[juhanima]

I suppose there is a concept of sentience from outside and a different concept from internal sentience. The movie "Johny Got His Gun" by Dalton Trumbo discusses a situation where a badly injured soldier in WW1 is considered brain dead by outsiders while he's fully conscious and sentient internally.

I haven't studied neuroscience so I don't know how you define consciousness. I have read Julian Jaynes's "The Origin of Consciousness..." which in my untrained opinion makes a compelling case that consciousness is a hard term to define.