Unwanted Memories Erased in Electroconvulsive Therapy Experiment
Scientists have zapped an electrical current to people's brains to erase distressing memories, part of an ambitious quest to better treat ailments such as mental trauma, psychiatric disorders and drug addiction.
In an experiment, patients were first shown a troubling story, in words and pictures. A week later they were reminded about it and given electroconvulsive therapy, formerly known as electroshock. That completely wiped out their recall of the distressing narrative.
'It's a pretty strong effect. We observed it in every subject,' said Marijn Kroes, neuroscientist at Radboud University Nijmegen in the Netherlands and lead author of the study, published Sunday in the journal Nature Neuroscience.
荷兰奈梅亨拉德伯德大学(Radboud University Nijmegen)神经科学家克勒斯(Marijn Kroes)说：效果非常明显，我们在所有受试者中都观察到了这一效果。克勒斯是这篇研究论文的主笔，论文周日发表在《自然神经科学》(Nature Neuroscience)杂志上。
The experiment recalls the plot of the movie 'Eternal Sunshine of the Spotless Mind,' where an estranged couple erases memories of each other.
这项试验让人想起《美丽心灵的永恒阳光》(Eternal Sunshine of the Spotless Mind)这部电影，影片中一对感情不合的情侣抹除了彼此的记忆。
Science has tinkered with similar notions for years. In exposure treatment, repetitive exposure to a phobia in a nonthreatening way is designed to help patients confront their fears and gradually weaken the fear response, a process known as extinction. Some researchers also are experimenting with antianxiety drug propranolol. The hope is that one day it may be possible to selectively eliminate a person's unwanted memories or associations linked to smoking, drug-taking or emotional trauma.
Scientists used to think that once a memory took hold in the brain, it was permanently stored and couldn't be altered. People with anxiety disorders were taught to overcome their fears by creating a new memory. Yet the old memory remained and could be reactivated at any time.
About a decade ago, scientists made a surprising discovery. They showed that when a lab rodent was given a reminder of some past fear, the memory of that event appeared to briefly become unstable. If nothing was done, that memory stabilized for a second time, and thus got ingrained-a process known as reconsolidation.
But when certain drugs, known to interfere with the reconsolidation process, were injected directly into the rodent's brain, they wiped out the animal's fearful memory altogether. Crucially, other memories weren't erased.
Whether it was possible to disrupt the memory-consolidation process in humans was thought to be difficult to answer because injecting drugs into the human brain is risky business. Dr. Kroes and his colleagues found a way around the problem.
Their test subjects were 39 patients who were undergoing electroconvulsive therapy, for severe depression. In ECT treatment, patients get a muscle relaxant and an anesthetic and an electrical current is passed to part of their brains, triggering a brief seizure that can help treat the depression. It isn't clear how the technique works: Some scientists have suggested it changes the pattern of blood flow or metabolism in the brain, while others believe it releases certain chemicals in the brain that battle the depression.
Patients who are treated with ECT are those who typically haven't responded to an array of other treatments, including the most powerful drugs available.
A lot more work needs to be done. It isn't clear whether the memory erasure is temporary or permanent. And while the technique might work for simple stories, it needs to be shown that it also works for real-world traumatic memories.
Some researchers looking to move beyond ECT are now also experimenting with propranolol, which inhibits the actions of a hormone that enhances memory consolidation. This summer, Karim Nader, a neuroscientist at McGill University in Canada, hopes to test the drug in about 50 patients suffering from post-traumatic stress disorder.
一些研究人员力图研发出较电休克疗法更好的治疗办法，他们正在对心得安进行试验，这种药物可抑制一种强化巩固记忆的荷尔蒙的活动。加拿大麦吉尔大学(McGill University)的神经科学家纳德尔(Karim Nader)希望在明年夏天能够请到约50名有创伤后应激障碍的病人参与测试这一药物。