Reanimating limbs after injury or disease.

Many diseases and injuries lead to loss of motor function. Can we reanimate paralyzed limbs to produce effective, graceful movements? Recent insights into the function of the motor system and greatly improved computing capabilities have made this a realistic goal, even in the absence of regeneration of motor pathways. Some approaches involve stimulating muscles, nerves or the spinal cord below the level of a lesion. Others involve recording a subject's intention from the cortex, and using this intention to control computers, robots or systems for stimulating the limbs. Here, we critically analyze the possibilities and limitations of various approaches for restoring motor function based on recent human trials and underlying neuroscience research.