If you're interested in this question, you should read some of Robert J. Sawyer's stuff. He's an awesome sci-fi author, and in his books, he brings up many theories about consciousness and what makes a human human. One of his books, Mindscan, involves this guy, Jake, who "copies" his consciousness into a synthetic body because his "real" body is dying. Before he does this, he signs over his rights of personhood to the synthetic body. His original body, which still has consciousness and memories, goes off to live on the moon in a retirement community-ish place. But once a cure for the thing that is killing the original body is found, the original body holds people hostage and demands his identity back. It's a good read.

A lot of his other books bring up consciousness, too. If you're into that kind of speculation, it's a recommended read.