I would also reference DS9’s “Life Support,” where Bareil is injured and as he declines, his brain is slowly replaced with a positronic implant. It becomes clear that even though he retains his memories, he loses his humanity (Bajoranity). This indicates that there is a difference between a brain and a copy of a brain.
That was an interesting one... though I enjoy the episode in general, I feel that aspect of it kind of descended into schlock territory. Prior to that, it was always pretty clear that the Soong-type androids were the only successful applications of positronic technology; what DS9 probably meant to say was "cybernetic", but the writer either got confused or just wanted to throw "positronic" in there was a TNG connection. It's canon, though, so we have to account for it somehow.
I'll say this; Julian Bashir is no Dr. Soong; nor even an Ira Graves-tier intellect (not even close, despite his genetic enhancements). Both those men developed ways of transitioning an active, living consciousness into an artificial neural net. Their work, techniques and technologies are virtually unknown in the wider Federation, given how reclusive both became as they got older; and even the specialists who may still remember their earlier work and know a bit more about them still don't actually have a working understanding of their greatest breakthroughs. Hell even Geordi, who probably spent more time working on Data than anyone except Dr. Soong himself, only has a rudimentary understanding of how his brain works and certainly couldn't create a stable neural net himself (the Holy Grail, as it were, and not even Data could do that).
We also don't know exactly which parts, or even how much of Bareil's brain tissue was replaced with "positronic" (cybernetic) implants. It was actually quite a disturbing episode, IMO, and a bit out of character for Star Trek, even for DS9. Whatever implants he did receive were likely very crude, designed to mimic the basic functions of the tissue they replaced. Since nobody other than Dr. Soong has successfully created a stable artificial neural net (which is what houses the actual consciousness), it's safe to assume that Bareil didn't receive anything like that. None of the organic brain regions responsible for memory or personality were probably replaced; but perhaps sections that allowed those regions to interact and express themselves were compromised.
As far as copies vs an original goes, the transporter in Trek has the same issue; real-life teleportation (were it possible on a macro scale) is said to result in the destruction of the original and the creation of a copy at the destination. But Trek's transporters have been said not to work this way; that the "reconstructed" person or object is the original, the same actual energy being "beamed" to the destination and used to rebuild the matter in the same exact way. Most would say that being disassembled at a molecular or atomic level would effectively "kill" you, no matter how well you're put back together, but who's to say, really? Consider that 500 years ago if you lost an arm or finger it was gone for good... today, if you're lucky and doctors work quickly, you may get it back. It's made clear that Ira Graves believes just as strongly that his method of consciousness transfer is just that; a true transfer rather than a copy. It's safe to assume that Dr. Soong believed the same of the process he used to save his wife (and in the books, himself as well).
Edited by TM2-Megatron, 01 September 2018 - 12:35 PM.