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Will You Ever Be Able To Upload Your Brain? (nytimes.com)
An anonymous reader points out this piece in the Times by professor of neuroscience at Columbia and co-director of the Center for Theoretical Neuroscience Kenneth Miller, about what it would take to upload a human brain. "Much of the current hope of reconstructing a functioning brain rests on connectomics: the ambition to construct a complete wiring diagram, or 'connectome,' of all the synaptic connections between neurons in the mammalian brain. Unfortunately connectomics, while an important part of basic research, falls far short of the goal of reconstructing a mind, in two ways. First, we are far from constructing a connectome. The current best achievement was determining the connections in a tiny piece of brain tissue containing 1,700 synapses; the human brain has more than a hundred billion times that number of synapses. While progress is swift, no one has any realistic estimate of how long it will take to arrive at brain-size connectomes. (My wild guess: centuries.)"
The estimate that it will take centuries is probably what is the farthest off.
The result is the same whether the brain is replaced a little at a time or all at once in a copy.
...or the copy, there's no way for them to tell
There's an old story about an axe that has it's handle replaced a few times. Eventually over the years it's used so much the head is replaced. And a few more handles after that. There was always a piece of the axe included when something was replaced. Is the current axe the same axe we started with? If not, at what point did it become a different axe?
As to whether an exact copy of you is actually you, I would say yes, unless you're going to argue something supernatural like a soul. It would be just the same as cloning a computer hard drive and placing it in identical hardware. From their perspective each computer is the original
You're probably thinking of a continuous point of view being the original, but human consciousness generally only exists in 16 hour spurts. When you sleep, is the 'you' that wakes up the same 'you' that went to sleep? There's certainly a gap in your consciousness which would be the same as being dead and coming back. Or the same as a copy waking up.
In Mind Children, Moravec described a fascinating scenario. A probe equipped with molecular-scale surgical tools, encloses a few brain cells and simulates them in software while you lie on a table. You have a switch in your hand; as you press it, you flip back and forth between the simulation and the working cells; when you can't tell the difference, the cells are removed. The probe continues to work its way through your brain until no real cells are left. You have been slowly, gradually uploaded into software. This is you, your continual awareness, not a copy of you that takes your place after you've died.
Suppose you have a stroke, and it damages a small section of your brain.
The (cerebral cortex surface) brain is made up of a repeating pattern of cortical columns, which is a structure that connects vertically among it's 6 layers, but not laterally beyond the column boundary. There are connections out the top to the higher order layers in the brain, and connections into the bottom from lower layers, but it's an independent function(*).
As far as anyone can tell, the cerebral cortex is composed of a repeating array of these columns.
Suppose you have a synthetic "plug" that can take the place of a number of cortical columns. You remove the damaged part of the brain and replace it with the synthetic plug.
The plug contains processing units which then learn from the existing connections. The human helps to train the connections by giving feedback: as the plug tries out the connections and actions, the human can tell whether the output is right or wrong, and act accordingly.
For example, if the plug was within the speech centers, the human would have to relearn that part of speech which was damaged, but he would have all the rest of his experiences and knowledge as a basis. His environment and other humans (family, friends) would also help support the learning process.
Eventually, the plug would learn the correct responses to any of the inputs, and it would be a replacement for the damaged part.
Now suppose you have another stroke, and it damages another part of the brain.
Continue the process to its logical conclusion, and you migrate the essence of the person from the biological into the synthetic. This is possible because the information in the brain is not stored in one place, but distributed over many areas. If you lose one area, the information can still be reconstructed from information in other areas.
I can well imagine when the technology gets advanced enough, that rich people might be able to get "stroke plugs" implanted, and over time completely replace the biological portions of their brain.
Is this not a sufficient definition for uploading?
(*) Yes, a glossy, simplistic description.
If the scale required is your only argument you have made a very common error regarding the speed of change in exponential processes.
What can we do now?
What is the rate of technology doubling, D?
How many times, X, do we need to do it to get to the required magnitude?
It will take D*X years where 2^X = one hundred billion
And that is without anything radically new being discovered in that time period, so 20 to 30 years is actually possible.
Imagine what a large scale 3D quantum computing array would be capable of. We have just seen silicon based quantum logic fabrication developed and we already have 3D silicon based memory arrays.