2009/09/24

Vegetative patients ’still learn’ 植物人還是能學習

◎鄭寺音

Patients with severe brain damage who do not appear to have signs of consciousness still seem able to learn, a Cambridge University study suggests.

一項劍橋大學的研究顯示,腦部嚴重受創、看來沒有知覺跡象的病患,似乎還是可以學習。

Researchers tested for Pavlovian-like responses in 22 people in a persistent vegetative state by playing a noise prior to a puff of air to the eye. Some subjects learnt to anticipate the puff of air causing the eye muscles to twitch, Nature Neuroscience reported.

自然神經科學期刊報導,研究人員先對22名處於持續性植物人狀態的病患發出聲音,再對著他們的眼睛噴氣,來測試這些病患是否會有巴普洛夫式反應。部分病患學到預期會有噴氣,會抽動眼部肌肉。

Study leader Dr Tristan Bekinschtein from the University of Cambridge said the consensus had been that learning to link one stimulus with another - in this case a noise and a puff of air - was dependent on explicit awareness of the association.

來自劍橋大學的研究領導人貝金斯肯坦說,一般認為,學習將一種刺激與另一種相連結——在這個案例中,是聲音與噴氣——必須要明確感覺到連結。

But the study, where up to 70 puffs of air were delivered over a 25 minute period, showed that this sort of conditioning is possible even in patients who are not conscious.

但在這份25分鐘內噴氣多達70次的研究顯示,即使是沒有知覺的病患,也有可能出現制約性反應。

Electrodes positioned by the eyes picked up whether the muscles began to respond or not. And a control experiment doing the same tests on people under general anaesthesia did not produce the same responses, suggesting that the learning does not happen when truly unconscious, and that some patients may have some level of consciousness not apparent on traditional tests.

放置在眼睛旁邊的電極,會捕捉到肌肉是否開始有反應,而對照組中接受全身麻醉進行同樣實驗的人,並未出現同樣反應,顯示學習不會在真正無意識時發生,也顯示部分病患或許有傳統測試看不出來的、某種程度的知覺。

新聞辭典

vegetative:形容詞,植物人狀態的。

puff:名詞,一陣,一股。例句: Sean blew a puff of smoke at his reflection in the mirror.

(史恩對著鏡子裡的自己吐了一口菸。)

twitch:動詞,抽動、使勁拉。例句:He tried to suppress a smile but felt the corner of his mouth twitch.(他試著要壓抑微笑,但還是感覺到嘴角動了一下。)

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