Scientists Use Light to Erase and Restore Memory in Rats

The Men in Black movies may have just predicted the future of science. Similar to the memory erase device in the movies, scientists have found a way to erase certain memories and then restore them using different types of light.

Dr. Robert Malinow is a professor of neurosciences at the University of California, San Diego. He and his researchers have spent years trying to figure out how memories are made and lost by studying synaptic connections, which are connections between brain nerve cells, or neurons.

The researchers figured this out by using light optics in order to stimulate a bundle of nerves in the experimental rats. In order to determine its effectiveness, the researchers also administered an electric shot on one of their feet at the same time to see if the rats associated the nerve stimulus with the foot pain. The rodents began to exhibit fear when the neurons were stimulated. As a result, the stimulated nerve areas in the brain revealed chemical changes that strengthened the memory-linked brain cells.

Then, the researchers delivered a low-frequency set of light pulses on the same nerves, which actually wiped out the pain-association memory. The rats stopped responding to the original stimulation of the bundle of neurons and were no longer fearful. Finally, the researchers sought to restore the original pain-association memory established during the first go-around.

Using a high-frequency pulse of light, they stimulated that same nerve bundle and found that the rats responded by exhibiting fear even though their feet were not being shocked. The researchers' use of optogenetics - using light to control neurons - was able to strengthen a memory, erase it, and then restore it.

"People have wanted to know what is it that changes when you learn something and why do you lose memories and why do you sometimes have memories that persist too long like post-traumatic stress disorder," said Dr. Manilow in this NPR article.

"We can form a memory, erase that memory and we can reactivate it, at will, by applying a stimulus that selectively strengthens or weakens synaptic connections," he added in this CBS News article.