[The meaning of the Weber-Fechner Law IV. The psychometric curve, the interaction between inter hemisphere and the interaction in intrahemisphere].

The subject was presented with a pair of lines. One line was an objective referent line Ro and did not change its length. The other was a test line and changed the its length. The observer must report--where the longer line was--above or below in the pair. On the basis neurophysiological, psychophysical data and new type of the psychometrical curve a complex neuronal construction was built. The comparison of action of the neuronal construction with the psychophysical data on different stages of introduction the visual information showed that in both cases at first stages of introduction the information referent subjective stimulus Rs is not equal to Ro. But at the last stages, when Weber's fraction is obtained Rs = Ro. This result allows to suggest that the suggested neuronal contraction is near to the real constriction of the visual brain.

Separate training of hemispheres to perform visual discrimination in conditions of blocking of interhemisphere transmission by masking.

Subjects were trained to discriminate three figures presented in the left field of vision and three other figures presented in the right field of vision. In these conditions, the two hemispheres usually show identical learning to discriminate the sets of stimuli because the hemispheres in healthy humans can exchange information. In the present study, training was performed in conditions in which, during presentation of stimuli, the opposite visual hemifield was covered by a mask. After training, the recognition of all six figures was compared by presenting them to the left and right visual fields. Each hemisphere recognized figures presented to the cognate hemifield but completely or very nearly failed to recognize figures learned by the other hemisphere. The mask would thus appear to block (completely or partially) the transmission of information from one hemisphere to the other. Thus, it was possible to train the hemispheres separately to recognize different sets of images in healthy subjects.

Spatial organization of subfields in receptive fields of cells in cat striate cortex.

Spatial organization of receptive fields (RF) of cells in cat striate cortex was investigated with moving and flashing light and dark bars and with grating-patterns of a varying number of cycles. It was shown that the maximum number of subfields in a simple cell is equal to eight or the number of periods in weighting function is equal to four. Quantitative comparison of the data with the results of seven other studies allows us to suggest that the number of periods in linear component of some complex cells is close to this value. The discrepancies between the results of different authors in estimation of the number of subfields are explained by the experimental data.

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.

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.

[Spectral characteristics of stimuli and responses in a complex receptive field]. / Spektral'nye kharakteristiki stimulov i otvety slozhnogo retseptivnogo polia

Responses of a complex receptive field of visual cortex of the cat are determined by the energy of stimuli in the band pass of equivalent space frequency characteristic of the receptive field. This is a proof that the complex receptive fields are spatial frequency band pass filters.

[Model of local spectral description of images in the visual system]. / Model' lokal'nogo spektral'nogo opisaniia izobrazhenii v zritel'noi sisteme.

On the basis of experimental evidence presented earlier a model of local spectral analysis of the image performed by the complex receptive fields of the visual cortex has been proposed. An essential feature of the model is that the generalized piece-wise Fourier transform is performed not over the image luminance function but over the logarithm contrast function resulted from analysis of the image by the round receptive fields of the preceding levels. Such an assumption removes a number of experimental objections offered against the hypothesis of two-dimensional Fourier transform in the visual system. The consequencies from the piece-wise expansion in a series of basic functions have been considered and among them: the channel frequency characteristics which can have more than one maximum; the possibility of describing the image by a limited number of channels with overlapping frequency characteristics.

[Adjustment of the cat visual cortex receptive fields to certain spatial frequency bands within definite ranges of movement frequencies of stimulating gratings]. / O nastroike retseptivnykh polii zritel'noi kory koshki na opredelennye polosy prostranstvennykh chastot v opredelennykh diapazonakh skorostei dvizheniia stimuliruiushchikh reshetok.

Reactions of simple and composite receptive fields (RF) of the 17th and 18th fields of cat's visual cortex to grating with various spatial frequency moving through the field with different velocities were studied. It has been shown that for each RF the velocity range is revealed within which spatial-frequency selectivity of RF exists. The narrow-band tuning for high frequency RF exists in the range of low velocities, and for low frequency ones in the range of higher velocities.

[Spatial-frequency characteristics of receptive fields of the cat visual cortex on homogeneous and nonhomogeneous backgrounds]. / Prostranstvenno-chastotnye kharakteristiki retseptivnykh polei zritel'noi kory koshki v usloviiakh odnorodnogo i neodnorodnogo fona.

Spatial frequency characteristics of the cortical receptive fields obtained with sinusoidal gratings were investigated on the background formed by orthogonally oriented gratings or on the homogenous background. The results correspond to the conjecture that the receptive fields as spatial frequency filters are linear independent in orientation.

[Spatial-frequency characteristics of the receptive fields of cat visual cortex with different rates of stimulus movement]. / Prostranstvenno-chastotnye kharakteristikie retseptivnykh polei zritel'noi kory koshki pri razlichnykh skorostiakh dvizheniia stimula

Velocity ranges exist for complex and simple receptive fields of cat's visual cortex. In these ranges there is a narrow band frequency tuning. In these velocity ranges the location of the maximum on frequency characteristics is constant and does not depend on the velocity of stimulating lattice movement. An increase of the movement velocity brings about a reduction of the reaction value of the receptive fields and a disappearance of the narrow band tuning expressed in the optimal velocity range.

[Mechanisms of visual generalization]. / O mekhanizmakh zritel'noi generalizatsii.

The phenomenon of differentiations transfer from grids of different frequency and orientation to bars of different width and orientation was examined by the method of alimentary motor conditioned reflexes elaborated in free behaving dogs. After formation of differentiations of rectangular high-contrast grids by spatial frequency or orientation, transfer to single lines with the width equal to the width of bars forming the grids, leads to a broadening of the range of frequencies and orientations eliciting a positive response. Due to this fact, differentiations disappear or considerably worsen. The obtained results do not agree with the detector hypothesis according to which a part of receptive fields of the visual cortex are detectors of borders or bars of different width and orientation. But the results are predicted quantitatively by the hypothesis of description of images by receptive fields of the visual cortex as by two-dimensional filtres tuned to different spatial frequencies and orientations.

[Piecewise Fourier analysis of images and the role of the occipital, temporal and parietal cortex in visual perception]. / Kusochnyi Fur'e-analiz izobrazhenii i rol' zatylochnoi, visochnoi i temennoi kory v zritel'nom vospriiatii.

On the basis of previously published data, a neuronal scheme of organization of the visual perception in the cerebral cortex, is suggested. An idea of neuronal module is introduced: a cylinder of cortical neurons whose receptive fields are directed towards the same area of the visual field and respond to different spatial frequencies and orientations. A system of overlapping modules is able of piece--wise Fourier--description of portions of the image. The modules of the Clare--Bishop area are composed of receptive fields of different size. Owing to that each neuron of the module projects inhibitory influence upon other neurons, the module acts as a filter picking out the texture. Therefore, the modules of the Clare--Bishop area single out and supply Fourier--description of subimages, the latters being characterized by the same local spectrum within their own limits. The lower portiön of temporal cortex performs a rough identification of subimages and images with the aid of systems of learning neurons. The parietal cortex conforms the description from temporal cortex to the complete description in the modules of occipital cortex, thus performing the transition from an image to a concrete picture.

[Neurophysiological correlates of visual perception]. / O nekotorykh neirofiziologicheskikh korreliatakh zritel'nogo vospriiatiia.

Structural organization of simple and complex receptive fields of the visual cortex was studied. The bidimensional weight function of the field determining its main properties as a filter of spatial frequencies (the space-frequency and the orientation sensitivity), was investigated. Two types of modules are discussed: the cylinders of cortical neurons whose receptive fields are oriented towards a single area of the visual field and adjusted for different spatial frequencies and orientations. One type of the modules contains neurons whose receptive fields describe the amplitude and phase of a visual signal and give the Fourier-description of a portion of picture; the second type's receptive fields describe the amplitude alone and give the power spectra. Comparison with psychophysical data suggests that the second type serves for texture description. Inhibition in the receptive field induced by frequencies which are lateral in respect to the optimal frequency and by orientations which are perpendicular in respect to the optimal orientation, reveals the mutually inhibiting influences among the module's neurons. Significance of this type of organization for visual perception is discussed.

[Neurophysiological mechanism of brightness scaling]. / Issledovanie neirofiziologicheskogo mekhanizma shkaly iarkosti

A model of statistical decisions was used to reveal the measure of neural activity according to impulse reactions. Effectiveness of two possible measures was compared: number of spikes in groups and instantaneous frequency. The former one provides greater probability of correct estimation of brightness at a lesser error probability. Neurophysiological scales of brightness were obtained in the form of dependences of index d' on the stimulus intensity. The dependences were the power those in all cases of analysis. The exponent depends on the stimulus size and alters like the exponent of psychological scale for quantitative estimations on alteration of the stimulus space. The same dependence of subjective estimation on intensity of the light stimulut is preserved for psychophysiological scales of grouping on scaling by 5-, 10- and 20-grade scale of a single set of illuminations. This shows that the brightness neurophysiological scale formed at the first stage of perception is independent of the rules of decision making at the second stage of perception.

[Relation between the spatial and spatial-frequency characteristics of receptive fields of the cat visual cortex]. / O zavisimosti mezhdu prostranstvennymi i prostranstvenno-chastotnymi kharakteristikami retseptivnykh polei zritel'noi kory koshki.

Spatial (the size and the eccentricity) and spatial-frequency (optimal frequency and the bandwidth) characteristics of receptive fields of the cat visual cortex were studied. The linear and quasilinear receptive fields of equal size were shown, in accordance with predictions of the piecewise Fourier analysis, to constitute a module in every field of which the complexity index (ratio of the field size vs. the number of its optimal frequency periods) equaled the optimal frequency multiplied by a coefficient constant for a given module. Five modules were found with field sizes 2.6 degrees; 3.8 degrees; 5.2 degrees; 6.2 degrees and 7.0 degrees moving toward the visual field periphery as the modules increased in size. According to the predictions, the bandwidth decreases in the reversed proportion to the field size in a fixed complexity index. The data obtained corroborate the hypothesis implying that the receptive fields perform a piece wise quasi--Fourier expansion of an image.

[Linear and nonlinear properties of cat visual cortex receptive fields]. / Lineinye i nelineinye svoistva retseptivnykh polei zritel'noi kory koshki.

Impulse responses of the simple fields cat visual cortex were found to be modulated by gratings passing the field. The complex fields proved to be of three types: with modulated responses, unmodulated responses, and with modulated responses against unmodulated background. Amplitude-phase characteristic (APC) measured were inverse Fourier transformed to obtain the field's weighting function. Simultaneously the APC was reconstructed from the responses to edges and bars, with the use of the Fourier transform. Cross-comparison of the reconstructed APC and the WF showed that a RF has some linear properties but, strictly considered, is a non-linear system. Simple fields display the largest degree of linearity. The more complex field is the greater departures from linearity. As linear methods are inadequate for dealing with cortical RFs, their identification was performed in model experiments on a computer. The evidence obtained suggest that the RFs form a system of operators which perform the expansion of the image in non-classical pattern. Such an expansion can be termed quasi-Fourier-description.

[Mechanism of responses to movement in the visual cortex neurons unresponsive to light flicker]. / O mekhanizme vozniknoveniia otvetov na dvizheniia u neironov zritel'noi kory, ne otvechaiushchikh na svetovye mel'kaniia.

The responses to moving and stationary stimuli in cat's striate cortical units were studied. Two stationary light bars, one located in the receptive field centre, and another--in the periphery, were used. The sequence of presentation and the time-interval between the stimuli varied thus making the presentation of a pair of stationary bars an analogue of a moving stimulus. Responses occurred in the neurons previously unresponsive to stationary stimuli when two stationary stimuli were presented successively in certain order. A model is proposed explaining the occurrence of responses to moving stimuli in the neurons, unresponsive to stationary ones.

[Inhibition and space-frequency characteristics of the complex receptive fields of the cat visual cortex]. / Tormozhenie i prostranstvenno-chastotnye kharackteristiki slozhnykh retseptivnykh polei zritel'noi kory koshki.

Responses of complex receptive fields of the cat straitum to moving sinusoidal grating were studied. Stimulation of the receptive field with some spatial frequencies suppresses spontaneous discharges. Responses of the receptive field corroborate previously made predictions that the spatial--frequency characteristics of the receptive field should have the main and the secondary maximums and negative areas in case the complex fields perform piece-wise Fourier--transformation of image. The changes of impulse frequency in field's response are predicted by comparing the changes of instantaneous spectrum of grating entering the field with spatial frequency characteristic of the field. The data evidence that the complex field is rather a spatial--frequency filter than a detector. Some complex fields reveal a lateral inhibitory area behind the field's nucleus in direction of stimulus movement. The complex fields with no lateral inhibitory areas seem to serve for piece Fourier--description of image, those with lateral areas--for picking out the countour between textures.

[2 types of generalization in the evolution of the visual brain]. / Dva vida obobshcheniia v évoliutsii zritel'nogo mozga.

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.