Can milk make you happy?
　　 Can fish make you smart?
　　 Imagine yourself lying in bed, your mind in turmoil. You toss and turn, but sleep won't come. Maybe a bedtime snack would help. What should you choose? If you think first of toaster waffles or popcorn, some experts would say you're on the right track. Foods high in complex carbohydrates-such as cereals, potatoes, pasta, crackers, or rice cakes-make many people relaxed and drowsy.
　　 Missed that one? Try again. Suppose the weather's rotten, you forgot your homework, and your best friend's mad at you. What's good medicine when you're feeling low? A sugary cola or candy may give you a quick lift, but you'll crash just as quickly. Better choices may be Brazil nuts (for selenium), skim milk (for calcium), or a spinach salad (for folic acid). In research studies, all three of those nutrients have been shown to lift spirits and battle the blues.
　　 Try one more. You have a math test coming up in the afternoon. You want to be sharp, but you usually feel sleepy after lunch. Is your best choice an energy fix of fries and a shake or a broiled chicken breast and low-fat yogurt? If you pick the high-fat fries and shake, you may feel sluggish and blow that test. The protein-rich chicken and yogurt are better choices. Protein foods energize, some experts say.
　　 How does food affect mood and mind? The answer may lie in the chemistry of the brain and nervous system. Molecules called neurotransmitters 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 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 its reuptake (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.
　　 考研詞匯：
　　 drowsy[ˈdrauzi]
　　 a.昏昏欲睡的, 催眠的, (街、市等)沉寂的
　　 skim[skim]
　　 n.脫脂 v.撇去，去除;瀏覽，略讀
　　 impulse[ ˈimpʌls]
　　 v.推動;n.①推動;②沖動，刺激
　　 [真題例句] As a result, the support for ambition as a healthy impulse (n.②), a quality to be admired and fixed in the mind of the young, is probably lower than it has ever been in the United States.[2000年閱讀5]
　　 [例句精譯] 因此，在美國，作為一種健康的沖動，一種應(yīng)該令人稱羨并扎根于青年人心靈的品質(zhì)的雄心，它所得到的支持也許比以往任何時期都低。
　　 obstacle[ˈɔbstəkl]
　　 n.障礙，妨礙，干擾
　　 [真題例句] The process is not the road itself, but rather the attitudes and feelings people have, their caution or courage, as they encounter new experiences and unexpected obstacles.[1995年閱讀2]
　　 [例句精譯] 成長過程不是道路本身，而是當(dāng)遇到新情況或意外困難時所持的態(tài)度和情感，是慎重行事還是勇往直前。
　　 relaxation[ri:lækˈseiʃən]
　　 n.放松，松弛，娛樂
　　 [真題例句] (72) Children will play with dolls equipped with personality chips, computers with in-built personalities will be regarded as workmates rather than tools, relaxation will be in front of smell television, and digital age will have arrived.[2001年翻譯]
　　 [例句精譯] (72)兒童將與裝有個性化芯片的玩具娃娃玩耍，具有個性內(nèi)置的計算機將被視為工作伙伴而不是工具，人們將在氣味電視機前休閑，屆時數(shù)字化時代就來到了。
　　 enhance[inˈhɑ:ns]
　　 v.提高，增強
　　 [真題例句] 52. In the passage, which of the following is NOT included in the advantages of advertising?[1995年閱讀1]
　　 [C] Enhancing living standards.
　　 [例句精譯] 52�北疚闹�，廣告的優(yōu)點不包括下列哪項?
　　 [C] 提高生活水平。

　　背景常識介紹： 
　　"醫(yī)學(xué)之父"希波克拉底說過："讓食物變成你的藥，讓藥變成你的食物。"作為一個生于公元前五世紀(jì)的希臘人，他的智慧遠遠超越了他所處的時代。如今，我們知道低脂肪而富含全麥、水果和蔬菜的飲食結(jié)構(gòu)能增強我們的免疫力，并能減少癌癥、心臟病和中風(fēng)的發(fā)病率。
　　但是，這些還不完全。新的證據(jù)顯示食品可能會影響健康人的思考和感覺方式。如果希波克拉底今天還在世的話，他也許會回顧他吃過的最后一頓飯，解釋他興奮(或憂傷)的心情。他可能還會改變自己的飲食習(xí)慣，使自己變得更幸�；蚋�聰明��
　　參考譯文：
　　喝牛奶能讓你快樂嗎?吃魚能使你變聰明嗎?
　　設(shè)想一下你躺在床上，腦子里一片混亂。你輾轉(zhuǎn)反側(cè)，但總也睡不著。也許睡覺時吃點零食會有幫助。你應(yīng)當(dāng)吃什么呢?如果你的首選是威化餅或爆米花，那么一些專家就會說你選對了。麥片、土豆、面食、餅干或米糕這些富含復(fù)合碳水化合物的食品會使人感到放松和困倦。
　　你選錯了嗎?再試一次。假如天氣很糟，你忘了做家庭作業(yè)，而你的好朋友又對你大發(fā)雷霆。在你情緒低落之時，對你來說什么是一劑良藥呢?一杯甜可樂或一塊糖可能會使你情緒很快高漲，但你的情緒又會很快地進入低潮。更好的選擇是吃一些巴西胡桃(獲得更多的硒)，脫脂牛奶(獲得更多的鈣)，或菠菜沙拉(獲得更多的葉酸)。研究表明，上述三種營養(yǎng)素都會使人們情緒高漲，擺脫憂慮。
　　再試一次吧。下午你有數(shù)學(xué)測驗。你想要精力充沛，可你總是在午飯后感到昏昏欲睡。能使你精神飽滿地面對考試的最佳食品是炸薯條和奶昔，還是雞胸肉和低脂酸奶?如果你選中了高脂肪的炸薯條和奶昔，你就會感到非常懶散，很可能考砸了。高蛋白的雞肉和酸奶是較好的選擇。有些專家說蛋白質(zhì)食品給人們提供能量。
　　食物如何影響情緒和思維?答案可能要到大腦和神經(jīng)系統(tǒng)的化學(xué)結(jié)構(gòu)中去找。被稱為神經(jīng)遞質(zhì)的分子是化學(xué)信使。它們把神經(jīng)沖動帶到神經(jīng)細(xì)胞之間的空隙中。神經(jīng)遞質(zhì)分子從一個神經(jīng)原釋放后，附著到另一個接受點，令神經(jīng)沖動保持運動的狀態(tài)。
　　神經(jīng)沖動能夠把周邊環(huán)境的信息帶到大腦中--例如，當(dāng)你腳趾被絆了一下時，你會感到疼。它們也能從反方向傳遞信息，比如說從大腦到肌肉。這就是為什么當(dāng)障礙物產(chǎn)生疼痛的信號時，你就會躲開障礙物，并且喊："哎喲!"
　　華盛頓大學(xué)的神經(jīng)科學(xué)家埃里克•查德勒說："許多神經(jīng)遞質(zhì)是靠我們所吃的食物形成的。" 查德勒指出過多或過少地通過飲食攝入一種營養(yǎng)素可以影響這些神經(jīng)遞質(zhì)的形成。例如，來自諸如酸奶、牛奶、香蕉和雞蛋的色氨酸會產(chǎn)生神經(jīng)遞質(zhì)的血清素。來自甜菜、杏仁、雞蛋、肉和谷物中的苯基丙胺酸會形成神經(jīng)遞質(zhì)的多巴胺。
　　我們已知的神經(jīng)遞質(zhì)有幾十種，實際存在的可能有幾百種。它們產(chǎn)生的效果取決于本身的數(shù)量和它們在大腦中工作的位置。例如，神經(jīng)遞質(zhì)血清素被認(rèn)為會產(chǎn)生平靜、放松和滿足的感覺。治療情緒低落時，大夫就開出一些能夠防止它返回(即進入到釋放出它的神經(jīng)元中)的藥。至少在一些健康和情緒不低落的人當(dāng)中，碳水化合物食物似乎能夠促進血清素的生成并能產(chǎn)生類似效應(yīng)。查德勒說："不同神經(jīng)遞質(zhì)之間的平衡幫助調(diào)節(jié)人的情緒。"
　　恰當(dāng)?shù)臓I養(yǎng)能提高人的大腦思考能力。膽堿是一種類似于維生素B的物質(zhì)。它存在于蛋黃、全麥、花生、牛奶、菜豆、肝、蠶豆、海鮮和黃豆中。大腦利用這種物質(zhì)生成神經(jīng)遞質(zhì)的乙酰膽堿。為了檢測膽堿對記憶和學(xué)習(xí)的影響，麻省理工學(xué)院的研究者們對大學(xué)生進行了記憶測驗。隨后，他們在被試驗者的飲食中增加膽堿的量，重新做了實驗。從總體上來看，學(xué)生的記憶力有所提高，能夠更加容易地學(xué)會一系列不相關(guān)的單詞�！�