If our universe/life/reality exists in entirely in one's mind, in their perception,then how do those with no contact with the outside world (i.e. comatose patients, those not living in society, or mute individuals) function?  Is there no self, if there are no elements of an outside world?  If we think back to Plato's cave analogy, then we can assume that one creates the universe based on his or her experiences.  But what happens when we add the element of solitude to that equation?  And what happens to an Alzheimer's patients thoughts; since the person had at one time a functioning sound mind, presumably, does the stream of consciousness flow from past to present experiences?  I'm curious.  I need to find out more on the subject(s).

This is where I might ask subscribers for further reading suggestions.  Due to logistical problems, I'll have to search for it myself.