X-Message-Number: 12583 Date: Sat, 16 Oct 1999 14:24:10 -0700 From: Jeff Davis <> Subject: Re: New laser method reveals high-density information storage In Message #12573, Eugene Leitl <> writes: >I guess I don't have to explain anybody what this means in regards to >the impact of the freezing damage -- a yet another high watermark in >the trend that nature's gadgets are cleverer than we thought has been >reached. I don't know about anyone else, but I have always been ready to be surprised at how clever "nature's gadgets" turn out to be. But in this case, I don't see a greater cleverness than anticipated. From the paper gene cited: >single synapses may undergo long-term depression >and each single synapse could be used to store information >separately from its neighbour. What this means is that each synapse is a single bit, with long-term depression(LTD) as the off/zero state and long-term potentiation(LTP) as the on/one state. Exactly as I expected. Which is not me bragging, but rather because "one bit per synapse" seems logical, parsimonious, elegant, and efficient, and I would expect anyone to be able to make this guess on the very first try. >It thus appears simply not prudent to adhere to the more optimistic >scenarios ("manipulation at molecular scale can repair any type of >damage"). Anything and everything, relevant or otherwise leads to the same conclusion with you: optimism is unwarranted. Sorry, gene, but you bring a prejudicial pessimism to your reading, analysis and discussion. It's a foregone conclusion for you, as it is for the other members of the Platt/Wakfer/Darwin school. The paper you cite doesn't bring anything new to the discussion--the idea that each synapse is a separate and independent bit is neither original nor unexpected--it merely announces the first achievement of a technique to confirm these expectations. Better tools to turn good guesses into established facts. Great. The conclusion reached by my analysis, that the success of cryonics is a near certainty, had previously to bear up under the uncertainty of the one-synapse-one-bit guess. That guess has now been confirmed, which supports the quality of the guess(es), the quality of the analysis, and the strength of the conclusion. I have not presented here any details of the analysis which leads me to my optimistic conclusion, it would take more time than I am willing to give at the moment, so no one need feel inclined to share that conclusion. But I will submit this one little comment which ever and again bears repeating and is central to that analysis. Always strive to distinguish between STRUCTURAL damage and INFORMATION damage. As an example: take an ornate glass sculpture, put it in a leather bag, flail the bag until the sculpture has been reduces to a million tiny glass shards, pour the shards into a bucket. The sculture has been almost obliterated structurally. Yet the conformal surfaces of the shards retain with almost perfect integrity the information about the original structure. The human body, to be sure, is not a glass sculpture, yet every synaptic transmitter on a (neuron to neuron)axon, has one and only one synaptic receptor on a dendrite, and every torn membrane, organelle, or microtubule has a unique, conformal, complementary other half; and the totality of these pieces constitutes a profoundly dense information "space" which maps back to the original structure from which we may seek to retrieve the vital crucial information. (Even if, like pieces of a jigsaw puzzle in a box, they have been separated and jumbled.) I frankly admit that I don't have the expertise in information theory to predict the final outcome of this question one way or the other. But while waiting for some scientist somewhere to announce that breakthrough, I'll make my guess based on the richness of the information "space" created by the cellular matrix. I see success as a near certainty. Structure is not information. Structure is visually accessible, tangible, and familiar; information is arcane, abstract, unfamiliar, and inaccessible. As such, as humans, we are naturally predisposed to have our attention drawn to, and our sense of what is relevant assigned to the former, and to misperceive or fail to perceive the latter. Yet if repair technologies ever become available, then structural integrity becomes irrelevant and information integrity becomes everything. -------------------------------------------------------------------------- Also from the paper cited: >Therefore, modifications of the amount of >neurotransmitter that is released during LTD can be neglected. Though the data is flimsy and the potential pitfalls many, let's see what can be made of the above comment. First, for clarification. The author uses the term "during LTD". I believe what he means is "while the receptor site is in the LTD state". That being the case, the author seems to be saying that regardless of the amount of neurotransmitter being squirted(expressed) at the receptor site, the receptor does not trigger(respond). Recently Mike Darwin suggested that the nature of identity/thought /memory/consciousness might be evanescent, he compared it to the fleeting, fluid quality of the film on a soap bubble (the swirling patterns seen on that film?). Now, if the LTD/LTP (off/on) binary state of the synapse has been found to be so robust that the researchers who wrote this paper suggest that, flush it with neurotransmitter how you will, off is off and this synapse will not trigger, then I leave it to you to "guess" just how fleeting may be the substrate of personality. ---------------------------------------------------------------------------- Finally, some comments. If a brain cell has a thousand synapses, is that five hundred dendritic receptors and five hundred axonal transmitters? If a receptor may be in the off state, what good is it, unless it may be reconfigured back to the on state, and then off, and then on,...etc.? If the inventory of receptors is some off and some on, and there are, say, five hundred receptors what is the total number of possible input configurations of that neuron? (2^500 (=3.27 x 10^150) ? Whoa, baby!) Plus, let us not forget that the total number of neurons in ye olde brain panne is a (by comparison) paltry, some n x10^9. Is there some weighting mechanism in the interior of the neuron, between dendritic receptors and axonal transmitters, which further modifies or refines whatever signal that may have been initiated by the stimulation of a given group of dendritic receptors? Somewhere in these unanswered questions I expect to find the *unexpected* cleverness of nature's gadgetry. I mention the numbers above, because I've given some thought to what happened to me when I went to see "Saving Private Ryan". In the darkness of the theater, I settled into that entranced, singularly focused mental state. Whereupon I was exposed to megabits of optical and audio data every one-thirtieth of a second, for two plus hours. Then I walked out of the theater with substantial quantities of it in LONG TERM memory. I don't see how that could be possible without the kind of numbers I've bandied about above. As always, more questions than answers. Best, Jeff Davis "Everything's hard till you know how to do it." Ray Charles Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=12583