Feeling Fake Pain

Phantom pain questions how the brain understands the body

By Colin Allen, published on June 1, 2003 - last reviewed on January 23, 2015

When it comes to pain, sometimes it's mind over body. Recent
research has found that the brain reacts to "injuries" committed to
inanimate objects as if they were parts of the body. In the study,
scientists found that subjects can confuse a fake rubber arm--or even a
table--with the body.

The brain's understanding of the body may not be so simple. Our
mental image of our own bodies seems to be continually updated by visual
and sensory clues explains Carrie Armel and Vilayanur Ramachandran,
cognitive neuroscientists at the University of California at San Diego
School of Medicine. For their study, 16 volunteers sat down at a table
that hid each person's right hand. In place of the right hand, the
researchers put a dummy rubber hand on the table. To measure stress,
electrodes were placed on the left hand.

Researchers then tapped the fake rubber hand as well as the real
right hand simultaneously. Then, researchers slightly bent a finger on
the real right hand while also pulling back the finger on the rubber hand
into a painful position. Subjects believed that their real fingers could
go back further than the fingers actually could.

In a second experiment, 24 subjects went through a similar set of
tasks, this time without the fake hand. After the tapping the table and
each subject's hand, researchers put a Band-Aid on both the table and the
hand. When the Band-Aid was partially ripped off the table subjects felt
and registered pain. Ramachandran notes that even though the mind
rationally understands that it is not being hurt, the visual cortex
overrides such thoughts.

The study was published in journal
Proceedings B, published by the Royal Society in