I've been reading the most amazing book. Its a book on neuropsychiatry called 'Phantoms in the Brain' and is part of the prescribed for our 'Introduction to Cognitive Science Course'.
There's this chapter where he talks about phantom limbs. A lot of amputees feel sensations in their amputated limb. The author of this book, a famous neurophysician, Ramachandran found out why this happens.
Different parts of our body are mapped onto different parts of our brain.
Quoting - 'A brilliant Canadian neurosurgeon Wilder Penfield performed extensive brain surgeries on patients under local anesthetic. Often, much of the brain was exposed during the operation and Penfield seized this opportunity to do experiments that had never been tried before. He stimulated specific regions of hte patients' brains with an electrode and simply asked them what they felt. All kinds of sensations, images and even memories were elicited by the electrode and the areas of the brain that were responsible could be mapped.'
The representation of the body surface on the surface of the human brain can be easily understood with this diagram of the homunculus ('little man') and imagining him upside down.
'This 'sensory homunculus' as it is now called, forms a greatly distorted representation of the body on the surface of the brain, with the parts that are particularly important taking up disproportionately large areas. For example, the area involved with the lips or with the fingers takes up as much space as the area involved with the entire trunk of the body. This is presumably because your lips and fingers are highly sensitive to touch and are capable of very fine discrimination, whereas your trunk is consdierably less sensitive, requiring less cortical space.'
'Upon close examination you will see that the map is not entirely continuous. The face is not near the neck, where it should be, but is below the hand. The genitals instead of being between the thighs, are located below the foot.'
Ramachandran had read about another neurologist's experiments on monkeys with amputated hands, who observed that stimulating certain parts of a monkey's face activated the neurons that would have been activated if the amputated hand had beent touched. Realizing that the areas for the face and the hand were close by, Ramachandran thought that maybe some parts of the area in the brain that was in charge of the hand had been taken over by parts of the area in the brain that was responsible for the face, more like a certain remapping had taken place.
To confirm his hunch, he met with a patient who had been complaining of a phantom hand and touched his face with a Q-tip. Voila! The patient felt certain parts of his hand being stimulated.After this he adds more examples -
'These findings raise an obvious question: What if some body part is lost other than the hand? Will some kind of remapping occur? When my studies on Tom were first published, I got many letters and calls from amputees wanting to know more. Some of them had been told that phantom sensations are imaginary and were relieved to learn that isn't true.
One day I got a call from a young woman in Boston. 'Dr. Ramachandran," she said, "I'm a graduate student as Beth Israel Hospital and for several years I've been studyign Parkinson's disease. But recently I decided to switch to the study of phantom limbs."
'Wonderful," I said. "The subject has been ignored far too long. Tell me what you are studying."
"Last year I had a terrible accident on my uncle's farm. I lost my left leg below the knee and I've had a phantom limb ever since. But I'm calling to thank you becausey our article made meunderstand what is going on." She cleared her throat."Something really strange happened to me after the amputation that dindn't make sense. Everytime I have sex I experience these strange sensations in my phantom foot. I didnn'tdare tell anybody because its so weird. But when I saw your diagrams, that in the brain the foot is next to the genitals, it became instantly clear to me."
She had experienced and understood, as fewofus everwill, the remapping phnomenon. This is what you'd expect if input from the genital area were to invade the territory vacated by the foot.
The next day the phone rang again. This time it was an engineer from Arkansas.
"Is this Dr.Ramachandran?"
"You know, I read about your work in the newspaper and it's really exciting. I lost my leg below the knee about two months ago but there's something I still don't understand. I'd like your advice."
"Well, I feel a little embarassed to tell you this."
I knew what he was going to say, but unlike the graduate student, he didn't know about the Penfield map.
"Doctor, everytime I have sexual intercourse, I experience sensations in my phantom foot. Howdo you explan that? My doctor said it doesn't make sense."
"Look," I said. "One possibility is that the genitals are right next to the foot in the body's brain maps. Don't worry about it."
He laughed nervously. "All that's fine, doctor. But you still don't understand. You see, I actually experience my orgasm in my foot. And therefore its much bigger than it used to be because its no longer just confined to my genitals."
Patients don't make up such stories. Ninety-nine percent of the time they're telling the truth, and if it seems incomprehensible, it's usually because we are not smart enough to fiugre out what's going on in their brains. The curious implication is that it's not just tactile sensation that transferred to his phantom but the erotic sensations of sexual pleasure as well. ( A colleague suggested that I title this book 'The Man Who Mistook His Foot For A Penis')."
This is one of the most thought provoking books I've ever read. And such books are even more fun to read because the author knows how to throw in the requisite amount of humour to make it interesting. A must buy, I'd say :)