A phenomenon called the "rubber hand illusion" is helping scientists
understand how the brain recognizes that a limb or other part belongs to the
body, according to a study by British scientists. The work was published on
July 2 in an online edition of Science (http://www.sciencemag.org).
H. Henrik Ehrsson, MD, PhD, and colleagues at University College London
and University of Oxford used functional magnetic resonance imaging to monitor
volunteers' brain activity during experiments featuring this illusion, in
which a prosthetic hand is placed on a table in the same orientation as the
volunteer's own hand (which is hidden from view beneath the table). First,
the researchers stroked both hands simultaneously with small brushes. Then,
when only the prosthesis was stroked, most subjects perceived the rubber hand
as their own and "felt" the touch of the brush on it.
Stephenson J. Brain and Body. JAMA. 2004;292(7):794. doi:10.1001/jama.292.7.794-b