From: "Eliezer S. Yudkowsky" <[EMAIL PROTECTED]> >Abstract: >> Neurons carry out the many operations that extract meaningful >> information from sensory receptor arrays at the organism�s periphery >> and translate these into action, imagery and memory. Within today�s >> dominant computational paradigm, these operations, involving synapses, >> membrane ionic channels and changes in membrane potential, are thought >> of as steps in an algorithm or as computations. The role of neurons in >> these computations has evolved conceptually from that of a simple >> inte-grator of synaptic inputs until a threshold is reached and an >> output pulse is initiated, to a much more sophisticated processor with >> mixed analog-digital logic and highly adaptive synaptic elements. > >I think Koch has a book about this, but I don't recall the title offhand.
"Biophysics of Computation" > In any case, people are still trying to break, e.g., the giant squid >axon (the largest nerve known, and hence an oft-studied one) down into >enough compartments that it can be computationally simulated with some >degree of accuracy. Long-term potentiation is another aspect that is only >beginning to be understood. Lots of mysteries. All very expensive to >simulate until we figure out what the higher-level functions are, since >you have to get every detail, not knowing which details are important. >Uploading without understanding is *not* cheap, if that's what you're >thinking of. You could easily end up having to go down to the molecular >level. Well, the compartmental model involves solving a matrix of differential equations and is insanely hard to simplify. Therefore currently neuroscientists are only able to talk about dendritic integration in a qualitative manner. That's part of the reason why Koch speculated on various nonlinear logic that the neuron might be doing. One important point that others (eg O'Riley) have pointed out is that, if dendritic logic is so complex, then how can neurons communicate that information with all-or-nothing action potentials? (Though the shape of action potentials could be variable due to neuromodulation). Long-term potentiation may be a step in the cascade of dendritic remodeling, which is intuitively very simple. A lot of molecular processes may conspire to achieve something simple. I agree that uploading is not easy. Notice that your idea of recursive self-improvement being able to work wonders may also be very much hyped =) Intuitively I guess the rate of RSI might be roughly inversely proportional to the complexity of the task... YKY ____________________________________________________________ Find what you are looking for with the Lycos Yellow Pages http://r.lycos.com/r/yp_emailfooter/http://yellowpages.lycos.com/default.asp?SRC=lycos10 ------- To unsubscribe, change your address, or temporarily deactivate your subscription, please go to http://v2.listbox.com/member/[EMAIL PROTECTED]
