updated 4/10/2007 1:36:27 PM ET 2007-04-10T17:36:27

Childhood memories might best be kept in a photo album, not in your mind. Turns out, storing old memories can make you forget an important appointment or what you needed to buy at the store today.

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Too many long-term memories make it hard to properly filter new information and process short-term memories, according to a study last month in the Proceedings of the National Academy of Sciences.

"In our world, we are constantly bombarded by new information so we are constantly filtering, and if we did not do this, we would be overwhelmed," said study team member Gaël Malleret of Columbia University Medical Center.

The new research indicates that those with better working memory may have fewer new neurons being developed in their hippocampus — a region of the brain involved in formation of memories. This "helps them forget old and useless information sooner and enables them to take in new information faster,” Malleret said.

Researchers previously believed that growth of new neurons in the hippocampus, known as neurogenesis, was beneficial to memory.

But the results of the new study, in which Malleret and colleagues suppressed neurogenesis in two independent groups of mice, showed improved working memory — short-term memory that maintains a limited amount of information relevant to the task at hand.

The mice had to locate food within areas in a maze. Those with suppressed neurogenesis made better choices and found the food faster.

"We were surprised to find that halting neurogenesis caused an improvement of working memory, which suggests that too much memory is not always a good thing, and that forgetting is important for normal cognition and behavior," Malleret said.

The researchers believe that the findings could eventually help those battling with memory dysfunctions.

"In medicine, these findings have significant implications for possible therapeutic interventions to improve memory," Malleret said. "A careful balance of neurogenesis would need to be struck to improve memory without overwhelming it with too much activity."

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