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  3. For many years, people believed that the brain, like the body, rested during sleep. After all, we are rendered unconscious by sl

For many years, people believed that the brain, like the body, rested during sleep. After all, we are rendered unconscious by sl

admin2012-02-02  86
问题     For many years, people believed that the brain, like the body, rested during sleep. After all, we are rendered unconscious by sleep. Perhaps, it was thought, the brain just needs to stop thinking for a few hours every day. Wrong, During sleep, our brain — the organ that directs us to sleep — is itself extraordinarily active. And much of that activity helps the brain to learn, to remember and to make connections.
    It wasn’t so long ago that the regretful joke in research circles was that everyone knew sleep had something to do with memory — except for the people who study sleep and the people who study memory. Then, in 1994, Israeli researchers reported that the average performance for a group of people on a memory test improved when the test was repeated after a break of many hours — during which some subjects slept and others did not. In 2000, a Harvard team demonstrated that this improvement occurred only during sleep.
    There are several different types of memory — including declarative (fact-based information), episodic (events from your life) and procedural (how to do something) — and researchers have designed ways to test each of them. In almost every case, whether the test involves remembering pairs of words, tapping numbered keys in a certain order or figuring out the rules in a weather-prediction game, "sleeping on it" after first learning the task improves performance. It’s as if our brains squeeze in some extra practice time while we’re asleep.
    This isn’t to say that we can’t form memories when we’re awake. If someone tells you his name, you don’t need to fall asleep to remember it. But sleep will make it more likely that you do. Sleep-deprivation experiments have shown that a tired brain has a difficult time capturing memories of all sorts. Interestingly, sleep deprivation is more likely to cause us to forget information associated with positive emotion than information linked to negative emotion. This could explain, at least in part, why sleep deprivation can trigger depression in some people: memories stained with negative emotions are more likely than positive ones to "stick" in the sleep-deprived brain.
    Sleep also seems to be the time when the brain’s two memory systems — the hippocampus (海马体) and the neocortex (新皮质) — "talk" with one other. Experiences that become memories are laid down first in the hippocampus, eliminating whatever is underneath. If a memory is to be retained, it must be shipped from the hippocampus to a place where it will endure — the neocortex, the wrinkled outer layer of the brain where higher thinking takes place. Unlike the hippocampus, the neocortex is a master at weaving the old with the new. And partly because it keeps incoming information at bay, sleep is the best time for the "undistracted" hippocampus to shuttle memories to the neocortex, and for the neocortex to link them to related memories.
We can infer from the 2000 Harvard report that______.
选项 A、people can only improve their memory by more sleep
B、sleep of only a few hours proves useless to improve memory
C、researchers didn’t agree with the conclusion of the 1994 Israeli report
D、comparisons were made between subjects who slept and those who didn’t
答案D
解析 根据题干中的2000和Harvard将本题出处定位在第二段。该段最后一句中提到了哈佛的一个研究小组的结论：this improvement occurred onlyduring sleep。这句话的具体意思需要结合上文中1994年以色列的试验来做出判断。原文中说，1994年以色列研究者说，在中断数小时之后再次进行的记忆测试中，被试者的表现比上次平均都有进步—一在中断的几个小时里，有的被试者睡了，有的被试者则没有睡。显然这个试验没有对睡眠的被试者和未睡眠的被试者进行对照分析。这样就容易理解本段最后一句的意思了：记忆进步只发生在那些在中断时间里睡眠了的被试者身上。可以推测，2000年的试验对睡眠 的被试者和未睡眠的被试者做了对照分析，[D]项正确。[A]“人们只能通过多睡来改善记忆”曲解了原文意思。[B]在文中找不到依据。2000年的试验是对1994年试验的细化，是对其补充，与1994年的试验结果并不矛盾，[C]错误。
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