Scientists have been able to successfully plant false memories in mice.

In the false memory study, the team was able to make mice associate a neutral environment with a previously unpleasant experience that took place in a different environment.

The findings could be applicable to understanding how false memories occur in humans. Unreliable memories have long been known to psychologists and lawyers-and the new findings might help with understanding the phenomenon.

In order to implant the false memories, the researchers used genetically engineered mice that were implanted with optic fibers. The fibers delivered pusles of light to the mice's brain. This technique is able to make individual neurons respond to light and known as optogenetics.

Memories are stored in cells, and when events are remembered, we reconstruct parts of he cells. Memory changes as it is being recorded and recalled. This is part of why eyewitness testimony is problematic, as numerous studies have shown.

 "Our memory changes every single time it's being recorded. That's why we can incorporate new information into old memories and this is how a false memory can form..." Dr Xu Liu said.

In the case of the mice, the false memory was indistinguishable from a real memory. Both memories spurred a fear response in the memory forming cells of the mouse's brain, said  Xu Liu of the RIKEN-MIT Center for Neural Circuit Genetics, who was  a  lead author in the study.

In the case of the mice, they were put in one environment, a blue box, and the brain cells encoding memory were labeled and made responsive to light. They then were put in a different environment, a red box, and "light" was delivered via the optic cable into their brains. This activated the labeled cells and made them recall the blue box. They also received mild shocks at the same time.

When the mice were put back into the blue box, they showed physical fear responses. This indicates that they had formed a false memory about the blue box, where, in reality, they were never actually shocked.

This experiment might help show how the human brain works.

"In the English language there are only 26 letters, but the combinations of letters make unlimited words and sentences, this is also true for memories," Dr Liu said to press. He added, "There are so many brain cells and for each individual memory, different combinations of small populations of cells are activated."

This is part of why memories constantly evolve-and, perhaps, traumatic memories could be erased.

"If you want to grab a specific memory you have to get down into the cell level. Every time we think we remember something, we could also be making changes to that memory - sometimes we realize sometimes we don't," Dr Liu explained.

The findings may also help in understanding how to silence neurons that create fear responses and in understanding diseases like schizophrenia.