You Are Two

Patients with chronic frequent grand mal seizures are sometimes helped by severing the corpus callosum, the membrane of nerves that connect the left and right hemispheres of the brain. This keeps a seizure from overwhelming the entire brain. But these patients with split brains also gave us a look at what the two hemispheres do independently of each other. 

CGP Grey asks the obvious question: if we have two halves that can work independently, which one is the real us? The right brain is different from left brain, but do we really need both to be the person we always thought we were? (via reddit)