Richard, On 6/5/08, Richard Loosemore <[EMAIL PROTECTED]> wrote:
> > There are two completely different types of project that seem to get > conflated in these discussions: > > 1) Copying the brain at the neural level, which is usually assumed to be a > 'blind' copy - in other words, we will not know how it works, but will just > do a complete copy and fire it up. I suspect that we will have to learn a LOT more to be able to make something like this work, in part because we will need new theory in order to compute parameters that we cannot directly measure. 1.5) Combining scanned information with mathematical constraints to produce diagrams of "perfect" neurons, even though the precise parameters of the real-world neurons is not fully scannable. > 2) Copying the design of the human brain at the cognitive level. This may > involve a certain amount of neuroscience, but mostly it will be at the > cognitive system level, and could be done without much reference to neurons > at all. The last 40 years of fruitless AI shows this to be pretty much of a dead end. There is simply too many questions that we don't even know enough to ask. 2.5) First understanding how we think with neurons, program computers to perform the same or better directly, without reference to neurons or their equivalents. > Both of these ideas are very different from standard AI, but they are also > very different from one another. The criticisms that can be leveled against > the neural-copy approach do not apply to the cognitive approach, for > example. My more "real" 1.5 and 2.5 proposals require nearly the same levels of understanding, and ultimately lead to very similar results as "simulation" gives way via optimization to the same sort of code as direct AGI programming would utilize. In short, I suspect that both paths will ultimately lead to approximately the same final result. Sure we can argue about which path is best, but "easiest wins" usually rules. It is frustrating to see commentaries that drift back and forth between > these two. > > My own position is that a cognitive-level copy is not just feasible but > well under way, whereas the idea of duplicating the neural level is just a > pie-in-the-sky fantasy at this point in time (it is not possible with > current or on-the-horizon technology, and will probably not be possible > until after we invent an AGI by some other means and get it to design, build > and control a nanotech brain scanning machine). There is nothing in the above sentence that I can agree with, from which to state objections to the remainder! Some of it may turn out to be correct, but too little is known and no one is even building the needed lab equipment to determine just WHAT the situation actually is. However, I believe that the whole "thinking" thing involves processes that no one here will EVER guess without learning more about biological brains - if nothing more than the mathematics of operation. However, your next paragraph asks some of the right questions, showing that sometimes it is possible to get to the correct place, even though the path to there is severely flawed. Duplicating a system as complex as that *without* first understanding it at > the functional level seems pure folly: I absolutely agree. So long as there is any sort of "unknown mathematics" there is no hope. one small error in the mapping and the result could be something that simply > does not work ... No, these MUST be correctable. SEM methods are unworkable because of the high "disaster rate" as slices are often destroyed. However, my scanning UV fluorescence microscope doesn't have such problems because the scanning is all within unsliced bulk brain, then some is sliced off and discarded and scanning within the unsliced bulk brain continues. Further, there will doubtless be parameters that evade scanning. SEM methods trash the complex molecules that underlie neural function, and so have no hope of success. However, even the UV fluorescence methods may prove to be inadequate to extract everything needed. Hence IMHO there will have to be lots of "fudging" as the scanner figures out what must have been there to make it all work. This will obviously require better mathematics than we now have. and then, faced with a brain-copy that needs debugging, what would we do? Debugging wetware is much the same as debugging software, only wetware is MUCH more forgiving of errors, since neurons routinely die at a horrendous rate even in "healthy" people. The best we could do is start another scan and hope for better luck next > time. You can NOT rescan. You MUST get it right the first time. Even genetically identical twins raised together have very different brains when you look at the (visible light) microscopic details - as a half-century-old experiment on identical twin lab mice showed. Steve Richfield ------------------------------------------- agi Archives: http://www.listbox.com/member/archive/303/=now RSS Feed: http://www.listbox.com/member/archive/rss/303/ Modify Your Subscription: http://www.listbox.com/member/?member_id=8660244&id_secret=103754539-40ed26 Powered by Listbox: http://www.listbox.com
