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V D Glezer

Publications and source records attributed to V D Glezer.

At least 55 records · Page 3Linked to original sources
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Relationship between spatial and spatial-frequency characteristics of receptive fields of cat visual cortex.

The spatial (magnitude and eccentricity) and spatial-frequency (optimum frequency and width of pass band) characteristics of the receptive fields of the cat visual cortex were investigated. It was shown that in accordance with the predictions of the theory of piecewise Fourier analysis, linear and quasilinear receptive fields of a single size comprise a modulus in each of the fields of which the index of complexity (ratio of size of field to number of periods of its optimum frequency) equals the optimum frequency multiplied by a coefficient that is constant for the given modulus. Five moduli were found with field sizes of 2.6, 3.8, 5.2, 6.2, and 7.0 degrees, shifting with increase in the size of the modulus towards the periphery of the field of view. In accordance with predictions, when the index of complexity is fixed the width of the pass band declines inversely proportionately to the size of the fields. The obtained data directly support the hypothesis according to which the receptive fields effect a piecewise quasi-Fourier expansion of the image.

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Some neurophysiological correlates of visual perception.

A study was made of the structural organization of simple and complex receptive fields of the visual cortex. The bidimensional weight function of the field that determines its basic properties as a filter of spatial frequencies (spatial-frequency and orientational sensitivity) was investigated. Two types of modules-cylinders of the cortical neurons, the receptive fields of which are directed toward a single area of the visual field, and adapted to different spatial frequencies and orientations, are discussed. One type contains neurons, the receptive fields of which describe amplitude and phase of the visual signal and give Fourier descriptions of a part of the image; in the second type, the receptive fields describe only the amplitude and give the power spectrum. A comparison with psychophysical data indicates that the second type serves to describe texture. Inhibition in the receptive fields induced by frequencies lateral with respect to the optimal frequency and orientation perpendicular to optimal orientation points to the mutually inhibiting effects between neurons of the module. The significance of such an organization for visual perception is discussed.

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[2 types of generalization in the evolution of the visual brain].

It has been shown that mechanism of generalization with respect to the size (shift of differentiation of the size from objects of one form to other forms) is located in dogs within the suprasylvian convolution, in cats--within the median part of the lateral suprasylvian region. After removal of these parts of the brain, other visual functions including the invariant description of the image, remain unaffected. The latter is disturbed after extirpation of the field 21; however, the shift with respect to the size does not undergo any significant changes. Therefore, two types of visual generalization, i.e. phylogenetically less ancient generalization of the detected properties and evolutionary more ancient subject generalization (invariant image), are located in different parts of the visual brain.

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