1. A real time closed loop brain-machine interface comprising: (a) a plurality of electrodes adapted to be chronically implanted in the nervous system of a subject and to acquire extracellular electrical signals from a population of single neurons; (b) a signal processing mechanism adapted to communicate with the plurality of electrodes and adapted to form extracted motor commands from the extracellular electrical signals; and (c) an actuator adapted to communicate with the signal processing mechanism and to respond to the extracted motor commands by effecting a movement, and to provide sensory feedback to the subject.