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"I couldn't get my body to stop shaking. I was trembling constantly, trembling and...memories of it would just come back, reoccurring over, over and over."

Beatriz Arguedas is a subway conductor, driving her normal route on the Red Line in Boston, when one of her worst fears came to pass.

"For I'm entering, one of the busiest stations, a man jumped in front of my train to commit suicide."

(Entering, path three ...)

"You actually saw him jumping?"

"I saw him jump, we, sort of made eye contact. And then I felt the thud, found him hitting the train, and then the crackling sound underneath 1 the train. And then, of course, my heart started thumping 2."

"She came into our, into our emergency room afterwards, very upset, no physical injury, entirely 4, a psychological trauma 5."

Doctor Roger Pitman is a psychiatrist 6 at Harvard Medical School who has studied and treated patients with Post-traumatic Stress Disorder 7, or PTSD for 25 years.

"They are caught up so much with this past event that is constantly in their mind. They are living in it over and over and over as if it's happening again, and they just can't get involved in real life."

When Beatriz arrived in the emergency room, Pitman enrolled 8 her in an experimental study of a drug called propranolol, a medication commonly used for high-blood pressure and unofficially for stage fright. Pitman thought it might do something almost magical: Trick Beatriz's brain into making a weaker memory of the event she had just experienced. In the study that is still underway, half the subjects get propranolol, half get placebo 9.

"Did you know whether she got the drug?"

"No, I didn't."

"You have no idea?"

"We have no idea, and she has no idea."

"Till this day?"

"And we'll have it for another two years."

"Almost she finds out ..."

If Pitman is right, the results could fundamentally change the way accident victims, rape 10 victims, even soldiers are treated after they experienced trauma. The story begins with some surprising discoveries about memory. It turns out our memories are sort of like jello 11, they take time to...and while they are setting , it's possible to make them stronger or weaker. It all depends on the stress hormone--adrenalin.

The man who discovered this is James McGaugh, a professor of neurobiology at the University of California, Irvine. McGaugh studies memory in rats, and he invited us to watch the making of a rat memory. In this case, how a rat who's never been in this tank of water before learns how to find a clear plastic platform just below the surface.

"Well, he'll swim around, randomly 12, and he does not..."

"Can he not see the platform?"

"No, he can't see the platform. His eyes are on the top of his head."

The rat will swim around the edge for a long time, until eventually, he ventures out, and by chance bumps into the platform. The next day, he'll find the platform a little bit faster. But watch this rat, who learnt where the platform was yesterday, then received a shot of adrenalin immediately afterward 3.

"Notice it starts out not on the edge."

"Wow!"

"There you go!"

"Oh! That's impressive."

Adrenalin actually made this rat's brain remember better, and McGaugh believes the same thing happens in people.

"Suppose I said to you: You know, I've, I've watched your programs a lot over the years. And although it pains me that I have to tell you this I think you are one of the worst people I've ever seen on...(Ha ha..) And don't take it, don't take it personally."

"So my stress system would go into overdrive, no question."

"Even, even with my telling you that it's not true. There is nothing to keep you from blushing, from feeling warm all over."

"I am warm all over."

"Yeah!"

"I am, no joke. Really."

"That's your adrenalin. And I dare say that you are going to remember my having said that long after you've forgotten the other details of our discussion here, I guarantee it."

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thud:a low sound made by something heavy falling or hitting something 抨击声
trauma:medical a serious injury 外伤
propranolol:a beta-blocker used to treat hypertension, angina pectoris, and cardiac arrhythmia 心得安
placebo:a substance that is not medicine but that a patient who is taking it believes is medicine, so they get better 安慰剂
jello:a soft solid food made from fruit juice, sugar,and gelatin that you can see through and that shakes when you touch it 凝胶物
neurobiology:the branch of biology that deals with the anatomy and physiology and pathology of the nervous system神经生物学