The BBC has a fascinating report on non-responsive persons who become transiently partly responsive while taking the drug Zolpidem.
It's not completely surprising. Over the past few years it's become apparent even to laypersons that consciousness (whatever that is), and lack of consciousness, are not simple or binary states. A human can have a lot of intact nervous system and yet not be "conscious", conversely humans can be "conscious" and responsive with a lot of damaged tissue. (One of the reasons Ms. Schiavo's physicians were confident of her prognosis was that she was both non-conscious and had severe tissue damage.)
The theory is that this medication can allow non-damaged parts of the brain to 'go online' and allow responsiveness, even in the absence of the normal mechanism of consciousness.
The story suggests that there are many grades and states of "consciousness" arising from interacting "islands" of neuronal subsystems, and that this and similar medications allows "islands" that are normally unable to interact, perhaps due to a physiologic suppression mechanism, to interact with each other and with the sensory and motor systems. Whether those interacting subsystems could ever produce a "person", and whether that would be the same "person" as the "original", is a matter for some thought. I would suspect that they may lack access to memory ...
[55 yo veterans of past "altered states of consciousness" can comment below ...]