Fascinating article on the BBC News website today. Alien Hand Syndrome. It’s about the effect of cutting the corpus callosum, which the two hemipheres of the brain use to communicate with each other. This is done as an extreme measure to prevent epilepsy. The conclusion is pretty startling.
“I am legion” indeed.
As the end suggests, this symptom is extremely rare in CC sectioning. Also, it occurs more often in patients who were cut decades ago; nowadays they can remove a small portion of it which contributes to epilepsy, leaving the rest intact. And even if it is fully removed, the hemispheres are still not isolated. The anterior commissure is a smaller tract of white matter connecting the hemispheres. Theories I have heard suggest that the cross hemisphere connections are done because it is more efficient to have two systems, each with their own strengths and weaknesses, than it is to have one unified system
Of course, nothing is complete without this clip.
Oh, and Haruki Murakami’s Hard-Boiled Wonderland and the End of the World has a fictionalized version of this in the main character.
Another fictional depiction: Alan Moore’s short story “A Hypothetical Lizard”. The story involves a prostitute who has had her corpus callosum severed and wears a mask covering the right side of her face and a restraining glove on her right hand. She serves as a prostitute to wizards, and the severing allows her to still think and see, but not communicate, so that the secrets of the wizards she serves cannot be disclosed. Weird story, but well written.
Read Julian Jaynes’ odd and fascinating book The Origins of Consciousness in the Breakdown of the Bicameral Mind. He talks a lot about experiments with patients who have had the corpus callosum severed, because it’s intimately tied up with his thesis that our experience of The Gods is one hemisphere of the brain communicating with the other via connections in the corpus callosum back in the days when our brain was less integrated. So we perceived them as hallucinations – usually voices – carried over that bridge. Even if you don’t buy his theory, there’s a lot of stuff on such split-brain research.
That’s truly fascinating.
Edit: Although snippets of “Evil Dead: The Musical” are coming to mind. “We’ve got yer ha-aaaand! We;ve got yer ha-aaaaand!”