Months after the accident, your amputee uncle's phantom limb pain subsides. One afternoon he is sleeping and you see a fly walk across his upper lip. He wakes up and tells you he just had the funniest feeling. It was as if someone was touching his missing index finger. You decide to experiment with your uncle and you blindfold him. As you touch his cheek he tells you that you are touching his

Question

cheek and his missing thumb! As you move around his face you map out his fingers and forearm on his face. Hypothesize how this could be possible.

What will be an ideal response?

Answer 1

A map of the somatosensory cortex would show that the area corresponding to the phantom hand and forearm is adjacent to the area corresponding to the face. What has happened is the hand cortex has been invaded by the sensory fibers that normally only activate the face area of the cortex. Since the territory for the hand is vacated (not receiving any stimulation), those facial sensory fibers have begun to activate cells there causing the phantom limb sensation.