannot accurately “file” new information, and confusion results.

“Our research uses brain imaging techniques that investigate both the brain’s functional and structural integrity to demonstrate that age is associated with a reduction in the hippocampus’s ability to do its job, and this is related to the reduced input it is getting from the rest of the brain,” Michael Yassa, assistant professor of psychological and brain sciences in Johns Hopkins’ Krieger School of Arts and Sciences, was quoted as saying. “As we get older, we are much more susceptible to ‘interference’ from older memories than we are when we are younger.”

“Maybe this is also why we tend to reminisce so much more as we get older: because it is easier to recall old memories than make new ones,” Yassa speculated.

Yassa and his team used MRI scans to observe the brains of 40 healthy young college students and older adults, ages 60 to 80, while these participants viewed pictures of everyday objects such as pineapples, test tubes and tractors and classified each — by pressing a button– as either “indoor” or “outdoor.”

The team used functional MRI to watch the hippocampus when participants saw items that were exactly the same or slightly different to ascertain how this region of the brain classified that item: as familiar or not.

“Pictures had to be very distinct from each other for an older person’s hippocampus to correctly classify them as new. The more similar the pictures were, the more the older person’s hippocampus struggled to do this. A young person’s hippocampus, on the other hand, treated all of these similar pictures as new,” Yassa explained.

Later, the participants viewed a series of completely new pictures (all different) and again were asked to classify them as either “indoor” or “outdoor.” A few minutes later, the researchers presented the participants with the new set of pictures and asked whether each item was “old,” “new” or “similar.”

Yassa said. “We found that older adults tended to have fewer ‘similar’ responses and more ‘old’ responses instead, indicating that they could not distinguish between similar items.”

Yassa said that this inability among older adults to recognize information as “similar” to something they had seen recently is linked to what is known as the “perforant pathway,” which directs input from the rest of the brain into the hippocampus. The more degraded the pathway, the less likely the hippocampus is to store similar memories as distinct from old memories.

“We are now closer to understanding some of the mechanisms that underlie memory loss with increasing age,” Yassa said. “These results have possible practical ramifications in the treatment of Alzheimer’s disease, because the hippocampus is one of the places that deteriorate very early in the course of that disease.”

SOURCE: Proceedings of the National Academy of Sciences, May 9, 2011




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