Phantom Limbs

I have been recently listening to this exceedingly interesting book-on-tape about the functions of the brain by neuroscientist Vilayanur Ramachandran. One of the aspects that really caught my attention was his discussion on a bizarre phenomenon of "phantom limbs." A phantom limb is a sensation that one is still feeling and moving an amputated limb. For example, if an amputee loses his right arm, he/she may still feel its presence and sensations associated with it. This is because the neurons in the brain have already established a connection to that limb, and even if it is removed, these neurons may still send signals to the brain. Thus, the brain can still make the amputated person feel his lost limb. Interestingly, these unique individuals are not delusional, as they know that the limb is not really there. However, their brain gives them strange sensations associated with the missing limb.

Many of the neurons and receptors that are associated with different body parts are also neurologically mapped to other body parts. For example, one of Dr. Ramachandran's patients experienced a sensation in his phantom right arm when he was rubbed on the chin with a Q-tip. This is because the same receptors/neurons that connect to the chin are also associated with the right arm; both are active and operated by the right side of the brain. Also, the same patient experienced a trickling feeling that traveled down his phantom arm when a drop of water was placed on his right cheek. To make this even more bizarre, the trickling feeling was able to go against gravity, since it still traveled in the same direction when he pointed his "stump" towards the ceiling.

"Phantom limbs" is further explained in Ramachandran's The Tell Tale Brain. I will continue to listen to it to gather more information on this interesting concept.

Is it really there?

                                          http://www.medindia.net/patients/patientinfo/images/phantom-limb-syndrome.jpg