Virtual massage could relieve phantom limb pain for amputees

The Daily Mail of London, England, reported that amputees who experience phantom limb pain could find relief in a surprisingly simple way - by watching someone else rub their hands together.

The treatment seems to fool the brain that it is their missing hand being massaged, according to the American researchers, who worked with combat veterans. Phantom limbs occur when an amputee feels the often painful sensation of touch arising from a limb that is no longer present.

Lead researcher Vilayanur Ramachandran from the Centre for Brain and Cognition at the University of California, used newly discovered properties of mirror neurons to soothe the ache. Mirror neurons fire when a person performs an intentional action - such as waving - and also when they observe someone else performing the same action. They are thought to help us predict the intentions of others by creating a "virtual reality" simulation of the action in our minds.

"You also find cells like this for touch," says Ramachandran. "They fire when you touch yourself and when you watch someone else being touched in the same location."

Ramachandran and his colleague and wife Diane Rogers-Ramachandran used a "mirror box" - a tool that creates the visual illusion of two hands for people who actually only have one. By placing an amputee's arms either side of a mirror - with the missing limb on the non-reflective side, the amputee sees the reflection of their normal hand superimposed on the location of their missing hand.

Two amputees watched their normal hand being prodded, and both felt the remarkable sensation of "being prodded" in their missing hand. In another experiment, when the amputees watched a volunteer's hand being stroked, they too began to experience a stroking sensation arising from their missing limb.
The amputees "felt" the actions of others because their missing limb provided no feedback to partially inhibit their mirror neurons, no longer telling them that they were not "literally" being touched, says Ramachandran.

One woman reported that watching a volunteer rubbing her hand caused the cramping sensation within the phantom limb to cease for 10 to 15 minutes. "If you do it often enough perhaps this pain will go away for good," suggests Ramachandran. "If an amputee experiences pain in their missing limb, they could watch a friend or partner rub their hand to get rid of it."

Massaging the skin helps relieve a painful sensation by restoring blood flow and activating sensory fibres, which inhibit pain messages to the brain. By watching another person rubbing their hand, these amputees are apparently tapping into this latter mechanism, says Ramachandran.

"If performed early enough, this type of therapy may also be used to help stroke patients regain movements by watching others perform their lost actions," he concluded.

Mirror Box Therapy from "Phantoms in the Brain" by Blakeslee & Ramachandran

Excerpted from The NY Review of Books Volume 55, Number 11 · June 26, 2008: How the Mind Works: Revelations by Israel Rosenfield & Edward Ziff

The problem of representation, meaning, and memory is also illustrated by the case of a patient who has lost his arm in an accident. As is often the case, the brain creates a "phantom" limb in an apparent attempt to preserve a unified sense of self. For the patient, the phantom limb is painful. The brain knows there is no limb; pain is the consequence of the incoherence between what the brain "sees" (no arm) and the brain's "feeling" the presence of a phantom that it has created in its attempt to maintain a unified sense of self in continuity with the past. Such pain is not created by an external stimulus and cannot be eliminated by painkillers.

One famous case is that of a young man who had lost his hand in a motorcycle accident. In a therapeutic procedure devised by V.S. Ramachandran, and described in his book with Sandra Blakeslee, Phantoms in the Brain, the patient put his intact hand in one side of a box and "inserted" his phantom hand in the other side. As the illustration on this page shows, one section of the box had a vertical mirror, which showed a reflection of his intact hand. The patient observed in the mirror the image of his real hand, and was then asked to make similar movements with both "hands," which suggested to the brain real movement from the lost hand. Suddenly the pain disappeared. Though the young man was perfectly aware of the trick being played on him—the stump of his amputated arm was lying in one section of the box—the visual image overcame his sense of being tricked. Seeing is believing! Pain—the consequence of the incoherence between the brain's creation of a phantom limb and the visual realization that the limb does not exist—disappeared; what was seen (a hand in the mirror) matched what was felt (a phantom).

According to the Italian neurologist Angela Sirigu, who used videos instead of mirrors to perform a similar experiment,

It is the dissonance between the image of oneself and the damaged body, that is at the origin of the phantom pain. Seeing the damaged hand once again functioning, reduces the dissonance even though the patient is aware of being tricked.

At one moment the patient experiences a painful phantom limb; at another he sees a mirror image of his intact hand and the pain disappears. This is only one of many neurological examples of what we might call the Dr. Jekyll and Mr. Hyde Syndrome: the patient in the experiment sees and remembers one world at certain times and a completely different world at other times.[4] The phantom limb is the brain's way of preserving a body image—a sense of self that is essential to all coherent brain activity. And as in the case of colors, the phantom limb suggests that what we see, hear, and feel are inventions of the brain—an integration of the past (the loss of the limb) and the present (a phantom that is essential for the brain's continuing to function "normally").

In general, every recollection refers not only to the remembered event or person or object but to the person who is remembering. The very essence of memory is subjective, not mechanical, reproduction; and essential to that subjective psychology is that every remembered image of a person, place, idea, or object inevitably contains, whether explicitly or implicitly, a basic reference to the person who is remembering.

Our conscious life is a constant flow, or integration, of an immediate past and the present—what Henri Bergson called le souvenir du présent (1908) and Edelman more recently called the remembered present (1989). Consciousness, in this view, is neither recalled representations nor the immediate present, but something different in kind (as colors are different in kind from the lightness and darkness of different reflected wavelengths).

The importance of body image and motor activity for perception, physical movement, and thought is suggested by the recent discovery of "mirror neurons" by Giacomo Rizzolatti and his colleagues. They observed that the neurons that fired when a monkey grasped an object also fired when the monkey watched a scientist grasp the same object. The monkey apparently understood the action of the experimenter because the activity within its brain was similar when the monkey was observing the experimenter and when the monkey was grasping the object. What was surprising was that the same neurons that produced "motor actions," i.e., actions involving muscular movement, were active when the monkey was perceiving those actions performed by others.

Phantoms in the Brain: Probing the Mysteries of the Human Mind

by V.S. Ramachandran and Sandra Blakeslee, with a foreword by Oliver Sacks
Quill, 328 pp., $16.00 (paper)

Mirrors in the Brain: How Our Minds Share Actions and and Emotions
by Giacomo Rizzolatti and Corrado Sinigaglia, translated from the Italian by Frances Anderson
Oxford University Press,242 pp., $49.95

A Universe of Consciousness: How Matter Becomes Imagination

by Gerald M. Edelman and Giulio Tononi
Basic Books, 274 pp., $18.00 (paper)