The man who lost his sense of touch - Antonio Cataldo

譯者: 穎君 紀 審譯者: Helen Chang

In 1971, Ian Waterman suddenly collapsed from a severe case

1971 年，沃特曼突然倒下，

出於嚴重的腸胃炎。

of what seemed to be gastric flu.

His illness passed after a few days,

幾天後，他的病狀消失，

but a stranger set of symptoms lingered.

但另一套更奇怪的症候群殘存下來。

Although his muscles and joints remained healthy,

即使肌肉和關節都還健康，

Waterman was unable to move.

沃特曼卻無法移動。

In fact, he was unable to feel anything from the neck down.

其實，他脖子以下的部位 都感覺不到任何事物。

Eventually, he was diagnosed with a rare and extreme form of deafferentation,

最後，他被診斷出一種稀有且極端的 「傳入神經阻滯」，

a neurological condition in which certain signals

一種神經現象，讓特定神經系統的訊號

from the nervous system are interrupted or impaired.

遭到阻礙或毀損。

Without his body's constant feedback on how his limbs were moving,

沒有了身體定時回傳的 四肢移動狀態訊號，

Waterman was unable to sit up, stand, or walk.

沃特曼沒辦法坐起來、 站起來，或走路。

But over time, he taught himself to use sight to judge the distance

但随着時間過去，他學會用視力

來判斷四肢和物體的距離。

of his limbs from other objects.

And eventually he regained complete control of his body—

最後，他重新得到 對自己身體的完整掌控，

so long as he could see it.

只要自己看得見就能掌控。

We often don’t think of touch as being a vital part of movement.

我們通常不會想到 觸覺是動作裡的重要部分。

But touch is just one part of the somatosensory system,

但觸覺只是「感覺系統」的一部份，

a network that oversees all the sensations

感覺系統是座網路系統，它控管所有

arising from the surface and interior of our bodies.

從體表和體內來的感覺。

Touch, pain, temperature, and our awareness of our bodies in space—

觸覺、痛覺、溫度， 和我們對己身的空間意識—

also known as proprioception— are regulated by this system.

又稱為「本體感覺」— 都受這系統管制。

And when something goes wrong, the effects can be dramatic.

即使只是產生些微誤差， 也可能導致很劇烈的影響。

All these sensations are processed by millions of tiny receptor cells

這些感官都經由幾百萬個接收細胞處理，

embedded in our skin, muscles, tendons, and organs.

它們埋在我們的皮膚、 肌肉、肌腱，和器官裡。

Every square centimeter of our skin is packed with hundreds of these cells,

每平方公分的皮膚約含幾百個接收細胞，

and their shape, size, and depth determine what kind of stimuli they respond to.

細胞形狀、大小、埋藏深度， 則取決於它們接收的刺激種類。

Mechanoreceptors sense mechanical deformation of the skin.

力學感受器接收皮膚變形的訊號，

This could be triggered by low or high frequency vibrations,

它可能被低或高頻率的震動、

a stretch, or simply light, static pressure.

拉伸，或輕壓觸發。

Thermoreceptors respond to temperature changes,

溫度感受器對溫度變化做出反應，

while nociceptors sense pain.

疼痛感受器則是感知疼痛。

And propriocepters sit deep in your muscles and tendons,

本體感受器深埋在你的肌肉和肌腱裡，

continually detecting and relaying information

持續偵測、接力傳遞

about the position of your body.

身體的位置資訊。

Your brain then combines this information with other sensory data

接著，大腦將這資訊 與其他感官資訊拼湊起來，

to move through space without needing to see your limbs.

讓你在空間中移動， 不用看著自己的四肢。

All of these receptors work by sending electrical signals to the brain

這些接收器的運作方式是 傳送電子訊號至大腦，

through fibers they’re attached to.

經由它們所附著在上的神經纖維。

And the speed of those signals varies with the fiber’s thickness.

訊號傳遞速度取決於纖維的粗細，

For example, some nociceptors are attached to fibers

比如說，有些疼痛感受器附著在

with slightly more conductive, fatty myelin than others.

傳遞速度更快的 髓鞘更厚的神經纖維上，

So when you get hurt, the electrical impulses from thicker nociceptors

所以你受傷時，較粗的神經上的 那些疼痛感受器，

trigger sharp, intense pain,

讓你感覺劇烈刺痛，

while thin, unmyelinated nociceptors are responsible

比較細、沒有髓鞘的 神經上的疼痛感受器，

for the dull, aching pain that follows.

則讓你感覺劇烈刺痛後的鈍痛。

And since the fibers carrying tactile information are much thicker

因為承載觸覺資訊的神經

than those carrying nociceptive signals,

比承載痛覺資訊的神經粗上許多，

rubbing an injury can produce temporary relief from the pain

所以揉受傷的部位可以暫時緩解疼痛。

These receptors generate a constant flood of signals

這些感受器產生穩定的訊號流，

that travel through the nervous system to the brain.

訊號流從神經系統一路傳輸至大腦。

But if this process is disrupted—

但如果這個過程被阻礙

either by damage to the skin, the nerves, or the brain—

—可能因皮膚、神經或大腦損傷—

the network breaks down.

這個傳輸網路就會崩壞。

And since it underpins so many bodily functions,

因為神經構成許多身體動作的基礎，

damage to the somatosensory system can manifest in a wide variety of ways.

所以感覺系統的損傷 有許多種可能的表現方式。

In Waterman’s case, an autoimmune reaction

以沃特曼的情況來說， 自動免疫系統反應

attacked a large swath of his nervous system,

攻擊到一大條神經系統，

leaving him with no tactile or proprioceptive sensations

使他從脖子以下的部位， 失去觸覺或本體感覺。

from the neck down.

But deafferentation is just one of many somatosensory disorders.

但傳入神經阻滯還只是 眾多感覺系統障礙中的一種。

Individuals can receive damage to a specific brain area or a section of skin,

人們可能傷到大腦的特定區域， 或某一區的皮膚，

resulting in the loss of certain sensations in particular locations.

導致該區失去特定感覺，

And the impact of this loss can be significant.

可能帶來巨大影響。

Losing tactile sensations makes it difficult to gauge how much strength

失去觸覺讓人難以拿捏

在不同情況下，自己動作的力道。

to use in a situation.

Without the warning signals provided by thermal and pain stimuli,

沒有了溫度計及痛覺刺激的警告，

we don’t react when our bodies are damaged.

當身體受傷時，會沒辦法反應過來。

And, being deprived of social touch can cause a condition

如果社交性撫摸不足，則可能引起

known as touch starvation,

名為「觸摸飢餓」的病狀，

characterized by anxiety, depression,

病徵包括焦慮、憂鬱、

high blood pressure, and even a weakened immune system.

高血壓，甚至免疫系統的弱化。

Many individuals who face these realities have found innovative ways to adapt.

許多有觸覺問題的人們 找出了新穎的方式來對抗它，

But it’s undeniable that all these invisible sensations

但我們無法否認這些看不見的感覺

play a vital role in how we navigate the world—

在我們的日常生活裡肩負重大任務—

even if they can be difficult to put your finger on.

即使你無法確切指出。