Whole Brain Emulation (WBE), often informally called “uploading”, is a proposed technique that involves using a computer to emulate the states and functional dynamics of a brain at a relatively fine‐grained level of detail to produce the same outward behaviour as the original brain. The basic idea is to take a particular brain, scan its structure in detail, and construct a software model of it that is sufficiently faithful to the original that, when run on appropriate hardware, it will behave in essentially the same way as the original brain.
An approach to WBE examined in in Bostrom and Sandberg (2008), a comprehensive study on the topic, is one that involves destructive scanning, in which the brain is separated from other tissue, sliced into thin slices, fixated and subsequently scanned accurately and a at a sufficiently high resolution. This process could be applied immediately after death or on cryogenically preserved brain tissue.
WBE has been proposed as a path to creating human-level digital intelligence. Emulations might also enable a type of “digital immortality” by creating back‐up copies of an individual's identity, thereby promising a type of continued survival in cyberspace after death.
There is considerable debate about the technological feasibility of WBE: though there is general (though not universal) agreement that the brain, being a physical system, is amenable to being simulated. However, the necessary scanning, data gathering, image interpretation, and amounts of computation required might still be beyond what our reach for some time to come. (see )
When will a whole human brain be successfully emulated?
This question resolves positive when a human brain is first successfully emulated on a computer, with the emulation being at least as faithful to the original brain as an “individual brain emulation” defined in Bostrom and Sandberg (2008) (page 11):
Success criterion of an individual brain emulation:
The emulation produces emergent activity characteristic of that of one particular (fully functioning) brain. It is more similar to the activity of the original brain than any other brain.
Required properties of an individual brain emulation:
Correct internal and behaviour responses. Retains most memories and skills of the particular brain that was emulated. (In an emulation of an animal brain, it should be possible to recognize the particular (familiar) animal.)
Emulation here is the process, described in Bostrom and Sandberg (2008), that is based on direct simulation of the neural connectome (and a requisite level of its physical instantiation). Donors need not have been alive before their brain is uploaded. Resolution requires just those portions of the human brain that have functionally relevant effects on actual behaviour to be emulated. The emulation needs to run sufficiently long to confirm that it successfully produces similar outward behaviour more similar to the activity of the original brain than that of any other human brain.