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Peter Cochrane's Hard Drive 1999 Axon dendrite questions? THE key feature of science is the manner in which discovery and understanding go hand in hand. Two decades ago, I was working on the edge of high-speed logic design at clock rates up to 1GHz. We encountered formidable problems with signal distribution across printed circuit boards. Everything was working against us - printed circuit dielectric properties, device physics and topology. In one of those rare flashes of inspiration, a solution emerged. Instead of using laminated or ceramic substrates, why not use glass with optical instead of electrical signal transport? So lasers were mounted on the bottom of chips facing down into the glass. Clock and other signals were broadcast within the glass boards, to be collected and detected by similarly positioned receivers. What a breakthrough: an instant reduction in wiring complexity and a considerably enhanced performance. Of course, there was a downside - reflections and multiple echoes needed subtle design at the edge of the structure, but it worked. In the final outcome, the glass board was overtaken by less elegant and cheaper solutions with improved dielectric materials and better chip physics. But that's the way it goes: only a small fraction of ideas make it to production. A decade later saw me engaged in an even more challenging study concerned with biological computing. Here we already had an existence theorem - the human brain - and we could at least try to unpick the results of millions of years of evolutionary progress. Entering this wet arena from the direction of dry computing saw many revelations and new mysteries. We seemed to be smarter, and to have far more computing power, than our (approximately) 10 (100 billion) neurons and average 10 (100,000) interconnecting dendrites and axons would dictate. Within a simplistic complexity count of 10 ? 10 = 10 (10 million billion), and on average more likely 10, we appear to be far too smart, and to have too great a memory capacity. We were obviously missing a trick in this soup of a mind. The invention of the telephone and the digital computer probably resulted in our "synaptocentric" view. Conventional thinking says the signals generated by the synapses - "wet spark plugs" - are guided by, and propagate along, the axons and dendritic connections filling the majority of this signal void. However, scientists have recently made fundamental and insightful discoveries yet to be fully corroborated and confirmed. It looks as if Mother Nature is (as ever) more sophisticated than we expected, and neuropeptides, dopamine, nitric and carbon monoxide, and probably more, propagate from one axon to another over several seconds. Specifically, nitric oxide will traverse up to 50 neurons in five seconds. We only need a fraction of this to be true to explain why we are so smart and dumb at the same time. Nature evolved sonar, and we invented it later. We invented radio, optical transmission through optical fibre, and glass circuit boards, but evolution got there first. A key to scientific advance in the 21st century has to be the dismantling of artificial walls between disciplines. It is increasingly obvious that we are in the preliminary stages of a most profitable convergence of thought and understanding. Computing = Mind = Chemistry. I like IT. Peter Cochrane holds the Collier Chair for the Public Understanding of Science & Technology at the University of Bristol. His home page is: |
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