You may like the short science fiction story Learning To Be Me, by Greg Egan. The idea is that people put a microchip in their brain (the "jewel") that learns t

You may like the short science fiction story Learning To Be Me, by Greg Egan. The idea is that people put a microchip in their brain (the "jewel") that learns to mimic the brain's signals, so when the brain fails the microchip can take over. The interesting question is: "am I the jewel?"