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In the framework of the work the description of sphere wave filed in the far observation region is discussed. The consideration is based on the decomposition of the wave field over the longitudinal and transverse spatial parameters of the problem in the direction of observation. It is shown that the approximation of a sphere wave by the flat field is correct only if the consideration is conducted in the limit of solid angle. The magnitude of the solid angle, which includes the area of flatness of the spherical wave, is determined using the so-called wave parameters corresponding to the observation area and the illuminated point. The wave field created by a small flat area is defined as a limit case of a superposition field generated by a system of point sources. It is shown that in an observation point the wave field of a small flat area can be characterized by the angle between the area normal and the vector indicting from the given area the observation point. The problem of description of a wave filed in the framework of a small flat aria is also discussed. A new method for deriving of the well-known obliquity factor of the Kirchhoff diffraction theory is suggested. [ABSTRACT FROM AUTHOR]

A new method for solving ordinary differential equations is suggested. As it is shown the deferential equation can be solved not only by means integration of its differentiation as well. It is shown that the differential equation can be solved not only by integration, but also by differentiation. The developed method is applied for consideration of corresponding equations for the exponential function and trigonometric functions. In the framework of the developed method the simple approach for derivation of Taylor series of a function is demonstrated. Based imminently on the geometric definition the connections between trigonometric functions and their derivatives are obtained as well. The well-known Euler formula is also produced, which establishes a connection between trigonometric functions and exponential function. [ABSTRACT FROM AUTHOR]

The paper considers the problem of an approximate wave field in the so-called near, middle and far zones of observation. The possibility of introducing a more accurate than the Fresnel approximation, the so-called quasi-exact approximation, is indicated. For the interference problem usually considered in the Fresnel approximation, the intensity distribution in the near field of observation is obtained. It is shown that the positions of intensity maxima in the near zone of observation are determined by a cubic equation. [ABSTRACT FROM AUTHOR]

Receptive field sizes of visually sensitive neurons in cortical centers are dynamic, mainly expanding at the application of moving visual stimuli. The results of experiments presented in this study show, that visually driven neurons in subcortical centers also have dynamic RFs sizes in relation to the applied visual stimulus. Visually sensitive neurons of the subcortical pretectal region reveal substantial modulations of RF sizes at the application of visual stimuli moving in different orientations, which resulted in strong diversification and more precise processing of incoming visual information. [ABSTRACT FROM AUTHOR]

Orientation sensitive properties of extrastriate area 21a neurons were investigated. Special attention was paid to the spatial characteristics of the neuron receptive fields (RF) to the different orientations of visual stimulus motion across neuron RF, defined by presentation of stationary visual stimuli. The results of provided experiments have shown that the neuron RF spatial dimensions undergo essential modulations concerning different orientations of applied visual stimuli. As a result, a high degree of diversification of neuronal response patterns depending of the orientation of moving stimuli was observed. Thus, the processing of visual information in the course of visual image recognition is realized by integrated activity of surrounding cortical networks of visually sensitive neurons. [ABSTRACT FROM AUTHOR]

The spatial structure of the receptive field (RF) of a visually sensitive neuron, as a rule, predetermines the central processing of incoming visual information concerning moving visual images. Thus, the properties of visually driven neurons as in the cortical, as well as in subcortical levels of the brain are chiefly determined by spatial constrains of the neuron RF. The results of presented experiments have shown that the spatial parameters of visually sensitive neuron RFs in subcortical dorsal hippocampal region are dynamic and undergo substantial expansions of dimensions at the appliance of a moving visual stimulus. Thus, it is evident that central processing of visual information is realized by integrated activity of a complex of the corresponding cortical networks of visually sensitive neurons. [ABSTRACT FROM AUTHOR]

The neurophysiological mechanisms underlying the central processing of incoming visual information is still a fundamental problem in the visual neuroscience. The response patterns of visually sensitive neurons in extrastriate area 21a of the cat cortex to the stationary and moving visual stimuli were studied in detail. The results of experiments show significant modulations of neuronal response patterns at the introduction of a moving visual stimulus, which could not be explained by the neuron receptive field (RF) stationary structure. The results of presented experiments have shown that neurons having homogenous stationary RFs structure may reveal multimodal patterns of responses to moving visual stimuli and such response profiles could be evoked from the isolated RF subfields too. Thus, with great probability, mutual interactions among simultaneously activated neighbouring neuron networks become to be of great importance in central processing of visual information, concerning the precise diversification and perception of visual images. [ABSTRACT FROM AUTHOR]

Nowadays it is generally accepted that when a moving visual image comes within the visual field, the receptive fields (RF) of visually sensitive cortical neurons undergo some directional changes in consequence of the modulation of RF surrounding. It is seen from the results of our recent experiments that a group of visually sensitive neurons with minor values of RF less than 1.5 deg.² as determined by means of the stationary flashing spot, exhibits significant expansion of RF sizes at appliance of a moving stimulus. Here the expansion is accompanied with a diversification of neuron response patterns depending on the shape, magnitude and direction of motion, as well as on the contrast of applied visual stimuli. It was suggested based on the presented results that on its move the visual image sequentially activates the surrounding neuronal networks having synaptic contacts with the neuron under investigation, as a result of which a temporary modulation of RF stationary spatial structure occurs. So, the sensing and recognition of a moving image is realized by virtue of coordinated activity of respective neuronal networks of brain. [ABSTRACT FROM AUTHOR]

Receptive fields (RFs) of visually driven neurons play crucial roles in visual information processing. We have examined the relationships between RFs structure defined by stationary visual stimuli and that of visual response properties of individual neurons when moving stimuli are introduced. The precise mapping of the RFs subfields were done by applying flashing light spots. The results of experiments have shown, that the majority of investigated neurons with homogenous "OFF" stationary structure of RFs, manifest significantly higher degree of discharge activity to the moving light stimuli, compared to that of the dark moving stimuli. Essential changes were observed in neuron response patterns related to the stimulus sizes, which indicate on significant modulation of RFs stationary subfield structure during the visual stimulus motion. The presented results of experiments have shown, that the RF stationary spatial structure may undergo certain changes depending on the magnitude and contrast of applied moving visual stimuli. [ABSTRACT FROM AUTHOR]

The properties of visually driven neurons in both primary visual cortex and extrastriate cortical areas are as a rule mostly determined by spatial and time-related constraints of the neuronal receptive fields (RF). In our experiments we tried to investigate in detail the relationship between the RF spatial and temporal parameters, during neuron activation by a visual stimulus. Extracellular recording of single-cell activity combined with visual field masking method was used. We find that in some cases the RF temporal parameters of the responses were not correlated with the spatial ones. Moreover, it was revealed that some regions in the RF, mainly the central region, when excited by visual stimulus presented in isolation through an aperture, while the rest of the RF and the whole visual field is masked, may elicit a response with spatial and temporal parameters comparable to that evoked by the same stimulus in the absence of masking. A suggestion is put forward on possible feedback influences in central processing of visual information in extrastriate cortical areas. [ABSTRACT FROM AUTHOR]

Visually sensitive neurons are commonly characterized by their classical receptive fields (CRF) structure and the important visual stimulus parameters for a visually sensitive neuron are determined by the CRF. However, the cells are also influenced by visual stimuli presented in areas surrounding CRF. The experiments described in this report were conducted to determine the existence and nature of CRF surround influences on the neuron response patterns of extrastriate cortex. From extracellular recordings in the cat area 21a we have found that for the majority of neurons investigated, the effect of the CRF surround stimulation was to suppress the neuron activity and the facilitatory effect was observed only in few cases. These results show that the surround suppression is a prevalent form of the surround influence and may play an important role in the central visual processing. A suggestion was put forward, that the information elaboration concerning particularly the shape and magnitude of moving objects is accomplished due to synchronous activation of the CRF surround, hence, the correlated activity of a group of neurons. [ABSTRACT FROM AUTHOR]