听力原文

【英文原文】

When you experience something new, do you know what happens to your brain?

Some of the neurons in your brain build new connections. The brain is rewired, as scientists often put it. Our brains are always changing, in response to new experiences or as a result of learning new information. That’s how we’re able to learn and remember new experiences and information.

However, the brain reacts quite differently when a person is exposed to drugs such as cocaine.

Evidence indicates that prior use of some drugs impairs the brain’s ability to forge new connections between neurons in response to new experiences. Scientists took a bunch of rats and gave some of them either amphetamine or cocaine for twenty days, while giving the others a saline solution for twenty days.

When the twenty days were up, half of the rats were moved from ordinary laboratory cages to fancy new cages equipped with all kinds of bridges, ramps, tunnels, and other toys. After three and half months the scientists examined all of the rats brains.

They discovered that the saline solution rats that were moved to the new cages had a greater number of neuronal connections than all the other rats, including the drugged rats in the new cages. These findings may aid in explaining some of the behavioral and cognitive impairments viewed in people who are addicted to drugs.

重点词汇

1.neurons n. [医]神经原，神经细胞（neuron的复数形式）

Preliminary efforts confirm that specific groups of neurons express the types of perceptions that form our daily experiences.
初步努力的结果证实，特定神经元群表现出的知觉类型，进而形成了日常经验。

2. impair vt. 损害；削弱；减少

Are you taking medications that could impair your ability to think, work, operate machinery, or drive?
你吃药是否会影响你的思考能力、工作、操作机器或者开车的能力吗？

3.forge vt. 伪造；锻造

The smith forged the horseshoe with great skill.
那铁匠非常熟练地锻造马蹄铁。

4. saline adj. 盐的；含盐分的

A nurse confided to him the injections were often just saline solution.
一个护士透露他们给病人注射的通常就是盐溶液而已。

5.behavioral adj. 行为的

How to transform chance constraint is a key problem in the optimization of behavioral portfolio.
在行为投资组合优化过程中，机会约束的转化是一个关键问题。