A “medical mystery” I’d not previously heard of… Terminal Lucidity. In short, there are a number of recorded instances of people with *extreme* cognitive failure – comas, Alzheimer’s, dementia, severe retardation and so on – suddenly becoming aware and intelligent to surprising degrees… and then dieing within hours or a few days.
Without invoking the supernatural, the explanation for this seems unavailable. There are enough reported cases that it is probably a real phenomenon; but the number of recorded cases is small enough that it seems to be quite rare.
As the body and brain start to shut down just before death, I wonder if – on rare occasions – the brains functions drop a certain amount and that actually opens a “window.” That there is a level of operation that produces a functional mind, but it requires some portion of the brain to have shut down. If this is the case, then a case might be made that for *some* rare cases of coma and Alzheimer’s and the like, the person trapped within can be brought back to the world not by trying to fix the brain… but by shutting parts of it down. In other words, the mind is there, but it’s been swamped by the operation of broken bits of the brain.