And Yet It Moves: What We Currently Know about Phantom Arm Movements

What is left over if I subtract the fact that my arm goes up from the fact that I raise my arm? Neurological evidence invites the provocative hypothesis that what is left over is a phantom arm movement-a movement of an arm that has been amputated. After arm/hand amputation, many amputees report that they can generate voluntary movements of the phantom limb; that is, they can move the arm that was amputated. But what is it like to move an arm/hand that is not there? Here, we review what is currently known about phantom limb movements at three descriptive levels: the kinematic level, the muscle level, and the cortical level. We conclude that phantom arm movements are best conceptualized as the real movements of a dematerialized hand.