Severance, which imagines a world where a person’s work and personal lives are surgically separated, will soon return to Apple TV+ for a second season. While the concept of this gripping piece of science fiction is far-fetched, it touches on some interesting neuroscience. Can a person’s mind really be surgically split in two? Remarkably, “split-brain” patients have existed since the 1940s. To control epilepsy symptoms, these patients underwent a surgery to separate the left and right hemispheres. Similar surgeries still happen today. Later research on this type of surgery showed that the separated hemispheres of split-brain patients could process information…