英語(yǔ)聽(tīng)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(guò)不愉快的記憶嗎，唐?

D: 當(dāng)然有，每個(gè)人都有的。

Y: 如果把它們永遠(yuǎn)從你的大腦里刪除，你覺(jué)得怎么樣?

D: 不喪失其他記憶?

Y: 是的?？茖W(xué)家們用老鼠做了實(shí)驗(yàn)。他們先訓(xùn)練老鼠對(duì)兩種不同的聲音產(chǎn)生恐懼。當(dāng)他們播放聲音的時(shí)候輕度電擊老鼠的爪子。這種巴普洛夫技術(shù)產(chǎn)生了這種結(jié)果：每次老鼠聽(tīng)到其中一種聲音就會(huì)怕被電擊而變得非常緊張?？茖W(xué)家想知道他們能否將刪除老鼠對(duì)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(huì)讓老鼠產(chǎn)生恐懼。

D: 我不知道科學(xué)家們?nèi)绾蝿h除記憶。

Y: 他們可以的。要知道，長(zhǎng)期性記憶并非我們想象的那么牢固。實(shí)際上它們是很容易被破壞的。每當(dāng)我們回憶起一段長(zhǎng)期記憶，它都是具有可塑性的。在播放聲音之前，科學(xué)家先給老鼠注射一種干擾再次鞏固記憶的藥物。因此，當(dāng)它們?cè)诨貞浡曇舻倪^(guò)程中，藥物就起作用了。

D:然后呢?

Y:當(dāng)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?cè)诼?tīng)到聲音的同時(shí)不再害怕。而聽(tīng)到第二種聲音的時(shí)候還是會(huì)害怕。

D:它們就會(huì)忘記害怕。嗯，這樣的實(shí)驗(yàn)讓我有點(diǎn)緊張。

Y:我知道你的意思，但對(duì)那些外傷后應(yīng)激障礙的人來(lái)說(shuō)，選擇性記憶刪除會(huì)起到非常大的作用。

D:是的，我想有些恐懼最好將它們埋葬。