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考研英语阅读题源来源广泛,取自《经济学人》、《纽约时报》、《新闻周刊》、《卫报》、《Nature》、《华盛顿邮报》、《The Scientist》等等【了解更多题源】,因此考生可以多关注一下此类文章。下面新东方在线分享一些考过的题源文章,并附上详细解析,本阶段复习,大家可以看看。
From The Economist
Aug. 2, 2007
Lest We Forget or Lest We Remember?
People remember emotionally charged events more easily than they recall the
quotidian. A sexual encounter trumps doing the grocery shopping. A mugging
trumps a journey to work. Witnessing a massacre trumps pretty well anything you
can imagine.
That is hardly surprising. Rare events that might have an impact on an
individual's survival or reproduction should have a special fast lane into the
memory bank-and they do. It is called the a2b-adrenoceptor, and it is found in
the amygdala, a part of the brain involved in processing strong emotions such as
fear. The role of the α2b-adrenoceptor is to promote memory formation-but only
if it is stimulated by adrenaline. Since emotionally charged events are often
accompanied by adrenaline secretion, the α2b-adrenoceptor acts as a gatekeeper
that decides what will be remembered and what discarded.
However, the gene that encodes this receptor comes in two varieties. That
led Dominique de Quervain, of the University of Zurich, to wonder if people with
one variant would have better emotional memories than those with the other. The
short answer, just published in Nature Neuroscience, is that they do. Moreover,
since the frequencies of the two variants are different in different groups of
people, whole populations may have different mixtures of emotional memory.
The reason Dr de Quervain suspected the variants might work differently is
that the rarer one looks like the commoner one when the latter has a
memory-enhancing drug called yohimbine attached to it. His prediction,
therefore, was that better emotional memory would be associated with the rarer
version.
And that did, indeed, turn out to be the case in his first experiment. This
involved showing students photographs of positive scenes such as families
playing together, negative scenes such as car accidents, and neutral ones, such
as people on the phone. Those students with at least one gene for the rarer
version of the protein (everyone has two such genes, one from his father and one
from his mother) were twice as good at remembering details of emotionally
charged scenes than were those with only the common version. When phone- callers
were the subject; there was no difference in the quality of recall.
That is an interesting result, but some of Dr de Quervain's colleagues at
the University of Konstanz, in Germany, were able to take it further in a second
experiment. In fact, they took it all the way along a dusty road in Uganda, to
the Nakivale refugee camp. This camp is home to hundreds of refugees of the
Rwandan civil war of 1994.
In this second experiment the researchers were not asking about
photographs. With the help of specially trained interviewers, they recorded how
often people in the camp suffered flashbacks and nightmares about their wartime
experiences. They then compared those results with the α2b-adrenoceptor genes in
their volunteers. As predicted, those with the rare version had significantly
more flashbacks than those with only the common one.
Besides bolstering Dr de Quervain's original hypothesis, this result is
interesting because only 12% of the refugees had the rarer gene. In Switzerland,
by contrast, 30% of the population has the rare variety-and the Swiss are not
normally regarded as an emotional people.
Whether that result has wider implications remains to be seen. Human
genetics has a notorious history of jumping to extravagant conclusions from
scant data, but that does not mean conclusions should be ducked if the data are
good. In this case, the statistics suggest Rwanda may have been lucky: the
long-term mental-health effects of the war may not be as widespread as they have
been in people with a different genetic mix. On the other hand, are those who
easily forget the horrors of history condemned to repeat them?
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