Your brain uses less power than your refrigerator light

The brain uses 12 watts of power, about the same amount of energy as in two large bananas. Curiously, even though the brain is very efficient, it's an energy hog. It is only 3 per cent of the body's weight, but consumes 1/6 (17 per cent) of the body's total energy. Most of its energy costs go into maintenance; the added cost of thinking hard is barely noticeableFrequent jet lag can damage memory

Jet lag is not simply annoying; in repeated doses it can be dangerous to your brain's health. People who often cross many time zones can experience brain damage and memory problems. This probably results from the stress hormones released during jet lag that are known to damage the temporal lobe and memory. You probably don't need to worry because, unless you work for an airline, few people fly across multiple time zones more often than every two weeks. Shift workers are more likely to be at risk. Like repeated jet travel, frequent drastic changes in working hours are likely to cause stress on the body and brain.

Why you can't hear phone conversations in a noisy room

Talking on your mobile phone in a noisy place can be difficult. Your mobile makes the brain's task harder by feeding sounds from the room you're in through its circuitry and mixing them with the sound it gets from the other phone. This makes it a harder problem for your brain to solve because your friend's transmitted voice and the room noise are tinny and mixed together in one source. Cover the mouthpiece when you're trying to hear your caller and you'll stop the mixing.

Shoot-'em-up video games can help you to multitask

Sustained multitasking increases your ability to pay attention to many things at the same time. A significant source of practice is playing action video games where the aim is to shoot as many enemies as possible before they shoot you. These games make you distribute attention across the screen, and quickly detect and react to events. Playing Tetris (an early puzzle-based video game) doesn't have the same effect, perhaps because you have to concentrate on only one object at a time, rather than multitask. Does this mean that you should encourage your kids to play shoot-'em-up action games? We wouldn't go out of our way to expose kids to violent images, but at least you can take heart that video game-playing has positive effects.

The brain has a joke centre

Humour is hard to define, but we know it when we see it. One theory suggests that humour consists of a surprise - we don't end up where we thought we were going - followed by a reinterpretation of what came earlier to make it fit the new perspective.

To make it a joke instead of a logic puzzle, the result needs to be a coherent story that isn't strictly sensible in everyday terms. Some patients with damage to the frontal lobe of their brain, particularly on the right side, don't get jokes at all. Typically, this is because they have trouble with the reinterpretation stage of the process. For instance, given a joke with a choice of punchlines, they can't tell which one is funny.

There's a reason you remember those annoying songsHaving a song or, more often, part of a song stuck in your head is incredibly frustrating. But sequence recall has a special and useful place in our memories. We constantly have to remember sequences, from the movements involved in signing our name or making coffee in the morning, to the names of the exits that come before the motorway turn-off we take to drive home every day.

The ability to recall these sequences makes many aspects of everyday life possible. As you think about a snippet of song or speech, your brain may repeat a sequence that strengthens the connections associated with that phrase. In turn, this increases the likelihood that you will recall it, which leads to more reinforcement.

You could break this unending cycle of repeated recall and reinforcement - which may be necessary for the normal strengthening and cementing of memories - by introducing other sequences. Thinking of another song may allow a competing memory to crowd out the first one: find another infectious song and hope that the cure doesn't become more annoying than the original problem.Sunlight makes you sneeze

Many people sneeze when they look into bright light. Why would we have such a reflex and how does it work? The basic function of a sneeze is fairly obvious: it expels substances or objects that are irritating your airways. The sneezing centre is located in the brainstem, in a region called the lateral medulla; damage to this site means that we lose the ability to sneeze.

Sneezing usually is triggered by news of an irritant that is sent through brain pathways and into the lateral medulla. This information gets to the brain from the nose through several nerves, including the trigeminal nerve, which carries a wide variety of signals from the face into the brainstem. It's a really crowded nerve, which might explain why bright light could induce a sneeze. A bright light, which would normally be expected to trigger pupil contraction, might also spill over to neighbouring sites, such as nerve fibres or neurons that carry nose-tickling sensations.

Bright light isn't the only unexpected sensation that is known to trigger sneezes; orgasm can also trigger sneezes in men. Fundamentally, a crossed-wire phenomenon, like the photic sneeze reflex, is possible because the circuitry of the brainstem is a jumbled, crowded mess.

You can't tickle yourself

When doctors examine a ticklish patient, they place his or her hand over theirs to prevent the tickling sensation. Why does this work? Because no matter how ticklish you may be, you can't tickle yourself.

This is because your brain keeps your senses focused on what's happening in the world; important signals aren't drowned out in the endless buzz of sensations caused by your actions. For instance, we are unaware of the feel of a chair and the texture of our socks, yet we immediately notice a tap on our shoulder.

To accomplish this goal, some brain region must be able to generate a signal that distinguishes our touch from someone else's. The cerebellum, or “little brain”, may be the answer. It is about 1/8 of our total brain size - a little smaller than our fist - and weighs about 4oz (113g). It is also the best candidate that scientists have for the part of the brain that predicts the sensory consequences of our own actions.

The cerebellum is in an ideal location for distinguishing expected from unexpected sensations. If a prediction matches the actual sensory information, then the brain knows that it's safe to ignore the sensation because it's not important. If reality does not match the prediction, then something surprising has happened - and you might need to pay attention.

Yawns wake up the brain

Although we associate yawning with sleepiness and boredom, its function appears to be to wake us up. Yawning expands our pharynx and larynx, allowing large amounts of air to pass into our lungs; oxygen then enters our blood, making us more alert. Many vertebrates do it, including all mammals and perhaps birds. It also has been observed in human foetuses after just 12 weeks of gestation. In non human primates, it is associated with tense situations and potential threats.

Think of yawns as your body's attempt to reach full alertness in situations that require it. They are contagious, as anyone who has attempted to teach a roomful of bored students knows. No one is sure why, though it might be advantageous to allow individuals quickly to transmit to one another a need for increased arousal. They are not contagious in non primate mammals, but the ability to recognise a yawn may be fairly general: dogs yawn in response to stressful situations and are thought to use yawning to calm others. You can even sometimes calm your dog by yawning.

Altitude makes the brain see strange visions

Many religions involve special visions that occurred at great heights. For example, Moses encountered a voice emanating from a burning bush on Mount Sinai and Muhammad was visited by an angel on Mount Hira. Commonly reported spiritual experiences include feeling and hearing a presence, seeing a figure, seeing lights (sometimes emanating from a person) and being afraid.

Similar phenomena are reported by mountain climbers, a group generally not thought to be very mystical. Could it be something about the mountains? Acute mountain sickness occurs above altitudes of 8,000ft (2,400m). Many of the effects are attributable to the reduced supply of oxygen to the brain. At 8,000ft or higher, some mountaineers report perceiving unseen companions, seeing light emanating from themselves or others, seeing a second body like their own, and suddenly feeling emotions such as fear. Oxygen deprivation is likely to interfere with brain regions active in visual and face processing, and in emotional events.

大腦的功率比冰箱上燈的功率還小

大腦的功率為12瓦，用的能量與兩只大香蕉所含的能量相當(dāng)。奇怪的是，大腦的效率即使很高，還是一個(gè)能量婪食者。它只占身體重量的百分之三，但消耗身體全部能量的六分之一(百分之十七)。所消耗能量的大部分用于維持正�；顒�(dòng)；冥思苦想所另外消耗的能量幾乎覺察不到。

頻繁的高速飛行引起生理節(jié)奏的改變可損害記憶力

高速飛行引起生理節(jié)奏的改變不僅僅使人心情煩燥，經(jīng)常這樣作對(duì)于大腦的健康也是危險(xiǎn)的。經(jīng)常穿越多個(gè)時(shí)區(qū)的人可遭遇腦損害及記憶問題。這可能是由于高速飛行期間分泌的應(yīng)激激素的緣故，人們已知應(yīng)激激素可損害顳葉和記憶力。你不必?fù)?dān)心，因?yàn)楹苌儆腥吮让績(jī)蓚�(gè)星期一次更頻繁地穿越多個(gè)時(shí)區(qū)，除非你在航空公司工作。輪班工人的危險(xiǎn)性可能更大一些。與經(jīng)常性的高速飛行一樣，頻繁地大幅度地變化工作時(shí)間可引起身體和大腦的應(yīng)激反應(yīng)。

在吵雜的房子里，為什么聽不到電話里的談話

在吵雜的地方用手機(jī)講話可能是困難的。由于你的手機(jī)將來(lái)自你所在房間的聲音通過電路傳送出去并將其與從另一部電話得到的聲音混合，這使得你的手機(jī)將大腦的任務(wù)弄得更為艱難。因?yàn)槟闩笥褌鱽?lái)的聲音和房間的聲音細(xì)弱無(wú)力，且共同混合成一個(gè)聲音源。所以這就給大腦出了一道難題。當(dāng)你試圖聽見對(duì)方電話的時(shí)候，蓋住話筒，這樣停止了聲音的混合。

射擊類電視游戲可幫助你一心多用

持之以恒的一心多用練習(xí)可提高同時(shí)注意多個(gè)事件的能力。一個(gè)重要的練習(xí)來(lái)源是玩動(dòng)作電視游戲，它的目標(biāo)是在敵人射擊你之前盡可能多地射擊敵人。這些游戲使你將注意力分散到整個(gè)屏幕，迅速發(fā)現(xiàn)事件并作出反應(yīng)。玩Tetris(我們稱之為俄羅斯方塊)(一種過時(shí)的電視游戲)沒有相同的效果，也許是因?yàn)閷⒆⒁饬�集中到一個(gè)目標(biāo)上的緣故。這意味著應(yīng)當(dāng)鼓勵(lì)孩子去玩動(dòng)作電視游戲嗎？我們不愿走將暴力畫面暴露給孩子這條路，但至少可以明白玩電視游戲具有正面效應(yīng)。

大腦有一個(gè)玩笑中心

很難給幽默一個(gè)定義，但當(dāng)我們遇到它的時(shí)候也就認(rèn)識(shí)了它。幽默由驚奇(沒在我們?cè)�想的地方結(jié)束)構(gòu)成，接著是對(duì)先前內(nèi)容的解釋使之符合新的觀點(diǎn)。
編一個(gè)并非邏輯問題的笑話，其結(jié)果必須是一個(gè)連貫的按日常條框并不很具欣賞性的故事。一些大腦額部特別是右側(cè)受損的病人根本感覺不到幽默。這一般是因?yàn)樘幚磉^程的重新解釋階段出了問題。比如，給他們一個(gè)帶有妙語(yǔ)選擇的笑話，他們不明白那一個(gè)可笑。

記住那些煩人的歌曲是有原因的

頭腦中牢記一首歌曲，或更多的時(shí)候是一首歌曲的一部分，很讓人灰心喪氣。但是次序回憶在我們的記憶當(dāng)中發(fā)揮著特殊而有益的作用。我們不得不堅(jiān)持不懈地記住一些次序，從簽名或早晨煮咖啡所涉及的動(dòng)作到汽車道關(guān)閉之前駕車回家所經(jīng)過的出口的名稱。

回想起這些次序的能力使得日常生活的許多方面成為可能。當(dāng)你想起一首歌曲或一段話的某一片段時(shí)，你有大腦也許在重復(fù)著一個(gè)次序，這個(gè)次序強(qiáng)化了與那個(gè)片段有關(guān)的聯(lián)系。反過來(lái)這又增加了你回想它的可能性，回想又導(dǎo)致進(jìn)一步強(qiáng)化。

你可以通過引入另外的次序來(lái)打破這個(gè)一遍又一遍回想并不斷強(qiáng)化的沒完沒了的循環(huán)---這對(duì)正常記憶的強(qiáng)化和鞏固是來(lái)說是必不可少的。想想另一首歌曲可引起競(jìng)爭(zhēng)記憶而將第一首歌曲排擠出去。找到另一首具有感染力的歌曲希望這副良藥不再變得比原來(lái)的問題更煩人。

陽(yáng)光使人打噴嚏

許多人望見明亮的光線時(shí)就打噴嚏。為什么我們具有這樣的反射作用而這是什么原因呢？噴嚏的基本作用是顯而易見的：它將刺激呼吸道的物質(zhì)或物體噴射出去。噴嚏中心區(qū)位于腦干，在一個(gè)被稱作外側(cè)腦髓的區(qū)域，此處的損壞意味著失去打噴嚏的能力。

打噴嚏通常由經(jīng)過腦路而進(jìn)入外側(cè)腦髓的刺激信號(hào)觸發(fā)。這個(gè)信息由鼻子經(jīng)過包括三叉神經(jīng)在內(nèi)的好幾條神經(jīng)到達(dá)腦干，三叉神經(jīng)承擔(dān)著從面部到腦干的一系列信號(hào)的傳遞。它真是一條擁擠的神經(jīng)，這也就解釋了明亮光線誘發(fā)噴嚏的原因。一道通常被認(rèn)為引起瞳孔收縮的明亮的光線，也可溢出到相鄰區(qū)，如傳遞鼻子反饋感覺的神經(jīng)纖維或神經(jīng)元。

明亮的光線并不是已知唯一的意想不到的觸發(fā)噴嚏的感覺，極度興奮也可誘發(fā)男子打噴嚏。從根本上講，由于腦干線路是擁擠且雜亂無(wú)章的，象光引起噴嚏反射這類交叉現(xiàn)象是可能的。

你不能把自己逗癢

當(dāng)醫(yī)生們檢查一位容易發(fā)癢的病人時(shí)，他們把他或她的手放到自己的手上以防癢感。這是怎么回事呢？這是因?yàn)闊o(wú)論你是怎么一位易發(fā)癢的人，你都不能把自己逗癢。

這是因?yàn)槟愕拇竽X將你的感覺集中到世上正發(fā)生的事上，重要的信號(hào)沒有淹沒在無(wú)窮無(wú)盡的由你的行為引起的的感覺的噪音當(dāng)中。例如，我們意識(shí)不到一把椅子或短襪圖案引起的感覺，但我們立刻注意到肩膀上的輕拍。

為達(dá)到這一目的，有些腦區(qū)必須能發(fā)出一個(gè)信號(hào)將我們自己的觸摸與他人的區(qū)分開來(lái)。小腦實(shí)現(xiàn)這一功能。小腦為整個(gè)腦大小的1/8(比拳頭略小)重量約為40z(133克)。

小腦處在將意料中的感覺和意想不到的感覺分辨開來(lái)的理想位置。如果實(shí)際感覺信息與預(yù)料的相符，那么大腦就明白忽略這一感覺是安全的，因?yàn)樗�不重要。如果現(xiàn)實(shí)與預(yù)料的不符，那么一定發(fā)生了驚人的事，你須注意 。

打哈欠使頭腦清醒

雖然我們把打哈欠與睡意和厭倦聯(lián)系在一起，但打哈欠的作用似乎是使人清醒。打哈欠擴(kuò)張咽喉，使大量的空氣進(jìn)入肺部，氧氣然后進(jìn)入血液使人更機(jī)警。包括哺乳類和鳥類在內(nèi)的脊椎動(dòng)物都這樣作。在懷孕只有12周之后的人類嬰兒當(dāng)中也觀察到這種現(xiàn)象。在非人類靈長(zhǎng)類動(dòng)物中，這與緊張境遇和潛在危協(xié)有關(guān)。

把哈欠看作身體在需要的時(shí)候?yàn)檫_(dá)到高度機(jī)警狀態(tài)所作的努力。哈欠具有傳染性，這點(diǎn)教過一屋子學(xué)生的人都知道。雖然這有利于將需要喚醒的信息很快傳遞給另一個(gè)人，但確切原因無(wú)人能知。哈欠在非靈長(zhǎng)哺乳動(dòng)物間沒有傳染性，但是分辨哈欠的能力卻是相同的：有時(shí)你甚至可以通過打哈欠來(lái)使你的狗平靜下來(lái)。

高度使大腦產(chǎn)生奇怪的視覺

許多宗教都涉及到發(fā)生在很高地方的特殊視覺。例如，莫西在西奈山上遭遇了從著火的灌木叢中發(fā)的聲音而穆罕默德在Hira山上遇到一位天使。被普遍報(bào)道的精神體驗(yàn)包括：感到或聽到一位精靈，看見一個(gè)人物，看見光線(有時(shí)從一個(gè)人身上發(fā)出)以及感到恐懼。

一群普遍認(rèn)為不很神秘的登山者報(bào)告了類似的現(xiàn)象。這可能與山有關(guān)嗎？嚴(yán)重的高山病發(fā)生在8000英尺(2400米)之上。其中多數(shù)是大腦供氧量減少的原因。有些登山運(yùn)動(dòng)員報(bào)告說感到無(wú)形的伴侶的存在，看見光線從自己或它人身上發(fā)出，看見第二個(gè)和他們一樣的身軀以及突然產(chǎn)生象恐懼這樣的情緒。氧氣的喪失對(duì)涉及視覺和面部表情處理過程及情緒方面的腦區(qū)域產(chǎn)生了干擾