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  • 1
    Electronic Resource
    Electronic Resource
    Size constancy, depth constancy and vertical disparities: a further quantitative interpretation (1994)
    Springer
    Biological cybernetics 71 (1994), S. 37-47 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract The size and depth constancies considered here operate only at near distances (〈 about 2 m) in a static stimulus situation with vergence as the only cue to distance. The innervation of the extraocular muscles, as evidenced by the corollary discharge, provides information about the vergence of the eyes and hence about the egocentric distance both for symmetrical and asymmetrical vergences. Size and depth constancies are regarded as the first and second stages of a linked two-stage process. In the lateral geniculate nuclei compensatory adjustments are separately applied to each retinal image as they are received from the two eyes. The modified ocular images, with their associated vertical and horizontal disparities, now provide synaptic inputs to binocularly activated cells in the visual cortex. Then, by a process akin to the induced effect, cortical cells with geniculate afferents with vertical disparities will have their outputs expressed in terms of horizontal disparities. The horizontal disparity outputs of these cortical cells are then further multiplied by the outputs from cortical cells with geniculate afferents with horizontal disparities. It is this second multiplicative process that brings about the quadratic relationship between horizontal retinal disparity and egocentric distance. The proposed mechanisms involve the known ability of the visual system to detect and respond to vertical as well as horizontal disparities and provide a definite role for the induced effect in the perceptual process. The above neural model is based on fairly simple equations that give a remarkably adequate description of the operation of the two constancies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00198910
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  • 2
    Electronic Resource
    Electronic Resource
    Theory of spatial position and spatial frequency relations in the receptive fields of simple cells in the visual cortex (1982)
    Springer
    Biological cybernetics 43 (1982), S. 187-198 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract Striate cells showing linear spatial summation obey very general mathematical inequalities relating the size of their receptive fields to the corresponding spatial frequency and orientation tuning characteristics. The experimental data show that, in the preferred direction of stimulus motion, the spatial response profiles of cells in the simple family are well described by the mathematical form of Gabor elementary signals. The product of the uncertainties in signalling spatial position (δx) and spatial frequency (δf) has, therefore, a theoretical minimum value of δxδf=1/2. We examine the implications that these conclusions have for the relationship between the spatial response profiles of simple cells and the characteristics of their spatial frequency tuning curves. Examples of the spatial frequency tuning curves and their associated spatial response profiles are discussed and illustrated. The advantages for the operation of the visual system of different relationships between the spatial response profiles and the characteristics of the spatial frequency tuning curves are examined. Two examples are discussed in detail, one system having a constant receptive field size and the other a constant bandwidth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319978
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Size constancy, depth constancy and vertical disparities: a further quantitative interpretation (1994)
    Springer
    Biological cybernetics 71 (1994), S. 37-47 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract. The size and depth constancies considered here operate only at near distances (〈about 2 m) in a static stimulus situation with vergence as the only cue to distance. The innervation of the extraocular muscles, as evidenced by the corollary discharge, provides information about the vergence of the eyes and hence about the egocentric distance both for symmetrical and asymmetrical vergences. Size and depth constancies are regarded as the first and second stages of a linked two-stage process. In the lateral geniculate nuclei compensatory adjustments are separately applied to each retinal image as they are received from the two eyes. The modified ocular images, with their associated vertical and horizontal disparities, now provide synaptic inputs to binocularly activated cells in the visual cortex. Then, by a process akin to the induced effect, cortical cells with geniculate afferents with vertical disparities will have their outputs expressed in terms of horizontal disparities. The horizontal disparity outputs of these cortical cells are then further multiplied by the outputs from cortical cells with geniculate afferents with horizontal disparities. It is this second multiplicative process that brings about the quadratic relationship between horizontal retinal disparity and egocentric distance. The proposed mechanisms involve the known ability of the visual system to detect and respond to vertical as well as horizontal disparities and provide a definite role for the induced effect in the perceptual process. The above neural model is based on fairly simple equations that give a remarkably adequate description of the operation of the two constancies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004220050066
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Simple cells in cat striate cortex: responses to stationary flashing and to moving light bars (1985)
    Springer
    Experimental brain research 60 (1985), S. 151-158 
    Details
    ISSN: 1432-1106
    Keywords: Striate simple cells ; Static-field plots ; Receptive field subregions ; Moving light bar responses ; Hand and quantitative methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cells in the simple family respond to a moving light bar with an average response histogram that is most commonly unimodal (single peak: encounter frequency, 64%) and less commonly bimodal (33%) or trimodal (3%). The mean width of the principal response peak given by hypercomplex I cells is narrower than that of simple cells and they have a lower mean optimal stimulus velocity. In a series of 74 cells (simple, 47; hypercomplex I, 27), detailed comparison of the spatial relations between the response peaks to the moving bar and the subregions to the stationary flashing bar led to the concept of a boundary response. The term “boundary response” refers to an isolated response peak occurring as a moving light bar leaves an OFF subregion that is the last in the sequence of subregions traversed by the bar. The presence of a boundary response leads to an apparent discrepancy between the number of response peaks to a moving light bar and the number of ON subregions in the static-field plot. The boundary response is necessarily completely direction selective. A detailed comparison of the properties of cells as revealed by hand and quantitative methods showed a very good agreement between the two methods in respect to the assignment of cells to the simple, B- and complex cell families. There were, however, serious discrepancies in respect to the receptive field organization of cells in the simple family. In particular, many cells that either failed to respond adequately to hand stimulation by a stationary flashing bar or exhibited only a single receptive field “subregion”, all responded with two or more subregions when examined quantitatively by the same kind of stationary stimulus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237027
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  • 5
    Electronic Resource
    Electronic Resource
    Binocular single vision and depth discrimination. Receptive field disparities for central and peripheral vision and binocular interaction on peripheral single units in cat striate cortex (1970)
    Springer
    Experimental brain research 10 (1970), S. 389-416 
    Details
    ISSN: 1432-1106
    Keywords: Striate neurons ; Receptive field disparity ; Retinal eccentricity ; Binocular single vision ; Stereopsis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Of binocularly-activated striate neurons only a proportion have their two receptive fields in exactly corresponding positions in the contralateral hemifield. Those which are not corresponding are said to show receptive field disparity. Because the eyes diverge in the anaesthetized and paralyzed preparation, the binocular receptive fields are horizontally separate. With increasing retinal eccentricity there is a gradual decrease in this horizontal separation as well as progressive changes in the local receptive field disparities. With increasing horizontal retinal eccentricity there is a progressive increase in horizontal receptive field disparities together with a smaller decrease in vertical disparities. Receptive field disparities are relatively unaffected by increasing vertical retinal eccentricity. A neurophysiological theory for binocular single vision and depth discrimination is put forward as a theoretical framework for the construction of the horopter for the cat as well as a region analogous to Panum's fusional area in man. Observations have been made on the responses, particularly to moving slit stimuli, of units with peripherally-located receptive fields. For several binocular units it was possible to study the full range of the binocular interaction when the two receptive fields were moved from exact correspondence to positions of increasing non-alignment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02324766
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  • 6
    Electronic Resource
    Electronic Resource
    Properties of end-zone inhibition of hypercomplex cells in cat striate cortex (1985)
    Springer
    Experimental brain research 60 (1985), S. 200-203 
    Details
    ISSN: 1432-1106
    Keywords: End-zone inhibition ; Hypercomplex cells ; Striate cortex ; Cats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The response properties of 96 striate cells in anaesthetized and paralyzed cats were examined by using narrow optimally-oriented light bars moved in the preferred direction at optimal velocity. The bar was lengthened systematically at both ends to plot and analyze bilateral length-response curves. We found a linear relationship between the maximum slope of the inhibitory phase of the curve and the strength of the end-zone inhibition for both cell families: simple and B-cells. This observation indicates that the length of the two end-zones as given by a bilateral length-response curve is approximately constant regardless of the strength of the end-zone inhibition for a change in the strength of the inhibition from 10 to 100%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237034
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  • 7
    Electronic Resource
    Electronic Resource
    The properties of the binocular receptive fields of lateral geniculate neurons (1971)
    Springer
    Experimental brain research 13 (1971), S. 178-207 
    Details
    ISSN: 1432-1106
    Keywords: Lateral geniculate nucleus ; Binocular inhibition ; Inhibitory receptive fields ; Binocular correspondence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The majority of cells in the dorsal nucleus of the lateral geniculate body (LGNd) in the cat have two receptive fields: one for each eye. Of the cells tested for binocularity (113), only 21 (18%) were purely monocular. The remainder had receptive fields for the non-dominant eye, the great majority of which (81 or 88%) were purely inhibitory and only 11 (12%) were excitatory. Cells with receptive fields for the non-dominant eye were found in all three laminae (A, A1 and B) of the LGNd. The proportion of inhibitory receptive fields for the non-dominant eye was slightly greater when the dominant eye was ipsilateral (77%) than when it was contralateral (68%). The distribution of the binocular receptive field pairs about points of exact correspondence in the visual field had a standard deviation of about 0.9° in both horizontal and vertical directions. The properties of the inhibitory receptive fields were studied with moving slits of light and stationary flashing spots. Most of the fields were purely inhibitory and varied in size from 1.5° to 6° across. There were no specific stimulus requirements other than a change in contrast within the receptive field. The inhibitory effect was usually fairly weak, the spontaneous discharge of the neuron being inhibited much more readily than the driven discharge. The latency of the inhibition to a stationary flashing spot was about 50 msec, the inhibition was maximal about 20 msec after the onset and lasted up to about 400 msec. Binocular inhibition is not mediated by a corticogeniculate pathway from the visual areas since it survives removal of areas 17, 18 and 19 and the middle suprasylvian gyrus. It was concluded that the most likely mechanism was via interneurons whose axons cross the borders from one cell layer to another.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234085
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  • 8
    Electronic Resource
    Electronic Resource
    Spatial summation of responses in receptive fields of single cells in cat striate cortex (1978)
    Springer
    Experimental brain research 32 (1978), S. 245-266 
    Details
    ISSN: 1432-1106
    Keywords: Spatial summation ; Receptive fields ; Striate cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Spatial summation of responses in striate neurons in cats under N2O/O2 anaesthesia was examined quantitatively both along the line of the optimal stimulus orientation (length summation) using moving light bars and single light and dark edge stimuli, and at right angles to the optimal orientation (width summation) using stationary flashing bars. Activity profiles and length-response curves were prepared from simple, complex and hypercomplex I and II cells. An activity profile indicates the responsiveness of a cell at locations along the length of its receptive field. The activity profiles from all cell types were usually well fitted by Gaussian functions. Length summation occurs both in end-free (simple and complex) and, to a lesser extent, in end-stopped (hypercomplex I and II) cells over a wide range of stimulus contrasts (0.13 to 0.95). The linearity of length summation was tested either by comparing the recorded length-response curves with the curves predicted from the linear integration of the activity profiles or by comparing the response to the activation of two regions of the receptive field with the sum of the responses to each region activated separately. Although length summation was usually non-linear (either greater than or less than direct proportionality) it was more nearly linear in complex than it was in simple and hypercomplex I cells. Mechanisms responsible for non-linear length summation were studied, including a threshold for discharge, response saturation and summation of end-zone inhibition. Complex cells show little width summation for bars wider than 0.3 °. In simple and hypercomplex I cells there was also relatively little width summation either in an ON or an OFF discharge region at contrasts above about 0.4 but at lower contrasts width summation may be approximately linear. Spatial summation of responses does not appear to be a useful characteristic for distinguishing one striate cell type from another.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239730
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  • 9
    Electronic Resource
    Electronic Resource
    Linear analysis of the responses of simple cells in the cat visual cortex (1981)
    Springer
    Experimental brain research 44 (1981), S. 386-400 
    Details
    ISSN: 1432-1106
    Keywords: Striate cortex ; Simple cells ; Linear analysis ; Spatial response profiles ; Spatial frequency tuning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Spatial response profiles to stationary and moving stimuli and spatial frequency tuning curves to drifting sinusoidal gratings were recorded from a series of cells in the simple family. The spatial response profiles were recorded both to stationary flashing bars and sinusoidal gratings as well as to light and dark bars and edges and gratings moving at the optimal velocity. On the assumption that cells in the simple family operate linearly, spatial response profiles recorded experimentally were compared with those predicted by inverse Fourier transformation of the spatial frequency tuning curves. Conversely, the spatial frequency tuning curves recorded experimentally were compared with those predicted from the response profiles to moving and stationary stimuli. As a result of these comparisons, it is clear that moving stimuli provide a more accurate estimate of the spatial organization of the receptive field than do stationary stimuli. Cells with the higher optimal spatial frequencies tended to have narrower bandwidths. The simple cell with the narrowest bandwidth (0.94 octave) had five, and possibly six, subregions in the spatial response profile to moving light and dark bars, the largest number of subregions we encountered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238831
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  • 10
    Electronic Resource
    Electronic Resource
    Responses to moving slits by single units in cat striate cortex (1968)
    Springer
    Experimental brain research 6 (1968), S. 373-390 
    Details
    ISSN: 1432-1106
    Keywords: Averaged responses ; Moving slit stimuli ; Single unit response types ; Striate cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A quantitative study has been made of the responses to moving slit stimuli by single units in the cat striate cortex whose receptive fields lay within 5° of the visual axis. Special attention was given to finding the optimal stimulus parameters including slit width, length, orientation and speed. The analysis was largely based on averaged response vs. time histograms. Using the classification of simple and complex responses types, the units were further subdivided on the basis of the number of modes in the response and on the presence or absence of directional selectivity. Simple unimodal units with directional selectivity (SUDS) had the most specific stimulus requirements and nearly always had zero background activity. Complex units usually had a high level of background activity. SUDS units also showed a preference for horizontally- and vertically ****-orientated stimuli. Whenever the response survived reversal of contrast the directional selectivity remained independent of the change. Optimal stimulus speeds varied widely from unit to unit with a mean at 4°/sec: simple bimodal units and complex units tended to have higher optimal stimulus speeds and responded over a wider range of speeds than did simple unimodal units. While SUDS units with very small receptive fields tended to prefer slowly moving stimuli, in general there was no correlation between receptive field size and optimal stimulus speed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233185
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