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  3. A new study on mice uncovers some answers that could someday offer a powerful target for eliminating the recurrence of bad memor

A new study on mice uncovers some answers that could someday offer a powerful target for eliminating the recurrence of bad memor

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问题     A new study on mice uncovers some answers that could someday offer a powerful target for eliminating the recurrence of bad memories in humans, especially known to those who suffer from post-traumatic stress disorder(PTSD: mental disorder caused by accidents of emergency).
    "Fear memories are the most robust memories—they can last over a lifetime," says Nadine Gogol-la, a biologist at Harvard University and lead author on the paper published recently in the journal Science. "You can push them far back, but spontaneous recovery and relapses will happen. " Until now, science has been unable to stop this process—in humans or in mice.
    By repeating the previously reported rat findings, Gogolla and her colleagues found that at some point during a young mouse’s development—between about 16 and 23 days postnatal—a molecular net of sorts is cast over a region of the brain called the amygdala, effectively crystallizing formerly changeable memories.
    "It looks just like what you would expect from a fisherman’s net," says Gogolla of the protein matrix(a living part in which something is formed)under the microscope. "And it acts as a structural constraint on the cells. How it does that, nobody really knows. " But the result is that memories are held inside. What the researchers did learn was that by cutting that net—with an injection of an enzyme that digests the chains linking the matrix together—memories could be once again destabilized.
    "The drug cuts the net into its pieces," Gogolla says, "just like when you cut the strings of a net and it falls apart. " Then, for a couple of weeks, the original youthful plasticity in the neuronal circuits of the amygdala is regained and any bad memory formed after the matrix digestion could be subsequently eliminated through "extinction" therapy, a common treatment during which a patient is presented with the original fear trigger but in a context that is not fearful. When the treatment was given after a mouse underwent fear conditioning, however, extinction was unable to cut out that memory completely.
    "Because the treatment has to occur before a traumatic event, it’s hard to make it immediately available," notes Gogolla. " But it does help us in finding the underlying mechanisms. " Eventually, she hopes tools can be found that can be applied after fear—inducing experiences, and that translate from mice to humans. This would be welcome relief for the approximately 20 percent of all military personnel who have returned from Iraq and Afghanistan reporting symptoms of PTSD, not to mention for heartbroken couples.
What was confirmed by Gogolla’s study on extinction therapy?
选项 A、It is already available to humans.
B、It will eliminate fearful memories.
C、It functions under fearful conditions.
D、It works before fearful experiences occurred.
答案D
解析 细节题。由题干关键词extinction therapy定位至第五段和第六段。作者在第五段提到“消退疗法”是一种常见的疗法，即在一种并不可怕的情境下，向患者再现原先引起恐惧的事物。并在本段末句进一步说明：如果在老鼠遭遇了恐怖经历之后再进行这种疗法，就不能把恐怖记忆彻底清除了。为了证实这一点，作者在第六段首句再次提及：“消退疗法”必须在创伤事件发生之前进行，这与选项[D]意思一致，故选项[D]为正确答案。
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