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  3. How does food affect mood and mind? The answer may he in the chemistry of the brain and nervous system. Molecules called neurotr

How does food affect mood and mind? The answer may he in the chemistry of the brain and nervous system. Molecules called neurotr

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问题     How does food affect mood and mind? The answer may he in the chemistry of the brain and nervous system. Molecules called neurotransmitters(神经传递素)are chemical messengers. They carry a nerve impulse across the gap between nerve cells. The release of neurotransmitter molecules from one neuron and their attachment to receptor sites on another keep a nerve impulse moving.
    Nerve impulses carry messages from the environment to the brain, for example, the pain you feel when you stub(踢碰)your toe. They also carry messages in the other direction, from the brain to the muscles. That’s why you back away from the obstacle that initiated the pain signal and exclaim, "Ouch!"
    "Many neurotransmitters are built from the foods we eat," says neuroscientist Eric Chudler of the University of Washington. Too little or too much of a particular nutrient in the diet can affect their production, Chudler says. For example, tryptophan from foods such as yogurt, milk, bananas, and eggs is required for the production of the neurotransmitter serotonin. Phenylalanine from beets, almonds, eggs, meat, and grains goes into making the neurotransmitter dopamine.
    Dozens of neurotransmitters are known; hundreds may exist. Their effects depend on their amounts and where they work in the brain. The neurotransmitter serotonin, for example, is thought to produce feelings of calmness, relaxation, and contentment. Drugs that prevent it from being taken again(into the neuron that released it)are prescribed to treat depression. In at least some healthy, nondepressed people, carbohydrate foods seem to enhance serotonin production and produce similar effects. "It is the balance between different neurotransmitters that helps regulate mood," Chudler says.
    Proper nutrition may also enhance brainpower. Choline is a substance similar to the B vitamins. It’s found in egg yolks, whole wheat, peanuts, milk, green peas, liver, beans, seafood, and soybeans. The brain uses it to make the neurotransmitter acetylcholine. To test the effects of choline on memory and learning, researchers at the Massachusetts Institute of Technology gave memory tests to college students before increasing the amount of choline in their subjects’ diets. Later, they retested. On the average, memories were better, and the students learned a list of unrelated words more easily.
What is the message the author intends to convey?
选项 A、The chemistry of the brain and nervous system.
B、The influence of foods on our mood and mind.
C、The functions of neurotransmitters.
D、The importance of a balanced diet.
答案B
解析 本文首句提出的问题是全文要解答的问题，也就是说，全文围绕这个问题展开讨论，由此可见，本文是为了说明食物对情绪和思维的影响，因此，本题应选B。A可以说是第1段至第4段的主要内容，C是第1段的内容，均没有全面概括全文内容。D中的balanced diet在文中不断提及，但本文的重点不是为了说明均衡饮食的重要性，而是饮食和情绪、思维的关系。
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