The mysterious science of pain - Joshua W. Pate

翻译人员: Yingyu Liu 校对人员: Liu Qi

In 1995, the British Medical Journal

1995 年，英国医学杂志

published an astonishing report about a 29-year-old builder.

发表了一份惊人的报告，

一个 29 岁的建筑工人不小心 踩上一根 15 厘米长的钉子，

He accidentally jumped onto a 15-centimeter nail,

which pierced straight through his steel-toed boot.

钉子直接刺穿了他的钢头靴。

He was in such agonizing pain that even the smallest movement was unbearable.

奇痛异常，连最小的晃动 都会让他痛到无法承受。

But when the doctors took off his boot, they faced a surprising sight:

但是当医生把他的靴子脱掉后，

他们惊讶的发现： 钉子根本没有刺到他的脚。

the nail had never touched his foot at all.

For hundreds of years,

几百年来，

scientists thought that pain was a direct response to damage.

科学家认为疼痛 是对伤害的直接反应。

By that logic, the more severe an injury is, the more pain it should cause.

按照这种逻辑，伤害越严重， 造成的疼痛感就会越强烈。

But as we’ve learned more about the science of pain,

但是当我们逐渐了解 痛感这门科学，

we’ve discovered that pain and tissue damage don’t always go hand in hand,

我们发现即使身体的 威胁信号机制正常运作，

痛感和组织损伤 也并不总是同时发生。

even when the body’s threat signaling mechanisms are fully functioning.

We’re capable of experiencing severe pain out of proportion to an actual injury,

我们能够经历剧烈的、 与实际伤害不成比例的疼痛，

and even pain without any injury,

甚至在没有受伤时感到疼痛，

like the builder, or the well-documented cases of male partners

像那个建筑工人，

以及案例中男性伴侣在孕妇怀孕或 分娩期间所经历疼痛。

of pregnant women experiencing pain during the pregnancy or labor.

What’s going on here?

这是为什么呢？

There are actually two phenomena at play:

实际上有两种现象在起作用：

the experience of pain, and a biological process called nociception.

痛苦的经历和被称作为 伤害感受的生物过程。

Nociception is part of the nervous system’s protective response

伤害感受是神经系统中

对有害或潜在有害刺激 保护性反应的一部分。

to harmful or potentially harmful stimuli.

Sensors in specialized nerve endings

传感器处于专门的神经末梢，

detect mechanical, thermal, and chemical threats.

用于检测机械、热和化学威胁。

If enough sensors are activated,

如果足够多的传感器被激活，

electrical signals shoot up the nerve to the spine and on to the brain.

电信号从神经输出到脊椎和大脑。

The brain weighs the importance of these signals

大脑衡量这些信号重要性，

and produces pain if it decides the body needs protection.

如果大脑认为身体需要保护， 就会产生痛感。

Typically, pain helps the body avoid further injury or damage.

通常，疼痛使身体 免受进一步伤害或损坏。

But there are a whole set of factors besides nociception

但是除了伤害感受，

还有一整套因素可以影响疼痛经历， 并降低疼痛的示警功能。

that can influence the experience of pain— and make pain less useful.

First, there are biological factors that amplify nociceptive signals to the brain.

首先，有些生物因素会 将伤害性信号放大到大脑。

If nerve fibers are activated repeatedly,

如果神经纤维被反复激活，

the brain may decide they need to be more sensitive

大脑可能认为

神经纤维需要变得更敏感 才能充分保护身体抵御威胁。

to adequately protect the body from threats.

More stress sensors can be added to nerve fibers

更多的压力传感器会 添加到神经纤维，

until they become so sensitive that even light touches to the skin

直到它们变得非常敏感，

即使只是轻微接触皮肤， 也会激发强烈的电信号。

spark intense electrical signals.

In other cases,

还有一些情况，

nerves adapt to send signals more efficiently, amplifying the message.

神经发送的信号更为有效， 并且将信息放大。

These forms of amplification

这些放大信号的形式

are most common in people experiencing chronic pain,

在慢性疼痛病人中最常见，

which is defined as pain lasting more than 3 months.

也就是疼痛持续超过三个月的病人。

When the nervous system is nudged into an ongoing state of high alert,

当神经系统被推入 持续的高度戒备状态，

pain can outlast physical injury.

疼痛持续的时间 会超过身体受伤的时间。

This creates a vicious cycle in which the longer pain persists,

这造成了一个恶性循环，

疼痛持续时间越长， 扭转就会变得越困难。

the more difficult it becomes to reverse.

Psychological factors clearly play a role in pain too,

心理因素当然也会影响痛感，

potentially by influencing nociception and by influencing the brain directly.

可能通过潜在影响伤害感受和 通过直接影响大脑。

A person’s emotional state, memories,

一个人的情绪状态、记忆，

beliefs about pain and expectations about treatment

对于疼痛的信念和对于治疗的期待

can all influence how much pain they experience.

都可以影响他们的疼痛感。

In one study,

一项研究中发现：

children who reported believing they had no control over pain

相比那些相信自己可以控制的孩子，

actually experienced more intense pain

认为自己无法控制疼痛的孩子

than those who believed they had some control.

真的会经历更剧烈的疼痛。

Features of the environment matter too:

环境因素也很重要。

In one experiment,

在一个实验中，

volunteers with a cold rod placed on the back of their hand

在志愿者的手背上放置冷冻的冰棍，

reported feeling more pain when they were shown a red light than a blue one,

虽然冰棍的温度每次都是相同的，

even though the rod was the same temperature each time.

看着红灯的人比 看着蓝灯的人痛感更强，

Finally, social factors like the availability of family support

最后，社会因素比如家庭的支持，

can affect perception of pain.

也可以影响疼痛的感知。

All of this means that a multi-pronged approach to pain treatment

所有这一切都意味着 疼痛治疗需多管齐下，

that includes pain specialists, physical therapists, clinical psychologists, nurses

由疼痛专家、物理治疗师、 临床心理学家、护士，

and other healthcare professionals is often most effective.

和其他医疗专业人士的介入， 这种方法通常最有效。

We’re only beginning to uncover the mechanisms behind the experience of pain,

虽然我们才刚刚开始 探索痛感的机制，

but there are some promising areas of research.

但是已经发现了 一些有前景的研究领域。

Until recently,

直到最近，

we thought the glial cells surrounding neurons were just support structures,

我们以前认为神经胶质细胞 周围神经元只是支撑结构，

but now we know they have a huge role in influencing nociception.

但现在我们知道他们对 影响伤害感受有很大的作用。

Studies have shown that disabling certain brain circuits in the amygdala

研究表明，禁用某些 杏仁核中的脑电路

can eliminate pain in rats.

可以消除大鼠的疼痛。

And genetic testing in people with rare disorders

对少见的没有痛感的人进行基因检测

that prevent them from feeling pain

have pinpointed several other possible targets for drugs

已经发现了其他几个 可以开发药物的方向，

and perhaps eventually gene therapy.

及最终可能实现的基因治疗。