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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.
According to Gogolla and her colleagues, fearful memories______.
选项 A、only appear in the amygdala
B、tend to form at a very early age
C、look like a fishing net in the brain
D、influence the growth of young mice
答案B
解析 推理题。由题干关键词Gogolla and her colleagues定位至第三段。该段介绍了格古拉和她的同事们在研究中的发现：在幼年老鼠成长过程中的某个时刻，一张由分子构成的“网”覆盖了大脑中的某个区域，并有效地将此前具有可塑性的记忆结晶化了。老鼠成长过程中的这个特殊时期大约是在出生后16～23天之间，由此可推断：恐怖记忆在生物成长初期就形成了，故选项[B]为正确答案。
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