Dawn Taylor and his colleagues from Arizona State university have introduced visual feedback into their cyber-monkey experiments and suggest that information from far fewer neurons than generally thought is necessary to generate movement. Theirs is an extremely clever experiment (more): It only used 18 electrodes which supplied information about the firing activity of only 18 nerve cells in the motor cortex, the part of the brain where movement originates. This information was used to move a cursor in a virtual 3D-environment.
The decisive point: As soon as you provide visual feedback in real time, it seems to be possible to reprogramme the nerve cells in motor cortex. Learning, thus, is crucial for Taylor's monkeys. When he prevented learning by not giving his monkeys the visual feedback they needed, the information produced by the 18 nerve cells remained random and cursor movement was inaccurate.