> > We do NOT know what mathematics are involved in the computations.
Wow. Hodgkin, Huxley, Nagumo, Izhikevich and the others must, then, be totally delusional. The more I know. [..] but we really don't know how they work and which of the observed > features are actually important. Sure, there are still a lot of white spots in our understanding of how brain works on its different levels. On the other hand, there exists a massive corpus of academical neuroscience, both empirical and computational, that *clearly *disagrees with the picture you apparently are painting here - one where we are nearly clueless about what and how goes on in our cerebral matter. /NJ/ On Wed, Aug 29, 2012 at 12:11 AM, Steve Richfield <[email protected] > wrote: > Arets, > > On Tue, Aug 28, 2012 at 10:00 AM, Arets Paeglis <[email protected]>wrote: > >> Are you seriously going to suggest that we still have no idea as to what >> "neurons are doing"? >> > > Yes. > > Most synapses are NOT the simplistic fractional transfer mechanisms used > in NNs, We have NO idea how neurons learn as fast as they do. We have NO > idea what guides their self-organization. We do NOT know what mathematics > are involved in the computations. We have observed some interesting things, > like some neurons becoming active under particular circumstances, but that > is about all we now "know". > > The equivalent in astronomy: We still think the earth is at the center of > the universe, that planets orbit in bizarre ways, and that celestial > spheres make it all work as it does. > > Steve > ================= > >> On Tue, Aug 28, 2012 at 7:52 PM, Steve Richfield < >> [email protected]> wrote: >> >>> Alan, >>> >>> Your discussion fits right in with some of my postings. I have discussed >>> the equivalent unity gain frequency of neurons (for 741s it is ~1MHz), >>> negative feedback in the form of variable driven impedance, etc. It appears >>> that internally, neurons may "compute" about as fast as vacuum tubes, and >>> NOT at the much slower pulse rates seen at the outputs of spiking neurons. >>> >>> However, I fear that we are throwing pearls before swine. >>> >>> Also, I wonder if everyone else is missing an essential point. We are >>> NOT saying "neurons are SO much faster and smarter that we can never >>> duplicate such function on a human scale", but rather "if we make the >>> effort to understand what neurons are doing, then we will have some chance >>> of understanding the problems they are solving, after which we can then >>> engineer human scale systems without being encumbered by the neuronal >>> legacy." >>> >>> Steve >>> =================== >>> On Tue, Aug 28, 2012 at 9:34 AM, Alan Grimes <[email protected]>wrote: >>> >>>> om >>>> >>>> The elemental unit of an analog computer, akin to an NAND gate, is the >>>> operational amplifier. The canonical opamp is the LM741, which was >>>> introduced in 1968 and is still the standard opamp that everyone uses. >>>> The Japanese have an equivalent part which has pretty much identical >>>> specs. >>>> >>>> Better parts are now available but engineers usually start out with the >>>> LM741 and chose a different part only if it can't meet their performance >>>> goals. I'm kinda fond of the Jfet input opamps myself but they can be a >>>> bit more fragile. >>>> >>>> I did some computer simulations of my father's stereo (made in 1974). >>>> The power amplifiers are basically power opamps made with discreet >>>> parts. >>>> >>>> You think of an amplifier as conveying a signal from input to output. A >>>> classic tube amplifier does exactly that, sometimes with 6-12 db of >>>> negative feedback.The creepy thing about the simulation was that the >>>> signal appeared to disappear in the middle of the circuit, so I had >>>> trouble even figuring out which wire was even conveying it. >>>> >>>> Logically, the signal MUST pass from the collector of Q402 to the base >>>> of Q410. However the voltage swing at that point is many decimal places >>>> below the DC voltage at that point. >>>> >>>> But that's the thing. The amplifier doesn't amplify signal! The >>>> difference between the voltages at the input parts, (Q402, non >>>> inverting, Q404 inverting). is in the microvolts range. (Q406 is >>>> basically a 2mA CCS with a 20-30 second time delay), so the input signal >>>> to the amplifier is essentially null. >>>> >>>> But the circuit does work. It has a gain defined by R410 and R414. >>>> >>>> It is an error amplifier. The brain works in much the same way. Neurons >>>> don't say much to each other unless there is an error signal. The >>>> amplifier's output is your imagination and the input signal are your >>>> sense organs. >>>> >>>> Anyway, just a different perspective. =P >>>> >>>> -- >>>> E T F >>>> N H E >>>> D E D >>>> >>>> Powers are not rights. >>>> >>>> >>>> >>>> >>>> ------------------------------------------- >>>> AGI >>>> Archives: https://www.listbox.com/member/archive/303/=now >>>> RSS Feed: >>>> https://www.listbox.com/member/archive/rss/303/10443978-6f4c28ac >>>> >>>> Modify Your Subscription: https://www.listbox.com/member/?&; >>>> Powered by Listbox: http://www.listbox.com >>>> >>> >>> >>> >>> -- >>> Full employment can be had with the stoke of a pen. Simply institute a >>> six hour workday. That will easily create enough new jobs to bring back >>> full employment. >>> >>> >>> *AGI* | Archives <https://www.listbox.com/member/archive/303/=now> >>> <https://www.listbox.com/member/archive/rss/303/20912103-eed2d0e1> | >>> Modify <https://www.listbox.com/member/?&;> Your Subscription >>> <http://www.listbox.com> >>> >> >> *AGI* | Archives <https://www.listbox.com/member/archive/303/=now> >> <https://www.listbox.com/member/archive/rss/303/10443978-6f4c28ac> | >> Modify <https://www.listbox.com/member/?&;> Your Subscription >> <http://www.listbox.com> >> > > > > -- > Full employment can be had with the stoke of a pen. Simply institute a six > hour workday. That will easily create enough new jobs to bring back full > employment. > > > *AGI* | Archives <https://www.listbox.com/member/archive/303/=now> > <https://www.listbox.com/member/archive/rss/303/20912103-eed2d0e1> | > Modify<https://www.listbox.com/member/?&;>Your Subscription > <http://www.listbox.com> > ------------------------------------------- AGI Archives: https://www.listbox.com/member/archive/303/=now RSS Feed: https://www.listbox.com/member/archive/rss/303/21088071-c97d2393 Modify Your Subscription: https://www.listbox.com/member/?member_id=21088071&id_secret=21088071-2484a968 Powered by Listbox: http://www.listbox.com
