What Is Pain?
Pain is an experience always created in the brain — not a direct readout of structural damage in the body. On the pain mechanism, and why damage and pain aren't always linked.
To put it simply — pain is a sensory and emotional experience created in the brain. Yes, in the brain. A popular belief is that pain always stems from an injury or damage in the body — a stiff muscle, a bulging disc, inflammation… but the truth is more complex: 100% of the time, pain is created in the brain. The body does send signals, but it's the brain that decides when to "sound the alarm" and produce pain.
Just as we don't see with our eyes or hear with our ears but with our brain (the eye and ear only transmit light and sound, while the brain creates the experience), we also don't really "feel pain in the back" — we feel it in the brain, which receives signals from there and interprets them.
Pain is a protective mechanism. If you pinch yourself gradually, you'll feel a rising pressure, and at some point it turns into pain. If you stop — nothing happens. If you keep going — you'll probably create a wound. The brain triggered pain to protect you from potential harm.
And once you're already hurt — say, a cut while making a salad — the pain is there so you'll let the wound heal and won't harm it again. It's a vital survival mechanism. The proof: people born with a rare mutation (CIPA syndrome) who feel no pain at all tend to suffer repeated injuries, worn-out joints, and a very short life expectancy.
But the Brain Doesn't Always Respond the Same Way
Sometimes it ignores signals of damage. This happens, for instance, in moments of existential danger: there are countless reports of people injured in accidents, attacks, fires and so on who felt no pain at all until they reached safety. The brain can "switch pain off" temporarily to allow survival. This process also involves adrenaline — the body's emergency hormone.
And sometimes the opposite happens — severe pain, even though there's no damage at all (!)
A real, famous example was published in the BMJ in 1995: a construction worker jumped onto a nail that went through his boot and came out the other side. He was screaming in pain and was rushed to the ER. He was given strong painkillers — which didn't ease the pain. When they removed his boot at the hospital, they discovered the nail had actually passed between his toes — without injuring anything. The pain in his foot was entirely real, but it came from the interpretation the brain gave the situation.
What Do You Mean the Brain Causes It? Don't I Decide?
Well, not exactly… The regions responsible for processing and experiencing pain in the brain are unconscious ones that operate automatically and beyond our control. One example is the "rubber hand" experiment, in which people are made to feel pain in a fake hand — just from the illusion of injury. These people know they aren't really being hurt, but that doesn't stop them from feeling pain.
The brain can also take a signal of real injury and amplify it (just like a guitar amp): in one experiment, people were asked to press a sharp device against themselves gradually — one that measures how much pressure is applied — and to stop when they felt pain. Then a stranger was asked to do exactly the same to them. When the stranger pressed, they reported pain earlier, at much lower pressure. In other words — the brain amplified the pain when the situation was perceived as more dangerous.
And what about findings on CT, MRI, and X-ray? Do they cause pain? — that's the topic of the next article in the series…
Recommended viewing: Lorimer Moseley — Why Things Hurt?