This fascinating video from the Mayo Clinic explains how 28-year-old Mary Meixner went through "awake surgery" during which surgeons used an intra-operative MRI to target her brain tumor.
At the end of the operation, she slept. Then, she says, "I woke up and I was so excited, and I was like, yes! I'm not dead! I can talk! I can think! Because you never know, right?"