Dynamic Mechano-allodynia: Dynamic mechano-allodynia will be determined by stroking the skin three times within 5 seconds at a rate of 5 cm/sec with a 2.5 cm wide standard foam paintbrush. Allodynia severity will be measured on the subject's response using a numerical rating scale. The subject reports both the amount of pain on a 0-10 scale (0: no pain; 10: worst pain ever experienced) and the extent to which the sensation spread.