The brain's normal pain-sensory system, in which nerve endings send messages to the brain about a threat, goes awry in migraines.

WSJ: Fresh Target in Hunt for a Migraine Cure

Experts disagree about how a migraine is triggered, but the trigeminal nerve an important pathway that carries sensory information about the face and its connections to numerous other nerves and the brain appear to be responsible for transmitting the pain.

WSJ: Fresh Target in Hunt for a Migraine Cure

Additionally, a sensory pad was applied onto our forearm's medial cutaneous nerve (around the elbow area) to pick up our muscular nerve signal -- similarly, Cyberdyne's lower-body exosuit requires two sensors on each leg.

ENGADGET: Cyberdyne HAL robotic arm hands-on (video) Hands-on