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  • 1
    Electronic Resource
    Electronic Resource
    Neuronal dynamics in the visual corticothalamic pathway revealed through binocular rivalry (1987)
    Springer
    Experimental brain research 66 (1987), S. 10-20 
    Details
    ISSN: 1432-1106
    Keywords: Corticothalamic feedback ; Binocular rivalry ; Lateral geniculate ; Vision ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Single unit activity was recorded from principal cells in the A-laminae of the cat dorsal lateral geniculate nucleus (dLGN). A steady state pattern of afferent activation was induced by presenting a continuously drifting square wave grating of constant spatial frequency to the eye (the dominant eye) that provided the excitatory input to the recorded cell. Intermittently, a second grating stimulus was presented to the other, nondominant, eye. In most neurones nondominant eye stimulation led to inhibition of relay cell responses. The latency of this suppressive effect was unusually long (up to 1 s) and its intensity and duration depended critically on the similarity between the gratings that were presented to the two eyes. Typically suppression was strongest when the gratings differed in orientation, direction of movement and contrast and when the nondominant eye stimulus was moving rather than stationary. Ablation of visual cortex abolished these long latency and feature-dependent interferences. We conclude that the visual cortex and the corticothalamic projections are involved in the mediation of these interocular interactions. We interpret our results as support for the hypothesis that corticothalamic feedback modifies thalamic transmission as a function of the congruency between ongoing cortical activation patterns and afferent retinal signals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236196
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Development of horizontal intrinsic connections in cat striate cortex (1986)
    Springer
    Experimental brain research 63 (1986), S. 443-448 
    Details
    ISSN: 1432-1106
    Keywords: Visual cortex (area 17) ; Intrinsic connections ; Visual deprivation ; Development ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Intracortical injections of horseradish peroxidase conjugated with wheat-germ agglutinin (WGA-HRP) reveal a characteristic patchy staining pattern within the superficial layers of cat striate cortex. The patches consist of a dense accumulation of labeled neurons and axonal arborizations. We have investigated the tangential organization and the development of these intrinsic cortical connections by using a flat-mount preparation of area 17. The diameter of the patches varied from 200 to 400 μm, the center-to-center distance ranged from 400 to 800 μm, and the spread of patches extended further in the anterior-posterior than in the medial-lateral direction. The expression of these horizontal patchy connections is age- and experience-dependent. From ten days to six weeks of age patches are exuberant and on occasion fuse to beaded bands extending radially from the injection site. From 6 weeks onwards the number and the tangential spread of the patches decreases to one or two rows of isolated clusters. Long-term binocular deprivation disrupts this pattern of intrinsic connections nearly completely. We infer from these results that there is an inborn pattern of discrete horizontal connections in striate cortex which is shaped by visual experience and requires contour vision for its maintenance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236865
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Topographic relations between ocular dominance and orientation columns in the cat striate cortex (1988)
    Springer
    Experimental brain research 71 (1988), S. 33-46 
    Details
    ISSN: 1432-1106
    Keywords: Columns ; Visual cortex ; Orientation ; Ocular dominance ; Maps ; Cat ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the visual cortex of four adult cats ocular dominance and orientation columns were visualized with (3H)proline and (14C)deoxyglucose autoradiography. The two columnar systems were reconstructed from serial horizontal sections or from flat-mount preparations and graphically superimposed. They share a number of characteristic features: In both systems the columns have a tendency to form regularly spaced parallel bands whose main trajectory is perpendicular to the border between areas 17 and 18. These bands frequently bifurcate or terminate in blind endings. The resulting irregularities are much more pronounced in the ocular dominance than in the orientation system. The periodicity of the columnar patterns was assessed along trajectories perpendicular to the main orientation of the bands and differed in the two columnar systems. The spacing of the ocular dominance stripes was significantly narrower than the spacing of orientation bands. The mean periodicity of a particular columnar system was virtually identical in the two hemispheres of the same animal but it differed substantially in different animals. However, the spacing of orientation columns covaried with that of the ocular dominance columns, the ratios of the mean spacings of the two columnar systems being similar in the four cats. The superposition of the two columnar systems revealed no obvious topographic relation between any of the organizational details such as the location of bifurcations, blind endings and intersections. We suggest the following conclusions: 1. The developmental processes generating the two columnar systems seem to obey the same algorithms but they act independently of each other. 2. The space constants of the two systems are rigorously specified and appear to depend on a common variable. 3. The main orientation of the bands in both columnar systems is related to a) the representation of the vertical meridian, b) the anisotropy of the cortical magnification factor, and c) the tangential spread of intracortical connections.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00247520
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The cholinergic innervation of the visual thalamus: an EM immunocytochemical study (1985)
    Springer
    Experimental brain research 59 (1985), S. 206-212 
    Details
    ISSN: 1432-1106
    Keywords: Lateral geniculate nucleus ; ChAT-immunocyto-chemistry ; Cholinergic pathways ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In this study we demonstrate at the ultrastructural level that both the dorsal lateral geniculate nucleus (dLGN), the visual relay of the thalamus, and the perigeniculate nucleus (PGN), the visual segment of the thalamic reticular nucleus (TRN), are densely innervated by fibres with Choline-Acetyl-Transferase (ChAT) like immuno-reactivity. These axons make synaptic contacts with interneurones considered to be inhibitory, both in the PGN and within the synaptic glomeruli of the dLGN. In addition, Chat positive terminals form intra- and extraglomerular synapses with dendrites thought to arise from relay cells. We interpret these results as evidence for direct cholinergic modulation of both relay cells and inhibitory interneurones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237681
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    The pattern of ocular dominance columns in flat-mounts of the cat visual cortex (1987)
    Springer
    Experimental brain research 68 (1987), S. 661-666 
    Details
    ISSN: 1432-1106
    Keywords: Visual cortex ; Ocular dominance columns ; Flat-mount ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ocular dominance (OD) columns in the cat visual cortex were visualized with autoradiography after intravitreal injection of (3H)proline. Extending previous studies, a flat-mount technique was applied that enabled the analysis of the distribution of label throughout extensive regions of the visual cortex without requiring reconstructions from serial sections. OD-columns were confined to layer IV and consisted of isolated patches and short bands. The latter were parallel to each other and regularly spaced, the main trajectory being orthogonal to the 17/18 border. This pattern of the geniculo-cortical terminals was similar in the hemispheres ipsi- and contralateral to the injected eye. The mean periodicities of the OD-bands were virtually identical in the two hemispheres of the same animal: 850 μm and 830 μm in cat D1 and 770 μm and 800 μm in cat D2. However, the ipsilateral OD-columns appeared smaller, more heavily labeled and more sharply delineated than the contralateral columns.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00249809
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    Paper (German National Licenses)
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