Two-dimensional Neural Basis of Achromatic Vision in Invertebrates and VertebratesстатьяТезисы
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 6 февраля 2017 г.
Аннотация:Background: Previous psychophysiological and neurophysiological studies on achromatic vision in human and vertebrates have shown that light intensity is coded by two-dimensional ‘excitation vector’ (Sokolov E.N., 2013). The components of this vector are responses of ‘brightness’ and ‘darkness’ neurons. It means that a current sensation of light intensity is determined by a corresponding interrelation between activities of Br- and Da- neurons responding in opponent way to light onset and offset. Here we answer to following questions: 1) what are the neural mechanisms of achromatic vision in the invertebrates’ visual system and how do they correspond to the neural mechanisms of light intensity in the vertebrates? 2) is the principle of two-dimensional vector encoding true for invertebrates’ vision? Methods: The experiments in grape snails were conducted in frame of E.N. Sokolov’s ‘Vector Psychophysiology’ Russian school of thoughts. Intracellular recordings of visual cells were conducted on the retina of a dark-adapted eyeball in half-intact preparation of mollusk Helix pomatia L. Diffuse flashes of white light and / or equiquantum monochromatic wavelengths between 400-700 nm were used for light stimulation. Stimuli intensity was varied within the limits of 1.5 log units. Maximal intensity of white light, measured at a level of mollusk eye, was equaled to 5.0*10^5 erg*sm^(-2)*s^(-1) (0.0 log units). Statistical analysis was performed using Statistica 10 software. The Wilcoxon T-test was used to evaluate the reliability of differences between averaged quantities of experimental data. Results and Discussion: Intracellular recordings from 105 cells were collected and analyzed. The cells were divided into two groups according to the sign of light response. White light or any monochromatic light depolarized the cells in the first group (D-type cells). The cells in the second group (H-type cells) responded to light of any wavelength or to white light with a hyperpolarization. Peak of spectral sensitivity for both D- and H-cells falls at 450-500 nm area and coincides with area of maximal sensitivity for photopigment ‘rhodopsin’. Responses of the D- and H-cells constitute a two-dimensional neural ‘vector-code’ of light intensity within a proposed two-channel model of snail achromatic vision. The length of the vector is constant but its direction (interrelation between activities of D- and H-cells) corresponds to light intensity. Conclusion: Intracellular snail’s data taken together with data of vertebrate animals supports idea that a 2-dimensional model of cellular brightness and darkness encoding utilizes a universal mechanism of ‘vector encoding’ for light intensity in neuronal vision networks.