New research shows that evolution worked out long ago how to protect the brain from being saturated by useless information - a useful technique in the modern world.

A Zurich scientist has discovered a protein molecule in the brain that not only makes learning more difficult but actively prompts the brain to forget things.

Professor Isabelle Mansuy from the Institute of Cell Biology at Zurich's Federal Institute of Technology discovered that by reducing the amount of the protein phosphatase 1 in the brains of mice, the rodents' learning abilities and memory were substantially enhanced.

Maysuy interpreted the results to mean that "PP1 represents a necessary controlling factor that is required to avoid saturation of the brain. Because the capacity of the brain is limited, it needs an active protective system."

She told swissinfo that people with very good memories demonstrated the brain's inability to cope with large amounts of information.

Useless information

"There are people with excellent memories - their memory is so good that they really do not forget anything. And this makes them very confused because they have this overload of information and most of this information is useless and they don't know how to deal with it.

"Having too good a memory is not good for you," she concludes.

In her experiments, Mansuy mice the task of finding an opaque platform located just under the surface of water in a tub.

The mice with reduced PP1 needed fewer training trials to locate the platform than those with normal levels, suggesting they learned faster.

Promoting forgetting

At regular intervals, she put the mice back in the tub. Those whose PP1 function was suppressed remembered its position surprisingly well and up to eight weeks after learning. The protein appears to promote forgetting.

The effect was also observed in aged individuals suggesting that suppression of PP1 may protect against memory decline. "The tests with the aged mice show that cognitive abilities may be rescued," said Isabelle Mansuy.

A related finding was that aged mice have more PP1 than their younger counterparts, suggesting that the learning difficulties and memory loss in old age are not necessarily unavoidable, irreversible processes.

"People initially thought that memory decline in old age is simply due to a normal deterioration of brain circuits. But here we show is that it is more likely due to the action of a specific protein," Mansuy explained.

swissinfo, Samantha Tonkin

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