When your neural circuits are severed, you lose the use of the portion of your body they were connecting to your brain. It's like a horrifying real-life version of cutting a puppet's strings. Every part of your body could be intact except for a tiny portion of the necessary neural pathway and you'd still be partially paralyzed.
It's this frightening reality that spurred on a joint team of scientists in Japan and the U.S. to develop a new type of "artificial neuron connection." Basically, they found a way to restore that severed bit of neural connection with electric impulses. The electric impulses from the monkey's brain successfully traveled down the animal's spinal cord and across an artificial circuit that bridged a paralysis-causing legion. The impulses then continued along the monkey's remaining healthy nerve network, restoring the use of the paralyzed paw.
The scientists were even able to restore the paw-to-spine circuits as well. This strengthened the connection to the monkey's paw and allowed the creature's brain to recognize that it was indeed in control of the paw once again. Needless to say, the restoration of at-will control of a paralyzed limb is the holy grail of paralysis treatments. And it looks like this team of scientists has taken a giant step forward in the search for that cure.