The researchers place a mouse in a brand new environment. As the mouse explores this environment (Place A), new memories are created in the hippocampus (the region of the mammalian brain that we know is deeply involved with memory formation). In Place A, the mouse has the time of its life. The mouse is then relocated to a different environment (Place B). While in Place B, the neuroscientists stimulate the memory of Place A using optogenetics . . . while simultaneously delivering electric shocks to the mouse’s feet, causing fear and pain. Then, when the mouse is returned to Place A, it freezes in fear. This is because the mouse’s brain has somehow confused the fear of electric shocks in Place B with its memory of Place A — in other words, a false memory has been created.
The next step, of course, is to actually do something with these findings. The research group would like to use its memory manipulation technology to fix/treat undesirable brain function, such as anxiety and depression. Being able to delete or reprogram bad memories, a la Eternal Sunshine of the Spotless Mind, would probably make short work of many mental woes. Perhaps more excitingly, though, is the potential to directly encode new memories into our neurons — kind of like when Neo learns to fly a helicopter in The Matrix. That’s probably a few years away yet, though.