Uploading our brains to computers

Bryan Caplan today mentioned the idea of achieving immortality via uploading one's brain to a computer. I've heard others propose such a concept, such as Ray Kurzweil, or seen it appear in fiction, such as in William Gibson, or in Stephen King's Lawnmower Man. It's a tantalizing idea.

Nonetheless, based on what I said earlier about consciousness and teleportation, my biggest fear is when you upload your brain, you won't really upload your consciousness.

In other words, imagine one day in the future, you're sitting there in a chair, with some brain-reader strapped to your head. It reads your brain, uploads it, and then voila, there's now some sort of digital intelligence newly created within the computer's memory. But you're still sitting in the chair, looking at the computer as this computer intelligence is greeting you. And even worse, this computer intelligence is absolutely convinced that it is the true you, and that the physical person sitting in the chair is an obsolete copy that needs to be deleted. From this point, one could spin some sort of sci-fi horror story about an omnipresent computer intelligence trying to kill you because it thinks it's the real you, which might make for an interesting story, but is not a very appealing reality.

If technology is going to give us virtual reality, it seems likely that there is going to have to be some sort of physical continuity for the brain In other words, we have to figure out ways to prolong and preserve our bodies, especially our nervous system, in order to achieve some sort of immortality, if such a thing is at all possible.