If and when scientists perfect this technology, it will have tremendous potential for blunting painful memories in those suffering from post-traumatic stress disorder, and it may also help to combat addictive urges. Even though there are some ethical considerations that must be addressed, the choice should ultimately be up to the individual, Liao says: "As long as you don’t harm other people, you should be allowed to use these memory modification drugs in order to improve your personal well-being."

Liao says that some memory modification drugs "may change what you believe to be true about yourself," but these problems are not so worrying, because small bits of misremembered falsehoods (believing that you had a good holiday so that you can feel more relaxed) don't affect anyone else.

But how far away is this technology really? Researchers, including NYU psychology and neuroscience professor Joseph LeDoux, have already been able to target and eliminate certain memories in rats. Based on the knowledge that memory formation relies on certain proteins in the brain, LeDoux administered protein inhibitors to rats to see what would happen. “We conditioned a rat to be afraid of a tone," LeDoux recounted in his Big Think interview. "So, the next day, he hears the tone and he freezes, because that’s how rats express their fear of the stimulus. But immediately after presenting that tone, we give the rat a certain kind of drug...and we test the rat the next day; the memory is no longer present—or at least can’t be accessed.” Next, LeDoux tried administering the protein inhibitors not during memory formation, but when the rat retrieved that memory of the tone at a later time. Again, the result was the same: no more memory. 

LeDoux’s experiment triggered a wave of similar studies. One researcher, Dr. Ted Sacktor of SUNY Downstate Medical Center in Brooklyn, pinpointed a specific protein in the brain called PKMzeta, which seems vital for long-term potentiation (the strengthening of connections between two neurons, which scientists see as an important mechanism underlying memory). With this in mind, he conducted a new study using rats in an electrified chamber. First the rats were conditioned to avoid areas of the chamber whose floor was electrified, something the rats would never forget. Later the rats were injected which the drug ZIP, which interferes with PKMzeta, causing them to forget which parts of the floor were electrified; in other words, these long-term memories had been wiped clean. This discovery challenged the prevailing view that memories were a structural mechanism and could not be erased chemically.