Bringing this back to the earlier discussion, What could be happening, not to say that it is provably happening but there certainly is no evidence (that I know of) against it, is the following, with probabilities represented internally by voltages that are proportional to the logarithm of the probability: External representation varies, e.g. spike rate for spiking neurons
Dendritic trees could be a sort of Bayesian AND, and the neurons themselves could be a sort of Bayesian OR of the dendrites. If each dendrite were completely unrelated to the others, e.g. one computed some aspect of "tree", another some aspect of "sweet", another some aspect of "angry", etc., then the dendrites on other neurons could easily assemble whatever they needed, with lots of other extraneous things OR'd onto the inputs. This sounds like a mess, but it works. Consider: Any one individual thing only occurs rarely. If not, it will be differentiated until it is rare. Additive noise on the inputs of a Bayesian AND only affects the output when ALL of the other inputs are non-zero. When these two rare events happen simultaneously, whatever the dendrite is looking for and another event that adds to one of its inputs, the output will be slightly increased. How slight? It appears that CNS (Central Nervous System) neurons have ~50K synapses, of which ~200 have efficacies >0 at any one time. Hence, noise might contribute ~1% to the output - too little to be concerned much about. Why evolve such a convoluted system? Because cells are MUCH more expensive than dendrites or synapses. By having a cell handle aspects of many unrelated things while other cells are doing the same, and ANDing them as needed, the cell count is minimized. Also, such systems are impervious to minor damage, cells dying, etc. Certainly, having a "tree" cell would only help if there were SO many uses of exactly the same meaning of tree that it would be efficient to do all of the ANDing in one place. However, a cell doing this could also do the same for other unrelated things at the same time, bringing us back to the theory. Hence, until I hear something to deny this theory, I am presuming it to be correct. OK, so why isn't this well known? Consider: 1. The standards for publication of laboratory results are MUCH tighter than in other areas. If they don't have proof, then they don't publish. Hence, if you don't know someone who knows about CNS dendrites, you won't even have anything to think about. 2. As Loosemore pointed out, the guys in the lab do NOT have skills applicable to cognitive, mathematical, or other key areas that the very cells that they are studying are functioning in. Flashback: I had finally tracked down an important article about observed synaptic transfer functions and its author in person. Also present was William Calvin, the neuroscience author who formerly had a laboratory at the U of Washington. Looking over the functions in the article, I started to comment on what they might be doing mathematically, whereupon the author interjected that they had already found functions that fit very closely that they has used as a sort of spline, which weren't anything at all like the functions I was looking for. I noted that it appeared to me that both functions produced almost identical results over the observed range, but mine was derived from mathematical necessity while the ones the author used as a spline just happened to fit well. The author then asked why even bother looking for another function that fits after you already have one. At that point, in exasperation, Calvin took up my side of the discussion, and after maybe 15 minutes of discussion with the author while I sat quietly and watched, the author FINALLY understood that these neurons do something in the real world, and if you have a theory about what that might be, then you must look at the difference between predicted and actual results to confirm/deny that theory. Later when I computer-generated points to compare with the laboratory results, they were spot-on to within measurement accuracy. Anyway, this seems to be a good working theory for how our wet engine works, but it doesn't seem to provide much to help Ben, because inside a computer, public variables don't cost thousands of times as much as a binary operator, instead, they are actually cheaper. Hence, there is no reason to combine unrelated things into what is equivalent to a public variable. However, this all suggests that attention should be concentrated on adjectives rather than nouns, adverbs instead of verbs, etc. I noticed this when hand coding rules for Dr. Eliza - that the modifiers seemed to be much more important than the referents. Maybe this hint from wetware will help someone. Steve Richfield ============================================= On 11/21/08, Ben Goertzel <[EMAIL PROTECTED]> wrote: > > And we don't yet know whether "the assembly keeps reconfiguring its > reprsentation" for conceptual knowledge ... though we know it's mainly > not true for percpetual and motor knowledge... > > On Fri, Nov 21, 2008 at 11:56 AM, Mike Tintner <[EMAIL PROTECTED]> > wrote: > > Ben: > The idea that concepts may be represented by cell assemblies, or > >> > >> attractors within cell assemblies, are more prevalent. > > > > Ben, > > > > My question was whether the concepts - or, to be precise, the terms of > the > > concepts, e.g. the sounds/ letters/word "ball" - may not be "neuronally > > locatable" (not BTW whether they are represented by single cells). A cell > > assembly would classify as that, no? Unless the assembly keeps > reconfiguring > > its representation. > > > > > > > > ------------------------------------------- > > agi > > Archives: https://www.listbox.com/member/archive/303/=now > > RSS Feed: https://www.listbox.com/member/archive/rss/303/ > > Modify Your Subscription: > > https://www.listbox.com/member/?&; > > Powered by Listbox: http://www.listbox.com > > > > > > -- > Ben Goertzel, PhD > CEO, Novamente LLC and Biomind LLC > Director of Research, SIAI > [EMAIL PROTECTED] > > "A human being should be able to change a diaper, plan an invasion, > butcher a hog, conn a ship, design a building, write a sonnet, balance > accounts, build a wall, set a bone, comfort the dying, take orders, > give orders, cooperate, act alone, solve equations, analyze a new > problem, pitch manure, program a computer, cook a tasty meal, fight > efficiently, die gallantly. Specialization is for insects." -- Robert > Heinlein > > > ------------------------------------------- > agi > Archives: https://www.listbox.com/member/archive/303/=now > RSS Feed: https://www.listbox.com/member/archive/rss/303/ > Modify Your Subscription: > https://www.listbox.com/member/?&; > Powered by Listbox: http://www.listbox.com > ------------------------------------------- agi Archives: https://www.listbox.com/member/archive/303/=now RSS Feed: https://www.listbox.com/member/archive/rss/303/ Modify Your Subscription: https://www.listbox.com/member/?member_id=8660244&id_secret=120640061-aded06 Powered by Listbox: http://www.listbox.com
