It’s surprising news bound to bring joy to students studying for exams everywhere. The best way to memorize newly-acquired knowl

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问题     It’s surprising news bound to bring joy to students studying for exams everywhere. The best way to memorize newly-acquired knowledge is to go to sleep, scientists believe. Researchers in Germany found that the brain is better during sleep than during wakefulness at resisting attempts to scramble or corrupt a recent memory.
    Their study, published in Nature Neuroscience, provides new insights into the hugely complex process by which we store and retrieve deliberately acquired information—learning, in short.
    Fresh memories, stored temporarily in a region of the brain called the hippocampus (海马体) ,do not take shape immediately, earlier research showed. It was also known that reactivation of those memories soon after learning plays a crucial role in their transfer to more permanent storage in the brain’s "hard drive" ,the neocortex (新大脑皮层). During wakefulness,however,this period of reactivation renders the memories more fragile. Learning a second poem at this moment,for example,will likely make it harder to commit the first one to deep memory. Dr. Bjorn Rasch of the University of Lubeck in Germany, and three colleagues assumed that the same thing happens when we sleep, and designed an experiment to find out if they were right.
    Twenty-four volunteers were asked to memorize 15 pairs of cards showing pictures of animals and everyday objects. While performing the exercise,they were exposed to a slightly unpleasant odor. Forty minutes later,half the subjects who had stayed awake were asked to learn a second, slightly different pattern of cards. Just before starting,they were again made to smell the same odor,designed to trigger their memory of the first exercise. The 12 other subjects, meanwhile, did the second exercise after a brief sleep,during which they were exposed to the odor while in a state called slow-wave sleep. Both groups, were then tested on the original task. Much to the surprise of the researchers,the sleep group performed significantly better,retaining on average 85 percent of the patterns, compared to 60 percent for those who had remained awake.
    Lead author Dr. Susanne Diekelmann said: " Reactivation of memories had completely different effects on the state of wakefulness and sleep. Based on brain imaging data, we suggest the reason for this unexpected result is that already during the first few minutes of sleep, the transfer from hippocampus to neocortex has been initiated. After only 40 minutes of sleep, significant chunks of memory were already downloaded and stored where they could no longer be disrupted by new information that is encoded in the hippocampus. "
    Dr. Diekelmann said the positive impact of short periods of sleep on memory consolidation could have implications for memory-intensive activities such as language training. The findings also point to a strategy for helping victims of post-traumatic (外伤后的) stress syndrome, a weak condition caused by extreme experiences. The reactivation techniques " might prove useful in re-processing and un-learning unwanted memories," she said. " And reactivation of newly learned memories during following sleep could then help consolidate the desired curative effects for the long-term. "
During sleep,the period of reactivation is to make the memories______.

选项 A、temporarily stored
B、more fragile
C、be awake
D、deeply stored

答案D

解析 事实细节题。本题考查人类存储记忆中“激活过程”的作用。第三段指出新的记忆暂时存储于海马体中,刚学习之后,激活记忆能将短期记忆转为长期记忆,但是清醒状态时,这一激活过程会使得转换过来的记忆很容易丢失。而通过研究发现,睡眠状态时的处理效果却大相径庭。由此判断,在睡眠中激活过程的目的就是将记忆长期存储,故D)为本题答案。
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