Even as prosthetic technology advances, the problem of phantom limb sensation persists. Essentially pain, pressure, or some other stimulus attributed by the brain to a limb that has been lost, the exact cause for this is unknown -- and it's a very real problem for amputees. Hoping to better understand (and someday maybe eliminate) the phenomenon, researchers at the University of Jena in Germany have developed a prosthesis that uses sensors and a stimulation unit to send feedback from the patient's artificial hand back to the brain, offering some relief to the individual in the process. So far, the team has had some success, but as the school's Dr. Thomas Weiss points out, there is quite a bit of work yet to be done to determine if "the hand is helpful to only a few people or if it is a therapeutic for all wearers of artificial limbs."