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  • 1
    Electronic Resource
    Electronic Resource
    A model of striate response properties based on geniculate anisotropies (1987)
    Springer
    Biological cybernetics 57 (1987), S. 11-23 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract The orientation biases seen in the responses of cells in the retina and dLGN are dependent on the spatial frequency of the stimulus, being appreciable only at higher spatial frequencies. An inhibitory mechanism that suppresses the responses to low spatial frequencies would leave a striate cell receiving a biased geniculate input with an orientation sensitivity at the higher spatial frequencies. Such an inhibition could in fact come from one or a small group of LGN cells (through cortical interneurones), since their response extends to spatial frequencies much lower than for cortical cells at the same eccentricity. According to this scheme, a number of other striate response characteristics, e.g., their length and spatial frequency response functions, can also be explained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318712
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Space and spatial frequency: analysis and representation in the macaque striate cortex (1986)
    Springer
    Experimental brain research 64 (1986), S. 5-18 
    Details
    ISSN: 1432-1106
    Keywords: Striate cortex ; Fourier analysis ; Receptive fields
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Simple cells in the macaque striate cortex were tested with bars, edges and gratings. Spatial frequency tuning curves could be predicted from the spatial profiles plotted with bars and edges and the bandwidth could be evaluated more accurately by computing the mean from measured and predicted tuning curves. The results suggest that the mean relative spatial frequency bandwidth (Δf/fo) is nearly constant and of a moderate value. But at each optimal spatial frequency, cells with different bandwidths (about a factor of two) were recorded. The shapes of spatial response profiles resemble the corresponding spatial and spatial frequency characteristics of line and edge detectors evaluated psychophysically. Among the remaining cell types, concentric cells tend to be tuned to lower spatial frequencies and have broader bandwidths, whereas periodic cells prefer higher spatial frequencies and have narrower bandwidths. Thus the mean relative bandwidth tends to decrease significantly with spatial frequency (as required by a system of patch-by-patch Fourier analysis) only when cells with poor orientation selectivity and the non-linear silent periodic cells are included along with the simple cells. Simple cells, on their own, seem to form a quasi-linear contrast processing system which is more biased towards spatial accuracy than spatial frequency selectivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238196
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  • 3
    Electronic Resource
    Electronic Resource
    Contribution of inhibitory mechanisms to the orientation sensitivity of cat dLGN neurones (1984)
    Springer
    Experimental brain research 55 (1984), S. 192-195 
    Details
    ISSN: 1432-1106
    Keywords: Lateral geniculate nucleus ; Orientation sensitivity ; GABA-mediated inhibition ; Bicuculline methiodide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of iontophoretically applied bicuculline methiodide, an antagonist of GABA-mediated inhibition, was tested on the responses of cat dLGN neurones to moving lines. Most geniculate neurones normally show an orientation bias when tested with slowly moving long lines. This sensitivity to the orientation of the line stimulus could be markedly reduced during iontophoretic application of bicuculline. It is concluded that the orientation bias shown by geniculate neurones is to a large extent due to intrageniculate GABAergic inhibition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00240517
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  • 4
    Electronic Resource
    Electronic Resource
    Orientation sensitivity of cat LGN neurones with and without inputs from visual cortical areas 17 and 18 (1982)
    Springer
    Experimental brain research 46 (1982), S. 157-169 
    Details
    ISSN: 1432-1106
    Keywords: Lateral geniculate nucleus ; Orientation sensitivity ; Visual cortical areas 17 and 18 ; Corticogeniculate projection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Orientation sensitivity was tested, using moving bars as stimuli, in 136 LGN cells in normal cats and 82 LGN cells in cats with areas 17 and 18 lesioned. The responses of most neurones showed some dependence on the orientation of the line stimulus. The orientation bias was more pronounced for long, narrow bars moving at rather slow velocities. Length-response curves revealed less end-inhibition along the optimum orientation than along the nonoptimum orientation. Thirty-two percent of the cells in the normal cats and 50% in the lesioned animals responded best to orientations within 10 ° of the vertical or horizontal. The oblique orientations were represented poorly in the lesioned group. Thus the corticogeniculate feedback may serve to confer a more uniform distribution of orientation preferences on the LGN. It is suggested that the orientation biases of LGN neurones may play a role in building orientation-selective cells in the visual cortex. Further, the preferences for horizontal and vertical orientations in the LGN may explain the preferences for these orientations reported for visual cortical cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237172
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  • 5
    Electronic Resource
    Electronic Resource
    Geniculate orientation biases seen with moving sine wave gratings: implications for a model of simple cell afferent connectivity (1984)
    Springer
    Experimental brain research 57 (1984), S. 196-200 
    Details
    ISSN: 1432-1106
    Keywords: Lateral geniculate nucleus ; Striate cortex ; Orientation sensitivity ; Sine wave gratings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Orientation bias of cat dorsal lateral geniculate (LGN) neurones varied with the spatial frequency of a moving sine wave grating. At low spatial frequencies there was little orientation bias, whereas near the high-frequency limit, the dependence on orientation was marked. It is proposed that, if such cells were to drive the cortical inhibitory interneurones responsible for the orientation sensitivity of striate simple cells, it would explain many distinguishing features of cortical cells besides their orientation sensitivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00231146
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  • 6
    Electronic Resource
    Electronic Resource
    Relationship between orientation tuning and spatial frequency in neurones of cat area 17 (1985)
    Springer
    Experimental brain research 57 (1985), S. 628-631 
    Details
    ISSN: 1432-1106
    Keywords: Striate cortex ; Orientation tuning ; Spatial frequency ; Inhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The orientation bandwidth was measured at different spatial frequencies for simple and complex cells. With increasing spatial frequency, the orientation tuning of simple cells became progressively narrower. This tendency was much less marked in complex cells. The results are interpreted in support of geniculate cells with orthogonal orientation biases providing the excitatory and inhibitory inputs to a simple cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237851
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Release from inhibition reveals the visual past (1999)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 399 (1999), S. 422-422 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Prolonged viewing of a high-contrast repetitive pattern such as a grating leads to adaptation of the corresponding visual-processing channels. We have found that such viewing also leads to the short-term establishment of a subthreshold trace in the brain that can cause a visual illusion of the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/20836
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  • 8
    Electronic Resource
    Electronic Resource
    Convergence of parvocellular and magnocellular information channels in the primary visual cortex of the macaque (2002)
    Oxford, UK : Blackwell Science, Ltd
    European journal of neuroscience 16 (2002), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We investigated whether responses of single cells in the striate cortex of anaesthetized macaque monkeys exhibit signatures of both parvocellular (P) and magnocellular (M) inputs from the dorsal lateral geniculate nucleus (dLGN). We used a palette of 128 isoluminant hues at four different saturation levels to test responses to chromatic stimuli against a white background. Spectral selectivity with these isoluminant stimuli was taken as an indication of P inputs. The presence of magnocellular inputs to a given cortical cell was deduced from its responses to a battery of tests, including assessment of achromatic contrast sensitivity, relative strengths of chromatic and luminance borders in driving the cell at different velocities and conduction velocity of their retino-geniculo-cortical afferents. At least a quarter of the cells in our cortical sample appear to receive convergent P and M inputs. We cannot however, exclude the possibility that some of these cells could be receiving a convergent input from the third parallel channel from the dLGN, namely the koniocellular (K) rather than the P channel. The neurons with convergent P and M inputs were recorded not only from supragranular and infragranular layers but also from the principal geniculate input recipient layer 4. Thus, our results challenge classical ideas of strict parallelism between different information streams at the level of the primate striate cortex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9568.2002.02137.x
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  • 9
    Electronic Resource
    Electronic Resource
    Function of GABAA inhibition in specifying spatial frequency and orientation selectivities in cat striate cortex (1994)
    Springer
    Experimental brain research 98 (1994), S. 31-38 
    Details
    ISSN: 1432-1106
    Keywords: Striate cortex ; Spatial frequency tuning ; Orientation sensitivity ; Intracortical inhibition ; Bicuculline methiodide ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Responses of simple and complex cells in cat striate cortex were studied with moving sine-wave gratings before and during application of the GABAA receptor antagonist bicuculline methiodide. Both simple and complex cells exhibited a broadening of their spatial frequency tuning functions under bicuculline. This was especially evident at spatial frequencies lower than the ones the cell was responding to before the drug administration. The effects cannot be explained by response saturation and could be reversed by cessation of the iontophoresis. The results indicate that the band-pass response characteristics of the spatial frequency response functions of striate cells derive largely from intracortical inhibition. The findings have implications also for the orientation selectivity of cortical cells. Since many geniculate cells are tuned for stimulus orientation at higher spatial frequencies, suppression of the low-spatial-frequency component would remove some of the orientation non-specific response in striate cortical cells and contribute to their orientation selectivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229106
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    Possible plasticity in the rat superior colliculus (1978)
    [s.l.] : Nature Publishing Group
    Nature 275 (1978), S. 140-141 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] It has been shown in the mouse3 and the hamster4 that many neurones in the intermediate and deep layers of the optic tectum receive nonvisual sensory inputs. They respond either to somatic stimuli from fur or whiskers on the contralateral half of the body or to complex sounds from the contralateral ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/275140a0
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