背誦為王第四冊第12課
- 聽力原文
- 參考譯文
短時和長時記憶
記憶理論中一個得到公認的區(qū)別是短時記憶和長時記憶之間的區(qū)別。短時記憶指的是我們能記住電話號以便撥打所需的能力，長時記憶涉及到曾經(jīng)擁有的經(jīng)歷在幾年后仍能影響行為的諸多方式。既然存在著這兩種不同的能力，假定它們在大腦里有著不同的表現(xiàn)方式就是理所當然的了?？茖W家們認為長時記憶牽涉到腦細胞的化學變化，而短時記憶涉及到神經(jīng)細胞里線路的脈沖方式，他們設計了一個試驗來驗證這個假設。
科學家們教會了一組老鼠如何走迷宮。學會后五分鐘，它們被冷卻到了五攝氏度，在這一溫度，大腦里所有的電活動都會停止。保持在這一溫度十五分鐘之后，它們恢復到正常的體溫。然后，它們被再次放入到了迷宮中。
第二組老鼠學會如何走同樣的這個迷宮之后，馬上就被冷卻到五攝氏度并保持十五分鐘。在恢復到正常體溫后，科學家們試圖讓第二組老鼠再次走迷宮。結果發(fā)現(xiàn)第一組老鼠在第二次很輕松地就走出了迷宮，說明它們不必重新學習這項任務。然而，學會走迷宮之后馬上就被冷卻的第二組老鼠卻不能成功地走出迷宮，也就是說，它們明顯記不起已經(jīng)學會的東西了。
這個實驗的結論是，短時記憶和長時記憶是有區(qū)別的。短時記憶涉及到電脈沖，因為在電活動停止的溫度條件下，記憶就不存在了。相比之下，長時記憶不會受到電活動中斷的影響，可能會涉及腦細胞的結構改變。
Lesson12 Short-term and Long-term Memory
A well-established distinction in memory theory is that between short-term and long-term memory. The former refers to our ability to do such things as remember telephone numbers long enough to dial them; the latter concerns the wide range of ways in which experiences can affect behavior many years later. Given the two different kinds of ability, it is reasonable to hypothesize that each is represented differently in the brain. An experiment was designed to test the hypothesis that long-term memory implies a chemical change in the brain cells while short-term memory involves patterns of impulses in circuits of nerve cells.
One group of rats was taught to run through a maze. Five minutes after learning the task, they were cooled to 50C., the temperature at which all electrical activity in the brain ceases. They were then kept at this temperature for 15 minutes before being allowed to return to their normal temperature.
They were then run through the maze again.A second group of rats were taught to run the same maze, and then immediately cooled to 50℃. for 15 minutes. After being allowed to return to their normal temperature, an attempt was made to run the second group through the maze again. It was found that rats in the first group had no difficulty with the maze the second time, suggesting that they did not have to relearn the task. Rats in the group which was cooled immediately after learning the maze, on the other hand, could not negotiate the maze successfully, i.e., they apparently could not remember what they had learned.
It was concluded from this experiment that short-term memory is unlike long-term memory. Short-term memory involves electrical impulses since at a temperature where electrical activity ceases, there is no memory. Long-term memory, in contrast, is unaffected by the disruption of electrical activity and may involve structural changes in brain cells.
A well-established distinction in memory theory is that between short-term and long-term memory. The former refers to our ability to do such things as remember telephone numbers long enough to dial them; the latter concerns the wide range of ways in which experiences can affect behavior many years later. Given the two different kinds of ability, it is reasonable to hypothesize that each is represented differently in the brain. An experiment was designed to test the hypothesis that long-term memory implies a chemical change in the brain cells while short-term memory involves patterns of impulses in circuits of nerve cells.
One group of rats was taught to run through a maze. Five minutes after learning the task, they were cooled to 50C., the temperature at which all electrical activity in the brain ceases. They were then kept at this temperature for 15 minutes before being allowed to return to their normal temperature.
They were then run through the maze again.A second group of rats were taught to run the same maze, and then immediately cooled to 50℃. for 15 minutes. After being allowed to return to their normal temperature, an attempt was made to run the second group through the maze again. It was found that rats in the first group had no difficulty with the maze the second time, suggesting that they did not have to relearn the task. Rats in the group which was cooled immediately after learning the maze, on the other hand, could not negotiate the maze successfully, i.e., they apparently could not remember what they had learned.
It was concluded from this experiment that short-term memory is unlike long-term memory. Short-term memory involves electrical impulses since at a temperature where electrical activity ceases, there is no memory. Long-term memory, in contrast, is unaffected by the disruption of electrical activity and may involve structural changes in brain cells.
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