Pup7:
If your cerebral cortex is dead, the person you present as is gone forever.
This may be true from a medical standpoint but not from a philosophical and theological standpoint. From those standpoints personhood is an aspect of the soul. So that when one dies and goes before God for the individual judgment, it is the person who is judged and conscious of the judgment even in the absence of the brain and body.
Even from a bodily standpoint, I think we have no way of knowing for sure whether consciousness perseveres in a brain impaired person. Certainly the brain function is not present and not acting to integrate and control the body, but is the soul present and somehow aware of what is happening?
Philosophically speaking, the soul animates the whole body, not just the brain.
I suppose that if artificial ventilation is stopped, and breathing and heartbeat stops, we can presume that the patient is dead or dying.