Scientists have zapped an electrical current to people's brains to erase¹ distressing² memories, part of an ambitious quest to better treat ailments³ such as mental trauma⁴, psychiatric disorders⁶ and drug addiction⁷.

近期研究发现，向脑中输入电流可以抹去人们不愉快的记忆。这是科学家在更好地治疗心理创伤、精神疾病和药物成瘾等疾病的研究过程中迈出的又一步。

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, formerly⁸ known as electroshock. That completely wiped out their recall of the distressing narrative⁹.

在一项试验中，科学家首先藉助文字和图片向患者呈现一则令人烦恼的故事。一周之后，科学家会提醒患者回忆这个故事，然后对患者实施电休克治疗（即人们熟知的电击疗法），结果是患者完全忘记了这个痛苦的故事。

'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 estranged¹⁰ couple erases¹¹ 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 extinction¹². 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.

科学界多年来也一直在进行相关研究。在暴露疗法中，医生以一种不具威胁性的方式让患者频繁暴露于所恐惧的事物中，帮助他们直面内心的恐惧并逐渐弱化其恐惧反应，这个过程被称作“消退法”(extinction)。一些研究人员还对抗焦虑药物“心得安”(propranolol)进行试验，希望有朝一日能选择性地筛除人们不想保留的记忆，或是与吸烟、吸毒或情感创伤联系在一起的记忆。

Scientists used to think that once a memory took hold in the brain, it was permanently¹³ 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.

科学家们曾经认为，一段记忆一旦印在脑子里就会永久保存下去而无法更改。过去，治疗焦虑症患者的办法是让他们创造新的记忆以克服恐惧。然而旧的记忆保存不动，并可能随时被重新激发出来。

About a decade ago, scientists made a surprising discovery. They showed that when a lab rodent¹⁴ was given a reminder¹⁵ of some past fear, the memory of that event appeared to briefly¹⁶ become unstable¹⁷. If nothing was done, that memory stabilized¹⁸ for a second time, and thus got ingrained-a process known as reconsolidation.

大约在10年前，科学家有了一个意外的发现。当提醒实验室中的啮齿类动物回忆过去的恐惧场景时，脑中的那段回忆会暂时呈现出不稳定状态。如果不采取措施，那段记忆会再一次稳定下来，并深植于脑中，这一过程被称作“再巩固”(reconsolidation)。

But when certain drugs, known to interfere²⁰ 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 erased²¹.

但如果将某些可以干扰“再巩固”过程的药物直接注射进啮齿动物的脑中，动物的恐惧记忆会被彻底抹除。而且关键在于，其他记忆并没有被抹去。

Whether it was possible to disrupt the memory-consolidation¹⁹ process in humans was thought to be difficult to answer because injecting drugs into the human brain is risky²² business. Dr. Kroes and his colleagues found a way around the problem.

至于能否对人脑的“再巩固”过程进行干预，则被认为是一个很难回答的问题，因为向人脑中注射药物风险较大。克勒斯和他的同事们找到了一种可以绕开这个问题的办法。

Their test subjects were 39 patients who were undergoing electroconvulsive therapy, for severe depression. In ECT treatment, patients get a muscle relaxant and an anesthetic²³ and an electrical current is passed to part of their brains, triggering a brief seizure²⁴ 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 metabolism²⁵ in the brain, while others believe it releases certain chemicals in the brain that battle the depression.

他们的试验对象是39名因患有严重抑郁症而接受电击治疗的患者。在电击治疗中，医生给患者使用肌肉松弛剂和麻醉剂，并让电流通过患者大脑的部分区域，电流可引发疾病短时间突然发作，有助于治疗抑郁症。人们还不清楚这种疗法的原理，一些科学家猜测是电流改变了血流模式或大脑的新陈代谢，还有人相信是电流促使脑部释放出某些可以抗击抑郁症的化学物质。

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.

接受电疗的患者通常都是在试用了各种其他治疗方法均不见效（包括最强力的药物）后转而接受该治疗的。

A lot more work needs to be done. It isn't clear whether the memory erasure²⁶ 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.

这项工作还远没有完成。科学家还不清楚这种记忆抹除是暂时还是永久性的。而且，尽管这一技术在抹去简单故事的记忆方面可能有效，但科学家还需要证明它能够让人忘记真实世界中的悲惨经历。

Some researchers looking to move beyond ECT are now also experimenting with propranolol, which inhibits²⁷ the actions of a hormone²⁸ 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 disorder⁵.

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。