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In a purely biological sense，fear begins with the body’s system for reacting to things that can harm us—the so called fight-or-flight response.“An animal that can’t detect danger can’t stay alive，”says Joseph LeDoux.Like animals，humans evolved with an elaborate mechanism for processing information about potential threats.At its core is a cluster of neurons deep in the brain.
LeDoux studies the way animals and humans respond to threats to understand how we form memories of significant events in our lives.The amygdala receives input from many parts of the brain，including regions responsible for retrieving memories.Using this information，the amygdala appraises a situation—I think this dog wants to bite me—and triggers a response by radiating nerve signals throughout the body.These signals produce the familiar signs of distress：trembling，perspiration and fast-moving feet，just to name three.
This fear mechanism is critical to the survival of all animals，but no one can say for sure whether beasts other than humans know they’re afraid.That is，as LeDoux says，“if you put that system into a brain that has consciousness，then you get the feeling of fear.”
Humans，says Edward M.Hallowell，have the ability to call up images of bad things that happened in the past and to anticipate future events.Combine these higher thought processes with our hardwired danger-detection systems，and you get a near-universal human phenomenon：worry.
That’s not necessarily a bad thing，says Hallowell.“When used properly，worry is an incredible device，”he says.After all，a little healthy worry is okay if it leads to constructive action like having a doctor look at that weird spot on your back.
Hallowell insists，though，that there’s a right way to worry.“Never do it alone，get the facts and then make a plan，”he says.Most of us have survived a recession，so we’re familiar with the belt-tightening strategies needed to survive a slump.
Unfortunately，few of us have much experience dealing with the threat of terrorism，so it’s been difficult to get facts about how we should respond.That’s why Hallowell believes it was okay for people to indulge some extreme worries last fall by asking doctors for Cipro and buying gas masks.
重点词汇：
biological 生物的，生物学的（adj.）
react 反应，回应（v./n.）
elaborate 复杂的；精密的（adj.）
mechanism 机制（n.）
potential 潜在的；潜力（adj./n.）
neurons 神经元（n.）
amygdala 杏仁体（n.）
retrieve 搜索（v.）
trembling 颤抖（n.）
perspiration 出汗；汗水（n.）(https://www.daowen.com)
anticipate 期待（v.）
incredible 难以置信的（adj.）
indulge 沉浸，沉溺（v.）
难句解析：
①Using this information，the amygdala appraises a situation—I think this dog wants to bite me—and triggers a response by radiating nerve signals throughout the body.
【结构分析】该句主干为the amygdala appraised a situation，Using this information是现在分词充当方式状语，破折号后的内容为对situation的解释。I think后的this dog wants to
为宾语从句
【理解难点】根据对并列结构的认知，trigger做appraise的并列谓语，and并列的前后成分一致，形式一致。
②Combine these higher thought processes with our hardwired danger-detection systems，and you get a near-universal human phenomenon：worry.
【结构分析】本句的结构是“祈使句+and+句子”，意思是“如果……那么……”，祈使句相当于一个if引导的条件状语从句。combine
with是固定搭配，意思是“……与……相结合”。
③That’s why Hallowell believes it was okay for people to indulge some extreme worries last fall by asking doctors for Cipro and buying gas masks.
【结构分析】本句的主干为主系表结构，表语为why引导的从句，表语从句中的主干为Hallowell believes。it was okay
为believes的宾语从句，从句为“it was+形容词+for sb.+to do sth.”句型，by asking
and buying是方式状语。
全文翻译：
从纯粹的生物学意义上讲，恐惧始于身体系统对可能伤害我们的事物做出反应也就是所谓的战斗或逃跑反应。“一个动物不能察觉到危险就无法生存下去，”勒杜说。像动物一样，人类进化出了精密的机制来处理关于潜在威协的信息。其核心是位于大脑深处的一束神经元。
勒杜研究动物和人类应对威胁的方式，以理解我们对生活中的重要事件是如何形成记忆的。杏仁体从大脑中的很多部位接受输入的信息包括负责提取记忆的区域。杏仁体利用这些信息评定一个现象：我认为狗想要咬我，触发器响应辐射整个身体的神经信号。这些信号产生熟悉的痛苦的迹象，颤抖、出汗和快速移动脚，或者三个迹象同时发生。
所有动物的这种恐惧机制对生存都是很重要的，但是没有人能确定除了人类，野兽是否也知道害怕。正如勒杜说：“如果你把这个系统变成一个大脑意识，那么你会感觉到恐惧。”
爱德华·哈洛威尔说，人类有能力调用过去发生的糟糕的事情图像和未来的预期事件。把这些高级思维过程与我们固有的危险探测系统相联系，您会获得一个几乎是人类所共有的现象：担心。
“这并不一定是坏事，”哈洛威尔说。“如果使用恰当，担忧是一个难以置信的策略。”毕竟，一些健康的担忧是正常的，如果它带来建设性的行动，比如你背上出现奇怪的斑点，那就得让医生检查一下。
然而，哈洛威尔坚持认为，可以以一种正确的方式去担心。“不能只是担心，要了解事实，然后制订一个计划，”他说。我们大多数人都在经济衰退中幸存了下来，所以我们熟悉渡过低潮的节约攻略。
不幸的是，很少有人有很多处理恐怖主义威胁的经验，因此，很难得到关于应该如何回应的事实。这就是为什么哈洛威尔相信允许人们去年秋天沉溺于一些极端的担忧是可以的，比如要求医生开环丙沙星和买防毒面具。