Organization of receptive fields of motion-senstitive neurons in the cat pulvinar

The distribution of 70 visually sensitive neurons in the cat pulvinar sensitive to motion in the receptive fields was studied. The experimental results showed that components with directional characteristics are present in the structure of these fields of both direction-selective and unselective neurons. In the receptive fields of direction-selective neurons the directional elements of the substructure have identical preferred directions, which coincide with the preferred directions of response to stimulus movement over the entire receptive field. The organization of receptive fields of direction-selective neurons of the visual association structure thus does not differ significantly from that of analogous fields of visual projection neurons. Directional elements of the receptive fields of direction-unselective neurons were found to have different preferred directions, thereby providing a basis for organization of the nondirectional response of the neuron to a stimulus moving across the entire receptive field.L. A. Orbeli Institute of Physiology, Academy of Sciences of the Armenian SSR, Erevan. Translated from Neirofiziologiya, Vol. 14, No. 4, pp. 339–346, July–August, 1982.     

Inhibitory zones of receptive fields of the lateral geniculate body and visual cortex of the cat

Unit responses to moving strips were investigated. The organization of the inhibitory zones in the receptive fields of the lateral geniculate body and visual cortex of the cat was compared. The response in the receptive field of the lateral geniculate body was inhibited only during simultaneous stimulation of the excitatory and inhibitory zones of the field. Stimulation of the inhibitory zone in the receptive field of the visual cortex was effective for a long time (several hundreds of milliseconds) after stimulation of the excitatory zone. The inhibitory zones of the simple and complex receptive fields of the visual cortex differed significantly. An increase in the width of the strip above the optimal size reduced the inhibitory effect in the complex fields. This was not observed in the simple receptive fields. The functional and structural models of the receptive field of the visual cortex are discussed.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 5, No. 2, pp. 201–209, March–April, 1973.     

Inhibitory components in the neuronal response of the lateral suprasylvian cortical area in the cat

Inhibitory components in the response evoked by presentation of mobile visual stimuli in neurons belonging to the lateral suprasylvian area of the cerebral cortex were investigated in cats. It was demonstrated by comparing poststimulus histograms of neuronal response to movement in two opposite directions that the location of discharge centers within the receptive fields changed in relation to movement direction. No spatial area giving rise to the inhibitory component of response could be found in any of the neurons with monotone stationary structure of their receptive fields. Findings from experiments involving techniques of stimulating a test area of the receptive field separately indicated that inhibitory components of response in neurons of the lateral suprasylvian area with monotone organization of the receptive field could represent inhibitory after-response following the neuronal excitation produced by the visual stimulus traveling across this field.L. A. Orbeli Institute of Physiology, Academy of Sciences of the Armenian SSR, Erevan. Translated from Neirofiziologiya, Vol. 19, No. 3, pp. 299–308, May–June, 1987.     

Retinotopic organization of the posterior suprasylvian area of the feline cerebral cortex

Representation of the visual field was investigated in the feline posterior suprasylvian area (PSA) using electrophysiological mapping techniques. The PSA is one of the extrastriatal visual structures of the cerebral cortex. The PSA retinotopic organization pattern was also studied. Neuronal receptive fields (RF) were mainly located in the upper contralateral quadrant and just a small number in the lower contralateral quadrant of the visual field. Approximately 10% of RF were located in the upper ipsilateral quadrant. The central area of the visual field extending in a radius of 20–30° from the area centralis was mainly represented in the upper section of the PSA (areas 21a and 21b). The RP of neurons located more peripherally to the area centralis are found in the lower portion of the PSA (areas 20a and 20b); these occupy a correspondingly greater area. Experimental finding did not confirm any substantial differences in the retinotopic organization of areas 21a, 21b, 20a, and 20b comprising the PSA. Data obtained would tend to indicate that the PSA consists of two areas, 21a and 21b, which do not appear to be subdivided, with more densely distributed visual neurons in the former than in the latter.Institute of Experimental Biology of the Armenian SSR, Erevan. Translated from Neirofiziologiya, Vol. 23, No. 3, pp. 290–296, May–June, 1991.     

Responses of receptive fields of frog retinal ganglion cells to the leading and trailing edges of moving stimuli

The position of on- and off-discharge centers in class 1 and 3 receptive fields of the frog retina was determined with the aid of moving bars of different lengths. On- and off-centers of receptive fields of the first group coincide, those of the second are spatially separate, and in fields of the 3rd group the discharge center of one contrast sign occupies the central position and discharge centers of the opposite sign are located at the periphery, to its right and left. Receptive fields of the frog retina thus have features which approximate them to the concentric receptive fields of geniculate neurons and the fields of the cat visual cortex. Asymmetry in the responses was found: during movement in opposite directions the distance between the discharge centers changed, during movement to one side only one of the peripheral centers was revealed, whereas during movement to the other side the second center was revealed on the opposite side of the receptive field. This asymmetry of spatiotemporal relations in the receptive fields is similar to that found in the fields of cortical neurons and is connected with their directional properties.Research Institute of Applied Mathematics and Cybernetics, N. I. Lobachevskii State University, Gor'kii. Translated from Neirofiziologiya, Vol. 12, No. 1, pp. 75–85, January–February, 1980.     

Rabbit visual cortical neurons with simple and complex receptive fields

Receptive fields of neurons of the rabbit visual cortex selective for stimulus orientation were investigated. These receptive fields were less well differentiated than those of the analogous neurons of the cat visual cortex (large in size and circular in shape). Two mechanisms of selectivity for stimulus orientation were observed: inhibition between on and off zones of the receptive field (sample type) and oriented lateral inhibition within the same zone of the receptive field (complex type). Lateral inhibition within the same zone of the receptive field also took place in unselective neurons; "complex" selective neurons differed from them in the orientation of this inhibition. A combination of both mechanisms was possible in the receptive field of the same neuron. It is suggested that both simple and complex receptive fields are derivatives of unselective receptive fields and that "complex" neurons are not the basis for a higher level of analysis of visual information than in "simple" neurons.A. N. Severtsov Institute of Evolutionary Morphology and Ecology of Animals, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 10, No. 1, pp. 13–21, January–February, 1978.     

Response of caudate nucleus neurons to a photic stimulus at various locations on the visual field in the awake cat

The response of caudate nucleus neurons to presentation of photic stimuli located at varying distances from the fovea centralis was investigated in awake cats. Stimulation of different sites on the visual field below the fovea produced dissimilar reactions in 25 of the 35 (or 71%) of these neurons responding to photic stimulation. This divergence of response indicates that in 6 of these cells (or 17%) the receptive fields in the test area of the visual field bordered on the central area of the latter and 6 neurons (17%) showed reduced sensitivity to the effects of stimuli nearer to the periphery than to the center of the visual field, while 13 units (37%) were receiving qualitatively different information from various sites on the field of vision. On the basis of our findings we deduced that caudate nucleus neurons are involved in the analysis of visual sensory signals.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 18, No. 2, pp. 241–250, March–April, 1986.     

Dependence of functional organization of receptive fields of the cat lateral geniculate body on visual stimulus contrast

The spatial organization of receptive fields of the lateral geniculate body in response to visual stimuli with different degrees of contrast was studied in cats. During variation of contrast changes in organization of the central zone were found to take place in some receptive fields. Inside the central zone of the receptive field as revealed by the use of low stimulus contrasts, an additional inhibitory ring appears in response to a stimulus of high contrast. The weighting function of the central zone of the receptive field becomes variable in sign. The role of this phenomenon in transmission of information on high spatial frequencies (increase in visus) at high contrasts is discussed.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 16, No. 6, pp. 789–796, November–December, 1984.     

Receptive field dynamics of neurons in the cat visual cortex and lateral geniculate body

Spike responses of single neurons in the primary visual cortex and lateral geniculate body to random presentation of local photic stimuli in different parts of the receptive field of the cell were studied in acute experiments on curarized cats. Series of maps of receptive fields with time interval of 20 msec obtained by computer enabled the dynamics of the excitatory and inhibitory zones of the field to be assessed during development of on- and off-responses to flashes. Receptive fields of all cortical and lateral geniculate body neurons tested were found to undergo regular dynamic reorganization both after the beginning and after the end of action of the photic stimulus. During the latent period of the response no receptive field was found in the part of the visual field tested, but later a small zone of weak responses appeared only in the center of the field. Gradually (most commonly toward 60–100 msec after application of the stimulus) the zone of the responses widened to its limit, after which the recorded field began to shrink, ending with complete disappearance or disintegration into separate fragments. If two bursts of spikes were generated in response to stimulation, during the second burst the receptive field of the neuron changed in the same way. The effects described were clearly exhibited if the level of background illumination, the intensity of the test bars, their contrast with the background, duration, angles subtended, and orientation were varied, although the rate and degree of reorganization of the receptive field in this case changed significantly. The functional importance of the effect for coding of information about the features of a signal by visual cortical neurons is discussed.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 14, No. 6, pp. 622–630, November–December, 1982.     

Visual cortical unit responses to photic stimulation of different zones of the receptive fields in cats

In acute experiments on unanesthetized curarized cats the intensity functions, response thresholds, inhibition thresholds, and differential sensitivity of 96 neurons in the primary visual projection cortex were investigated by extracellular recording of unit activity during central and peripheral stimulation of their receptive fields. In darkness the neurons had wide threshold and above-threshold reliefs (3–30°). The threshold reliefs of the receptive fields of some cells were found to be V-shaped, whereas others were marked by alternation of zones of increased and reduced excitability. Sensitivity of both excitatory and inhibitory inputs of the receptive field as a rule was greatest in the center. Inhibitory inputs of different cortical neurons were much more standard and less sensitive to light, and they were mainly activated within the intermediate (mesoptic) range of brightnesses. During light adaptation the threshold contour of the receptive field narrows sharply, mainly because of the fall in sensitivity of its peripheral inputs. Compared with the lateral geniculate body and retina, the relative number of low-threshold elements, sensitivity in the system of inhibitory elements, and differential brightness sensitivity are greater in the cortex. The mechanisms of formation of receptive fields of cortical neurons and their modification during changes in the level of adaptation, and also the role of excitatory and inhibitory inputs of the cell in these effects are discussed.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 11, No. 3, pp. 227–235, May–June, 1979.     

Receptive fields of neurons in the lateral suprasylvian area of the cat

The structure of receptive fields of single neurons in the lateral suprasylvian area of the cat's cortex was studied. Receptive fields of neurons in this area are larger (up to 2000 deg² or more) than those of the visual projection cortex. A difference was found in the sizes of these fields of the same neuron when measured by presentation of a black object and spot of light. Experimental results showed that most neurons of the area (104 of 148) that are sensitive to visual stimulation respond clearly to flashes of a stationary spot of light. Because of this feature the structure of the receptive fields of the neurons were studied by point by point testing of their whole surface. Intensities of on- and off-components of on-off neurons were found to differ. Only 16% of receptive fields had equal numbers of discharges in on- and off-components of the on-off response. Dominance of one component was observed in 84% of on-off neurons. Receptive fields with several discharge centers are a characteristic feature of neurons in this area. A concentric organization of the receptive fields was found in 11% of neurons.L. A. Orbeli Institute of Physiology, Academy of Sciences of the Armenian SSR, Erevan, Translated from Neirofiziologiya, Vol. 14, No. 3, pp. 278–283, May–June, 1982.     

Responses and properties of receptive fields of neurons in the visual projection zone of the pigeon hyperstriatum

Unit responses in the hyperstriatal region of the pigeon forebrain to the action of various visual stimuli were investigated. Particular attention was paid to the discovery of retinotopic projection in the Wulst region. It was shown that as the electrode was advanced in the caudal direction in the zone of visual projection of the hyperstriatum the receptive fields of the neurons recorded shifted in the opposite direction in the visual field. The receptive fields of neurons of the ventral and dorsal hyperstriatum lie higher in the visual field and are larger in diameter than those of neurons of the accessory hyperstriatum. Unit responses in the visual projection zone of the Wulst depend on the intensity of illumination, size, and speed and direction of movement of the test objects across the receptive field. The functional role of the retino-thalamo-telencephalic system in visual interpretation in birds is discussed and it is suggested that the Wulst region is comparable with the striatal and also with the frontal regions of the mammalian cortex.M. V. Lomonosov Moscow State University. Translated from Neirofiziologiya, Vol. 8, No. 3, pp. 230–236, May–June, 1976.     

Orientation-selective neurons in the squirrel visual cortex

The organization of receptive fields of neurons sensitive to orientation of visual stimuli was investigated in the squirrel visual cortex. Neurons with mutually inhibitory on- and off-areas of the receptive field, with partially and completely overlapping excitatory and inhibitory mechanisms, were distinguished. Neurons of the second group are most typical. They exhibit orientation selectivity within the excitatory area of the receptive field because, if the stimulus widens in the zero direction, perpendicular to the preferred direction, lateral inhibition is much stronger than if it widens in the preferred direction. Additional inhibitory areas (outside the excitatory area) potentiate this inhibition and increase selectivity. It is suggested that there is no strict separation of simple (with separate excitatory and inhibitory mechanisms in the receptive field) and complex (with overlapping of these mechanisms) neurons in the squirrel visual cortex.A. N. Severtsov Institute of Evolutionary Morphology and Ecology of Animals, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 11, No. 6, pp. 540–549, November–December, 1979.     

Are receptive fields of the visual cortex detectors or spatial frequency filters?

Besides its principal maximum, the spatial frequency characteristic curve of the complex visual cortical receptive field of curarized cats also has additional maxima and also negative regions, as predicted by the theory of piecewise Fourier analysis. Comparison of responses of the complex receptive field to sinusoidal gratings completely and incompletely contained in the field and comparison of responses to sinusoidal and square-wave gratings indicate that the receptive field, as a spatial frequency filter, has linear properties. The response of the complex receptive field rises with an increase in the number of periods of the sinusoidal grating. Several periods of optimal frequency match the complex field. Receptive fields tuned to a broad band of spatial frequencies were found in neuron columns. The results confirm the view that complex receptive fields are spatial frequency filters and not detectors.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 11, No. 5, pp. 403–411, September–October, 1979.     

Dynamic and static receptive field characteristics of single neurons in the lateral suprasylvian area in cats

Static and dynamic properties of receptive fields of neurons in the lateral suprasylvian area of the cat cerebral cortex were studied. Neurons with different dynamic characteristics may have an identical static organization of their receptive fields; strict correlation is thus not found between these two characteristics of neurons in this area. Most black-sensitive neurons were found to have a receptive field with off-response. Stimulus contrast reversal tests showed that generation of responses to presentation of both black and light stimuli takes place as a result of excitation of the same area of the receptive field and is not due to spatially different on- and off-zones.L. A. Orbeli Institute of Physiology, Academy of Sciences of the Armenian SSR, Erevan. Translated from Neirofiziologiya, Vol. 16, No. 1, pp. 116–123, January–February, 1984.     

Color sensitivity in the receptive fields of neurons of the squirrel visual cortex

Color-opponent properties in neurons of the primary visual cortex were investigated in the squirrel. All neurons responded to the presentation of both black and white visual stimuli and of colored stimuli — mainly to blue and green. In 65% of test neurons a response only occurred when blue and green stimuli were applied while the remaining cells partially responded to red. Neurons were divided into groups according to how they responded to the presentation of stimuli composed of black and white: whether nonselective, directionally selective, or orientationally selective (simple or complex). No color-opponent properties were found in any of these groups at receptive field level. The whole or parts of the receptive field responded similarly to the presentation of white, blue, or green stimuli of the same shape. The way in which the receptive fields were divided into on- and off-regions and between directional and orientational selectivity does not depend on the color of the visual stimuli. Findings are discussed with regard to the presence of opponent-color cells in squirrel retina and lateral geniculate body.A. N. Severtsov Institute of Evolutionary Morphology and Animal Ecology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 17, No. 6, pp. 764–770, November–December, 1985.     

Laminar distribution of neurons with different types of receptive fields in the rabbit visual cortex

Investigation of receptive fields of 232 primary visual cortical neurons in rabbits by the use of shaped visual stimuli showed that 21.1% are unselective for stimulus orientation, and 34.1% have simple, 16.4% complex, and 18.5% hypercomplex receptive fields, and 9.9% have other types. Neurons with different types of receptive fields also differed in spontaneous activity, selectivity for rate of stimulus movement, and acuteness of orientational selectivity. Neurons not selective to orientation were found more frequently in layer IV than in other layers, and very rarely in layer VI. Cells with simple receptive fields were numerous in all layers but predominated in layer VI. Neurons with complex receptive fields were rare in layer IV and more numerous in layers V and VI. Neurons with hypercomplex receptive fields were found frequently in layers II + III and IV, rarely in layers V and VI. Spontaneous unit activity in layer II + III was lowest on average, and highest in layer V. Acuteness or orientational selectivity of neurons with simple and complex receptive fields in layers II + III and V significantly exceeded the analogous parameter in layers IV and VI.A. N. Severtsov Institute of Evolutionary Morphology and Ecology of Animals, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 17, No. 1, pp. 19–27, January–February, 1985.     

Structure of receptive fields of cat pulvinar neurons sensitive to photic stimulation

Receptive fields of 262 pulvinar neurons were studied. Receptive fields of 142 of these neurons were studied in detail with the aid of a stationary spot of light, flashing in different parts of the receptive field. Depending on responses to presentation of the stationary stimulus the neurons were divided into six groups. The first group included neurons with on—off responses to photic stimulation (44 of 142), the second group neurons with off responses only (42 of 142). In cells of the third group (19 of 142) an on response only was recorded in all structures of the receptive field tested. Neurons of the fourth group (eight of 142) had a receptive field of similar structure to that of the simple receptive fields of neurons in cortical area 17. The fifth group (10 of 142) included neurons with a receptive field of concentric structure, the sixth (19 of 142) consisted of neurons with receptive fields with multiple discharge centers. The structure of the receptive field of these neurons was mosaic, with an irregular distribution of exciting and "silent" zones. The mean response latency of the pulvinar neurons was 40–70 msec. Responses of neurons with shorter (20 msec) and longer (130–160 msec) latent periods also were recorded.L. A. Orbeli Institute of Physiology, Academy of Sciences of the Armenian SSR, Erevan. Translated from Neirofiziologiya, Vol. 11, No. 1, pp. 3–10, January–February, 1979.     

Receptive fields of auditory cortical neurons in the cat

Receptive fields of auditory cortical neurons were studied by electrical stimulation of nerve fibers in different parts of the cochlea in cats anesthetized with pentobarbital. The dimensions of the receptive fields were shown to depend on the topographic arrangement of the neuron in the auditory cortex. The more caudad the neuron on the cortical projection of the cochlea in the primary auditory cortex, the more extensive its receptive field. The receptive fields were narrowest in the basal turn of the cochlea and were symmetrical with respect to their center. It is suggested that the region of finest discrimination of acoustic stimuli in cats is located in the basal region of the cochlea, i.e., in that part of its receptor system which has the narrowest receptive field and is represented by significantly more (than the middle and apical regions of the cochlea) nerve cells in the primary auditory cortex [1].A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 13, No. 5, pp. 467–473, September–October, 1981.     

Investigation of functional organization of receptive fields in the cat visual cortex

Receptive fields of neurons in Area 17 of the visual cortex were investigated in cats. Concentrically shaped fields, fields responding selectively to orientation of a strip or edge, and fields which can be regarded as intermediate between the first two types are described. The boundary between zones of summation and of lateral inhibition coincides in some receptive fields with the boundary between central and peripheral zones with opposite forms of response, while in other fields they do not coincide. For some cells there is no peripheral zone or it may disappear with worsening of the state of function. Cells were observed for which an increase in area of the stimulus in the central zone inhibits the response reaction. Analysis of these data suggests that several cells of the geniculate ganglion converge on some cortical neurons, and several cortical cells on others. An effect of adaptive inhibition was found in which constant illumination of an area in the center of the receptive field inhibits the response in another part. It is shown that this effect is unconnected with the action of scattered light. Constant illumination of the peripheral part of the receptive field deinhibits adaptive inhibition. The boundary between the zones of summation and of lateral inhibition coincides with the boundary between the zones of adaptive inhibition and deinhibition.I. V. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 1, No. 1, pp. 90–100, July–August, 1969.