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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 280 (1979), S. 58-60 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Three kittens were dark reared until the age of 5 weeks and then, with one eye closed, exposed to a normal environment for 9 consecutive days. Control experiments and a number of previous studies have shown that by this time most cortical cells have become dominated by the open eye and display ...
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1106
    Keywords: Visual cortex ; Development ; Plasticity ; Central core ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Fifteen dark-reared, 4- to 5-week-old kittens were stimulated monocularly with patterned light while they were anesthetized and paralyzed. Six of these kittens were exposed to the light stimuli only, in four kittens the light stimuli were paired with electric stimulation of the mesencephalic reticular formation and in five kittens with electric activation of the medial thalamic nuclei. Throughout the conditioning period, the ocular dominance of neurons in the visual cortex was determined from evoked potentials that were elicited either with electric stimulation of the optic nerves or with phase reversing gratings of variable spatial frequencies. In two kittens, ocular dominance changes were assessed after the end of the conditioning period by analyzing single unit receptive fields. Monocular stimulation with patterned light induced a marked shift of ocular dominance toward the stimulated eye, when the light stimulus was paired with electric activation of either the mesencephalic reticular formation or of the medial thalamus. Moreover, a substantial fraction of cells acquired mature receptive fields. No such changes occurred with light or electric stimulation alone. It is concluded that central core projections which modulate cortical excitability gate experience-dependent modifications of connections in the kitten visual cortex.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 48 (1982), S. 301-305 
    ISSN: 1432-1106
    Keywords: Visual deprivation ; Synaptic plasticity ; Orientation selectivity ; Visual cortex ; Kitten
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Kittens were reared wearing masks that contained strong cylindrical lenses, which allowed them to see only contours of one orientation. Selective exposure was alternated between the two eyes on successive days, while each time the other eye was covered by the mask. The total duration of exposure was different in the two eyes, amounting to 50 h for one eye and at least 100 h for the other. This resulted in asymmetric distributions of ocular dominance: neurones preferring precisely the experienced orientation favoured the eye with longer exposure, whereas neurones preferring oblique orientations adjacent to the experienced one surprisingly were dominated by the eye with shorter exposure. Thus neurones originally belonging to this group and dominated by the longer exposed eye must have tuned their orientation preference to the experienced orientation as a result of the longer exposure. Such instructive changes seem to be limited by the original response borders of the cortical neurones, as predicted by Hebb's rules for synaptic plasticity.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 50 (1983), S. 69-83 
    ISSN: 1432-1106
    Keywords: Superior colliculus ; Visual deprivation ; Auditory responses ; Multisensory convergence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Neurones in the superior colliculus of normal and visually deprived cats were analyzed for their responses to visual, auditory and somatosensory stimuli. The percentage of auditory-responsive cells throughout all layers had increased from 11% to 42% after binocular deprivation. Some auditory responses were found even in superficial layers. The number of somatosensory responses, though not systematically tested, was also higher in the visually deprived animals. Visually responsive units did not significantly decrease in number, thus resulting in an increased proportion of multisensory neurones. The vigour of auditory responses had increased after visual deprivation, while the vigour of visual responses had decreased significantly. In addition to the auditory effects of visual deprivation found, our study confirms previous findings on the visual effects of visual deprivation in the superior colliculus. Since only qualitative changes of visual responses, but no suppression of visual by non-visual activity was found, the neuronal mechanisms responsible for these changes may be different from competition as present in the visual cortex.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 52 (1983), S. 307-310 
    ISSN: 1432-1106
    Keywords: Strabismus ; Ocular dominance ; Visual cortex ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cats with a natural convergent squint were discovered within a colony of normal Mill Hill cats. In two of them single unit recording was undertaken in area 17. The ocular dominance distribution showed a clear disruption of binocularity in both hemispheres. This lack of binocular units was comparable to cats with artificial, surgically-induced strabismus and differed significantly from the ocular dominance distribution of a normal control group. The existence of these natural, non-albino squinters strengthens the use of cats as an animal model for strabismic amblyopia.
    Type of Medium: Electronic Resource
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