Gary B. Rollman,
Emeritus Professor of Psychology,
University of Western Ontario
(In addition to links below, see weekly archives in the right column)
Saturday, August 23, 2014
Why Do Amputees Feel the Ache of Nothingness? - Facts So Romantic - Nautilus
or amputees, it's adding insult to injury. They've already lost pieces of themselves that they thought they could always count on, limbs that they first discovered while waving the chubby things in their cribs. Yet after that life-changing loss comes a new kind of suffering: They begin to feel pain in the voids, in the places where their limbs used to be.
The phenomenon of phantom limb pain is both cruel and common; some studies have estimated that about 75 percent of amputees feel pain in their nonexistent limbs. It's also so mysterious that psychologists, doctors, and neuroscientists have argued for centuries about the pain's cause, with some asserting that the trouble is manufactured in the mind, and others insisting that it comes from a bodily malfunction. Now a study by Israeli and Albanian researchers has brought a new twist.
The affliction, which was described as early as the 1500s, was long thought to be a product of a mind twisted by loss; in the early 20th century, psychologists formalized this idea with arguments that the pain stemmed from some "neurotic process" or "obsession" with the missing limb. In later decades, scientists began to spurn psychoanalytic explanations for mental problems and turned instead toward neurological explanations. Doctors identified overgrowths of nerve fibers in amputees' limb stumps, called neuromas, and declared that phantom limb pain must originate in signals from those misfiring peripheral nerves.
Then the pendulum swung back again. Over the last 20 years, as brain science has increasingly taken the spotlight, researchers consensed around a top-down explanation for the phenomenon. Imaging techniques revealed that the area of the cortex responsible for receiving signals from the amputated limb gets taken over, essentially colonized, by neurons associated with other body parts. Why that "cortical reorganization" should result in phantom pain—well, that scientists couldn't exactly say. But there was strong evidence for a relationship. One influential paper, published in 1995 in Nature, found that amputees with more extensive brain changes experienced greater pain in their phantom limbs.