英語聽力文摘 選擇性記憶刪除

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選擇性記憶刪除

Ya?l: Have any unpleasant memories, Don?

Don: Sure. Who doesn't?

Y: What would you say to having them permanently erased from your brain?

D: Without losing other memories?

Y: Right. Scientists did just that with rats. They trained rats to fear two different sounds by sending a mild electric shock through the rats' paws when they played the sounds. This Pavlovian technique resulted in the rats freezing up in nervous anticipation of the shocks every time they heard either sound. Scientists wanted to know whether they could erase one of the memories without erasing the other one, even though both sounds result in the same fear.

D: I didn't know scientists knew how to erase memories at all.

Y: They do. You see, long-term memories aren't nearly as solid as we like to think. They're actually very fragile. Every time we recall a long-term memory, it becomes malleable. Just before playing one of the sounds, scientists injected half the rats with a chemical that interferes with memory reconsolidation. Thus, when they were in the process of remembering what accompanies the sound, the drug went to work.

D: Then what?

Y: When they played both sounds a day later, the rats that had been injected with the chemical did not freeze up when they heard the sound that had accompanied the drug. They froze as usual when they heard the second sound.

D: They had forgotten to be afraid. Hmm. This business makes me kind of nervous.

Y: I know what you mean, but for people with post-traumatic stress disorder, selective memory erasure could prove enormously useful.

D: True. I guess some fears are best laid to rest.

Y: 你有過不愉快的記憶嗎，唐?

D: 當然有，每個人都有的。

Y: 如果把它們永遠從你的大腦里刪除，你覺得怎么樣?

D: 不喪失其他記憶?

Y: 是的?？茖W家們用老鼠做了實驗。他們先訓練老鼠對兩種不同的聲音產生恐懼。當他們播放聲音的時候輕度電擊老鼠的爪子。這種巴普洛夫技術產生了這種結果：每次老鼠聽到其中一種聲音就會怕被電擊而變得非常緊張。科學家想知道他們能否將刪除老鼠對其中一種聲音的恐懼，而且要保留另外一組記憶。盡管兩種聲音都會讓老鼠產生恐懼。

D: 我不知道科學家們如何刪除記憶。

Y: 他們可以的。要知道，長期性記憶并非我們想象的那么牢固。實際上它們是很容易被破壞的。每當我們回憶起一段長期記憶，它都是具有可塑性的。在播放聲音之前，科學家先給老鼠注射一種干擾再次鞏固記憶的藥物。因此，當它們在回憶聲音的過程中，藥物就起作用了。

D:然后呢?

Y:當他們播放兩種聲音一天后，再給老鼠注射注射一種藥物，讓它們在聽到聲音的同時不再害怕。而聽到第二種聲音的時候還是會害怕。

D:它們就會忘記害怕。嗯，這樣的實驗讓我有點緊張。

Y:我知道你的意思，但對那些外傷后應激障礙的人來說，選擇性記憶刪除會起到非常大的作用。

D:是的，我想有些恐懼最好將它們埋葬。