A 1968 study found memory could be erased through electroshock therapy, but that theory was disputed and then forgotten for decades; but new research could bring researchers close to making the movie "Eternal Sunshine of the Spotless Mind" a reality.
In the study researchers conditioned rats to fear a specific sound, The next day they were confronted with the same sound but received an electroconvulsive shock to the head immediately afterwards, National Geographic reported.
After the rodent was shocked it was no longer afraid of the sound, and forgot the conditioning (or memory) altogether.
Researchers had always thought memories were "unstable" (able to be forgotten or changed) for only up to a few hours after they were formed.
"For decades people had thought that once a memory is wired in the brain it stays there forever," Karim Nader, a neuroscientist at McGill University, said, National Geographic reported.
Studies following the 1960s trial came up with mixed results; and the idea was eventually abandoned.
"Part of the field believed it, but the other part of the field just didn't believe it," Nader said. "And the ones who didn't believe it were the dominant ones."
In the recent study, the researchers looked at around 40 "severely-depressed" patients who were being treated with electroconvulsive therapy (ECT). This type of therapy is usually used as a "last resort" in treating mental and emotional disorders, it has been associated with memory loss in the past, Time reported.
The participants were asked to watch a morbid slideshow involving death and molestation. The study subjects were told they were having their memory tested and were asked to "pay close attention" to the stories.
"A week later, all were shown a partially covered version of its first slide and asked to recall just one of the stories. Then the patients were divided into three groups- two groups were given ECT immediately after recall and testing - one group was quizzed on both stories immediately after waking from the anesthesia used for the procedure while the other was tested 24 hours later. The third group simply got the cue and the test, but not ECT," Time reported.
The group that was quizzed immediately after they woke up proved to remember both stories fairly well and relatively equally. The group that did not receive ECT remembered the story they had been tested on better.
The group that was tested 24 hours after waking remembered some of the study they had not been cued to think about before right before receiving their ECT treatment. On the other hand, the researchers found the patients were not able to remember the story they had been thinking about right before receiving ECT.
The team concluded the timing of the memory played a huge role in whether the process was successful or not. The researchers believe it takes time for "electricity to interfere with the brain storage process"; which would explain why the memories could be recalled immediately after the treatment, but not 24 hours later.
Far from being the faithful record of the past that we like to imagine it as, memory is actually used by the brain mainly to predict the future- and this means that old memories are vulnerable to being re-written every time we access them. Previous research showed that this time-dependent 'reconsolidation' occurs in animals, but this is the first time it has been demonstrated in humans," Time reported.
The breakthorugh is exciting to the scientific community, but comes with some important moral issues.
"What if we wiped out all of the memories of the Holocaust?" Hank Greely, director of the Center for Law and the Biosciences at Stanford University, told Time. "That would be terrible. On the other hand, the suffering caused by some memories is really powerful and I would want to prioritize letting people who want to relieve their suffering, as a general matter, relieve their suffering."
