However, I'm skeptical about these claims coming from a neuroscientist because they're not consistent with neuroscientific terms.
He says he was in a "deep coma, a vegetative state." Comas and vegetative states are different. In a coma, you're unawake and unaware. In a vegetative state, you're awake and unaware (and, after four weeks, you're in a persistent vegetative state).
You don't equate a coma with a vegetative state.
He claims "scans showed no conscious activity whatever [in my brain]." Yes, but did scans show any brain activity? They must have, or else he would not have been declared to be in a coma or a VS. He would have been declared brain-dead.
So, one strike, and one parsing of words.
Time is strange. I've had dreams that lasted for weeks but occurred in one night. Who's to say this long heavenly experience didn't occur in a second or two of consciousness coming out of a coma?
Apparently Dr Alexander’s story has changed with the passage of time, and some of his colleagues who took care of him in the hospital dispute some of what he says. He has been in serious professional trouble and was facing major financial problems before he wrote the first book. His professional reputation was not good. So quite apart from the unBiblical visions he claims to have had, the story smells.
It says right in the excerpt that it was the neocortex with no activity.