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[TED] 【TED】睡眠到底有多重要?

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发表于 2017-4-17 23:47:34 | 显示全部楼层 |阅读模式



0:11

Sleep. It's something we spend about a third of our lives doing, but do any of us really understand what it's all about?

0:19

Two thousand years ago, Galen, one of the most prominent medical researchers of the ancient world, proposed that while we're awake, our brain's motive force, its juice, would flow out to all the other parts of the body, animating them but leaving the brain all dried up, and he thought that when we sleep, all this moisture that filled the rest of the body would come rushing back, rehydrating the brain and refreshing the mind. Now, that sounds completely ridiculous to us now, but Galen was simply trying to explain something about sleep that we all deal with every day. See, we all know based on our own experience that when you sleep, it clears your mind, and when you don't sleep, it leaves your mind murky. But while we know a great deal more about sleep now than when Galen was around, we still haven't understood why it is that sleep, of all of our activities, has this incredible restorative function for the mind.

1:17

So today I want to tell you about some recent research that may shed new light on this question. We've found that sleep may actually be a kind of elegant design solution to some of the brain's most basic needs, a unique way that the brain meets the high demands and the narrow margins that set it apart from all the other organs of the body.

1:41

So almost all the biology that we observe can be thought of as a series of problems and their corresponding solutions, and the first problem that every organ must solve is a continuous supply of nutrients to fuel all those cells of the body. In the brain, that is especially critical; its intense electrical activity uses up a quarter of the body's entire energy supply, even though the brain accounts for only about two percent of the body's mass. So the circulatory system solves the nutrient delivery problem by sending blood vessels to supply nutrients and oxygen to every corner of our body.

2:19

You can actually see it in this video here. Here, we're imaging blood vessels in the brain of a living mouse. The blood vessels form a complex network that fills the entire brain volume. They start at the surface of the brain, and then they dive down into the tissue itself, and as they spread out, they supply nutrients and oxygen to each and every cell in the brain.

2:44

Now, just as every cell requires nutrients to fuel it, every cell also produces waste as a byproduct, and the clearance of that waste is the second basic problem that each organ has to solve. This diagram shows the body's lymphatic system, which has evolved to meet this need. It's a second parallel network of vessels that extends throughout the body. It takes up proteins and other waste from the spaces between the cells, it collects them, and then dumps them into the blood so they can be disposed of.

3:17

But if you look really closely at this diagram, you'll see something that doesn't make a lot of sense. So if we were to zoom into this guy's head, one of the things that you would see there is that there are no lymphatic vessels in the brain. But that doesn't make a lot of sense, does it? I mean, the brain is this intensely active organ that produces a correspondingly large amount of waste that must be efficiently cleared. And yet, it lacks lymphatic vessels, which means that the approach that the rest of the body takes to clearing away its waste won't work in the brain.

3:53

So how, then, does the brain solve its waste clearance problem? Well, that seemingly mundane question is where our group first jumped into this story, and what we found as we dove down into the brain, down among the neurons and the blood vessels, was that the brain's solution to the problem of waste clearance, it was really unexpected. It was ingenious, but it was also beautiful. Let me tell you about what we found.

4:25

So the brain has this large pool of clean, clear fluid called cerebrospinal fluid. We call it the CSF. The CSF fills the space that surrounds the brain, and wastes from inside the brain make their way out to the CSF, which gets dumped, along with the waste, into the blood. So in that way, it sounds a lot like the lymphatic system, doesn't it? But what's interesting is that the fluid and the waste from inside the brain, they don't just percolate their way randomly out to these pools of CSF. Instead, there is a specialized network of plumbing that organizes and facilitates this process. You can see that in these videos. Here, we're again imaging into the brain of living mice. The frame on your left shows what's happening at the brain's surface, and the frame on your right shows what's happening down below the surface of the brain within the tissue itself. We've labeled the blood vessels in red, and the CSF that's surrounding the brain will be in green. Now, what was surprising to us was that the fluid on the outside of the brain, it didn't stay on the outside. Instead, the CSF was pumped back into and through the brain along the outsides of the blood vessels, and as it flushed down into the brain along the outsides of these vessels, it was actually helping to clear away, to clean the waste from the spaces between the brain's cells. If you think about it, using the outsides of these blood vessels like this is a really clever design solution, because the brain is enclosed in a rigid skull and it's packed full of cells, so there is no extra space inside it for a whole second set of vessels like the lymphatic system. Yet the blood vessels, they extend from the surface of the brain down to reach every single cell in the brain, which means that fluid that's traveling along the outsides of these vessels can gain easy access to the entire brain's volume, so it's actually this really clever way to repurpose one set of vessels, the blood vessels, to take over and replace the function of a second set of vessels, the lymphatic vessels, to make it so you don't need them. And what's amazing is that no other organ takes quite this approach to clearing away the waste from between its cells. This is a solution that is entirely unique to the brain.

6:57

But our most surprising finding was that all of this, everything I just told you about, with all this fluid rushing through the brain, it's only happening in the sleeping brain. Here, the video on the left shows how much of the CSF is moving through the brain of a living mouse while it's awake. It's almost nothing. Yet in the same animal, if we wait just a little while until it's gone to sleep, what we see is that the CSF is rushing through the brain, and we discovered that at the same time when the brain goes to sleep, the brain cells themselves seem to shrink, opening up spaces in between them, allowing fluid to rush through and allowing waste to be cleared out.

7:45

So it seems that Galen may actually have been sort of on the right track when he wrote about fluid rushing through the brain when sleep came on. Our own research, now it's 2,000 years later, suggests that what's happening is that when the brain is awake and is at its most busy, it puts off clearing away the waste from the spaces between its cells until later, and then, when it goes to sleep and doesn't have to be as busy, it shifts into a kind of cleaning mode to clear away the waste from the spaces between its cells, the waste that's accumulated throughout the day. So it's actually a little bit like how you or I, we put off our household chores during the work week when we don't have time to get to it, and then we play catch up on all the cleaning that we have to do when the weekend rolls around.

8:34

Now, I've just talked a lot about waste clearance, but I haven't been very specific about the kinds of waste that the brain needs to be clearing during sleep in order to stay healthy. The waste product that these recent studies focused most on is amyloid-beta, which is a protein that's made in the brain all the time. My brain's making amyloid-beta right now, and so is yours. But in patients with Alzheimer's disease, amyloid-beta builds up and aggregates in the spaces between the brain's cells, instead of being cleared away like it's supposed to be, and it's this buildup of amyloid-beta that's thought to be one of the key steps in the development of that terrible disease. So we measured how fast amyloid-beta is cleared from the brain when it's awake versus when it's asleep, and we found that indeed, the clearance of amyloid-beta is much more rapid from the sleeping brain.

9:28

So if sleep, then, is part of the brain's solution to the problem of waste clearance, then this may dramatically change how we think about the relationship between sleep, amyloid-beta, and Alzheimer's disease. A series of recent clinical studies suggest that among patients who haven't yet developed Alzheimer's disease, worsening sleep quality and sleep duration are associated with a greater amount of amyloid-beta building up in the brain, and while it's important to point out that these studies don't prove that lack of sleep or poor sleep cause Alzheimer's disease, they do suggest that the failure of the brain to keep its house clean by clearing away waste like amyloid-beta may contribute to the development of conditions like Alzheimer's.

10:18

So what this new research tells us, then, is that the one thing that all of you already knew about sleep, that even Galen understood about sleep, that it refreshes and clears the mind, may actually be a big part of what sleep is all about. See, you and I, we go to sleep every single night, but our brains, they never rest. While our body is still and our mind is off walking in dreams somewhere, the elegant machinery of the brain is quietly hard at work cleaning and maintaining this unimaginably complex machine. Like our housework, it's a dirty and a thankless job, but it's also important. In your house, if you stop cleaning your kitchen for a month, your home will become completely unlivable very quickly. But in the brain, the consequences of falling behind may be much greater than the embarrassment of dirty countertops, because when it comes to cleaning the brain, it is the very health and function of the mind and the body that's at stake, which is why understanding these very basic housekeeping functions of the brain today may be critical for preventing and treating diseases of the mind tomorrow.

11:35

Thank you.

11:37

(Applause)

0:11

睡眠 占用了我们一生三分之一的时间 但是真正有人知道它到底是怎么回事吗?

0:19

两千年前 古时候的名医 伽林提出 当我们醒着的时候 我们大脑的原动力,它的液体 会流动到身体所有其他部位 维持它们的活力,但这却使大脑枯竭 并且他认为,在我们睡觉的时候 这些充满了我们身体其他部位的液体 会再回到我们的大脑 为大脑补充水分 并且使我们更有精神 虽然这些观点如今我们听来很荒谬 但是伽林很好的解释了那些 我们每天都要面对的 睡眠的事情 那么,根据自身的经验我们都知道 如果我们睡觉了,我们的头脑会变的清醒 而如果我们没有睡觉 大脑就会变糊涂 我们现在对睡眠的了解 比伽林那个时期多了很多 但是我们仍然不知道 为什么在我们所有的活动中,只有睡眠 有如此这般可以促使我们 头脑变得清晰的功能

1:17

所以今天,我想给大家讲一些 近期的研究 这些研究可能会揭示这些问题。 我们发现,睡眠实际上可能是 对大脑的一些最基本的要求 的一种简洁的解决方案, 是大脑满足身体高需求的 一种独特的方式。 这种独特的方式 将它与我们身体其他器官区分开来。

1:41

所以几乎我们所研究的生物学 都可以被认为是生物体中 需要被解决的一些问题 和相应的解决方案, 并且,每个器官第一个要解决的问题 就是提供持续不断的营养 去供应身体的所有细胞。 对大脑来说,这是至关重要的, 它巨大的电波活动 用尽了身体整个能量供应的四分之一 即使大脑仅仅占据了 人体重量的百分之二。 所以这个循环系统 通过血管的传输 将营养和氧气送到身体的每一个角落 来解决我们身体营养供应的问题

2:19

我们可以从视频中看到 这里,显示了活老鼠的 大脑中的血管 血管形成了一个复杂的网络 充满了整个大脑容量 它们从大脑的表层开始 深入组织 然后伸展开来,提供营养和氧气 到大脑中的每一个细胞

2:44

那么,就在每一个细胞 消耗营养的同时 每个细胞也都会产生相应的垃圾和废物 那么,这些废物的清除 就成为了每个器官要解决的 第二个基本问题。 这个图片展示了通过演变来 达到这种需求的系统—— 淋巴系统 它是贯穿整个身体的 第二套网络系统 淋巴管从细胞之间的间隙中 得到蛋白质和其他垃圾 然后收集这些蛋白质和垃圾,将它们 卸到血液中去处理

3:17

但是如果你仔细地看这个图表 你会发现一些 不合常理的东西 假使我们钻进了这个人的脑袋 你会发现, 大脑中没有淋巴管! 那不符合道理,不是吗? 我的意思是说,大脑是那么活跃的一个器官 它产生大量的废物,这些垃圾必须要被 及时、有效地清理掉 然而大脑中却没有淋巴管,那就意味着 身体的其他部位 清除垃圾废物的途径 在大脑中并不适用。

3:53

那么,大脑是怎样解决 它的垃圾清理问题的呢? 那么,这个看上去普通的问题 就是我们团队最初做这个项目的原因。 我们发现, 当我们深入到大脑中, 一直深入到神经元和血管, 去寻找大脑解决垃圾清理的问题 的机制时,得到的结果 是出乎我们意料的 我们发现的东西很特别 又很美丽。 我来说说我们发现的东西

4:25

我们的大脑有一个区域,里面装满了 干净透明的液体,那种液体叫做脑脊液 我们简称CSF(脑脊液) CSF(脑脊液)填充了大脑周围的空间。 来自大脑中的废物 从大脑中出来,到达CSF(脑脊液)中 CSF和废物一起卸下,进入血液。 照这样,听起来这就像一个 淋巴系统,不是吗? 但有趣的是,从大脑中出来的 液体和废物 它们不是随意地渗透到 CSF的区域中 相反,有一个专门的管道网络,来组织和促进 这个过程。 你可以从这些视频中看到。 看,我们又一次看到了 活老鼠的大脑 在你左边的组织展示了 大脑表层正在发生的事, 而你右边的组织显示了 大脑表层底下和它的组织 所发生的事。 我们把血管标记成红色 把大脑周围的CSF标记成 绿色 那么,让我们吃惊的是 大脑外面的液体(脑脊液) 它们不在外面呆着 相反,CSF(脑脊液)沿着 血管外壁,流回 大脑中,并且 在它沿着这些血管 流向大脑的同时, 它正在忙于将废物 从这些 脑细胞的间隙中带走。 如果你仔细想想就会发现 利用这些血管外壁 真的是一个巧妙设计的解决方法。 因为大脑在一个坚硬的头骨中 是封闭的, 并且它里面装满了细胞。 所以在大脑中已经没有空余的位置 留给第二套像淋巴系统那样的管路 然而这些血管 却从大脑的表层延伸出来 到达大脑中的每一个独立的细胞, 这也就意味着,脑脊液 只要沿着这些血管的外壁流动 就可以轻易到达大脑中。 所以这就是,安排一套血管 去代替第二套如淋巴管一样功能 的一种巧妙办法。 这样就不需要 那另外的一套淋巴管了。 更神奇的是,没有其他任何一种器官 具有这种清理细胞之间废物 的功能 这是大脑所独有的解决办法。

6:57

但是,刚刚我所讲的这一切当中 最最让我们感到 惊奇的是 大脑中所有这些液体的工作状态, 只出现在睡眠时的大脑中! 看,左边的这个视频 显示了在一只醒着的老鼠的大脑中 有多少脑脊液在流动—— 几乎没有。 然而同样是这只老鼠 如果我们稍稍等待一下,到它睡着 我们就可以看到脑脊液 在大脑里快速地流动 同时我们发现, 在大脑即将睡着的时候 脑细胞看起来变小了 这样,细胞之间就产生了空隙 这些空隙得以让脑脊液流动, 也让废物被清除了。

7:45

这样看起来,伽林提出的 人睡觉时大脑中会有液体流动 的想法 应该是正确的思路。 2000年后,我们自己的研究证明了 大脑清醒时 所发生的一切。 在大脑紧张工作时, 它一直将清理那些 细胞空隙间的废物的工作推迟。 然后,在大脑要睡觉时 它不必那样紧张工作, 大脑就切换到了“清理模式”, 开始清理 脑细胞间隙之间 已经积累了一天的废物。 所以这有点像我,或者你, 我们在周内工作的时候,没有时间做家务 于是将家务推迟了 等周末到了,我们就会把所有要做的家务 都做好。

8:34

到现在,我们已经说了很多关于废物清理的事 但是我还没有具体介绍 废物的种类—— 那些为了保持我们健康, 大脑必须要清理的废物——的种类。 近期的研究关注最多的废物 是淀粉样β蛋白 这是一种大脑始终会产生的蛋白质 就在此刻,我的大脑就正在产生淀粉样β蛋白 你的也是。 但是患有老年痴呆症的人 在他们脑细胞的间隙中 淀粉样β蛋白生成,聚集, 不能被及时清除。 淀粉样β蛋白的累积 是形成这种疾病的 关键步骤。 所以我们测量了大脑在清醒状态下 淀粉样β蛋白的清理速度 与大脑沉睡时的清理速度进行对比。 我们发现 在睡眠中的大脑 淀粉样β蛋白的清除速率更快。

9:28

那么,如果睡眠 是大脑进行废物清理的 关键步骤, 那么这就会奇迹般地改变我们 对睡眠,淀粉样β蛋白和老年痴呆症 的认识。 一系列临床试验证明 在那些老年痴呆症 还不是很严重的患者中, 睡眠质量和时间的恶化 是与大脑中淀粉样β蛋白的的集聚 有着很大的关系的。 然而,值得指出的是 这些研究没有证实 睡眠的缺乏或者低质量的睡眠 会引起老年痴呆症。 但明确指出如果大脑 不及时清理废物(如淀粉样β蛋白) 来维持它自身的清洁, 很可能会促进像老年痴呆症 这样的病症的发展。

10:18

那么,这个新的研究告诉我们, 也就是我现在要告诉你们每个人的 现在我们都知道, 即使伽林也都知道, 关于睡眠最重要的一点 大概就是睡觉会使 我们的思维变得清醒。 那么,我们, 每晚都在睡觉, 但是我们的大脑却从未休息过。 虽然我们的身体看起来不动了, 但是我们的思维却在到处梦游。 大脑的这些组织 始终在辛苦地工作, 保持这个及其复杂的“机器” 的清洁。 就好像我们的家务 那是个脏兮兮、费力不讨好的工作 但是却是那么的重要。 如果你有一个月都不打扫 你的厨房 很快,你的家就会变得 不适合居住, 但是如果换作大脑,拖延“不做家务”的结果 将会比我们不清理厨房台面的结果 要严重得多。 那是因为,对于大脑来说 不清理的后果会危及我们 思维、身体的健康与功能。 今天我们大脑所做的这些 基础的、“家务”一般的苦差事, 可能对防止与治疗明天的精神疾病 具有重要的意义。

11:35

谢谢。

11:37

(掌声)

[发帖际遇]: Candy_hao 发帖时在路边捡到 3 元 家元,偷偷放进了口袋. 幸运榜 / 衰神榜
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