http://www.bbc.co.uk/news/science-environment-23447600 Scientists can implant false memories into mice A team was able to make the mice wrongly associate a benign environment with a previous unpleasant experience from different surroundings. The researchers conditioned a network of neurons to respond to light, making the mice recall the unpleasant environment. Reporting in Science, they say it could one day shed light into how false memories occur in humans. The brains of genetically engineered mice were implanted with optic fibres in order to deliver pulses of light to their brain. Known as optogenetics, this technique is able to make individual neurons respond to light. Unreliable memory Just like in mice, our memories are stored in collections of cells, and when events are recalled we reconstruct parts of these cells - almost like re-assembling small pieces of a puzzle. It has been well documented that human memory is highly unreliable, first highlighted by a study on eyewitness testimonies in the 70s. Simple changes in how a question was asked could influence the memory a witness had of an event such as a car crash. When this was brought to public attention, eyewitness testimonies alone were no longer used as evidence in court. Many people wrongly convicted on memory statements were later exonerated by DNA evidence. Xu Liu of the RIKEN-MIT Center for Neural Circuit Genetics and one the lead authors of the study, said that when mice recalled a false memory, it was indistinguishable from the real memory in the way it drove a fear response in the memory forming cells of a mouse's brain.