Hearing the faint notes of a song, or catching a whiff of some familiar scent, can send people back many years to events that happened in their past. New research in Nature suggests that a few tiny neurons triggered by these minute changes can activate whole memories - and even cause a change in behavior reports Scientific American.
The work uses a relatively new area of research called optogenetics - triggering specific set of cells using light. In this case, researchers used neurons that were genetically modified to include a light sensitive protein. When the light shines on these modified neurons, they fire. The researchers put those modified neurons into the hippocampus - the area of the brain that helps us learn, and stores information about locations.
After they inserted these light sensitive proteins, they had to create a memory in their mouse to recall. To do so, they shocked the mouse's foot every time it encountered a specific environment. Eventually the mouse learned that that environment meant it would get a shock and would freeze when it encountered that new environment.
The idea was that the mouse was storing this memory of the environment, and thus the shock, in its hippocampus. So if the researchers were able to stimulate the hippocampus without the mouse being in that environment, they might be able to induce that same fear response. And in fact they were. Shining a light onto the genetically modified neurons made rats freeze in their tracks, expecting a shock even when they were not in the environment that they had learned to associate with the pain.
Optogenetics has been used in humans before too - although never to control memory quite this way. Some studies have looked at depression, anxiety, schizophrenia and Parkinson's disease, using the modified neurons to examine how these diseases effect our brains. While we're a long way from memory control in humans, it's possible that light controlled neurons could enhance, or erase, our memories one day.
via: Scientific American