Bach, Beethoven and the Neuromatrix
Alright, we're gonna talk about the theory that Ronald Melzack introduced concerning phantom pain. His theory involves the integration of three seperate pathways in the brain with a concept called the neurosignature. Melzack proposes that a large number of interconnected neurons, a neuromatirx, exists in every person. That neuromatrix analyzes the sensory information and gives perception of sensation. The neurosignature comes into play at this point. It tells the brain that the perceptions of sensation are from the "self." The neurosignature tells the brain that your arm is YOUR arm, not someone elses. (Melzack,1992, 1990) The parietal lobe is heavily involved in the neurosignature.(Saks 1990) - Patients with lesions in the parietal lobe have been known to throw their own leg out of bed in the middle of the night because it felt like someone else's leg!
Uhh.....What's a Neurosignature?
Melzack presents a very good metaphor for understanding the neurosignature. He relates it to an piece of classical music with the neurosignature being the theme of the piece, that constant thing which defines the piece. The sensory inputs and outputs are the other instruments. The instruments change key, tempo and sometimes even rhythmn, but there is always that theme giving the piece is personality.
Genetics and Posthetics
The theory that Melzack proposes carries with it the presupposition that the neuromatrix is prewired by genetics. Melzack points to cases in which people are born without limbs, yet still experience phantom pain. 
The other theories that involve the neuromatrix consider experience and learning the determining factor behind the wiring of the neuromatrix.(Melzack, 1992)
So what?
Phantom pain can be explained through the use of genetics and the neuromatrix. If the theory is correct, then the brain has been prewired to think that its body is going to have a right arm. Even if the right arm is amputated, the brain is still prewired to believe that the arm is there. This may be the cause of phantom limb sensations. If the brain believes that limb is there, it might tell the limb to move by zapping certain neural pathways in the neuromatrix. Since the limb is not there, and the brain receives no sensory feedback, it will increase the strength of its zapping. This may be the cause of the phantom pain.(Melzack 1990,1992)