托福阅读材料--压力与老年性失忆

　　压力导致的问题很多，老年性失忆也与压力太大有关。今天的新托福考试阅读练习资料就会关注这个话题。

　　Scientists claim to have solved the mystery of how stress contributes to memory loss in old age.

　　Researchers at Edinburgh University found that one receptor was activated by low levels of the stress hormone cortisol, which helped memory. However, once levels of the hormone were too high they spilled over on to a second receptor, activating brain processes which contribute to memory impairment.

　　When the receptor linked to poor memory was blocked, the memory recall problem was reversed.

　　The research helps explain why too much stress over a prolonged period interferes with the normal processes in storing everyday memories.

　　The experiment, which was based on older mice, was published in the Journal of Neuroscience.

　　科学家近日宣称已找到压力导致老年性失忆的原因。

　　爱丁堡大学的研究人员发现，当压力激素皮质醇水平较低时，一种受体会被激活，从而增强记忆力。而当该激素皮质醇水平太高时，另外一种受体便会受到影响，使得让记忆受损的脑部运作更加激烈。

　　而当与记忆力低下有关的受体功能受阻后，记忆问题不再出现。

　　该研究有助于解释为何长时间过多压力会干扰日常记忆存储的正常程序。

　　该实验以老年鼠为试验对象，日前已刊登于《神经系统科学期刊》。