https://www.vice.com/en_us/article/dy3p3w/scientists-detect-brain-activity-in-dying-people-linked-to-dreams-hallucinations

We’ve all heard eerie stories about people who almost perished, but survived to tell the tale of the strange visions and emotions they experienced when they were close to death. Now, scientists have observed a surge of energetic activity in the brains of dying patients, a discovery that reveals that our brains can be active even as our hearts stop beating, reports a new study. 

The results challenge a longstanding assumption that brains become nonfunctional as they lose oxygen during cardiac arrest, and could eventually open a new window into the weird phenomena associated with near-death experiences (NDE).