Simon's post suddenly reminds me of phantom pain: pain that one can feel in amputated limbs. So your left foot hurts, while you don't even have a left leg at all. Talking about the brain making stuff up.
This phantom pain in amputated limbs can be treated: using a mirror, so the eyes see the reflection of the remaining healthy limb at the location of the amputated limb.
When the healthy limb moves, so does the reflection...and the brain starts to assume both limbs are present and healthy.....reducing the phantom pain.
http://www.medicinenet.com/script/main/mobileart.asp?articlekey=88097