This article reprinted from The conversation under a Creative Commons license.
Separationimagining a world where one’s work and personal life are surgically separated, returns Friday for its long-awaited second season. Although the premise of this amazing piece of science fiction is simple, it touches on a question that neuroscience has been trying to answer for decades: Can the human mind really be split in two?
Notably, “split brain” patients have been around since the 1940s. To control epileptic symptoms, these patients underwent surgery to separate the left and right hemispheres. Similar operations are still taking place today.
A recent study on this type of surgery showed that the different hemispheres of different brain patients can process information independently. This suggests that this process may have created two separate minds residing in the same brain.
In one season SeparationHelly R (Britt Lower) faced a conflict between her “innie” (the side of her mind that remembered her work life) and her “work” (the non-work side). Similarly, there is evidence of a conflict between the two hemispheres of actual patients with a split brain.
When you talk to patients with split brains, you’re usually talking to the left hemisphere of the brain, which controls speech. However, some patients can communicate with their right hemisphere by writing, for example, or arranging Scrabble letters.
A young patient in one study was asked what career he would like in the future. His left hemisphere chose the office work of making technical drawings. However, his right hemisphere was arranging the letters to spell “car race.”
Cerebral palsy patients have reported “alien hand syndrome,” in which one of their hands appears to move of its own accord. This observation suggests that two distinctly different “persons” may coexist in the same brain and may have conflicting goals.
In Separationhowever, both innie and outie have access to speech. This is one indication that the proposed “dissection process” must involve a complex dissection of brain networks.
An example of a complex division of labor was described in a case report by Neil, 1994. Neil was a young man with several complications following a pineal gland tumor. One of these difficulties was a rare form of amnesia. It meant that Neil could not remember the events of his day or report what he had learned at school. He still couldn’t read even though he could write, and he couldn’t say things with words, even though he could draw.
Amazingly, Neil was able to continue his education. The researchers became interested in how he was able to complete his schoolwork despite memorizing what he was studying. They asked him about the novel he was reading at school, Cider With Rosie by Laurie Lee. When he talked, Neil couldn’t remember anything about the book—not even the title. But when the researcher asked Neil to write down everything he could remember about the book, he wrote “Geranium windows shooting blood Cider and Rosie Dranium the smell of wet pepper. [sic] and mushroom growth”—all words related to this novel. As Neil could not read, he had to ask the researcher: “What did I write?”