In the movie Eternal Sunshine of the Spotless Mind, two former lovers go through some pretty excruciating situations to erase their memories and move on with their lives. And although most of us may have at least once wanted to forget painful breakups and ugly redundancies, never before had scientists been so close to actually turning that wish into a reality.
Professor Roberto Manilow and his team at the University of California have conditioned a fear response in rats by making them associate nerve stimulation with pain, and then erased that memory by stimulating the nerve cells in which the memory had formed.
Once a memory is formed there are visible changes in the connecting nerve cells. The memory will remain intact if nothing tampers with these connections (synapses), but if a low frequency train of electrical pulses stimulates them and weakens the circuitry, the memory simply vanishes. But can these memories come back?
The researchers found that lost memories can be reactivated by stimulating the same connections with a high-frequency train of optical pulses. “We can cause an animal to have fear and then not to have fear again by stimulating the nerves at frequencies that strengthen or weaken the synapses,” said Sadegh Nabavi, the study’s lead author, in a news release.
This is great news for people with Alzheimer’s and other neurodegenerative diseases as the study shows that the processes that weakens synapses can be reversed.