Lets suppose for a moment that we achieve in the next decade or so a series of breakthroughs in nanotechnology and AI to allow the creation of essentially perfect duplications of someones personality as an AI construct. I would be willing to say that if a person receives massive brain damage at some point in this era it would make sense to equip them with something of an artificial brain. Now remember that I said that the reproduction of their personality would be exact and so all of their characteristics would remain intact when this change took place. I would be an advocate of this sort of procedure and actually I would be an advocate of essentially the same procedure even if it was death instead of brain damage that had occurred. For the moment ignoring the moral implications of the resulting overpopulation problems and possible stagnation problems.
But what about people (like my mother) who experienced debilitating brain damage decades ago and has since evolved into someone who is very different from their original self although still sharing similarities? What if you could go in and "correct" their brain and restore their old capacities and old personality while letting them retain their accumulated memories of the intervening time. That would be unfair to the person living now but leaving things as they are is perhaps unfair to the person as they were. The problem is of course not really very much of a problem because the moral dillemma really only has one solution. The person who exists now can choose what they want. I guess I'm just babbling isn't the internet wonderful? I can post crap like this and nobody cares! wait... nobody cares... /sob