How can anyone feel pain where the part of the body is amputated?

“Phantom Pain” is caused because the pain is registered by the nerves and the brain, not the organ or limb itself.

The broad answer is that you don’t feel pain in the place where you think you feel pain. You feel pain in your brain. The feeling that it’s out there in your body, that’s an illusion. A very useful illusion, given you by millions of years of evolution, but an illusion nonetheless.

When a limb is amputated, the brain doesn’t always figure out that it was amputated. The parts of the brain that were responsible for sensation in that limb get confused, and send confusing signals. The part of your brain that makes the illusion does its best with the signals it’s getting, and phantom limb is the result. Your illusion-maker is choking on bad input, and its best guess is that something really bad is happening, so it sends a pain signal.

Peace and luck

There’s a neuro guy called Ramachandran who has done some phenomenal work on phantom limb pain, completely eradicating it for some of his patients. Look him up on youtube. And dig that accent.

I’d tell you about my (removed) prostate but this is a “family friendly” site.

Some neurological disorders like multiple sclerosis often have “painful non-pain” that is a very real perceived pain from damaged pain signal pathways not from the damage they are supposed to be reporting.
I imagine that sense of a phantom limb involves cells recalling something.

I don’t get it.

Pain is the interpretation in your mind of signals that there is some kind of damage happening or happened. For example, when your feet are aching, you know that in a different place than your feet. The information got there by a relay of pain signals nerves. Some signals aggregate or get interpretted at the spine in ganglion.

Let’s say feet aching feeling is the interpretation of 52 pain nerve cells in your feet sending a mild signal of stress. The signals might be consolidated before they leave the foot then get further interpreted at the spine.

Let’s say those nerve cells are severed in one foot, that foot is lost at the ankle so that there is now no connection from those pain cells to the consolidating and interpreting cells. But when you think of your feet, those interpreting and consolidating cells that survive the amputation might respond with the best information they have, which might be “foot is aching last time I got good info from the field” or “there is a tickle” or numb.

I’ll stop wasting time trying to get it.

The pain is not in the foot. The damage may be. But your brain is what the pain from the damage in the foot is registered in, and nerves say the foot hurts.

The reason you feel pain in a body part is because the signal is carried to the brain. So lets say you were stabbed in the leg, the reason you feel pain, is because the knife cutting you sends a signal up the nerve to the brain, and the brain sends out the pain signal. It is telling you, he we are hurt really badly, we have to stop what is happening.

Sometimes your brain will misfire and tell you, hey we are being hurt really badly, but nothing is actually happening. That’s sort of what goes on with phantom pain. A part of the brain doesn’t realize the leg is gone.

There has been some work with mirrors to help people get over this problem. They hold a mirror so it looks like they have both legs, and it helps their brain retrain.

The complexities of the brain haven’t been completely understood by anyone yet.
I think you might understand it better in a way which isn’t accurate, but gives you a better visual of what takes place.

Imagine the United Nations as being always in session, and running the world together. Phone calls come in constantly from each country, and must go through an operator. Each country has its own language.
The brain, in charge of the whole UN, sees an empty chair. It asks where that person went. Operator tries to call, but nobody answers. She reports they are gone. The leader has no word for gone. The closest interpretation is emergency. The leader has no idea what the emergency is, so they get a little freaked out. It imagines fire, or explosions, or flooding. It can’t send help without knowing what the emergency really is.

Phantom pain is what we feel when the brain is confused about which emergency it should deal with, and is trying to make different guesses fit.
There isn’t an emergency anymore. Brain just doesn’t have a word for gone. Other countries try to tell it don’t worry about it, and mostly it focuses on real issues, like hungry, and tired, but sometimes it sees that empty chair and thinks, I still gotta fix things over there. WHAT THE HELL IS YOUR EMERGENCY!!??

Your brain processes all of the senses. It also has a very vivid imagination. Think about some of your more bizarre dreams. Your brain thinks you HAVE to have pain there, so it makes it so.

“What is this grey matter that is aware of it’s own existence?”