Nearly all amputees feel their missing limb as if it still existed, and many experience chronic phantom limb pain. The going theory is that this pain is triggered by the brain. But scientists have now located and blocked these sensations in the body itself — a finding that upends conventional thinking.
According to the popular top-down theory, phantom limb pain happens when there's a sudden loss of sensory input and the brain hasn't had a chance to adapt — what scientists call maladaptive cortical plasticity. And indeed, neuroscientist Vilayanur Ramachandran's Mirror Box experiment — in which two outward-facing mirrors alleviate phantom limb pain by "tricking" an amputee into thinking their missing limb is still there — would seem to indicate that something's going on in the brain.