Phantom limb phenomenon

Factual Questions
1

I have just finished reading a fascinating article on the “phantom limb phenomenon”.

According to this article, despite many attempts to explain the phenomenon in both biological and neurological terms, the mechanisms and processes of the condition still remain a mystery.

However, the really interesting thing in this article was the discussion about numerous experiments that have been performed on amputees who experience this phenomenon.

Specifically: the amputee is seated on one side of a screen; invisible to him/her on the other side of the screen sits a researcher. This researcher has various instruments and things available with which to apply a stimulus, such as hot, cold, sharp, dull, electric shock, etc, etc.

The amputee puts the stump of their limb up against the screen, and then reports any sensations they experience.

At random intervals, the researcher applies the stimulus to the area on their own side of the screen where the limb would be, if it were still attached to the body of the amputee and protruding through the screen.

Apparently, a large number of the amputees can identify unambiguously and accurately when, and what stimulus is being applied. Ie: “I feel ice cold on my thumb”; or “I feel a sharp needle prick on my palm”. etc, etc.

So two things appear to be occurring in these experiments: the amputee still has the sensation that the absent body part is still attached to their body; and that absent body part still has the capacity to process sensations, just as it had before being detached.

Does anyone know anything about this phenomena, and these experiments?

More importantly, what does it all mean???

2

Somewhat related.
Sanjay Gupta transcript. About 2/3 of the way down.

Anderson Cooper 360. Same topic.

3

I’ve never heard of this experiment, where did you find it? I’m extremely skeptical that people were correctly identifying the non-exisistent stimulus in any sort of reliable fashion.

Phantom Limb Phenomenom itself is fascintating though. I didn’t really realize just how common phantom pain is among amputees.

It’s experienced by more than just amputees too. Severe nerve damage (like in certain paraplegics for example) can also lead to people experiencing it. Even stranger, people who were born without a limb also sometimes feel the same thing. I know they’ve hooked a few up to MRIs and the scans showed activity in the parts used for motor control when they claimed to be “moving” the limb they never had.

Its got to really suck when the arm you never even had in the first place suddenly feels like you just smashed your elbow.

4

I don’t think you can talk about “phantom limb” without mentioning the fascinating Mirror Box experiments and therapy.

5

Or hearing the guy who invented it talk about it (perhaps only tangentially related to the thread, but it’s one of my very favourite TED talks).

Anyway, I’d also be very interested in seeing the article/experiments the OP mentions… I’m more than a bit sceptical, too. I know there were experiments done where the stimulus was applied to the stump, with the amputee registering it as applied to various parts of their missing limb; besides, how did the experimenter on the other side of the screen now where exactly the phantom limb was located in space?

6

I think this and optical illusions and a variety of other oddities are all artifacts of the way we manage the interaction between brain and physical world. We usually get the wrong idea about this - the eyes are video cameras, the ears are microphones, and so forth, and our mind uses and manipulates these to decide what to do. But it is nearer the truth that we have an intermediary in there, a model of the physical world. There are wholly unconscious mental processes that maintain this model from the cameras and microphones, and our mind only ever interacts with the model. Computer programmers will recognize this as the proxy design pattern. The processes that maintain the model aren’t perfect, and we get all excited about the pathological cases where the process goes way off, because we experience it as for example a rotating cubic outline that flips back and forth through a fourth dimension, or in the OP a missing limb that still feels. But, it would be way harder to go through life without the proxy system. Which, by the way, isn’t just in the brain; the retinas have a great deal of processing in them, and for example recognize things like straight lines and right angles all on their own.

7

I’ve heard that amputees with strong phantom limbs are often those who best learn to use a prosthesis, and vice versa.

Not well understood - but for years it was thought to be a “delusion” or mental aberration on the part of amputees, so it wasn’t studied. Now it’s know to be a real phenomena and is finally being studied.

8

What it means is that someone’s either lying, or misinterpreting things. There is no Gil Hamilton in the real world.

9

I’ve read accounts of amputees complaining their phantom hand is in a clenched, painful fist and they can’t make it go slack, which is what the above linked mirror box is all about curing it seems. Fate is cruel.

10

Anecdotally, I’ve had independent conversations with several (three) acupuncturists who have treated phantom limb pain with acupuncture treatments to limbs that weren’t there. That is, instead of inserting the needles into the stump or other parts of the body, the acupuncturist held the needle in midair at the spot where the needle would be inserted if the limb was intact.

All of them reported good results, but none of them had anything definitive to say about why it worked or why they even tried it the first time!

There are a couple of very limited trials which show some success treating phantom limb pain with acupuncture, but in all that I can find, they’ve needled the stump or meridians corresponding to the area, not the air.

11

I’d guess that the midair needling works the same way as the mirror box treatments–by providing cues to relax the phantom limb and visual feedback. I wonder if just stroking/tracing/massaging the phantom limb would have a similar effect?

12

Have a look at the book The Brain That Changes Itself. The author spends a chapter on pain and talks about brain maps, and how they explain phantom limbs. Or maybe google Vilayanur Subramamanian Ramachandran, the doctor that the author discusses in that chapter.

(On review I see that one of the links above is to a video of Dr. Rmachandran)

13

To those that asked the question: all I have is a photocopy of a newspaper article that was given to me by a friend. She picked this newspaper up while traveling, and doesn’t even remember which country she was in when she did so.

As is the case with many newspaper articles, there is no specific reference to the content presented.

This is why I posted the question; I was hoping that someone out there would have read about these experiments and have further information.

However, I have asked other people about the subject, and two names have come up: Rupert Sheldrake and James Le Fanu. Apparently, they have written books on the subject.

When I finish this post, I will be checking Amazon to see what they have.

14

You might try Googling some distinctive exact phrases from the article, to see if you can find an online edition of the newspaper. That’d at least give a lead to follow up on.

15

No matter how many books they’ve written, it hasn’t been proven and it won’t be. They are either misleading themselves with poorly designed experiments or lying to sell books.

16

What hasn’t been proven yet? And why won’t it be? What is it they are lying about?

Please explain?

17

That applying a stimulus to air where a phantom limb “should be”, without any knowledge by the subject, causes feeling in the phantom limb, stump, or brain.

18

Wouldn’t this be a neurological disorder? (After all, people used to scoff at Restless Leg Syndrome?)

I’ve heard that it usually causes intense pain, or itching.

19

Have you read any of the studies that have apparently been done on the subject? Or have you read any of the books that Sheldrake or Le Fanu have written?

Given the short time interval, all I have managed to do is check Amazon. They have a couple of books listed by each of Sheldrake and LeFanu. Obviously, I haven’t had time to read any of them yet, but certainly would like to explore the subject some more.

So do you have any references to this?

Please tell us what you know.

20

I know that if true, it would be supernatural.

I know that it’s similar to therapeutic touch, which was disproven by a nine year-old.

I know that I don’t have the burden of proof.