[Principle of least action, physiology of vision, and conditioned reflexes theory].
The variation principles such as principle of least action by Maupertuis (1740) and Fermat principle (1660) are fundamental for physics. They permit to establish a property by which the actual state is differing from all possible states of the system. The variation approach permits to establish equation of motion and equilibrium of a material system on the basis of one common rule which reduces to the search of the function extremes, describes this property of the system. So for the optical systems, crucial is the time and not the length of the way. According to Fermat principles, the light "choosen" from all possible ways connects two dots in the way which needs the least time. Generality of the variation principles guarantees success of their use in brain function investigations. Between different attempts to apply the variation principles to psychology and linguistics, the Zipf principle of least effort must be distinguished. Zipf (1949) demonstrated that languages and some artificial codes satisfied the least principle. For the brain physiology, classical conditioned reflex theory is the ideal area of variation principles application. According to this approach, conditioning leads to finding the extreme during fixation of the temporal link. In vision, physiological investigations are difficult because the signal has many dimensions. For example, during perception of spatial properties of surrounding world, in vision is realized minimization (reduction) of spatial-frequency spectrum of the scene. The receptive fields provide optimal accumulation of the signal. In ontogenesis, signal--noise ratio becomes optimal as receptive fields minimized the internal noise spectrum. According to the theory of match filtration, in the visual system recognition is carryied out by minimal differences between the image description in the visual system and storage in the human memory template of that image. The variation principles help to discover the physical property of phenomenon. The law discovered for mechanical system may be translated to quantum level. In physiology, variation principles permit us to connect information approach with concrete physiological mechanisms of pattern recognition and conditioned reflex.
Shelepin
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I. P. Pavlov Institute of Physiology, Russian Acad. Sci., 199034, St. Petersburg, Nab. Makarova, 6, Russia.
Krasil'nikov
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D003214:Conditioning, Classical / Q000502:physiology*; D006801:Humans; D013598:Systems Theory; D014785:Vision, Ocular / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*
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