What is consciousness? - Michael S. A. Graziano

翻译人员: Yuchen Lu 校对人员: Yuyang Zhao

Here are two images of a house.

这里是同一间房子的两张图。

There’s one obvious difference,

他们有一个明显的区别，

but to this patient, P.S.,

但对这个名叫P.S.的病人来说，

they looked completely identical.

它们看上去完全相同。

P.S. had suffered a stroke that damaged the right side of her brain,

P.S.曾经中风，并导致损伤了大脑右部，

leaving her unaware of everything on her left side.

这使她对在她左侧的东西没有意识。

But though she could discern no difference between the houses,

虽然她识别不出这两间房子的区别，

when researchers asked her which she would prefer to live in,

当研究人员问她 比较喜欢住哪一间的时候，

she chose the house that wasn’t burning—

她还是选了没有着火的那间。

not once, but again and again.

这不是一两次，是始终。

P.S.’s brain was still processing information

P.S.的大脑仍然是根据她的整个视野

from her whole field of vision.

来处理信息的。

She could see both images

她是可以看见这两张图像

and tell the difference between them,

并看出它们的区别的，

she just didn’t know it.

她只是不知道。

If someone threw a ball at her left side,

如果有人朝她的左边丢一个球，

she might duck.

她也许会躲闪。

But she wouldn’t have any awareness of the ball,

但她并不会意识到有球向他飞来，

or any idea why she ducked.

也不明白为什么她会躲闪。

P.S.’s condition,

P.S.的病症

known as hemispatial neglect,

叫做半侧空间忽略症，

reveals an important distinction between the brain’s processing of information

它揭示了大脑处理信息

and our experience of that processing.

和我们对于信息处理的经历的重要区别。

That experience is what we call consciousness.

这种经历我们称之为意识。

We are conscious of both the external world and our internal selves—

我们对外在世界和自身内在有意识。

we are aware of an image

我们意识到图像，

in much the same way we are aware of ourselves looking at an image,

和我们意识到自己 在看图像的方式差不多，

or our inner thoughts and emotions.

这与意识到我们内在的思想感情， 基本是一样的。

But where does consciousness come from?

但意识是从何而来呢？

Scientists, theologians, and philosophers

科学家，神学家和哲学家们

have been trying to get to the bottom of this question for centuries—

几个世纪以来一直致力于 解决这个问题，

without reaching any consensus.

但都没有达成共识。

One recent theory is that

近来，有理论称

consciousness is the brain’s imperfect picture of its own activity.

意识是大脑对其自身活动的不完美写照。

To understand this theory,

理解这个理论之前，

it helps to have a clear idea

我们先来理清

of one important way the brain processes information from our senses.

大脑是怎么根据我们的感知 来处理信息的。

Based on sensory input,

大脑会根据我们的感官输入建立模型，

it builds models,

which are continuously updating, simplified descriptions

这些模型不断地更新

of objects and events in the world.

形成对于世间事物的简化描述。

Everything we know is based on these models.

我们所知的每件事物 都是基于这些模型。

They never capture every detail of the things they describe,

它们从不会抓住它所描述的事物的细节，

just enough for the brain to determine appropriate responses.

但足以让大脑做出适当的反应。

For instance, one model built deep into the visual system

比如，视觉系统中的一个模型

codes white light as brightness without color.

将白光编译为没有颜色的亮光。

In reality,

事实上，

white light includes wavelengths

白光包含了所有

that correspond to all the different colors we can see.

不同颜色的可见光的波长。

Our perception of white light is wrong and oversimplified,

我们对于白光的感知是错的 而且是被过于简化的，

but good enough for us to function.

但是足够我们用了。

Likewise, the brain’s model of the physical body

相同的，大脑中关于身体的模型

keeps track of the configuration of our limbs,

会记录我们四肢的构型，

but not of individual cells or even muscles,

但不会细致到记录单个细胞甚至肌肉，

because that level of information isn’t needed to plan movement.

因为我们不需要这个层面的信息来活动。

If it didn’t have the model keeping track of the body’s size, shape,

如果大脑没有一个追踪 身体尺寸，形状

and how it is moving at any moment,

以及动作的模型，

we would quickly injure ourselves.

我们很快就会伤到自己。

The brain also needs models of itself.

大脑也需要关于它自己的模型。

For example,

例如，

the brain has the ability to pay attention to specific objects and events.

大脑有注意具体事物的能力。

It also controls that focus,

它还会根据我们的需要

shifting it from one thing to another,

来控制这种专注，

internal and external,

从一个东西转移到另外一个，

according to our needs.

从内在到外在。

Without the ability to direct our focus,

没有了转移注意的能力，

we wouldn’t be able to assess threats, finish a meal, or function at all.

我们就完全无法评定危险，

无法吃饭，无法活动。

To control focus effectively,

为了有效控制注意力，

the brain has to construct a model of its own attention.

大脑需要建立一个注意力模型。

With 86 billion neurons constantly interacting with each other,

大脑中有860亿个神经元持续交互，

there’s no way the brain’s model of its own information processing

大脑信息处理的模型无法完美地 记录描述自身的所有细节。

can be perfectly self-descriptive.

But like the model of the body,

但就像身体的模型一样，

or our conception of white light,

或者是我们对于白光的概念，

it doesn’t have to be.

这个模型并不需要是面面俱到的。

Our certainty that we have a metaphysical, subjective experience

我们确信我们有 形而上学的主观体验

may come from one of the brain’s models,

可能是因为某一个大脑模型。

a cut-corner description of what it means to process information

这个模型简易地描述了

in a focused and deep manner.

以集中而深入的方式 处理信息的意义。

Scientists have already begun trying to figure out

科学家们已在尝试研究

how the brain creates that self model.

大脑如何创造自我模型。

MRI studies are a promising avenue for pinpointing the networks involved.

核磁共振可以帮助我们查明关联的网络。

These studies compare patterns of neural activation

这些研究对比当人是否意识到感官刺激时 （比如图像）

when someone is and isn’t conscious of a sensory stimulus, like an image.

不同的神经活跃模式。

The results show that the areas needed for visual processing

结果表明， 不论试验人员是否意识到图片

are activated whether or not the participant is aware of the image,

大脑中视觉处理的区域都会被激活。

but a whole additional network lights up

但只有当他们有意识地看图像时，

only when they are conscious of seeing the image.

其他的网络才会全部活跃。

Patients with hemispatial neglect, like P.S.,

患有半侧空间忽略症的病人， 比如P.S.,

typically have damage to one particular part of this network.

通常是在这个网络的 特定部位受损。

More extensive damage to the network can sometimes lead to a vegetative state,

对这一网络更严重的损伤 可能会造成植物状态，

with no sign of consciousness.

使人完全失去意识。

Evidence like this brings us closer to understanding

类似这样的证据让我们进一步明白

how consciousness is built into the brain,

意识是怎样建立在大脑中的。

but there’s still much more to learn.

但还有更多有待学习。

For instance,

比如，

the way neurons in the networks related to consciousness

我们目前的技术无法知晓

compute specific pieces of information

在这一网络中和意识有关的神经元

is outside the scope of our current technology.

是如何计算具体某段信息的。

As we approach questions of consciousness with science,

随着我们利用科学解决意识的问题，

we’ll open new lines of inquiry into human identity.

我们将会开启关于人类特性的新探究。