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  • 1
    Electronic Resource
    Electronic Resource
    Rearrangements in the retino-geniculate projections of rats following ablation of the superior colliculus in infancy (1985)
    Springer
    Experimental brain research 59 (1985), S. 372-381 
    Details
    ISSN: 1432-1106
    Keywords: Superior colliculus ; Dorsal lateral geniculate nucleus ; Aberrant retinal projections ; Early brain damage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The superior colliculus was bilaterally or unilaterally ablated at different early postnatal ages in rats. When adult, each rat received a unilateral eye injection of Horesradish peroxidase to reveal the crossed and uncrossed retinal terminal fields within the dorsal lateral geniculate nucleus. Collicular ablation in the first seven days after birth, but not thereafter, produced a small hole or vacancy within the contralateral retinal terminal field which was occupied by an aberrant ipsilateral retinal terminal field. These rearrangements in the retino-geniculate projections occurred in the caudal quarter of the nucleus dorso-laterally just beneath the optic tract, solely ipsilateral to the ablated colliculus. Possible causes of the formation of these rearrangements are discussed, and similarities with other aberrant retinal projections following early damage to the visual system are considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230917
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Contrast sensitivity in rats with increased or decreased numbers of retinal ganglion cells (1988)
    Springer
    Experimental brain research 70 (1988), S. 513-526 
    Details
    ISSN: 1432-1106
    Keywords: Rats ; Superior colliculus ; Enucleation ; Contrast sensitivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Contrast thresholds were measured electrophysiologically on striate cortex in normal rats and in rats in which either the superior colliculi were removed bilaterally or unilaterally at 5 days of age, or one eye was removed on the day of birth. Despite the fact that the collicular ablation leads to the degeneration of more than half the retinal ganglion cells, contrast sensitivity was normal in this group, with the possible exception of sensitivity at very low spatial frequencies below 0.1 c/deg. The result is strong evidence that retinal ganglion cells which project to thalamus as well as to mid-brain escape the degenerative effects of neonatal mid-brain lesions. The contrast sensitivity of neonatally operated one-eyed rats was significantly and substantially better than that of normal rats tested monocularly. The increased sensitivity was greatest in the cortex ipsilateral to the remaining eye. This supernormal sensitivity is presumably related to the increase in the number of ganglion cells in the remaining eye, especially those projecting ipsilaterally from the temporal retina and which show a five-fold expansion of their terminal zone in the thalamus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00247599
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Effects on visual acuity of neonatal or adult tectal ablation in rats (1982)
    Springer
    Experimental brain research 48 (1982), S. 149-152 
    Details
    ISSN: 1432-1106
    Keywords: Superior colliculus ; Neonatal rats ; Acuity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Tectal ablation in neonatal rats leads to retrograde degeneration of retinal ganglion cells whereas similar damage in adults does not. We show here that the behavioral effects are comparably different. When rats with neonatal tectal ablation are tested as adults they are impaired in learning a discrimination between vertical and horizontal stripes and their visual acuity for square-wave gratings is slightly but significantly reduced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239583
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The nature of the visual discrimination impairment after neonatal or adult ablation of superior colliculi in rats (1986)
    Springer
    Experimental brain research 61 (1986), S. 403-412 
    Details
    ISSN: 1432-1106
    Keywords: Rats ; Superior colliculus ; Infant vs adult lesions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The superior colliculi were removed in rats at either one or five days of age or in adulthood. Seven months later they were tested on four successively presented two-choice intensity discriminations. The intensity difference between the discriminanda was reduced across the four problems to encourage choice by comparison. The purpose was to establish whether impoverished scanning is a feature of rats with collicular lesions and whether the age at which the lesion is incurred is important. The number of door-push and approach errors made in reaching criterion were used as measures of performance and the number of head-scans during acquisition was counted. The results provide no evidence that either one- or five-day operated rats exhibit sparing or recovery of the ability to scan discriminanda since all operated animals were impaired. Furthermore, novel retinal projections, present in one-day operated animals, fail to mediate such sparing. Finally, the results did not demonstrate a selective increase in approach errors following collicular lesions and were therefore inconsistent with the view that the impairment is one of visually-guided locomotion. It is concluded that visual discrimination learning is impaired following collicular lesions in circumstances where scanning of discriminanda is required for efficient performance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239529
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Tectal ablation at different ages in developing rats has different effects on retinal ganglion cell density but not on visual acuity (1983)
    Springer
    Experimental brain research 51 (1983), S. 368-376 
    Details
    ISSN: 1432-1106
    Keywords: Superior colliculus ; Rats ; Development ; Acuity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The superior colliculi were removed in rats on the day of birth or five days after birth. When tested as adults the visual acuity of the two groups was not significantly different but both groups had significantly poorer visual acuity than an unoperated control group that was otherwise similarly treated from birth. However, the two operated groups had significantly different retrograde ganglion cell degeneration as a result of the collicular damage, indicating that there is no simple relationship between ganglion cell density and visual acuity. The results can be explained if the still unknown population of ganglion cells that projects to the dorsal lateral geniculate nucleus in rats is not differentially affected by collicular damage at different ages in the first week of life.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237873
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of damage to superior colliculi and pre-tectum on movement discrimination in rhesus monkeys (1984)
    Springer
    Experimental brain research 56 (1984), S. 79-91 
    Details
    ISSN: 1432-1106
    Keywords: Superior colliculus ; Pretectum ; Visual movement ; Oculomotor disorders ; Monkeys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Eight rhesus monkeys (Macaca mulatta) were trained to detect an instantaneous lateral displacement of a small spot of light. The smallest movement for 79% correct performance was then determined. Severing the splenium of the corpus callosum, which has to be done to reveal the superior colliculi, had no effect on the movement threshold. But when the superior colliculi were damaged in addition, there was an initial substantial impairment in the detection of movement and a smaller but permanent elevation in the threshold. Only if the rostral superior colliculi and pretectum were spared, was there no change in threshold, and there was evidence that the pretectal rather than collicular damage may be more important in relation to movement discrimination. Tests with human observers performing the same task showed that the threshold can be elevated by imprecise fixation and accomodation, suggesting that the consequences of mid-brain damage on movement detection may be wholly or in large part attributed to oculomotor disorders.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237444
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Effects on visual search of lesions of the superior colliculus in infant or adult rats (1987)
    Springer
    Experimental brain research 65 (1987), S. 465-470 
    Details
    ISSN: 1432-1106
    Keywords: Superior colliculus ; Lesion ; Visual search ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The superior colliculus was removed from rats at either one or five days of age or in maturity. Four months later they were tested on two versions of a visual search task. Experiment 1 required animals to retrieve food pellets concealed in a depression in the top of identical narrow pillars arranged in an arena. Rats with lesions of the superior colliculus, regardless of the age at operation, showed a large number of ‘return’ errors compared with sham-operated controls. Return errors were defined as occasions on which the animal returned to pillars that had previously been visited on that trial, before every pillar had been visited at least once. Experiment 2 compared the ability of infantand adult-operated animals to detect and locate a single, baited white pillar in an array of black ones. There were no group differences in response latencies to targets presented in the rostral visual field (within 40° of the midline). However, animals operated on in adulthood or at 5 days of age were slower than both sham-operated animals and animals operated on at one day of age in their responses to more peripheral targets. The latter two groups were indistinguishable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236320
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    Paper (German National Licenses)
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