There was a pretty fascinating talk at TED by Jill Bolte Taylor, a neuroscientist who experienced a massive stroke ("my stroke of insight"). On the one hand she observed her own neurological functions shut down with clinical curiosity, and on the other she had a very strong impression of losing her sense of self and being completely connected with the world.

http://www.ted.com/talks/jill_bolte_taylor_s_powerful_stroke...