Forgetting can be the result of an active deletion process in the brain rather than a failure to remember -- a mechanism that helps us adapt our behavior according to the surroundings, says a new study.

The findings could point towards new ways of tackling memory loss associated with conditions such as Alzheimer's disease and other types of dementia.

"Our study looks at the biological processes that happen in the brain when we forget something,” said Oliver Hardt from University of Edinburgh in Scotland.

"The next step is to work out why some memories survive whilst others are erased. If we can understand how these memories are protected, it could one-day lead to new therapies that stop or slow pathological memory loss," Hardt said.

The findings were published in The Journal of Neuroscience.

The study conducted in rats could also help scientists to understand why some unwanted memories are so long-lasting - such as those of people suffering from post-traumatic stress disorders.

Memories are maintained by chemical signaling between brain cells that relies on specialized receptors called AMPA receptors. 

The more AMPA receptors there are on the surface where brain cells connect, the stronger the memory.

The team found that the process of actively wiping memories happens when brain cells remove AMPA receptors from the connections between brain cells.

Over time, if the memory is not recalled, the AMPA receptors may fall in number and the memory is gradually erased.

Blocking the removal of AMPA receptors with a drug that keeps them at the surface of the cell stopped the natural forgetting of memories, the study found.