[ScarletEmerald]

It doesn't sound quite like the story the previous poster was thinking of, but Hannu Rajaniemi's Jean le Flambeu series (beginning with The Quantum Thief) has uploaded, edited, and copied human minds as a significant component of the story.

[gwern]

Can't be Quantum Thief, because in Hannu's -verse, AGIs (or 'dragons', IIRC) exist, are actually pretty easy to make, and much smarter than the uploads or derived human brains - so smart that they are far too dangerous for any side to use, and that's why they still run on brains.