A man loses his right hand in a farm accident, four years later, he has episodes of severe pain in the missing hand (phantom limb pain). A detailed PET scan study of his cerebral coex might be expected to show

Between 50% and 80% of amputees experience phantom sensations, usually pain, in the region of their amputated limb. Phantom sensations may also occur after the removal of body pas other than the limbs, for example, after amputation of the breast, extraction of a tooth (phantom tooth pain), or removal of an eye (phantom eye syndrome). Numerous theories have been evoked to explain this phenomenon. The current theory is based on evidence that the brain can reorganize if sensory input is cut off. The ventral posterior thalamic nucleus is one example where this change can occur. In patients who have had their leg amputated, single neuron recordings show that the thalamic region that once received input from the leg and foot now respond to stimulation of the stump (thigh).(Reference: Ganong review of medical physiology 23rd edition Page no: 176)