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记忆缺失:科学研究发现的正反两面

更新时间:2019/2/6 10:54:23 来源:纽约时报中文网 作者:佚名

Could you have this memory disorder?
记忆缺失:科学研究发现的正反两面

Susie McKinnon doesn’t remember being a child or remember being any age other than she is now: in her 60s. She can’t remember special events, either. She knows she went to her nephew’s wedding. She knows her husband went with her. But she can’t actually remember being there.

麦金农(Susie McKinnon)现在60多岁。她不记得童年时光,也没有任何过往岁月的记忆,除了当下。她也想不起重大事件,她知道曾去参加侄子的婚礼,知道与丈夫一同前往,但她不记得当时的情景。

In fact, she has very few memories from her life – but she doesn’t have amnesia.

事实上,她只对人生中极少数的事情有印象 — 但她得的不是失忆症。

For many years, McKinnon had no idea she was different. We tend to assume our minds work in the same way. We don’t often discuss what having a memory feels like. McKinnon assumed that when people told in-depth stories about their past, they were just making up the details to entertain people. But then a friend who was training in medicine asked if she could try out a memory test on her as part of her of studies. This is when both of them realised McKinnon’s autobiographical memory was lacking.

多年来,麦金农不知道她和正常人不一样。我们常常以为所有人大脑的运转方式都一样,也不太会谈起拥有记忆的感觉。麦金农以为,人们对往事娓娓道来时,只是胡编滥造博人一笑。但后来一位正在接受医师培训的朋友提出,作为她研究的一部分,是否可以对麦金农进行一项记忆试验。两人这才意识到麦金农患有自传式记忆缺失。

McKinnon researched amnesia, but the stories of people who lost their memories as a result of illness or brain injuries didn’t seem to fit her experience. She could remember that events had happened; she just didn’t recall what it was like to be there. A little more than a decade ago, after breaking her foot and having little to fill her time, she began reading about research on mental time travel and made the decision to contact a research scientist working in the field.

麦金农仔细研究了失忆症。那些病例是由于疾病或脑外伤而导致的失忆,似乎与她的情况不相符。她知道这件事情发生过,可是想不起来具体的情景。就在十多年前,她的脚骨折了,几乎没别的事可做,就开始读一些心智时间旅行的研究资料。最后,她决定联系一位该领域的专家。

She was nervous the day she sent an email to Brian Levine, a memory scientist at the Rotman Research Institute at Baycrest in Toronto. Levine called it was one of the most exciting days of his career. The result of their communication was the identification of a new syndrome – Severely Deficient Autobiographical Memory.

莱文(Brian Levine)是多伦多贝克斯特医院罗特曼研究所研究记忆的科学家。麦金农忐忑不安地给莱文发了一封电子邮件。莱文称那是他职业生涯中最为激动的一天。经过交流,麦金农的病症得到确诊,那是一种新的病症 — 自传式记忆重度缺失(Severely Deficient Autobiographical Memory,SDAM)。

Humans have the extraordinary ability to mentally time travel, going backwards and forwards in our minds at will. Think back to being in the classroom at primary school, or imagine that next weekend you’re sitting on a beach towel watching dolphins cross the horizon. It’s probably not just the facts about those situations that you imagine; you picture the actual experience of being there. This is what McKinnon is unable to do.

人类有很强的心智时间旅行能力,可以在脑海中穿越到过去或眺望未来,来去自如;你可以想像回到小学的教室,或设想下个周末坐在沙滩浴巾上看海豚在天际翻腾跳跃。可能你脑子里构建的不仅仅是这些场景,还有设身处地的实际感受,而这是麦金农做不到的。

As Brian Levine told me on All in the Mind on BBC radio, “For her, past events are experienced almost as if they were in the third person, as if they could have been someone else’s past episodes.”

正如莱文在BBC广播节目 All in the Mind(《尽在头脑中》 ) 告诉我的,“对她而言,发生过的事情几乎像是第三人叙事,仿佛是别人的往事。”

To an extent we all do this, forgetting most things that happen to us, but for McKinnon it’s much more extreme.

在一定程度上,我们都这样,把经历过的大多数事情置之脑后。但对于麦金农,显然情况更加极端。

This syndrome is very different from amnesia, which usually occurs after a particular event or brain injury, and makes it difficult for the person to retain new information in order to make new memories. People with Severely Deficient Autobiographical Memory or SDAM can learn and retain new information – but that information is devoid of the richness of real life experience. If McKinnon can remember details about an event, it’s because she’s seen a photo or deliberately learnt a story about what happened. She can’t picture being there or what she was wearing or who she was with.

这种症状和失忆症完全不同。失忆症通常由某一事件或脑外伤引起,患者在整合新的信息方面有障碍,因而无法形成新的记忆。自传式记忆重度缺失的患者能够理解或整合新的信息,但无法为之赋予饱满的现实生活体验。如果麦金农想起某一事件的细节,则是因为她看过照片,或有意去了解事情的具体细节。她无法回忆起自己曾置身其中,也不记得当时的穿戴,与谁同行,等等。

As she said to me on All in the Mind, “It could just have well have been somebody else attending a family wedding and not me. Inside my head I don’t have any proof that I was there. It doesn’t feel like it’s something that I did.”

正如她在All in the Mind 节目中对我所说,“就好像是别人曾去参加了亲戚的婚礼,而不是我。在我的大脑里,没有证据显示我曾在现场。感觉不像是我参与过的事。”

This means McKinnon can’t experience the nostalgia of reliving the best times in life – but the upside is that she can’t recall the pain associated with the bad things either. Something difficult like the death of a family member feels just as intense at the time, but the feeling soon fades. And it could make her a nicer person too. She doesn’t hold grudges, because she can’t conjure up the emotion that made her feel bad in the first place.

这意味着重温生命中的美好时光时,麦金农没有怀旧之感;好处呢, 是失意之事也不会令她感到痛苦。有些坎坷,比如家人去世,当时的感觉堪称煎熬,但这种体会很快便消退。这也使她更为随和。她不会心存怨恨,因为那种恼怒之感无法出现在她的脑中。

As for the cause, so far researchers can’t find any disease or injury associated with the condition and have to conclude that people are probably born with it. But Levine and his team are studying possible links with other conditions.

至于病因,目前研究人员没有发现与此症状有关的任何疾病或外伤,只好认为也许是先天因素导致的。莱文和他的团队正在研究SDAM与其它症状之间的关联。

McKinnon also has aphantasia, which means she can’t picture images.Is this preventing her from holding rich recollections of events in mind, compared to other people? It’s hard to know for sure. Decades of memory research have shown that we reconstruct an event in our minds each time we recall it – but we don’t know if we all do this in the same way. Some people might see an image or video in the mind’s eye; others might think more in terms of abstract ideas or facts.

麦金农同时还患有幻像可视缺失症(aphantasia),这就是说她无法想像画面。相较于其他人,这是否妨碍了她在脑海中保留对事物的饱满回忆?现在难以断定。数十年来对记忆的研究表明,每当我们在脑海中回忆往事,都会对事件进行重塑,但不清楚是否大家的做法都一样;有的人可能通过心智看到图像或视频片段,有的人则可能更多侧重于抽象概念或具体事实。

Catherine Loveday, professor of cognitive neuroscience at the University of Westminster, wonders whether there are parallels with our memory of very early life. We are able to describe events that happened to us before the age of three, because we might have heard a lot about them or seen photos. But we find it difficult to recall what the experience felt like.

威斯敏斯特大学认知神经科学教授拉夫迪(Catherine Loveday)想知道,人类在生命初期的记忆是否也有相似情况。我们能够复述三岁以前发生的事,因为我们可能听人提起过很多这方面的内容或见过照片,但很难回想起实际的体验。

At the moment the prevalence of SDAM is unknown, although Levine and his team are trying to find out, with an online survey. Five thousand people have already taken part, with many saying they believe they have this condition. This is of course a self-selecting sample, but the numbers suggest it might not be rare.

迄今为止,自传式记忆重度缺失的发病率尚不得而知。莱文和他的团队正通过在线调查进行统计。问卷调查参与者已达5000人,很多人称自己认为有此症状。当然,这是自我筛选的抽样,可从人数看可能患者并不少。

Levine’s team is investigating the idea that autobiographical memory might lie on a spectrum. SDAM might lie at one end, while people with highly superior autobiographical memory who barely forget anything, however mundane, are at the other.

莱文的团队正在研究的一个问题是,自传式记忆可能有一个类似于光谱的范围,自传式记忆重度缺失位于一极,而另一端则是那些自传式记忆超强的人,无论是多么寻常的事情,他们几乎都过目不忘。

So does it matter if you have this condition? If it’s not affecting the way you live your life, probably not.

那么,你介意有这种症状吗?如果这不影响你的生活方式,也许不会介意。

For McKinnon, she’s always lived like this – so knowing that it’s an actual condition which has probably been with her all her life is simply interesting and makes sense of the differences she’s sometimes noticed between her and other people. And she now understands that other people are not making up stories. “I’ve never had it any other way. So for me it’s not a loss,” she says. “Since I’ve never really had that ability, I can’t really feel the lack of it.”

对麦金农而言,她的生活历来如此,因此得知这一症状可能要与她终生相伴,反而觉得很有意思,同时也解开了她对于自己跟别人不同的困惑。现在她知道了,别人不是在编故事。她说:“我从来都是这样,因此对我来说并不算什么损失。既然我未曾真正拥有过那种能力,的确也感觉不到缺了什么。”

And McKinnon sees another advantage of not being about to dwell on the past or daydream about the future: “I know that a lot of people strive for that notion of really being in the moment, but it’s effortless for me because it’s the only way my brain operates. So I really am in the moment all the time.”

不沉湎于过去,也不幻想未来,在麦金农看来焉知非福:“我知道很多人要努力才能真正把握当下,但对我而言这是轻而易举的事,因为我的大脑只能这样运转。因此,我一直都在真正把握当下。”

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