Uncovering the brain's biggest secret - Melanie E. Peffer

翻译人员: 校对人员: Helen Chang

In the late 1860s, scientists believed they were on the verge

1860年代末，科学家相信

of uncovering the brain’s biggest secret.

他们即将揭开大脑之谜。

They already knew the brain controlled the body through electrical impulses.

他们已经知道大脑通过 电脉冲控制身体。

The question was, how did these signals travel through the body

问题是，这些信号是如何

without changing or degrading?

保持不变得穿过身体的？

It seemed that perfectly transmitting these impulses

为了能完美地传送这些脉冲

would require them to travel uninterrupted along some kind of tissue.

它们必须不停顿地穿梭于一些组织。

This idea, called reticular theory,

被称为“网状学说”的这一想法

imagined the nervous system as a massive web of tissue

认为神经系统就像一张组织巨网

that physically connected every nerve cell in the body.

连接着身体中的每一个神经细胞。

Reticular theory captivated the field with its elegant simplicity.

网状学说及其简约的理论 征服了学说界。

But soon, a young artist would cut through this conjecture,

但很快，一位年轻的画家 将会推翻这一推测

and sketch a bold new vision of how our brains work.

并会重新绘制出我们的大脑 是如何工作的。

60 years before reticular theory was born,

早于“网状学说”60年，

developments in microscope technology

显微镜科技的发展

revealed cells to be the building blocks of organic tissue.

让我们认识到生物组织基于细胞之上。

This finding was revolutionary,

这一发现是极具变革意义的，

but early microscopes struggled to provide additional details.

但早期的显微镜却无法提供更多的细节。

The technology was especially challenging for researchers studying the brain.

在研究大脑这一块，显微镜科技遇到了一些麻烦。

Soft nervous tissue was delicate and difficult to work with.

软神经组织十分脆弱， 人们很难处理。

And even when researchers were able to get it under the microscope,

而且即使研究人员成功提取至显微镜下，

the tissue was so densely packed it was impossible to see much.

这一组织的紧密程度， 让人无法看清细节。

To improve their view,

为了看清细节

scientists began experimenting with special staining techniques

科学家测试了特殊的染色方法，

designed to provide clarity through contrast.

通过对比来提高清晰度。

The most effective came courtesy of Camillo Golgi in 1873.

最成功的来自于卡米洛·高尔基 于1873年得出的方法。

First, Golgi hardened the brain tissue with potassium bichromate

首先，高尔基将脑部组织浸于重铬酸钾

to prevent cells from deforming during handling.

防止组织细胞在过程中受到伤害

Then he doused the tissue in silver nitrate,

然后他再将组织浸于硝酸银中，

which visibly accumulated in nerve cells.

用来在视觉上将神经细胞聚集起来。

Known as the “black reaction,”

这个方法叫做“黑反应”，

Golgi’s Method finally allowed researchers to see the entire cell body

高尔基的方法让研究者 可以看到整个细胞，

of what would later be named the neuron.

这个细胞后来被命名为神经元。

The stain even highlighted the fibrous branches

被染色的地方甚至凸显出了 纤维状的分支。

that shot off from the cell in different directions.

Images of these branches became hazy at the ends,

这些分支的图像在末端变得模糊，

making it difficult to determine exactly how they fit into the larger network.

很难确定它们究竟如何融入更大的网络。

But Golgi concluded that these branches connected,

但是高尔基得出结论说 这些分支都是链接在一起的，

forming a web of tissue comprising the entire nervous system.

从而建立了一个网状物的组织， 组成了整个神经系统。

14 years later, a young scientist and aspiring artist

14年后，一个名叫 圣地亚哥·拉蒙-卡哈尔的

named Santiago Ramón y Cajal began to build on Golgi’s work.

年轻又有抱负的科学家兼艺术家 开始在高尔基的基础上做研究。

While writing a book about microscopic imaging,

当卡哈尔在写一本关于 微小图像的书的时候，

he came across a picture of a cell treated with Golgi’s stain.

他无意中看到了一张 高尔基染液细胞的照片。

Cajal was in awe of its exquisite detail— both as a scientist and an artist.

卡哈尔作为一名科学家和艺术家， 是十分敬畏这样精致的细节的。

He soon set out to improve Golgi’s stain even further

他很快就进一步改善高尔基的染液，

and create more detailed references for his artwork.

同时也可以给他的艺术作品 创造更加细节的参考。

By staining the tissue twice in a specific time frame,

卡哈尔发现当他在一定的时间内 给细胞组织上染两次的话，

Cajal found he could stain a greater number of neurons with better resolution.

就能看到更多、更清晰的神经元。

And what these new slides revealed would upend reticular theory—

这样的发现支撑起了网状学说的假设：

the branches reaching out from each nerve cell

神经细胞的分支

were not physically connected to any other tissue.

并未和任何别的组织链 实体上接在一起。

So how were these individual cells transmitting electrical signals?

那么这些独立的细胞是 怎么传递电信号的呢？

By studying and sketching them countless times,

在无数次的学习和列草稿后，

Cajal developed a bold, new hypothesis.

卡哈尔发展出一个胆大、 全新的假设。

Instead of electrical signals traveling uninterrupted across a network of fibers,

他提出电信号不是通过一张 不间断的纤维网移动的，

he proposed that signals were somehow jumping from cell to cell

而是在各个细胞中间跳动的，

in a linear chain of activation.

像连线行的激活一样。

The idea that electrical signals could travel this way was completely unheard of

当卡哈尔在1889年提出这个 关于电信号想法的时候，

when Cajal proposed it in 1889.

这样的移动方式是前所未闻的。

However his massive collection of drawings supported his hypothesis from every angle.

但是他的无数张草稿从每一个角度 支撑起了他的假设。

And in the mid-1900s, electron microscopy further supported this idea

在19年代的中期，电子显微镜 又进一步地证实了这个想法。

by revealing a membrane around each nerve cell

电子显微镜发现每个神经细胞的 周围都有一层膜，

keeping it separate from its neighbors.

让它和隔壁的细胞分隔开来了。

This formed the basis of the “neuron doctrine,”

“神经元学说”的基础就这么形成了。

which proposed the brain’s tissue was made up of many discrete cells,

神经元学说提议脑子里的组织 是由很多独立的细胞构成的，

instead of one connected tissue.

而不是一张有链接的网。

The neuron doctrine laid the foundation for modern neuroscience,

神经元学说给现代神经系统科学 铺垫了基础，

and allowed later researchers to discover that electrical impulses

也让后来的研究者发现

当电脉冲在每个神经元中跳动的时候，

are constantly converted between chemical and electrical signals

as they travel from neuron to neuron.

它们的化学和电信号 是不停变换的。

Both Golgi and Cajal received the Nobel Prize

高尔基和卡哈尔都拿到了诺贝尔奖，

for their separate, but shared discoveries,

由于他们独立却又相连的发现。

and researchers still apply their theories and methods today.

科研者到今天都会一直使用 他们的理论和方法。

In this way, their legacies remain connected as discrete elements

这样来看的话，他们的传奇 是在一张巨大的知识网里

in a vast network of knowledge.

紧紧相连的两个分离的元素。