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.

大脑的功率比冰箱上灯的功率还小

大脑的功率为12瓦，用的能量与两只大香蕉所含的能量相当。奇怪的是，大脑的效率即使很高，还是一个能量婪食者。它只占身体重量的百分之三，但消耗身体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维持正常活动；冥思苦想所另外消耗的能量几乎觉察不到。

频繁的高速飞行引起生理节奏的改变可损害记忆力

高速飞行引起生理节奏的改变不仅仅使人心情烦燥，经常这样作对于大脑的健康也是危险的。经常穿越多个时区的人可遭遇脑损害及记忆问题。这可能是由于高速飞行期间分泌的应激激素的缘故，人们已知应激激素可损害颞叶和记忆力。你不必担心，因为很少有人比每两个星期一次更频繁地穿越多个时区，除非你在航空公司工作。轮班工人的危险性可能更大一些。与经常性的高速飞行一样，频繁地大幅度地变化工作时间可引起身体和大脑的应激反应。

在吵杂的房子里，为什么听不到电话里的谈话

在吵杂的地方用手机讲话可能是困难的。由于你的手机将来自你所在房间的声音通过电路传送出去并将其与从另一部电话得到的声音混合，这使得你的手机将大脑的任务弄得更为艰难。因为你朋友传来的声音和房间的声音细弱无力，且共同混合成一个声音源。所以这就给大脑出了一道难题。当你试图听见对方电话的时候，盖住话筒，这样停止了声音的混合。

射击类电视游戏可帮助你一心多用

持之以恒的一心多用练习可提高同时注意多个事件的能力。一个重要的练习来源是玩动作电视游戏，它的目标是在敌人射击你之前尽可能多地射击敌人。这些游戏使你将注意力分散到整个屏幕，迅速发现事件并作出反应。玩Tetris(我们称之为俄罗斯方块)(一种过时的电视游戏)没有相同的效果，也许是因为将注意力集中到一个目标上的缘故。这意味着应当鼓励孩子去玩动作电视游戏吗？我们不愿走将暴力画面暴露给孩子这条路，但至少可以明白玩电视游戏具有正面效应。

大脑有一个玩笑中心

很难给幽默一个定义，但当我们遇到它的时候也就认识了它。幽默由惊奇(没在我们原想的地方结束)构成，接着是对先前内容的解释使之符合新的观点。
编一个并非逻辑问题的笑话，其结果必须是一个连贯的按日常条框并不很具欣赏性的故事。一些大脑额部特别是右侧受损的病人根本感觉不到幽默。这一般是因为处理过程的重新解释阶段出了问题。比如，给他们一个带有妙语选择的笑话，他们不明白那一个可笑。

记住那些烦人的歌曲是有原因的

头脑中牢记一首歌曲，或更多的时候是一首歌曲的一部分，很让人灰心丧气。但是次序回忆在我们的记忆当中发挥着特殊而有益的作用。我们不得不坚持不懈地记住一些次序，从签名或早晨煮咖啡所涉及的动作到汽车道关闭之前驾车回家所经过的出口的名称。

回想起这些次序的能力使得日常生活的许多方面成为可能。当你想起一首歌曲或一段话的某一片段时，你有大脑也许在重复着一个次序，这个次序强化了与那个片段有关的联系。反过来这又增加了你回想它的可能性，回想又导致进一步强化。

你可以通过引入另外的次序来打破这个一遍又一遍回想并不断强化的没完没了的循环---这对正常记忆的强化和巩固是来说是必不可少的。想想另一首歌曲可引起竞争记忆而将第一首歌曲排挤出去。找到另一首具有感染力的歌曲希望这副良药不再变得比原来的问题更烦人。

阳光使人打喷嚏

许多人望见明亮的光线时就打喷嚏。为什么我们具有这样的反射作用而这是什么原因呢？喷嚏的基本作用是显而易见的：它将刺激呼吸道的物质或物体喷射出去。喷嚏中心区位于脑干，在一个被称作外侧脑髓的区域，此处的损坏意味着失去打喷嚏的能力。

打喷嚏通常由经过脑路而进入外侧脑髓的刺激信号触发。这个信息由鼻子经过包括三叉神经在内的好几条神经到达脑干，三叉神经承担着从面部到脑干的一系列信号的传递。它真是一条拥挤的神经，这也就解释了明亮光线诱发喷嚏的原因。一道通常被认为引起瞳孔收缩的明亮的光线，也可溢出到相邻区，如传递鼻子反馈感觉的神经纤维或神经元。

明亮的光线并不是已知唯一的意想不到的触发喷嚏的感觉，极度兴奋也可诱发男子打喷嚏。从根本上讲，由于脑干线路是拥挤且杂乱无章的，象光引起喷嚏反射这类交叉现象是可能的。

你不能把自己逗痒

当医生们检查一位容易发痒的病人时，他们把他或她的手放到自己的手上以防痒感。这是怎么回事呢？这是因为无论你是怎么一位易发痒的人，你都不能把自己逗痒。

这是因为你的大脑将你的感觉集中到世上正发生的事上，重要的信号没有淹没在无穷无尽的由你的行为引起的的感觉的噪音当中。例如，我们意识不到一把椅子或短袜图案引起的感觉，但我们立刻注意到肩膀上的轻拍。

为达到这一目的，有些脑区必须能发出一个信号将我们自己的触摸与他人的区分开来。小脑实现这一功能。小脑为整个脑大小的1/8(比拳头略小)重量约为40z(133克)。

小脑处在将意料中的感觉和意想不到的感觉分辨开来的理想位置。如果实际感觉信息与预料的相符，那么大脑就明白忽略这一感觉是安全的，因为它不重要。如果现实与预料的不符，那么一定发生了惊人的事，你须注意 。

打哈欠使头脑清醒

虽然我们把打哈欠与睡意和厌倦联系在一起，但打哈欠的作用似乎是使人清醒。打哈欠扩张咽喉，使大量的空气进入肺部，氧气然后进入血液使人更机警。包括哺乳类和鸟类在内的脊椎动物都这样作。在怀孕只有12周之后的人类婴儿当中也观察到这种现象。在非人类灵长类动物中，这与紧张境遇和潜在危协有关。

把哈欠看作身体在需要的时候为达到高度机警状态所作的努力。哈欠具有传染性，这点教过一屋子学生的人都知道。虽然这有利于将需要唤醒的信息很快传递给另一个人，但确切原因无人能知。哈欠在非灵长哺乳动物间没有传染性，但是分辨哈欠的能力却是相同的：有时你甚至可以通过打哈欠来使你的狗平静下来。

高度使大脑产生奇怪的视觉

许多宗教都涉及到发生在很高地方的特殊视觉。例如，莫西在西奈山上遭遇了从着火的灌木丛中发的声音而穆罕默德在Hira山上遇到一位天使。被普遍报道的精神体验包括：感到或听到一位精灵，看见一个人物，看见光线(有时从一个人身上发出)以及感到恐惧。

一群普遍认为不很神秘的登山者报告了类似的现象。这可能与山有关吗？严重的高山病发生在8000英尺(2400米)之上。其中多数是大脑供氧量减少的原因。有些登山运动员报告说感到无形的伴侣的存在，看见光线从自己或它人身上发出，看见第二个和他们一样的身躯以及突然产生象恐惧这样的情绪。氧气的丧失对涉及视觉和面部表情处理过程及情绪方面的脑区域产生了干扰