How spontaneous brain activity keeps you alive - Nathan S. Jacobs

翻译人员: xinfeng zhang 校对人员: 一鸣 胡

You probably don't need to be told how important your brain is.

关于大脑的重要性，我想你一定已经知道了。

After all, every single thing you experience,

不管怎样，你经历过的任何事情，

your thoughts and your actions,

任何想法和行动，

your perceptions and your memories

任何感知和记忆，

are processed here in your body's control center.

都是在你身体的这个控制中心中被处理的。

But if this already seems like a lot for a single organ to handle,

尽管看上去对于一个豆腐一样的器官来说，这已经是很多工作了。

it's actually only a small part of what the brain does.

但是实际上，这只是大脑工作的一小部分。

Most of its activities are ones you'd never be aware of,

大脑真正大量的活动，实际上那些我们没有意识到的部分。

unless they suddenly stopped.

除非，它突然停止工作，否则我们将永远不会意识到，大脑的这些“后台”工作的存在。

The brain is made up of billions of neurons,

大脑是由上百计脑神经元组成的，

and trillions of connections.

这上百亿神经元相互之间有上千亿连结。

Neurons can be activated by specific stimuli or thoughts,

每个神经元都能被特定的刺激或者想法激活。

but they are also often spontaneously active.

但是，即使没有这些刺激，神经元也能"自我激活"。

Some fire cyclically in a set pattern.

有些神经元根据一些模式周期性“自我激活”，

Others fire rapidly in short bursts before switching off,

有些神经元则能够在关闭前，突然快速爆发出一系列脉冲信号，

or remain quiet for long periods

或者有些，在安静了很久以后，

until thousands of inputs from other neurons line up in just the right way.

在上千个其他神经元的信号的正确刺激下，突然就被激活了。

On a large scale,

从整个系统的大尺度来说，

this results in elaborate rhythms of internally generated brain activity,

这导致了大脑从内部产生了非常精妙的内在旋律。

humming quietly in the background

这旋律，就好象一首歌曲的背景音乐一样。

whether we're awake, asleep,

不管我们是醒着，睡着，

or trying not to think about anything at all.

或者试着放空头脑(发呆)，这个旋律始终都在。

And these spontaneously occurring brain functions

而且这些自发的大脑功能，

form the foundation upon which all other brain functions rely.

构成了其他大脑功能赖以存在的基础。

The most crucial of these automatically occurring activities

自发大脑活动中最重要的那些活动，

are the ones that keep us alive.

也正是那些保持我们存活的活动。

For example, while you've been paying attention to this video

例如，虽然你现在正无比沉浸在这段美妙的视频中，

spontaneous activity in your brain has been maintaining your breathing

但是，在你没有意识到的时候，大脑中的自发活动正在维持你每分钟12-16次的呼吸，

at 12 to 16 breaths a minute, making sure that you don't suffocate.

确保你不会因为过于沉醉而窒息。

Without any conscious effort,

即使没有任何有意识的控制，

signals from parts of your brainstem are sent through the spinal cord

从你脑干中发出的信号仍然能够通过脊椎传递

to the muscles that inflate your lungs,

到控制肺部张驰的肌肉上去，

making them expand and contract, whether or not you're paying attention.

确保即使在你没有意识到的情况下，肺部仍能正常扩张与收缩。

The neuronal circuits underlying such rhythmic spontaneous activity

这些控制节奏性自发活动的脑神经元环路

are called central pattern generators,

叫做中央模式发生器。

and control many simple repetitive behaviors,

其主要作用就是控制这些简单重复性动作。

like breathing,

比如，呼吸

walking,

走路

and swallowing.

吞咽

Ongoing neural activity also underlies our sensory perception.

在我们每个感觉器官的背后也有神经元的活动。

It may seem

有可能，你会认为

that the neurons in your retina that translate light into neural signals

我们视网膜中把光信号翻译成神经元信号的神经元

would remain quiet in the dark,

在一片漆黑的环境中会是完全“沉默"的。

but in fact,

但是，实际上不是这样的，

the retinal ganglion cells that communicate with the brain

与大脑通讯的视网膜神经节细胞

are always active.

始终是活跃的。

And the signals they send are increases and decreases in the rate of activity,

这些细胞只是发送不同高低强度的信号，

rather than separate bursts.

而不是发送完全间隔的脉冲信号。

So at every level, our nervous system is teeming with spontaneous activity

所以不管何时，我们的神经系统都充满了各种自发活动，

that helps it interpret and respond to any signals it might receive.

这些自发活动能够帮助我们理解接收到的各种信号并作出正确的反应。

And our brain's autopilot isn't just limited to our basic biological functions.

并且，我们大脑的这种“自我驾驶”功能并不仅仅限于基本的生理学功能。

Have you ever been on the way home,

你有没有过这种经历，一个人默默的走回家，

started thinking about what's for dinner,

同时脑子里开始想象当天的晚餐，

and then realized you don't remember walking for the past five minutes?

然后突然意识到，过去五分钟你压根没有意识到你其实一直在走路？

While we don't understand all the details,

虽然我们现在尚未理解所有的细节，

we do know that the ongoing activity in multiple parts of your brain

但是我们已经知道了在这个过程中，你大脑的好几个区域都在活动。

is somehow able to coordinate what is actually a complex task

让这些区域协同工作实际上是一个非常复杂的任务。

involving both cognitive and motor functions,

这些区域包括认知和运动功能，

guiding you down the right path and moving your legs

认知功能保持你沿着正确的路走下去，运动功能保持保持腿部的协调运动。

while you're getting dinner figured out.

这一切都发生在你神游天外，想着晚饭的时候。

But perhaps the most interesting thing about spontaneous brain function

但是实际上关于这些自发脑部活动最有趣的事情是，

is its involvement in one of the most mysterious

它在我们身体一个最最神秘但是我们却几乎一无所知的阶段：睡觉

and poorly understood phenomena of our bodies: sleep.

中所扮演的角色。

You may shut down and become inactive at night,

一到晚上，你看上去就好象机器断了电一样(夜猫子除外)。

but your brain doesn't.

但你的大脑可没有断电。

While you sleep,

当时睡着了以后，

ongoing spontaneous activity gradually becomes more and more synchronized,

各种自发活动会逐渐变得越来越同步，

eventually developing into large, rhythmic neural oscillations

最终变成了一个非常巨大的，有旋律的神经元震动，

that envelop your brain.

包裹住你的整个大脑。

This transition to the more organized rhythms of sleep

这个从清醒状态转变成”睡眠协奏曲“的过程，

starts with small clusters of neurons tucked in the hypothalamus.

是由下丘脑内一些小簇的神经元开始的。

Despite their small number,

尽管这些神经元数量不多，

these neurons have a huge effect

但是他们在关闭脑干中一些特定区域方面有非常大的影响，

in turning off brainstem regions that normally keep you awake and alert,

这些区域通常能使你保持警醒状态。

letting other parts, like the cortex and thalamus,

对于其他的一些区域，比如大脑皮质和丘脑

slowly slip into their own default rhythms.

这些神经元也会让他们慢慢的进入默认的旋律。

The deeper we fall into sleep,

我们睡的越深，

the slower and more synchronized this rhythm becomes,

这个旋律越是慢也越是同步。

with the deepest stages dominated by large amplitude, low frequency delta waves.

当到达最深的阶段以后，我们的大脑中会充斥着高强度，低频率的三角波。

But surprisingly, in the middle of this slow wave sleep,

但是令人惊奇的是，在慢波睡眠中，

the brain's synchronized spontaneous activity

大脑的自发同步活动

repeatedly transitions into the sort of varied bursts

会周期性的转变为不规律脑脉冲状态。

that occur when we're wide awake.

这个状态就跟我们醒着一样。

This is the sleep stage known as REM sleep,

我们把这一状态叫做REM(快速眼动阶段)

where our eyes move rapidly back and forth as we dream.

顾名思义，在这一阶段，我们的眼睛会随着我们的梦境不断的运动。

Neuroscientists are still trying to answer many fundamental questions about sleep,

神经科学家仍在不断探求很多关于睡眠的基本问题的答案。

such as its role in rejuvenating cognitive capacity,

例如睡眠与认知能力恢复的关系，

cellular homeostasis,

与细胞同态的关系，

and strengthening memory.

与增强记忆力的关系是怎样的？

And more broadly, they are exploring

更广泛来说，他们正在研究

how it is that brain can accomplish such important and complex tasks,

大脑是如何完成一些非常重要和复杂任务的，

such as driving, or even breathing, without our awareness.

例如开车，甚至是无意识的呼吸。

But for now, until we are better able

但是就目前来说，在我们能够更好的

to understand the inner workings of their spontaneous functioning,

理解大脑内部自发功能之前，

we need to give our brains credit for being much smarter

我们必须大大的嘉奖一番大脑，

than we ourselves are.

他实在是比我们自己都聪明。